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A multidisciplinary study for mining landscape reclamation: A study case on two tailing ponds in the Region of Murcia (SE Spain)
Abstract
The aim of this work was to evaluate the mobility of Pb, Cu, Zn and Cd in two tailing ponds (Brunita and San Cristobal) from mine activity in the Southeast of Spain before applying reclamation measures for reducing the risk for human and environment. To achieve this objective, five profiles of electrical resistivity imaging (ERI) in Brunita, three profiles in San Cristobal, a drill-hole in each pond and undisturbed columns amended with marble waste for leaching experiments were taken.Results showed that all layers of the two ponds exceed the maximum Pb and Zn concentrations allowed by the selected European legislations. In both ponds, the mixture of tailings with natural soil is the main process involved in soil pollution under the ponds. However, due to high pH in the substrate the metals are precipitated and their solubility reduced, therefore there is not a risk of leaching to groundwater. At Brunita tailing pond electrical resistivity sections displayed some lower electrical resistivity region into the bedrock which has been described as some fault occurrence due to breaking events suffered by the tailing pond. At San Cristobal tailing pond geochemical results were consistent with data obtained by the electrical resistivity imaging (ERI) method where no evidence of faults or cracks into the bedrock and the ponds were observed. Therefore, no preferential pathways of acid mine drainages containing heavy metals were reported. Leaching experiments indicated that, after 11weeks of leaching, amended and control columns showed comparable values of pH (∼2.3) and similar trends for Cu, Cd and Zn, with a very drastic decrease up to week 3 and thereafter the tendency was to reach near steady-state conditions. In contrast, the evolution of Pb showed that marble amended reduces significantly its concentration over time compared with the control.In accordance with the results, future reclamation action should be based on the reduction of heavy metal mobility by means of long-term and large-scale marble waste application, which increases the pH and prevents the formation of acid mine drainage.
... Although this site was abandoned twenty-five years ago, many tailing ponds remain in the area without any restoration [22]. These mining residues resulted from the generation of a large volume of waste that was dumped into the riverbeds or stored in ponds, which are known to have a significant environmental impact [52]. Moreover, the oxidation of wastes containing sulfides (such as pyrite, blende and galena) causes the release of toxic elements such as arsenic or cadmium to the environment, besides an increase in acidity and salinity, that finally induce to develop of little or no vegetation in these regions. ...
... In this study, to understand the effect of tailing properties on metal (loid)s and REEs association, multivariate analysis methods like principal component analysis (PCA) and cluster analysis (CA) were used [1,34,49,52]. Principal Component Analysis (PCA) and Cluster Analysis (CA) group the studied variables into a few components or clusters. ...
... The highest EC (6.4 ds m − 1 ) was observed in E3-gravimetric waste, which was correlated with the highest silt percentage (Table 1). According to the results of Martínez-Pagán et al. [52], the electrical conductivity is strongly related with silt and poorly with clay or sand, which indicated that the presence of soluble salts increases when the percentage of silt is higher. Particle size Table 1 Geochemical properties and metal(lod)s and REE concentrations (mg/kg), mean ± standard deviation, in mining wastes. ...
The concern about the environmental impacts of mining waste due to its high concentrations of heavy metals is a widespread aspect worldwide, however, the presence and relationship of these metals with rare earth elements (REEs) has been little studied. In addition, the evaluation of the degree of contamination by REEs and their distribution in mining waste has not been widely evaluated. Therefore, the objective of this study is to evaluate the depth distribution, relationship and pollution of metal(loid)s and REEs in a mine tailing composed by sludge and gravimetric waste, which was divided in four units according their morphology and location. For this purpose, twenty-two surface samples were collected in two depths according with the waste layers (sludge on surface and gravimetric waste in deep), also two mechanical drills (6 to 10 m depth) were performed. Total concentration of 29 metal(loid)s and REEs, and physicochemical properties of the wastes were determined. Principal component analysis and cluster analysis were used to evaluate the elements association and relationship, and enrichment factors of elements were calculated to determine the degree of pollution. The results indicated that all waste materials have a high acidity and low or medium salinity. Moreover, the acidity decreases with increasing depth, which resulted in the precipitation of studied elements and reduction of their mobility, however the most predominant particle sizes were the coarsest ones (sand) promoting water infiltration. There were no significant differences in total concentrations of metal(loid)s and REEs between the sludge and gravimetric waste, indicating that the treatment process of the ore is not a key factor in metals and REEs concentrations in the wastes. Results showed that concentrations of As, Cd, Cu, Pb, Fe, Al, Mn, Mo and Zn exceeded the limits to consider soil as contaminated, and therefore control and management actions should be implemented to decrease the potential environmental and health risks. Finally, results showed that multivariate analysis, either PCA or cluster analysis, is a good tool to study the relationships between heavy metals and REEs, since allowed to identify mine activity and natural enrichment as the main sources of these elements.
... In Spain, the electrical resistivity tomography (ERT) technique has been used in a variety of mining districts. For example, in Cartagena (SE Spain), multiple studies have recently evaluated the mobility of metals in tailings dams [16,17], using a combination of ERT, mechanical drilling, and geochemical techniques [18]. In the mining districts of Linares and La Carolina (southern Spain), different tailings ponds and slag heaps have been characterized by applying all of these techniques [3][4][5][6][7]. ...
... The technique is being used with good results in different earth science fields: Stratigraphy [6,37,38], hydrogeology [39], environment [7,16,17,20,38], and mining [40,41]. ...
This work analyzed the effectiveness of two electrical geophysical methods in characte-rizing tailings dams. A large flotation cell used for sludge thickening in the concentration plant of the Federico Mine (closed in 1985) within the old mining district of La Carolina (southeastern Spain) was selected for this research. In addition to the direct information provided by the geology of the study area and the surface exposure of the waste deposits, information regarding the construction of this mining structure was available, which helped in the interpretations of the geophysical survey data. In this study, two geophysical surveying methods were used simultaneously: Electrical resistivity tomography (ERT) and induced polarization (IP). Six profiles were acquired, processed, and interpreted. The length of the profiles allowed the obtaining of data reaching maximum investigation depths ranging between 7 and 65 m. These profiles provided information for a detailed analysis of the internal characteristics of the deposited materials. The lateral and vertical observed variations are linked to different degrees of moisture content. The study also defines the geometry of the top of the bedrock and the tectonics that affect the pouring/dumping hole. Old flotation sludge has resistivity values that range between 1 and 100 Ωm (i.e., wet waste 1–30 Ωm, dry waste 30–100 Ωm), while phyllites in the rocky substrate have resistivities larger than 200 Ωm and can even reach va-lues greater than 1000 Ωm. Between the waste and unaltered phyllites, there is a supergene alteration zone (weathering) with resistivity values between 100 and 200 Ωm. The IP method was used to detect the presence of metals in the accumulated waste in the pond by analyzing the presence of large chargeability anomalies. Anomalies were detected in four of the profiles, which ranged from low (i.e., between 0 and 8 mV/V) to medium (i.e., between 8 and 18 mV/V) and high values (i.e., 18 and >30 mV/V).
... Indeed, today, these mine wastes pose a serious threat, as they represent a source of contamination for the nearby soils and sediments. Pollution processes due to the emission of pollutants through wind and water erosion and leaching of mine wastes have been extensively studied (e.g., Marín-Guirao et al. 2005a;Navarro et al. 2008;Martínez-Pagán et al. 2011;Bes et al. 2014). ...
... Sierra de Cartagena-La Unión district ( Fig. 1) has been subject of intense mining since ancient times for the extraction of silver, iron, lead, and zinc (Manteca & Ovejero 1992;Martínez-Pagán et al. 2011). This mining district reached its peak during the nineteenth century. ...
This work explores the ability of the Spanish Geochemical Database to identify the existence of polluted stream sediments due to the presence of abandoned mine wastes. The mining district of Sierra de Cartagena-La Unión has been used as test area. A total of 18 abandoned tailings facilities were selected and samples were taken for analysis of the content in potential toxic elements. The results were contrasted with geochemical background values in order to identify which geochemical elements could entail anomalies potentially reflected in the Spanish Geochemical Database. For the study area, As, Cd, Pb, and Zn have been identified as potential toxic elements which can be used as geochemical indicators of sediment pollution processes originated in abandoned mine wastes. Furthermore, the correlation between Cd and Zn allows them to be considered as the best indicators of potential sediment contamination. The study of anomaly thresholds, through the analysis of accumulated frequencies of the contents of these elements in the sediments of the Spanish Geochemical Database, allows identifying sediments that may have been contaminated. A Mann-Whitney test contrasting the data of tailings, polluted sediments, and non-polluted sediments has been performed in order to verify differences among these types of samples. In addition, a geospatial analysis has demonstrated a very close relationship between contaminated sediments and the presence of mining wastes upstream. This methodology can be applied to any other mining region, to recognize the possible influence of pollution processes derived from the presence of abandoned mine wastes taking advantage of existing geochemical databases.
... In these tailing ponds, waste usually contains acid materials rich in Fe-oxyhydroxides, sulphides, sulphates, and trace elements. As a consequence, these soils remain bare of vegetation and have low fertility (Acosta et al., 2011;Martínez-Pagán et al., 2011). All the heavy metals with high concentrations have strong toxic effects and are regarded as environmental pollutants (Chehregani et al., 2009). ...
... In these tailing ponds, waste usually contains acid materials rich in Fe-oxyhydroxides, sulphides, sulphates, and trace elements. As a consequence, these soils remain bare of vegetation and have low fertility (Acosta et al., 2011;Martínez-Pagán et al., 2011). All the heavy metals with high concentrations have strong toxic effects and are regarded as environmental pollutants (Chehregani et al., 2009). ...
Environmental pollution has a dangerous effect on bio-resources, including agricultural crops. It is produced through many industrial activities such as mining. The toxicity of Ait Ammar iron mine soil was evaluated using crop plant assays (germination test). Experimental data regarding the germination process of garden cress (Lepidium sativum L) are presented here. Germination index (GI), germination percentage (GP), vigor index (VI), percent phytotoxicity (PP), shoots length (SL), root length (RL) and RL/SL ratio were determined. Root elongation and germination index were more sensitive indicators of toxicity than seed germination. Physiological aspects evidenced both by visual observation and biometric measurements (mean root, aerial part and plant length) were examined. These results suggest that the direction from the iron mine have not significant affection on Garden cress seed germination. The toxicity of metals in heavily contaminated soils with Fe and P and with a neutral soil pH did not impact the seed germination of L. sativum L.
... En lo que se refiere a los contenidos totales de Mn, los valores medidos en las muestras tomadas sobre la instalación Brunita oscilaron entre 1600 y 2410, que son valores normales en suelos. Para esta instalación, existen datos de un sondeo publicados porMartínez-Pagán et al. (2011), los cuales muestran que, puntualmente, las capas superiores de la instalación podían contener concentraciones mayores de Cd, Pb y Zn que las comentadas con anterioridad. Además, del citado trabajo, y del de Martín-Crespo et al. ...
La Sierra Minera de Cartagena-La Unión ha sido uno de los distritos mineros más importantes de España, en el que se explotaron fundamentalmente Pb, Zn, Ag y Fe, presentes originalmente en menas de sulfuros metálicos o en gossans. La actividad minera se ha prolongado en la zona a lo largo de más de 2000 años, si bien el paisaje minero actual es consecuencia sobre todo de la actividad del siglo XX, que ha dejado un vasto legado de áreas alteradas y residuos mineros abandonados, origen de importantes impactos y riesgos ambientales.
... La interpretación de datos y documentos históricos, así como de la información aportada por diversos estudios (Martínez-Pagán et al., 2011;Rodríguez et al., 2011;Moreno-Perales, 2016;Martín-Crespo et al., 2018;HORYSU, 2023;GEOZONE, 2023), permitieron definir las propiedades físico-mecánicas de los materiales, geometría y condiciones de contorno de la presa antes de la rotura; y elaborar modelos para simular numéricamente su comportamiento hidromecánico y geotécnico, en condiciones similares a las que existían en el momento de la falla (Figura 12). ...
The geotechnical-structural risk of tailings storage fasilities (TSF) has been analysed mainly considering their geotechnical-structural characteristics, dividing them into: 1) TSF, 2) tailings ponds and 3) dumps. The main geotechnical-structural risk characterising TSF is the occurrence of flow failures caused by phenomena associated with static and dynamic liquefaction, seepage, tubification, capillarity, suction, etc. In the case of tailings ponds, the risk is associated with the presence of collapse due to subsidence or excessive settlement of the foundations. The TSF present risks of geotechnical instability due to landslides. The results of studies carried out and images are presented to allow the reader to identify the different geotechnical-structural risks present in the TSF and dumps in the field by means of the principle of observation.
... Hence, this work proposes a conceptual model of hydromechanical functioning and demonstrates zonation within the deposit. Using a holistic approach that combines geological [7,18], geotechnical [8,10,13,15,[19][20][21][22][23][24], hydrogeological [4][5][6][7]20,21,25], and geophysical [7,26,27] information the model helps to understand the different zones within the TSFs and to identify the unique characteristics and behaviors of each zone. ...
This study introduces a conceptual model for understanding the hydromechanical behavior and zonation within tailings storage facilities (TSFs) constructed using the hydraulic backfill method, which constitutes over 98% of TSFs worldwide. The model identifies four distinct zones—dike, discharge, transition, and distal—each characterized by unique physical, geotechnical, and hydraulic properties. Key findings highlight gradients in parameters which systematically vary from the dam toward the settling pond. This study observes that seven parameters such as grain size, friction angle, shear strength, dry density, permeability, shear wave velocities, and liquefaction capacity decrease in value from the dike to the lagoon. Conversely, thirteen parameters such as fine content, porosity, cohesion, plasticity, degree of saturation, volumetric and gravimetric water content, capillary height, specific and volumetric surface of tailings, suction, air and water entry value in the soil water characteristic curve increase in value from the dike to the lagoon. These trends underscore the complex behavior of tailings and their implications for stability, drainage, and environmental impact. By integrating geological, geotechnical, hydrogeological, and geophysical data, this study provides a holistic framework for TSF management, addressing both current challenges and long-term environmental considerations.
... Among them, the oxidation of sulfide ultimately produces a highly acidic leaching solution of high concentration of sulfate, iron and other heavy metals, which is called acid mine drainage. Therefore, to ensure the long-term environmental integrity of the tailings pond, it is important that the sulfide minerals contained are not quickly decompose and promote the leaching of heavy metals (Martínez-Pagána et al. 2011). Sulfide deposits contain large amounts of copper, nickel, zinc, lead and other economically important metals, usually in chalcopyrite (CuFeS 2 ), sphalerite [(Zn, Fe) S] and galena (PbS), and gangue minerals such as pyrite (FeS 2 ) and pyrrhotite (Fe (1−x) S) are the dominant sulfide combinations (Lindsay et al. 2015;Abdel-Karim et al. 2022a;Abdel-Karim et al. 2009). ...
To explore the mineralogy and heavy metals (HMs) pollution changes of sulfide tailings under different weathering degrees, and systematically reveal the possible environmental effects in the oxidation process, the shallow profile of typical sulfide tailings in Tongling City, Anhui Province is selected as the research object, which provides a theoretical basis for controlling the acidification of tailings, heavy metal release and environmental risks. The results showed that there were faults or cracks that affected the stability of tailings dam. The minerals in the profile were mainly iron crystalline facies, and the quartz content was the highest in hardened layer. With the increase of profile depth, minerals such as calcite, pyrite and goethite gradually appeared in loose layer. S was mainly concentrated in hardened layer and tends to be stable with the profile depth, and was the main element for producing acidic wastewater. In addition, Cr and As were no risk, Cu, Zn, Pb were low risk, Ni was medium risk, and Cd was high risk in risk assessment code (RAC) analysis of the tailings. It can be seen that the toxic leaching contents of Cu, Zn, Pb, Cr, Ni, As were lower than limits, while Cd was higher than limit. Therefore, the pollution of the tailings pond to surrounding environment was mainly the acidic mine wastewater and HMs migration caused by rainwater scouring, and additional attention should be paid to Cd pollution in the later environmental remediation process.
... The result showed that the mean Fe concentration in Unit S1 was higher than in Unit S2 (58,318 and 38,408 mg kg −1 , respectively) ( Table 2). It was suggested that the mining districts of Mazarron are composed of high amounts of Fe-oxyhydroxides, Pb, Zn, and Fe sulfides, that are related to the parent materials [28,39]. The fifth most abundant metal in studied soils was obtained for Sr, which was 2.39 times higher in Unit S2 than the concentration found in Unit S1 (459 and 135 mg kg −1 , respectively) ( Table 2). ...
Mining activity has an adverse impact on the surrounding ecosystem, especially via the release of potentially toxic elements (PTEs); therefore, there is an urgent need to develop efficient technologies to remediate these ecosystems, especially soils. Phytoremediation can be potentially used to remediate contaminated areas by potentially toxic elements. However, in soils affected by polymetallic contamination, including metals, metalloids, and rare earth elements (REEs), it is necessary to evaluate the behavior of these toxic elements in the soil-plant system, which will allow the selection of the most appropriate native plants with phytoremediation potential to be used in phytoremediation programs. This study was conducted to evaluate the level of contamination of 29 metal(loid)s and REEs in two natural soils and four native plant species (Salsola oppositifolia, Stipa tenacissima, Piptatherum miliaceum, and Artemisia herba-alba) growing in the vicinity of a Pb-(Ag)-Zn mine and asses their phytoextraction and phytostabilization potential. The results indicated that very high soil contamination was found for Zn, Fe, Al, Pb, Cd, As, Se, and Th, considerable to moderate contamination for Cu, Sb, Cs, Ge Ni, Cr, and Co, and low contamination for Rb, V, Sr, Zr, Sn, Y, Bi and U in the study area, dependent of sampling place. Available fraction of PTEs and REEs in comparison to total concentration showed a wide range from 0% for Sn to more than 10% for Pb, Cd, and Mn. Soil properties such as pH, electrical conductivity, and clay content affect the total, available, and water-soluble concentrations of different PTEs and REEs. The results obtained from plant analysis showed that the concentration of PTEs in shoots could be at a toxicity level (Zn, Pb, and Cr), lower than toxic but more than sufficient or natural concentration accepted in plants (Cd, Ni, and Cu) or at an acceptable level (e.g., V, As, Co, and Mn). Accumulation of PTEs and REEs in plants and the translocation from root to shoot varied between plant species and sampling soils. A. herba-alba is the least efficient plant in the phytoremediation process; P. miliaceum was a good candidate for phytostabilization of Pb, Cd, Cu, V, and As, and S. oppositifolia for phytoextraction of Zn, Cd, Mn, and Mo. All plant species except A. herba-alba could be potential candidates for phytostabilization of REEs, while none of the plant species has the potential to be used in the phytoextraction of REEs.
... To find solutions to environmental problems of polluted sites, several global evaluations, such as mineralogical, chemical, geophysical, statistical, and other studies were caried out (Navarro et al. 2008;Acosta et al. 2011;Conesa et al. 2011;Martínez-Pagán et al. 2011;Trifi et al. 2019). However, these approaches believed incomplete to identify the appropriate remediation technics. ...
The Jbel Ressas (NE Tunisia) is an ancient mining site, where the three tailings were since 1952 and until today exposed without any protection. It is a site of great interest, because it is typical of carbonate Pb–Zn deposits, where the environmental stakes are enormous. To consider the remediation or protection of these dumps and their surrounding soil, the evolution evaluation of their total and labile toxic trace elements (TTE) quantities and the pollutants spatial distribution and risks, since their initial deposition is a crucial step. The draw up of their complete balance sheet showed that the total Pb, Zn and Cd quantities in the initial waste were 46,640 t (tone), 134,780 t and 1150 t, respectively. In the initial waste, 98% of pollutants were in stable form (without environmental risk). From 1952 to 2021, around 75% of the initial TTE was mobilized and a large quantity unloaded from the tailings toward the surrounding areas. In 2021, the three dumps kept 10,300 t of Pb, 27,500 t of Zn and 291 t of Cd. The range values of the whole-soil removal (Uts) and relative binding intensity (IR) indexes (“equilibrium” parameters) of the TTE tailings from 1952 to 2021 were 0.24–13.2 and 0.4–6.2, respectively. These data confirmed the mining waste instability and the high environmental risk levels. It was also carried out that the danger levels increased with its exposition time. Among the strong TTE quantities released from the dikes, only 6.1%, 4.8%, and 4.1% of Pb, Zn, and Cd, respectively, were found in the agricultural soil. The highest percentages of the mobile TTE were in the agricultural soil surrounding the tailings. Then, the bioavailable TTE concentrations decreased with distance from the pollution sources. Based on the background values, the soil potential ecological risk (Eⁱr), except 3%, was very high (14 < Eⁱr < 3200). The soil equilibrium parameters of Jbel Ressas tailings and soil confirmed their high instability and risk. These results proved the interest of the historical study of a polluted site. Considering the soil and tailing pollution levels, the remained TTE quantities in the tailings and the acceleration speed of the pollutant’s remobilization, the management of this site is urgent.
... Many studies in the literature have shown that indirect (geophysical) methods are useful for characterising former tailings dams in terms of reconstructing the morphology, locating recharge-discharge areas, and identifying points of contact between the substrate and the deposited waste of. The direct current (DC) resistivity method is one of the most frequently used techniques with demonstrated utility for numerous mining districts (Grangeia et al., 2011;Martínez-Pagán et al., 2011;Martín-Crespo et al., 2015;Pierwoła, 2015;Zarroca et al., 2015;Tycholiz et al., 2016;Martínez et al., 2021). This technique has been used in conjunction with induced polarization (IP) to locate leachate and contamination areas (Pierwoła, 2015;Power et al., 2018;Rey et al., 2020;Martínez et al., 2021). ...
The accumulation of waste materials in old, abandoned mining districts without prior sealing of the substrate currently poses a significant risk of contamination to soils and surrounding waters. Some of these mining dams have undergone a reclamation and sealing process in recent years to alleviate this problem. The current study is an analysis of the effectiveness of using different geophysical techniques for characterising these structures and monitoring the isolation performed. This study was carried out in the old mining district of Linares-La Carolina (southern Spain). The following techniques were investigated in this study: direct current (DC) resistivity, induced polarization (IP), ground-penetrating radar (GPR) and the time domain electromagnetic method (TDEM).
Combining DC and IP made it possible to characterise the internal structure of the abandoned mining dams, whereby the geometry of these deposits was determined and the corresponding potential risks were assessed. In addition, percolation zones of mining leachates were detected that indicate defects in the sealing stage.
TDEM was a good complementary technique for calculating the depth of the bedrock on which the mining dam is located. GPR could only be used to investigate shallow depths at all of the antenna frequencies used (100, 250 and 500 MHz) but was useful for obtained detailed information about the last stages of filling and characterising the encapsulation performed during sealing.
... The depth of the bottom row of blocks is set to be approximately equal to the equivalent depth of research. The root-mean squared (RMS) error for each electrical section was obtained as a parameter showing the accuracy of the match between the measured and predicted apparent resistivity values (Martínez-Pagán et al., 2011). The models shown in this work were all obtained after 4 iterations. ...
In-situ geophysical techniques based on electrical resistivity tomography were performed to determine the spatial and temporal distribution of heavy metals. This paper aimed to pursue a novel methodology consisting in combining electrical resistivity tomography measurements, soil chemical data, and statistical analysis to predict As and Cd distribution in paddy soils. The resistivity surveys were performed at 2 m depth in nine locations of Tolima district in Colombia. Chemical concentrations of both As and Cd were introduced in a standardization procedure to estimate their electrical resistivity values. Soil and fertilizers information were acquired to determine As and Cd input in the studied area. The laboratory standardization showed a direct linear regression for Cd and an inverse one for As. A high positive Spearman correlation between electrical resistivity and As / Cd content was determined, with 0.98 and 0.99 values, respectively. Results showed that As-like compounds were distributed mainly in shallower soil layers (0.45 m) and were characterized by lower electrical resistivity values (181–2318 Ω.m). On the contrary, Cd-like compounds were observed in a deeper profile (0.80 m) with higher electrical resistivity values (559–4879 Ω.m). This work underlies the utility of the combined geophysical techniques, soil chemical parameters and statistical analysis to improve the understanding of As and Cd dynamics and origin in topsoil, supporting the need of an agricultural management of paddy soils.
... Ambient fluorinated dust from abandoned mines and unconfined fluorite tailings containing a high fluoride load may be suspended by wind or transported by water runoff, or leached to ground water (Gonzalez-fernandez et al., 2011;Martinez et al., 2011). ...
The north east of Tunisia ore deposits (Hammam Zriba) contain a large amount of fluorides constituting a risk of environmental pollution as well as risks to human and animal health. The aim of our work was to assess the levels of fluorides in the water and blood of sheep in the east of Tunisia region. This analysis study included 78 water samples and 60 blood samples taken during 3 days in the year 2019, from a sheep herd at Hammam Zriba delegation. The determination of fluorine concentration in the samples was carried out by potentiometry with a selective electrode type ISE combined Fluoride perfectION™. High Fluoride concentrations were found at a mean of 1.62 ± 1.18, 1.45 ± 0.98, and 2.65 ± 1.61 mg/l, respectively, in running, deep, and stagnant waters. In addition, 83.3% of the animals reared within 400 m of the study area had elevated fluoride levels in the blood exceeding the usual values (fluoremia> 0.15 mg/l). The concentration of fluoride in the blood of the animals decreases with increasing distance from the mine.
... A higher content of soluble sulphates and jarosite can be related to materials from ponds with a high degree of alteration, the presence of greenalite with gangue from volcanic rock mineralisation (trachytes-andesites) and iron oxyhydroxides with a more evolved state of alteration [39]. Figure 5 summarises the main supergene alteration processes affecting these materials, their implications for biogeochemical cycles and the resulting products [29,[35][36][37][38][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. The minerals neoformed in these processes can retain different amounts of PTEs and release them when environmental conditions change. ...
A bibliographic review was carried out to establish the state of knowledge of a mining area with several centuries of exploitation and currently abandoned. The selected case study, the Sierra Minera de Cartagena-La Union (Spain), has a long history of mining activity, ending in 1990. The area is rich in metallic sulphide (lead, zinc and iron), with underground mines and quarries. The zone is very close to important populations and affects protected sites of special ecological value. It is also adjacent to areas dedicated to agriculture and important centres of tourist interest. It is a territory that meets the requirements to be classified as a critical area, as it is in a state of unstable physical and geochemical equilibrium, giving rise to possible risks to human health and ecosystems. A literature review was carried out according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) methodology criteria, consulting a large number of related publications. The results obtained using the Source-Pathway-Receptor model make it possible to identify the main impacts caused by the contamination sources, the main routes of contamination, as well as the transfer to the biota and the influence on adjacent agricultural soils. In this study, lead, cadmium, zinc, arsenic, copper and manganese were considered as potential toxic elements (PTEs), and data were obtained on concentrations in soil, water and air as well as in fauna and flora. Finally, once the receptors and the associated risks to the ecosystem and human health were identified, a conceptual model of the contamination was drawn up to consider a management proposal to tackle the problems associated with this area, which would also be applicable to critical mining zones.
... Most of the studies carried out on tailing ponds using ERT have been focused on identifying the tailings' internal structure, defining the morphology of the tailing-bedrock contact, highlighting the occurrence of faults or cracks that could put the pond stability at risk, and/or pinpointing preferential pathways for heavy metal transport or acid mine drainage [6,7,11,12,29,30]. However, the use of ERT to establish relationships among electrical resistivity data and physicochemical variables such as moisture, heavy metal concentration, pH, particle size distribution, and Al/Si as a proxy for clay content in tailing ponds or soils severely polluted by mining has not been widely studied [6,31]. ...
... Most of the studies carried out on tailing ponds using ERT have been focused on identifying the tailings' internal structure, defining the morphology of the tailing-bedrock contact, highlighting the occurrence of faults or cracks that could put the pond stability at risk, and/or pinpointing preferential pathways for heavy metal transport or acid mine drainage [6,7,11,12,29,30]. However, the use of ERT to establish relationships among electrical resistivity data and physicochemical variables such as moisture, heavy metal concentration, pH, particle size distribution, and Al/Si as a proxy for clay content in tailing ponds or soils severely polluted by mining has not been widely studied [6,31]. ...
The legacy of the mining industry has left a large number of tailing ponds in the Cartagena-La Unión mining district exposed to water and wind erosion, which causes serious environmental and health problems and requires remediation. Before applying any remediation technique, an intensive sampling of the materials infilling the pond is required to determine the geochemistry of the pond, which will condition the remediation process. However, sampling the large number of tailing ponds that compose the district could be expensive. Thus, the main objective of this study is to evaluate the usefulness of electrical resistivity tomography (ERT) as a non-invasive tool to provide an image of spatial subsurface resistivity distribution and its relation to the physicochemical composition of near-surface mine wastes. To achieve this objective, three short ERT profiles were conducted, and 12 samples in each profile were collected at different depths for its geochemical characterization. Several non-linear regression models were fitted to predict physicochemical properties and metal concentrations from electrical resistivity measures. As a result, a high resistivity area was depicted in the ERT profiles G2 and G3, while the low resistivity ERT profile G1 was also obtained in accordance with the site's surficial characteristics. Relationships among low resistivity values and high salinity, clay content, high metal concentrations, and mobility were established. Specifically, calibrated models were obtained for electrical conductivity, particle sizes of 0.02-50 µm and 50-2000 µm, total Zn and Cd concentration, and bioavailable Ni, Cd, and Fe. The ERT technique was shown to be a useful tool for the approximation of the location and distribution of the highest ranges of fine particle sizes, moisture, and, to a lesser extent, metal accumulation in the near-surface waste materials.
... It increases the risk of spreading contaminants such as heavy metals in the environment. The technology used in ore processing causes flotation waste to have a high percentage of very fine particles (usually around 85%) and a minimal percentage of skeletal parts, which has a negative influence on their physical properties (Martinez-Pagan et al. 2011;Moreno-Barriga et al. 2017). Additionally, the disadvantageous growth conditions result from the alkaline pH (Kordas et al. 2018). ...
PurposeThe study aimed to determine the effect of the addition of innovative combinations of organic-mineral mixtures obtained from biochar (BC), zeolite (Z), soil (S), poultry litter (PL), and slurry (SL) to post-flotation sediment (PFS) on (i) heavy metal mobility, (ii) heavy metal accumulation in willow, and (iii) PFS respiratory activity.Materials and methodsThe tests were carried out under laboratory conditions in containers with 500 g of PFS, to which 1% (w/w) of organic-mineral mixtures were added. Willow was grown for 90 days on substrates with the addition of organic and mineral mixtures.Results and discussionThe addition of mixtures BC + Z + S + PL and BC + Z + S + SL to PFS significantly reduced the pH to, respectively, 7.12 and 7.02. This can be attributed to the release of the hydrogen load combined with organic anions deriving from the mineralisation of organic materials and the nitrification process. The addition of BC + Z and BC + Z + S mixtures to PFS reduced the content of Zn-H2O by 65%, Cd-H2O by 48%, and Ni-H2O by 30%. The addition of BC + Z + S + PL and BC + Z + S + PL mixtures to PFS increased the content of water-extracted Pb, respectively, 40 and over 60 times. The content of bioavailable heavy metals (extraction with 1 M NH4NO3) in PFS was comparable in all treatments to which mixtures were added. Altered mobility of heavy metal ions may be associated with a change of substrate properties, including redox potential, pH value, as well as the introduction into the soil of materials with significantly developed sorption surfaces. In the first 2 weeks of incubation of mixtures with PFS, respiratory activity was very low, except for that in BC + Z + S + PL and BC + Z + S + SL treatments. In these treatments, oxygen consumption was more than 50 times higher compared to the control treatment and more than 10 times higher in relation to BC + Z and BC + Z + S treatments.Conclusions
The mixtures of BC + Z and BC + Z + S effectively reduced the content of water-extracted heavy metals in PFS. BC + Z + S + PL and BC + Z + S + PL mixtures were not effective in reducing water-extracted mobile heavy metals in PFS. The introduction into PFS of mixtures partially composed of biologically unstable materials (PL, SL) increased the biochemical activity measured by respiratory activity and reduced biomass increment of willow aerial parts. The adverse response of willow to the introduction of mixtures with poultry litter or slurry into PFS indicates the need to verify the amount of these materials in the mixtures or to stabilise them by biological or thermal processes.
Graphical abstract
... Most of the studies carried out on tailing ponds using ERT have been focused on identifying the tailings' internal structure, defining the morphology of the tailing-bedrock contact, highlighting the occurrence of faults or cracks that could put the pond stability at risk, and/or pinpointing preferential pathways for heavy metal transport or acid mine drainage [6,7,11,12,29,30]. However, the use of ERT to establish relationships among electrical resistivity data and physicochemical variables such as moisture, heavy metal concentration, pH, particle size distribution, and Al/Si as a proxy for clay content in tailing ponds or soils severely polluted by mining has not been widely studied [6,31]. ...
Legacy mining industry has left a large number of tailings ponds exposed to water and wind erosion that causes serious environmental and health problems. Prior to rehabilitation actions a deep sampling of the materials infilling the pond used to be necessary. Thus, the primary objective of this study is to demonstrate the usefulness of the Electrical Resistivity Tomography (ERT) method as a non-invasive tool to determine the physicochemical composition of mine tailings ponds, enabling more efficient and low-cost surveys. To achieve this objective, three ERT profiles and three boreholes in each profile were carried out, from each borehole three waste samples from differents depths were collected and a geochemical characterization of the samples was carried. In order to estimate the composition of the infilling wastes in tailing ponds from electrical resistivity measures, several regression models were calculated for different physicochemical properties and metal concentrations. As a result, a high resistivity area was depicted in profiles G2 and G3 while a non-resistive area (profile G1) was also found. Relationships among low resistivity values and high salinity, clay content and high metal concentrations and mobility were established. Specifically, calibrated models were obtained for electrical conductivity, particles sizes of 0.02-50 µm and 50-2000 µm, total Zn and Cd concentration, and bioavailable Ni, Cd and Fe. Therefore, the ERT technique could be considered as a useful tool for mine tailings ponds characterization, and it can be used to estmate some physicochemical properties and metal concentrations of this mine waste.
... The AMD used in this study came from the Sierra Minera of Cartagena-La Unión (southeast of Spain), specifically from Brunita quarry where lead and zinc ores were mined, and whose mining operations finished in 1990, being operative for more than 2500 years [28]. Although the mining activity was abandoned thirty years ago, millions of tons of waste were accumulated on the surface of the land forming mining ponds and [29] causing changes in the visual characteristics of the area and produced physiographic modifications and alterations in the landscape [7]. These mining ponds are composed by high amounts of Fe-oxyhydroxides, sulphates, and potentially leachable metal(loid)s due to extreme acidic conditions and salinity. ...
Acid Mine Drainage (AMD) is an important source of pollution to the environment, characterized by a very low pH and high metal(loid)s concentration. The objective of this research was to evaluate the effect of three alkaline materials: marl, sandstone and calcareous crust on AMD neutralization and metal precipitation. To achieve this objective, a batch test was design, where a 5/10 alkaline material(g)/AMD(mL) ratio was used. In order to optimize the process, three particle sizes (2–10, 10–20 and 20−30 mm) of each material were used, and water samples were collected during the neutralization time. Due to the extreme pH of AMD used (pH < 2.5), it was necessary to carry out an AMD pretreatment, which consisted of adding 2.5 g of Ca(OH)2 per liter of AMD to raise a pH of 4. This pretreatment was essential because when AMD (pH < 4) was in contact with alkaline material a fast disintegration had place and a viscous substance was forming which prevented water rehabilitation. The results showed that the three alkaline materials reduced Fe, As, Cd, Cu, Pb and Zn concentrations in AMD, due mainly to their high carbonates content, which allowed metal(loid)s precipitation. The removal percentages were 100 % for Fe, Cu and Pb for marl, sandstone and calcareous crust, and about 60 % for Zn and Cd when sandstone was used. The optimal size particle was 20−30 mm for marl, while for sandstone with a size particle of 10−20 mm a considerable reduction of metal(loid)s in AMD was observed. Besides, the contact time required to neutralization of AMD and metal(loid)s reduction was lower for marl and sandstone than calcareous crust. Therefore, the results of this study showed that anyone of these alkaline materials could be used in AMD treatment depending on availability in the study area.
... Para Martínez-Pagán et al. (2011), la presencia de cortas con restos de mineral no confinados representa uno de los principales riesgos por la emisión de polvo de áreas mineras abandonadas, ya que estos materiales finos pueden ser fácilmente suspendidos por el viento o transportados por la escorrentía, tanto superficial como subterránea una vez lixiviados. La tasa de deposición de contaminantes depende de varios factores relacionados con el origen de los elementos traza, el clima y los eventos de viento, así como las características del paisaje receptor, en relación a la rugosidad superficial, por lo que existe una gran incertidumbre en cuanto al área que podría verse afectada. ...
La prolongada actividad de la minería en la Sierra Minera de Cartagena-La Unión ha
dejado importantes impactos, no sólo en los aspectos socio-económicos, sino también en los aspectos ambientales y de riesgos para la salud. Además de los efectos de la colmatación de la bahía de Portmán por los vertidos, en este trabajo se describen los cambios sufridos en el paisaje de la Sierra Minera del entorno de la bahía, debido a las actividades extractivas, y los peligros asociados a la existencia de antiguas estructuras mineras. Entre ellos, destaca la contaminación del suelo y de las masas de agua, así como los efectos negativos para la salud por la inhalación, ingestión y absorción de restos minerales, por lo que es posible considerar este enclave como un Pasivo Ambiental Minero (PAM). Sin embargo, buena parte de la población de los núcleos urbanos de esta comarca, no son conscientes de las posibles consecuencias para la salud, lo que hemos denominado como ‘alienación del residente’. En este trabajo se discute la necesidad de empoderar a la población en cuanto a la percepción de los peligros de los PAM, para poder plantear una buena gestión de los riesgos asociados.
... Remediation of mine sites is a complex process, as a variety of contaminants and soil physicochemical conditions influence the process (Ma et al. 2015). One of the main impacts of mine residues is the mobility of metals in the soil and water phase, where toxic pollutants may be transported to adjacent soils (Martínez-Pagán et al. 2011). To improve the quality of mine soils and reduce the mobility of metals, several techniques can be applied. ...
Mining activities often cause important impacts on soil and water quality. The main objective of this study was to evaluate the effect of amendments (compost and technosol made from waste) on metal concentrations in a mine soil planted with Brassica juncea. A greenhouse experiment with cylinder pots was carried out during 11 months. The mine soil was collected from the settling pond of the depleted copper mine of Touro (Galicia, Northwest Spain). A series of characteristics were analysed including soil pseudototal metal concentrations, soil CaCl2-extractable (phytoavailable) metal concentrations and metal concentrations in soil pore water. The results showed that at depth 0–15 cm SCP (mine soil + compost, grown with B. juncea) had a significantly lower CaCl2-extractable Cu, Pb, Ni and Zn concentration than STP (mine soil + technosol, grown with B. juncea) over the time (P < 0.05). At depths 15, 30 and 45 cm, STP and SCP had lower Cu pore water concentration than S over the time. The highest translocation factor (TF) values for all metals (Cu, Pb, Ni and Zn) were observed at time 1 (3 months) in the settling pond soils treated with technosol and B. juncea L. The conclusions of this experiment revealed that SCP compared to STP caused a higher reduction on Cu, Pb, Ni and Zn phytoavailable concentrations in the first depths.
... In the past fifty years, the numbers of studies of remediation in areas affected by mining activities and assessments of the influence of waste on the environment have significantly increased. Currently, most investigations of mine tailing areas are conducted using geophysical methods to determine the mine drainage distribution in a given coordinate space (Martín-Crespo et al., 2010;Placencia-Gómez et al., 2010;Martínez-Pagán et al., 2011;Martínez et al., 2012Martínez et al., , 2016Zarroca et al., 2015;Tycholiz et al., 2016;Olenchenko et al., 2016;Yurkevich et al., 2015Yurkevich et al., , 2017a2017b) and trace the paths of toxic elements in mine waste (Kazakis et al., 2017). ...
Geochemical and geophysical investigations were performed in the area of the Komsomolsk tailings impoundment. Gold ore tailings produced with cyanidation have been generated by the Komsomolsk Gold Extraction Plant. The relatively low sulfide content in the Komsomolsk tailings and the presence of carbonates result in a low acid production potential (AP) for these tailings. The tailings pond is characterized by neutral to slightly alkaline conditions and metal concentrations, except for those of As and Sb, below the maximum permissible concentration (MPC). The situation is complicated by the fact that the displaced Berikul tailings are stored in the southern part of the Komsomolsk tailings impoundment. Sulfide concentrate cyanidation tailings were produced by the former Berikul Gold Extraction Plant. In the Berikul tailings, the sulfide content is approximately 25%. This high content has resulted in a high AP and the formation of acidic and ultra-acidic surface ponds (pH ∼2) with extremely high concentrations of metals and metalloids (As up to 4.1 g L⁻¹). The estimated duration of acid drainage generated by the Berikul tailings is approximately 2400 years. Surface drainage from the tailings enters the Voskresenka River; as a result, the concentrations of As and Sb in the river water approach the MPCs established by the Russian Ministry of Health. Based on electrical resistivity tomography (ERT), the uncontrolled leakage of acidic and highly mineralized solutions through a natural geological fault into groundwater horizons was revealed. Groundwater contamination was confirmed via an analysis of drinking water from a well located near the fault.
... on their physical properties [2][3]. Additionally, the disadvantageous growth conditions result from the alkaline pH and the presence of heavy metals -mainly copper and lead [4][5]. ...
The aim of our study was to evaluate the influence of reclamation activities in a tailing pond, consisting in the application of mineral (rock aggregate) and organic substances (crop willow chips, swarf) and reclamation plants such as various species of grass and their mixtures with water-absorbing geocomposites, on the selected physical and biological parameters of the sediment. The experiment was started on Konrad tailing pond in Iwiny village in Poland. The pond had been filled with post-flotation sludge from copper ore mining until 1971. Since then, no activities have been conducted there. The mine tailings with absorbent (geocomposite) were characterised by higher moisture content. Intensified CO2 emissions were also noted, along with a noticeable reduction in the compactness of sediment in comparison to the values obtained for mine tailings without geocomposites. Various types of additives that were mixed with tailings in order to improve its disadvantageous physical and biological properties had a noticeable influence on mine tailings. The best results were obtained after using crop willow chips, which contributed to improved moisture conditions, reduced compactness, and increased amounts of emitted CO2. Individual species of reclamation plants or their mixtures had a relatively slight influence on the analysed properties of the post-flotation sediment. Significant differences were noted only for moisture content of the tails, which was highest after the introduction of switchgrass (Panicum virgatum L.).
... It was thought that the preferential flow paths allow leachate, laden with dissolved heavy metals, to contaminate the aquifer. The ERT method has been used successfully in many cases of abandoned mines (Martínez et al., 2014;Martín-Crespo et al., 2011;Martínez-Pagán et al., 2011;Grangeia et al., 2011;Martínez et al., 2012;Martín-Crespo et al., 2012) and tailings (e.g., Booterbaugh et al., 2015). In this study, all ERT surveys were implemented with the ABEM SAS 4000. ...
The abandoned lead mine of Zeida is located at the center of the High Moulouya watershed between the Middle and the High Atlas Mountains of Morocco. Zeida has produced a total of 640,000 tons of concentrated lead during the 14 years of its activity (1972–1985). Three large tailings were left at the center of the mine on both sides of Moulouya River without any risk reduction measures or monitoring and there is a concern regarding heavy metal contamination of local groundwater. Samples taken from and around the tailings were found to contain average lead and zinc concentrations of 3,000 ppm and 140 ppm, respectively, primarily in the form of galena and barite. Prior studies have also found high concentrations of lead and zinc in both local wells near the town of Zeida and along the banks of Moulouya River. In this study, five electrical resistivity imaging surveys were performed to identify the risk of pollution and trace the pathways of mine-based contaminants to groundwater and to the Moulouya River. The analysis of electrical resistivity data has provided new insights showing: 1) an average tailings thickness of 15 m; 2) rounded structures with high resistivity values at the center and gradually decreasing toward their edges that are assumed to be granite, with fractures and a weathered zone; and 3) the potential pathways of heavy metal occur predominantly along these fractures and in the thick layers of the sandstone overlaying granitic bedrock.
... The main risk for atmospheric dust emission from abandoned mine areas is the presence of the unconfined tailings ponds with fine sized material containing a high metal load, which may be resuspended by wind or transported away by water runoff, or leached to groundwater; especially if confining layers are discontinuous (Martínez-Pagán et al., 2011;Gonzalez-Fernandez et al., 2011b). ...
Samples of waste from the surface of mine tailings and agricultural topsoil samples in the vicinity of the mine
were collected. The soil samples and a control sample from unpolluted area, were taken in the direction of
prevailing northwest and west winds. Chemical analysis of these solids was performed using both X-ray fluorescence and X-ray diffraction. To determine the transfer from mine wastes to the soils, soluble fraction was
performed by inductively coupled plasma and ionic chromatography.
The fine grained size fraction of the un-restored tailings, still contained significant levels of barium, strontium,
sulphur, fluorine, zinc and lead with mean percentages (wt%) of 30 (calculated as BaO), 13 (as SrO), 10 (as
SO3), 4 (F), 2 (Zn) and 1.2 (Pb). Also, high concentrations of cadmium (Cd), arsenic (As) and mercury (Hg) were
found with an averages of 36, 24 and 1.2 mg kg−1, respectively. As a result of the eolian erosion of the tailings
and their subsequent wind transport, the concentrations of Ba, Sr, S, F, Zn and Pb were extremely high in the
soils near to the tailings dumps, with 5%, 4%, 7%, 1%, 0.8% and 0.2%, respectively. Concentration of major
pollutants decreases with distance, but they were high even in the farthest samples. Same spatial distribution
was observed for Cd, As and Hg. While, the other elements follow different spatial patterns.
The leaching test revealed that most elements in the mining wastes, except for the anions, had a low solubility
despite their high bulk concentrations. According the 2003/33/CE Decision Threshold, some of these tailings
samples were considered as hazardous. Furthermore, other waste samples, considered non hazardous, were not inert. In contrast, the SO42-, Ba, Pb and Sb leachable contents measured in most of the soil samples were relatively high, exceeding the inert threshold for landfill disposal of wastes
... Environmental transformations related with mining activities entail changes in the morphology of the area owing to the extraction of minerals and dumping of residues, with reduction of vegetation cover and fauna diversity, and changes in soil quality and structure ( Sadhu et al., 2012;Zawadzki et al., 2016). Metalliferous mine residues dumped into the environment have numerous restrictions such as extremely low pH, high concentrations of metals and metalloids and extremely low organic matter content, hindering their development into soils that support rooted plants without human intervention ( Martínez-Pagán et al., 2011;Zanuzzi et al., 2009). These materials can also provoke acid mine drainage, a dangerous source of water contamination ( Barrie and Hallberg, 2005). ...
Creation of Technosols by use of different materials can be a sustainable strategy to reclaim mine tailings spread on the environment. A proper selection of materials is critical to efficiently contribute to soil creation, with development of soil structure, organic matter stabilization and stimulation of microbial growth. For this purpose, a 90 days incubation experiment was designed with biochars derived from different feedstocks, added to tailings alone or in combination with marble waste (MaW). We aimed to assess the effects of the different materials on the evolution of C and N contents and pools, greenhouse gas (GHG) emissions, aggregate stability, and microbial biomass and activity. Results showed that carbonates provided by MaW increased pH around the target value of 8, with significant decrease in salinity by precipitation of soluble salts. Organic C and total N remained stable during the incubation, with high recalcitrant indices. Labile and soluble C and N pools were low in Technosols, with no differences with unamended tailings at the end of incubation. All biochars increased aggregate stability with regard to control by ~ 40%, with no effect of addition of MaW. Biochars significantly increased microbial biomass C during the first 7 days of incubation; however, from this date, there were no significant differences with unamended tailings. The β-glucosidase activity was below detection limit in all samples, while arylesterase activity increased in biochar-amended samples favored by increases in pH. CO2 emissions were not significantly affected by any amendment, while N2O emissions increased with the addition of biochars with lower recalcitrance. CH4 emissions decreased in all Technosols receiving biochar. Thus, the combined use of biochar and MaW contributed to soil C sequestration and improved soil structure. However, labile sources of organic compounds would be needed to stimulate microbial populations in the Technosols.
... Metalliferous mining is a key economic activity that can result in land degradation due to changes in the morphology of the area owing to the extraction of minerals and dumping of residues and tailings, causing changes in the water cycle, the biota alteration and soil degradation ( Masto et al. 2015). Tailings dumped into the environment owing to mine ore processing activities have numerous restrictions affecting their development into natural soils, such as strong acidity, high concentrations of metals and metalloids, high salinity and extremely low organic matter content, which hinders the development of vegetation ( Martínez-Martínez et al., 2013;Martínez-Pagán et al., 2011). In addition, bare tailing surfaces can be sources of water pollution and metalcontaining dusts ( Smart et al., 2016). ...
Creation of Technosols with the use of different materials is a sustainable strategy to reclaim mine tailings and reduce metal mobility. For this purpose, a short-term incubation experiment was designed with biochars derived from pig manure (PM), crop residues (CR) and municipal solid waste (MSW) added to tailings alone or in combination with marble waste (MaW). We aimed to assess the efficiency of the different amendments to decrease Cd, Pb and Zn availability in the Technosols and the fractions where metals were retained. Results showed that all amendments reduced metal mobility, directly related to increases in pH. Those materials with higher content of carbonates were more effective to immobilize metals (~99%). MSW was highly effective to decrease metal mobility owing to the higher carbonate content, but addition of MaW was needed to enhance metal immobilization with PM and CR. Decreases in Cd mobility were related to retention by the carbonate, Mn/Fe oxides and oxidizable (organic compounds) fractions. Decreases in Pb mobility were related to retention in the Mn/Fe oxides and residual fractions, while decreases in Zn mobility were related to retention in Mn/Fe oxides and oxidizable fractions. Association of Zn and Pb with the oxidizable fraction was also related to the recalcitrance of the organic compounds, and so dependent on biochar type. SEM/EDX showed that biochar showed great affinity to interact with iron oxides, calcium sulfates and phyllosilicates.
... Traditional geochemical approaches require significant investments of time and money and often do not allow the selection of optimum sampling sites. Vertical electrical sounding allows outlining the mine tailing dump location, detecting the depth of the waste and the penetration area of highly mineralized fluids into groundwater, calculating the resources of valuable components in technogenic deposits and, with the appropriate technology, assessing the feasibility of re-extraction [13][14][15]. It is also true that site-specific chemical characterisation is in any case necessary in order to calibrate the electromagnetic sounding results. ...
Sulfide-bearing mill wastes of the Salair Ore Processing Plant situated in the Kemerovo region (Russia) were investigated in the time period 1999-2011. Multipurpose studies of the Talmovskie mining tailings allowed the determination of the composition of the wastes, the acid mine drainages, and the affected groundwater. Geophysical sounding techniques (frequency sounding and electrical tomography) were used to trace the geoelectric zoning of the wastes, expressed as a consistent change of the electrical resistivity specific electrical resistance (SER) from zone to zone. Layers with low resistivity indicate areas with pore spaces filled by highly mineralized solutions. These layers extend to depths of 4-5 m, indicating the penetration of toxicants into the groundwater horizon. The pollution of groundwater was confirmed by chemical analysis, according to which the concentrations of Zn, Pb, and Cd in water samples from the wells are two to three orders of magnitude higher than the maximum permissible concentration (MPC). The authors provide an attempt to identify the correlation and quantitative relationships between SER and the total amount of various metal species present in the wastes and water extracts. The proposed approach permitted to estimate the amount of accumulated tailings, in order to predict changes in the total concentrations of Mn, Al, Fe, Cu, Zn, Cd, and Pb in waste and water extracts to a depth of 30 m.
... A great number of studies focuses on contamination of various natural media in the impact zones of oredressing enterprises. Associations of chemical elements in different physical and chemical phases of soil were revealed (Yurgenson et al. 2008;Favas et al. 2011;Mileusnic et al. 2014), and the environmental fate and transport of heavy metals (HMs) and metalloids in dust and aerosol from mining activities were observed (Brotons et al. 2010;Taylor et al. 2010;Csavina et al. 2012), with special attention to waste storage sites, tailing ponds and neighboring soils Anawar et al. 2011;Conesa et al. 2011;Martínez-Pagán et al. 2011;Martínez-Martínez et al. 2013). Biogeochemical studies deal with trace element concentration in roots and leaves of different plant species (Martínez-Sánchez et al. 2012;Santos et al. 2014), and technogenic changes in rates of HM migration in soil-plant system (Alloway 2012;Wahsha et al. 2012;Ghaderian and Ravandi 2012;Santos et al. 2012). ...
The anthropogenic geochemical transformation of soil cover in large nonferrous mining centers of the Selenga River basin was assessed. The results of the geochemical survey of 2010–2012 revealed the spatial distribution patterns and abundances of 18 hazardous heavy metals and metalloids in the soils of Erdenet (Mongolia) and Zakamensk (Buryat republic, Russian Federation). In both cities, mining activities disturbed soil cover which accumulates Mo, Cu, As, Sb, W in Erdenet and Bi, W, Cd, Be, Pb, Mo, Sb in Zakamensk. Maximum accumulation of elements in Erdenet is restricted to the industrial zone. In Zakamensk, it has spread on ½ of the territory with the degree of multielemental pollution exceeding the extremely dangerous level by 16 times. The effect of mining centers on the state of the river system is local and does not spread to the Selenga River. Downstream from Erdenet, an artificial pool intercepts heavy metal and metalloid flows of the Erdenetii-Gol River. By contrast, downstream from the tailing dumps of the Dzhida tungsten–molybdenum plant the concentrations of ore elements W and Mo and their accessories Bi and Cd in the Modonkul River exceed background values by 146, 20, 57, and 21 times, respectively, decreasing by an order of magnitude 30 km downstream.
... Accumulated mine tailings without proper management are major cause of soil heavy metal pollution in mining region (Ding et al. 2011;García-Lorenzo et al. 2014;Jordanova et al. 2013). Numerous studies have been carried out on the negative impact of mine tailings on soil environment (Favas et al. 2011;Li et al. 2014b;Martínez-Pagán et al. 2011;Rodriguez et al. 2009;Wang and Mulligan 2009), while most of them were only focused on metal spatial distribution in mining soil (Liu et al. 2010(Liu et al. , 2013Martínez-Martínez et al. 2013;Monterroso et al. 2014) or leaching behavior of metal ions from mine tailings (Cukrowska et al. 2004;García-Lorenzo et al. 2014;Guo 2013;Kossoff et al. 2011;Schwab et al. 2007;Song et al. 2015;Wang and Mulligan 2009). In fact, heavy metals that released from mine tailings are mostly associated with colloidal particles (Lower et al. 2004;Pascaud et al. 2015;Slowey et al. 2007). ...
Exposed mine tailings could release substantial amounts of toxic metal-rich colloidal particles into soils during drying–wetting (D–W) cycles, but the mechanisms are still incompletely understood. In this study, two-layered (tailings above and soils below) packed columns were set to explore the effects of D–W cycles on tailing particle (TP) mobilization and transport in soil, and the mediating effect of TPs on the release and transport of heavy metals (Pb and Cu) was also examined. Results show that D–W cycles enhanced colloidal TP (approximately 190–712 nm) release from the column. The enhancing effect depends on duration of drying period, being slight for short-term drying (1, 3, 7, and 14 days) and significant for long-term drying (30, 60, and 90 days). The most interesting observation is the concentration valley of the effluent TPs during wetting event after 7- and 14-day drying. Based on these results, the dependence of TP mobilization and transport upon drying duration can be attributed to a combined action of different particle generation mechanisms during different drying periods, which appears to be relevant to the pore water content. The release and transport of Pb and Cu from the tailings into soil were dominantly mediated by the TPs and significantly enhanced by D–W cycles. These findings improve the understanding of TPs mobilization and transport in soil under fluctuating weather conditions.
... Metalliferous mine soils have numerous restrictions affecting their development into natural soils, such as extremely low pH, high concentrations of metals and extremely low organic matter content ( Zanuzzi et al., 2009;Martínez-Pagán et al., 2011). The importance of soil microbial communities for successful plant establishment and growth has been demonstrated by numerous studies ( Kulmatiski et al., 2008;Epelde et al., 2010). ...
... El establecimiento de plantas vegetales en dichos jales es impedido por numerosos factores fisicoquímicos, entre los que se incluyen el drenaje ácido de minas (DAM), temperaturas extremas, especialmente en la superficie de los jales, baja precipitación y fuertes vientos. Estos factores, asociados a la alta evaporación y a la baja infiltración de agua, contribuyen al desarrollo de altas concentraciones de sal con valores mayores a 22 mS/cm (Munshover 1994, Hesketh et al. 2010, Martínez-Pagán et al. 2011. ...
The mine tailings are characterized by a wide heterogeneity in physical and chemical composition that can alter the response of susceptible plants in different ways. In this work we explore the effect of abandoned mine waste on the toxicity of plant test for heavy metal. Four seedlings species were grown on extracts from six mine tailing samples with different capacity of producing acid mine drainage (AMD) and heavy metal concentrations (Pb, Zn and Cu). The mine tailings were amended with or without compost. Root elongation and germination rate were used as indicators to assess phytotoxicity on four species: Lactuca sativa, Cucumis sativus, Brassica juncea and Nasturtium officinale. Hormesis was found in B. juncea growth in almost all the mine tailings with or without compost and in L. sativa in only three mine tailings. The most sensitive species were L. sativa and C. sativus, compared to B. juncea and N. officinale. Root index was the best alternative to assess the phytotoxicity of mine tailings even above the calculation of NOEL and LOEL, which provided a qualitative evaluation.
... This study were based on multidisciplinary analyses using geochemical, geophysical, hydrogeological and modelling techniques. Non-destructive geophysical methods have proven effective tools in detecting contaminated sites and can be used in the detection of AMD generation and its flow paths, for instance in groundwater [9][10][11][12][13]. This investigation aimed to understand the processes that led to the current conditions and AMD generation, and the possible attenuation mechanisms mitigating the effects of highly mineralized solutions at the Karabash mine site. ...
The Karabash mine area was chosen as the research site for its potential hazardous influence on the environment of Chelyabinsk region. This work presents the results of a geochemical and geophysical characterization of an old tailing containing high contents of sulfide minerals, primarily pyrite (up to 25 wt%), chalcopyrite (3 wt%) and up to 1 wt% of sphalerite and galena. In order to obtain a representative characterization of the study area, geochemical analysis of surface water samples, groundwater composition, bottom sediments analysis and thermodynamic modelling were selected. In all compounds, high levels of trace elements (including Pb, Zn, Cu, Cd, Co, Ni, Fe, Mn) were observed. A thermodynamic modelling study (WATEQ4f) revealed the mobilization of heavy metals mostly through the aqueous and sulfate complexes. Due to the large amounts of dispersed sulfide minerals, the pyrite-rich tailing characterized by an electrically conductive geophysical signature in comparison to the surrounding resistive bedrock. Meteoric water, getting on a tailings surface, gradually penetrates, on the way dissolving secondary minerals and metal salts, being saturated with them. Poorly permeable grounds are capable to accumulate waters, forming underground reservoirs. The distribution of layers with low resitivities suggests that the infiltration of highly mineralized solutions spreads in a direction transverse to the river flow zone. These layers extend to depths of 1–15 m, indicating the penetration of toxicants into the groundwater horizon. The pollution of groundwater confirmed by chemical analysis, according to which the concentrations of Zn, Pb, Ni, Cu and Cd in groundwater samples are two to three orders of magnitude higher than the maximum permissible concentrations (MPC). ERT technique combined with 3D models suggests along with the vertical penetration into groundwater, there is a lateral spread of low resistivity within water-saturated layers, which in this case may be termed an "acid wave".
... A geophysical survey was conducted using Electrical Resistivity Imaging (ERI). This technique has been previously used for tailings analyzes (Martínez-Pagán et al. 2009, 2011Gómez-Ortiz et al. 2010;Martín-Crespo et al. 2010;Placencia-Gómez et al. 2010;Martínez et al. 2012Martínez et al. , 2014Martín-Crespo et al. 2012Zarroca et al. 2015). ...
Geochemical and geophysical techniques have been applied to investigate the potential environmental impact of the abandoned La Aquisgrana mine tailings, one of the most important sulfide-bearing tailings ponds of the Linares-La Carolina mining district (Spain). The geometry of the pile has been defined through geological field work and electrical resistivity imaging (ERI) surveys. The ERI profiles revealed the position of the bedrock surface below the tailings central area (more than 40m in thickness) and helped in placing drill core sampling for geochemical analysis and a piezometer installation. In the 21 extracted samples, the total content of Pb, Zn, Cu, Fe, Mn, Sr, Rb and As were determined, with significant values being found for Pb and Zn (>2000mgkg-1), Mn (>700mgkg-1) and As (>170mgkg-1). Although AMD has not been identified, water samples from the saturated zone of the tailings are characterized by elevated dissolved sulfate (2495mgL-1), Fe (20mgL-1), Mn (16mgL-1) and Zn (7mgL-1) contents, with an E.C. value of 3.3mScm-1 and pH from 5.6 to 6.9, suggesting a process of metal mobilization. Physical and chemical data obtained from drill core and groundwater samples were combined with the electrical resistivity profile of the tailings to characterize areas with higher metal concentrations. A central low resistivity area (<30Ω.m) was identified in the vadose zone of the pile, correlated with higher Fe, Zn, Pb, As, and sulfide concentrations, and with a significant increase in silt and clay content. The lowest resistivity values (<5Ω.m) were measured in the saturated zone of the tailings, related with the highest metal(oid) contents in both solid phase and water. A lower resistivity area close to the fractured zone of the bedrock suggests a preferential flow path for subsurface water infiltration. The generated geophysical-geochemical model has allowed to depict areas of the tailings characterized by high metallic and water contents that present the greater risk for contamination.
Cemented paste backfill (CPB) technology is a green mining method used to control underground goaves and tailings ponds. The curing process of CPB in the stope is the product of a thermo-hydro-mechanical-chemical multi-field performance interaction. At present, research on the multi-field performance of CPB mainly includes indoor similar simulation experiments, in-situ multi-field performance monitoring experiments, multi-field performance coupling model construction of CPB, and numerical simulation of the multi-field performance of CPB. Because it is hard to study the in-situ multi-field performance of CPB in the real stope, most current research on in-situ multi-field performance adopts the numerical simulation method. By simulating the conditions of CPB in the real stope (e.g., maintenance environment, stope geometry, drainage conditions, and barricade and backfilling rates), the multi-field performance of CPB is further studied. This paper summarizes the mathematical models employed in the numerical simulation and lists the engineering application cases of numerical simulation in the in-situ multi-field performance of CPB. Finally, it proposes that the multi-field performance of CPB needs to strengthen the theoretical study of multi-field performance, form the strength design criterion based on the multi-field performance of CPB, perform a full-range numerical simulation of the multi-field performance of CPB, develop a pre-warning technology for the CPB safety of CPB, develop automatic and wireless sensors for the multi-field performance monitoring of CPB, and realize the application and popularization of CPB monitoring technology.
The accumulation of waste materials in old, abandoned mining districts without prior sealing of the substrate
currently poses a significant risk of contamination to soils and surrounding waters. Some of these mining dams
have undergone a reclamation and sealing process in recent years to alleviate this problem. The current study is
an analysis of the effectiveness of using different geophysical techniques for characterising these structures and
monitoring the isolation performed. This study was carried out in the old mining district of Linares-La Carolina
(southern Spain). The following techniques were investigated in this study: direct current (DC) resistivity,
induced polarization (IP), ground-penetrating radar (GPR) and the time domain electromagnetic method
(TDEM).
Combining DC and IP made it possible to characterise the internal structure of the abandoned mining dams,
whereby the geometry of these deposits was determined and the corresponding potential risks were assessed. In
addition, percolation zones of mining leachates were detected that indicate defects in the sealing stage.
TDEM was a good complementary technique for calculating the depth of the bedrock on which the mining dam
is located. GPR could only be used to investigate shallow depths at all of the antenna frequencies used (100, 250
and 500 MHz) but was useful for obtained detailed information about the last stages of filling and characterising
the encapsulation performed during sealing.
New legislation that requires “decharacterizing” or decommissioning tailings storage facilities (TSFs) has motivated this review of “decharacterization” methods and techniques for and their environmental impacts. Out of 105 papers, published since 1983, that describe solutions or discuss challenges to closed TSFs, regarding geotechnical and geochemical stability, revegetation, or reuse of tailings, generally aiming at safely integrating the facility to the landscape, only six papers approach environmental impacts of decommissioning works – such as increased road traffic —, and risks associated with phytoremediation — in particular the transfer of metals to the food chain. The subject is little explored in international literature. There is no shared understanding about the meaning of decommissioning, closure and related terms. The Brazilian experience that will result from complying with legislation, if properly analyzed and documented, will contribute to the advancement of knowlegde about TSFs closing techniques.
Keywords:
decommissioning; tailings dams; systematic review
Abandoned tailings generated from copper mining are exposed to the environment for a long time will cause related risks, such as stability, landslides, surface and groundwater pollution, acid mine drainage (AMD) and secondary mineral deposits. This research started from multiple methods and comprehensively assessed the current status of mine tailings through the joint application of geophysics, geochemistry and mineralogy techniques to identify relevant environmental hazards. A thick oxidized hardened layer was formed on the surface of the tailings dam, but there were still faults or crack that affected its structural stability. According to the low-resistivity distribution of the tailings, the surface oxide compaction was judged, and the existence of high-resistivity cracks judged the potential migration path of heavy metals (HMs). The microscopic morphology and existing mineral phases of tailings particles at different depths in the profile were determined by SEM and XRD of representative samples as the main feature of iron crystalline phase. As the profile depth increased, the minerals such as calcite, pyrite and goethite gradually appeared. In addition, Cr and As were no risk, Cu, Zn, Pb were low risk, Ni was medium risk, and Cd was high risk in risk assessment code (RAC) analysis of the tailings. Judging whether HMs in the tailings are hazardous substances according to the results of toxicity characteristic leaching procedure (TCLP), it was found that the leaching contents of Cu, Zn, Pb, Cr, Ni, As were all lower than the limit, while the leaching content of Cd was higher than the limit, and additional attention should be paid to Cd pollution.
Based on research carried out at 67 tailings dams in Spain: (1) tailings dams contain alternating sedimentary layers with contractive and dilative geomechanical behaviours; (2) tailings saturate quickly but drain more than 10 times slower due to the high-suction capacity of the porous sediments (2–300 MPa); and (3) over the long-term, a stationary flow regime is attained within a tailings basin. Four temporal and spatial conditions must all be present for a tailing dams flow failure to occur: (1) the tailings must experience contractive behaviour; (2) the tailings must be fully saturated; (3) the effective stress due to static or dynamic load must approach zero; and (4) the shear stress must exceed the tailings residual shear stress. Our results also indicate that the degree of saturation (Sr) is the most influential factor controlling dam stability. The pore-pressure coefficient controls geotechnical stability: when it exceeds 0.5 (Sr = 0.7), the safety factor decreases dramatically. Therefore, controlling the degree of tailings saturation is instrumental to preventing dam failures, and can be achieved using a double drainage system, one for the unconsolidated foundation materials and another for the overlying tailings.
When mines are decommissioned, tailings piles can act as sources of contamination for decades or even centuries. Tailings, which usually contain high concentrations of metals and trace elements, can be reprocessed for a secondary recovery of valuable elements with an innovative approach to a circular economy. This study offers new results for tailings ponds characterisation and chemical content prediction based on an integrated geophysical-geochemical approach. The study of the Raibl Pb-Zn tailings impoundment was done using bulk chemical analysis on borehole samples, Electrical Resistivity Tomography surveys, and Ground Penetrating Radar measurements. We found valuable and statistically significant correlations between the electrical resistivity of the mining impoundments and the metal distribution, thus providing a practical opportunity to characterise large volumes of metal-bearing tailings. In particular, these results can be useful to aid in the development of environmental monitoring programs for remediation purposes or to implement economic secondary recovery plans.
Geophysical methods based on electrical properties can be used to study tailings ponds studies because a site’s spatial and temporal subsurface electrical resistivity values vary depending on its physical and chemical properties (texture, salinity, metals, water content, temperature, pH, etc.). This paper reviews published case studies in which electrical resistivity tomography (ERT) was successfully used to characterize and monitor tailings ponds.
The tailings of Zeida’s abandoned mine are found near the city of Midelt, in the middle of the high Moulouya watershed between the Middle and the High Atlas of Morocco. The tailings occupy an area of about 100 ha and are stored either in large mining pit lakes with clay-marl substratum or directly on a heavily fractured granite bedrock. The high contents of lead and arsenic in these tailings have transformed them into sources of pollution that disperse by wind, runoff, and seepage to the aquifer through faults and fractures. In this work, the main goal is to identify the pathways of contaminated water with heavy metals and arsenic to the local aquifers, water ponds, and Moulouya River. For this reason, geophysical surveys including Electrical Resistivity Tomography (ERT), Seismic Refraction Tomography (SRT) and Very Low-Frequency Electromagnetic (VLF-EM) methods were carried out over the tailings, and directly on the substratum outside the tailings. The result obtained from combining these methods has shown that pollutants were funneled through fractures, faults, and subsurface paleochannels and contaminated the hydrological system connecting groundwater, ponds, and the river. The ERT profiles have successfully shown the location of fractures, some of which extend throughout the upper formation to depths reaching the granite. The ERT was not successful in identifying fractures directly beneath the tailings due to their low resistivity which inhibits electrical current from propagating deeper. The seismic refraction surveys have provided valuable details on the local geology, and clearly identified the thickness of the tailings and explicitly marked the boundary between the Triassic formation and the granite. It also aided in the identification of paleochannels. The tailings materials were easily identified by both their low resistivity and low P-wave velocity values. Also, both resistivity and seismic velocity values rapidly increased beneath the tailings due to the compaction of the material and lack of moisture and have proven to be effective in identifying the upper limit of the granite. Faults were found to lie along the bottom of paleochannels, which suggest that the locations of these channels were caused by these same faults. The VLF-EM surveys have shown tilt angle anomalies over fractured areas which were also evinced by low resistivity area in ERT profiles. Finally, this study showed that the three geophysical methods were complementary and in good agreement in revealing the pathways of contamination from the tailings to the local aquifer, nearby ponds and Moulouya River.
The processing and the geologic interpretation aimed at marine geological mapping (realization of the marine map of the sheet n. 502 “Agropoli”, ISPRA, National Geological Survey of Italy) of a detailed grid of very high resolution seismic profiles (Subbottom Chirp) recorded in the Campania continental shelf between the Solofrone river mouth and the Agnone town have been carried out. The seismic profiles, recorded through the Subbottom Chirp profiler, have been processed using an open-source software for single-channel seismic data processing, the SeisPrho, licensed by the Institute of Marine Sciences of the National Research Council of Bologna, Italy and made available. In particular, more than one hundred seismic sections, previously recorded onboard of the RV Urania (CNR) have been read and processed through the application of a vertical linear gain, allowing for a significant improvement of the seismic signal. The study area can be divided in three zones, which have been distinguished based on the trend of the seismic profiles and on the line spacing. The interpretation of the seismic profiles, carried out accordingly to the criteria of the seismic stratigraphy, has allowed to distinguish the main seismo-stratigraphic units separated by significant seismic reflectors, corresponding with unconformities and/or conformities. In the inner continental shelf between the Solofrone river mouth and the Licosa Cape the seismo-stratigraphic analysis has shown that the recent sedimentary cover ranging in age from the Late Pleistocene and the Holocene is organized in three main seismo-stratigraphic units. In its northern sector this shelf represents a depocentral area of marine deposits, mainly sands. Coarse-grained sandy belts parallel to the shoreline have been identified, suggesting the activity of alongshore currents. In its southern sector this shelf represents the seawards prolongation of the Licosa Cape structural high and is characterized by wide outcrops of rocky acoustic basement, genetically related with the Cilento Flysch Auct.
An integrated analysis of volcanic structures located in the subsurface of Naples and Gaeta Gulfs (Eastern Tyrrhenian margin, Southern Italy) based on the geologic interpretation of seismic profiles is herein presented. This study is aimed at improving the seismo-stratigraphic knowledge of volcanic structures occurring in this sector of the Tyrrhenian offshore and at highlighting the relationships between these structures and the regional tectonics of Campania-Latium offshore. The Pithecusa volcano, located in the Northern Campania offshore, the buried volcanic structures occurring in the Procida Channel and the Ischia Bank, a wide relict volcanic edifice of the Ischia south-eastern offshore have been analyzed. The Pithecusa volcano is related with the Massico normal faults down throwing the volcanic acoustic basement. A large, previously unknown, buried volcanic edifice has been identified offshore the Miliscola town (northern Phlegraean Fields offshore), while a smaller buried volcanic edifice has been recognized in the Procida Channel. The tectonic control on these volcanoes is not completely clear and additional geological interpretations are still in progress. The Ischia Bank is probably controlled by NE-SW striking normal faults.
One of the wastes generated in fertiliser production from phosphoric rock is phosphogypsum, whose mismanagement lead to environmental and health risks. Therefore, a detailed evaluation of the chemical composition of phosphogypsum is necessary to determine effective means of its management. Due to the high amount of generated waste, the cost and time consumed for this characterisation by chemical analysis is limiting. Hence, efficient tools should be developed to predict the chemical composition of this waste. Thus, this study aims to: 1) determine the physic-chemical characterisation of phosphogypsum pond using geochemical and geophysical techniques and 2) predict the heavy metals spatial distribution through statistical models. Results show that the most concentrate metal is chromium with a maximum of ≈900 mg.kg ⁻¹ and cadmium is the least concentrated (maximum ≈23 mg.kg ⁻¹ ). The Electrical Resistivity Tomography revealed the superposition of two layers. The top one (waste) presents low resistivity (≈17Ω.m) while the bottom layer shows higher resistivity (>124Ω.m). Metal concentrations and resistivities were combined by applying non-linear regression models. Cr showed the strongest correlation (R ² = 0.68), yielding an accurate model that was used for revealing the spatial distribution of the highest Cr concentrations in the pond, with the consequent reduction of expensive traditional methods.
Today industries play comprehensive role in modern and developed societies. Pollution and wastes as output of these processes- here: mine and drilling - are important concerns of both environmental authorities and managers. Recently green studies are favored as a key factor in environmental management systems. It can also be served as a study field in sustainable development. One environmentally-concerned phase of industries is closure and abandonment of mine and well when permanent environmental impacts must be dealt with. Reclamation and/or rehabilitation of mined and drilled lands not only can decrease environmental problems but also can establish environment-friendly conditions having substantial benefits. Wastes can be lowered or even eliminated by being returned into source or by remediation and reuse processes. Circumstantially in mining, the mined land can approach post-mining land uses such as recreational, residential and agricultural uses. These make losses and disadvantages to turn into benefit and advantage. In terms of drilling, practices like subsurface injection can procure demanding disposal. Post closure acts are the long-term phases of industries which should integrate well-designed engineering, management and monitoring to bring about the aimed results and to comply with the environmental management systems.
Tailings impoundments associated with former mining districts are currently sources of pollutants to soils and waters. Because of this issue, many of these tailings ponds have been treated by restoration and sealing processes in recent years.
Residual heavy metals are commonly considered to be immobile in soils, leading to an underestimation of their environmental risk. This study investigated the distribution and transport of residual heavy metals along soil profiles, using the Xiaoqinling gold mining region in North China as a case study. Soil samples were collected at three depths from three locations near the tailing heap. The speciation of copper (Cu) and lead (Pb) (exchangeable, carbonate-bound, Fe-Mn oxide-bound, organic matter-bound, and residual fractions) was determined using a sequential extraction procedure. The residual fraction's morphology was observed using scanning electron microscopy (SEM). Results showed that metal fraction distributions along the soil profiles were influenced by each fraction's mobility. Residual fraction with high chemical stability can not be transformed from or into other fractions. This led to the conclusion that the high concentration of residual metals in soils mainly resulted from residual fraction transport. The SEM analysis showed that fine particles (submicrons) were mainly attached to large particles and were likely released and transported by water flow. The more sorptive fractions (non-residual fractions) were mainly retained in the top soil, and the more mobile fractions (residual fraction) were mainly leached to the deep soil. Cu and Pb concentrations in the residual fraction decreased slightly and those in the non-residual fractions decreased significantly with soil depth. These suggest a relatively higher residual metal mobility along the soil profiles. Therefore, residual metals can be transported in soils and their environmental risk can not be ignored in assessing soil contamination.
Surface coal mining may disrupts the carrying capacity of water, hence the sustainability of water resources during mining operations and post-mining depends on environmental services of mining void. This research was designed to study the environmental costs and benefits of mining void water (general term of pit lake in Indonesia) in PT. Adaro Indonesia on site Tanjung, Kabupaten Tabalong, South Borneo, Indonesia to understand the factors influencing mining sustainability through utilization of mining void or mining pit, and to develop a model for water resources sustainability in coal mining. The main factor influencing mining sustainability is the void water quality. pH is the key factor which determines how mining void water may be used. Water utilization is based on the demands of the surrounding community, andincludes drinking water, fish farming, and land farming. Calculations on the environmental services provided by mining void water for tourism, drinking water supply, and fish farming in PT. Adaro Indonesia shows an Extended NPV of Rp 7.124.884.062.739.430 (± USD 593, 740, 338, 561.62) and B/C ratio of 8, 25.
The objective of this research was to consider cadmium (Cd) mobility in organic rich soils. Cadmium was selected for the study due to its tendency to be more mobile in soils than other heavy metals, such as Pb and Cu. Samples were collected from three principle soil horizons at a research site in the Caribou-Poker Creek Research Watershed, near Fairbanks, Alaska. A dilute cadmium solution was added to the soil andthe soil solution was allowed to mix for 72 hours. The soil solution was then sieved to isolate specific size fractions. Samples were analyzed by atomic absorption (AA) to determine on which particle sizes cadmium preferred to bind. For each size fraction, natural organic matter (NOM) was analyzed by pyrolysis-gas chromatograph/mass spectrometry (py-GC/MS) to determine the nature of the NOM present in each size fraction. Results suggested that the relationship between total Cd and total solids was almost equal among the particle sizes in each horizon. Since the ratio of Cd to solids normally changes as a function of particle size, this result suggested unusual sorption behavior. The relationship between total Cd and NOM were not distributed evenly among particle sizes. Based on py-GC/MS analysis, the abundance of polysaccharide (sugar) compounds was positively correlated to Cd distribution in the particle size range tested (i.e., 0.3-75um). The organic nature of the soil was considered to be a primary factor influencing the unusual sorption characteristic of the boreal soil.
Mine tailing ponds are environmental hazards because of high susceptibility to leaching and erosion by water and wind. Vegetation establishment is an effective technique to reclaim tailing ponds but requires knowledge of the spatial relationship between the structural composition and physical and chemical properties of soils. In this study we have demonstrated the use of electrical resistivity imaging (ERI), combined with soil chemical analyses, to determine the structural and chemical composition of mine tailing ponds to assess efficient measures of environmental protection. We used a Syscal R1 resistivity meter to generate two-and three-dimensional (2-D/3-D) ERI images from El Lirio and Brunita mine tailing ponds. Soil samples were collected at 1-m intervals to a depth of 15 m, and were analyzed for pH, electrical conductivity and cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) contents. Results show that materials in the ponds can be classified into three categories: fine tailings - low ER (<8 Ω-m), coarse waste rock - intermediate ER (8-150 Ω-m), and bedrock - high ER (> 150 Ω-m. Our interpretation of the 2-D/3-D ERI images with respect to the historical depositions of materials in the ponds show that at El Lirio, decant water outlet was initially at the center and advanced to the east of the tailing pond as the mining activities progressed. At Brunita, the intermediate ER values on the west side of the pond marked the deposition of coarse waste rock materials released during a pond breakage in 1972. The ERI helped us image the spatial distribution of tailings and its qualitative spatial correlation with chemical properties (i.e., pH, EC, metals content). Low ER values are related to high amounts of Zn, Pb, Cu and Cd. These qualitative relationships underlie the usefulness of the combined geophysical and soil chemical approaches to improve our understanding of the properties of mine tailing ponds in the Sierra Minera (and other parts of the world).
Depth of investigation and vertical resolution values are determined and tabulated for 30 surface geoelectric arrays that have non-zero response, i.e., a depth of investigation characteristic (DIC) function due to a buried thin horizontal sheet. In accord with experience, results show a general reciprocal relationship between depth of investigation and vertical resolution. The most frequently used arrays in multi-electrode studies (i.e., Wenner-α, Wenner-β, Schlumberger, dipole-axial arrays and the pole-dipole array) offer reasonable compromises between depth of investigation and vertical resolution. Depth of investigation can be increased by using the pole-pole array; vertical resolution can be improved with, for example, the α10 or γ10 arrays. Current focussing does not increase the depth of investigation for the horizontal thin-sheet model. The complete set of depth of investigation and vertical resolution values permits exact physical comparison of various geoelectric arrays and provides simple but useful rules for practical geoelectric applications, e.g., how to develop multi-electrode systems with higher vertical resolution, or how to select arrays to satisfy special exploration requirements.
Resistivity imaging (electric tomography) is a methodology for defining lateral variations of resistivity associated with structural anomalies such as caves, water contamination, and fractured zones among others. Important urban areas in Mexico City are currently at high risk of collapse. Cavities and shallow fractures have been created as a result of mining in hilly regions beneath several of today’s urbanized neighborhoods located in the southwestern portion of Mexico City. Selected areas have been investigated. Caves and tunnels were found for depths ranging between 5 m up to 15 m . Diameters of such features were between 5 m up to 30 m . Some of these structures are across paved roads and beneath buildings and houses, running for several tens of meters in length. Topographic effects were also studied in one profile. It showed important inaccuracies in resolving the geometry of the cave, mainly in terms of depth to the top, where differences of 2 m to 3 m were encountered. GPR (Ground Penetrating Radar) was also used to confirm the results obtained in a resistivity profile surveyed on a test site. Results are very encouraging, demonstrating that the resistivity imaging helped to locate and characterize mined areas, jointly with other geophysical methods. Unfortunately, true resistivity is not well resolved, because of inherent ambiguity of the inverse method used.
A soil column study was conducted to assess the vertical movement
of certain heavy metals in soils amended with urban waste compost
(90 t ha- 1 ) . The effect of the complexing capacity of water soluble
organic matter from compost on metal mobility has been previously
reported. The results of this investigation demonstrate the enhanced
levels of Cu, Zn, Ni, and Cr eluted from 50-cm soil columns when
compost is added to a Fluventic Xerochrept clay-loamy, mixed, mesic
and a Typic Xerochrept, fine sandy-loamy, mixed, mesic. The increase
in these metal concentrations is greater in sandy-loam soil than
in clay-loam. The water soluble organic fraction of the compost has
minimal impact on the metals concentration. Seventy to eighty percent
of the water-soluble organic fraction was retained in the upper 10-cm
layer of soils, with only 5% eluted from clay-loam soil and 10% from
the sandy-loam.
We collected approximately one hundred independent geoelectric arrays from published geophysical literature. We have presented them in a systematic way and with a unified notation. The classification of arrays is based on three divalent parameters: “superposition” of measurements, “focusing” of currents and “colinearity” of the array, creating 8 classes of geoelectric arrays.
Among the 102 independent arrays we found in the geophysical literature, we managed to classify 92 arrays in the aforementioned way. Ten further techniques fell beyond the proposed classification.
The classification we propose may open the way to new geoelectric arrays, hopefully providing improving responses to the infinite variety of field problems we may face. It may bring to daylight, exclusively in a logical way, currently unused arrays. In searching new geoelectric arrays this paper helps to avoid rediscovering the discovered. Although it might be thought that the modern multielectrode systems will supersede all former arrays, such systematization is not only for historical and tutorial interests: some of the “old” arrays can be perhaps built into new multielectode systems, further enhancing their effectivity in the future. Finally, this collection of arrays establishes the possibility of systematic intercomparisons of arrays on the basis of various theoretical or practical aspects.
Magnetotelluric (MT) data are inverted for smooth 2-D models using an extension of the existing 1-D algorithm, Occam's inversion. Since an MT data set consists of a finite number of imprecise data, an infinity of solutions to the inverse problem exists. Fitting field or synthetic electromagnetic data as closely as possible results in theoretical models with a maximum amount of roughness, or structure. However, by relaxing the misfit criterion only a small amount, models which are maximally smooth may be generated. The models are composed of a large number of rectangular prisms, each having a constant conductivity. A prior information, in the form of boundary locations only or both boundary locations and conductivity, may be included, providing a powerful tool for improving the resolving power of the data. Joint inversion of TE and TM synthetic data generated from known models allows comparison of smooth models with the true structure.
A fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer. This technique is based on the smoothness-constrained least-squares method and it produces a two-dimensional subsurface model from the apparent resistivity pseudosection. In the first iteration, a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically. For subsequent iterations, a quasi-Newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times, respectively, compared to the conventional least-squares method. Tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly. This technique takes about one minute to invert a single data set on an 80486DX microcomputer.
A field study was conducted to determine the plant uptake of metals in soils amended with 500 Mg ha–1 of municopal sewage sludge applied 16 yr previously. Results showed that metals were available for plan uptake after 16 yr, but that liming greatly reduced the plant availability of most metals. The application of sludge also resulted in high rates nitrification and subsequent lowering of the soil pH before the uptake study was started. The sludge-amended soil (a mesic Dystric Xerochrept) was adjusted with lime one month prior to planting from an unlimed pH of 4.6 to pH 5.8, 6.5 and 6.9. Food crops grown were: (i) bush bean (Phaseolus vulgaris L. cv. Seafarer), (ii) cabbage (Brassica oleracea L. v. capitata L. cv. Copenhagen market), (iii) maize (Zea mays L. cv. FR37), (iv) lettuce (Lactuca sativa L. cv. Parris Island, (v) (Solanum tuberosum L. cv. (vi) tomato (Lycopersicum esculentum L. cv. Burpee VF). With the exception of maize, yields were significantly reduced in the unlimed sludge-amended soil. However, liming increased yields above the growth level of the unlimed untreated soil for cabbage, maize, lettuce, potato tuber and tomato fruit. Soluble and exchangeable of Cd. Ni and Zn were also reduced after liming the sludge-amended soil. In both limed and unlimed soils, the majority of the soil Cu was found in insoluble and unavailable soil fractions. To evaluate trace metal uptake, the edible portion of each crop was analyzed for Cd, Cu, ni and Zn. Liming redoced uptake of Cd, Ni and Zn in most crops, but generally did not change Cu, This study shows the benefit of pH adjustment in reducing relative solubility and plant uptake of metals as well as increasing crop yield in acid soils.
Intensive urbanisation of the Croatian capital of Zagreb has led to a situation where very good agricultural soils, developed mostly on Pleistocene eolian sediments and alluvial and proluvian Holocene sediments are entrapped within urban and suburban areas. Therefore the influence of urban and industrialised environments on the accumulation of metals in agricultural topsoils has been investigated. On an area of 860 km2 of the wider Zagreb region, 331 samples were taken according to a regular 1ǵ km square mesh. Samples were dissolved in aqua regia and analysed for Cd, Cu, Fe, Mn, Ni, Pb and Zn with flame atomic aqua regia absorption spectroscopy. The following concentration ranges have been determined: Cd 0.25-3.85 mg kg-1 (average 0.66 mg kg-1), Cu 4.30-183 mg kg-1 (average 20.8 mg kg-1), Fe 5.8-51.8 g kg-1 (average 27 g kg-1), Mn 79.2-1282 mg kg-1 (average 613 mg kg-1), Ni 0.70-282 mg kg-1 (average 49.5 mg kg-1), Pb 1.50-139 mg kg-1 (average 25.9 mg kg-1), and Zn 15.2-277 mg kg-1 (average 77.9 mg kg-1). Visualisation of the spatial data is made by the aid of GIS, and selected maps of the heavy metal concentrations in topsoils are displayed. Statistical multivariate analysis was carried out for quantitative study and data were processed by means of R-mode factor analysis, applying the varimax-raw rotational technique. F1, which grouped Cd, Pb, Cu, Zn and partially Ni, is characterized as a factor with strongly scattered anthropogenic influence. The elements in F2, Fe, Mn and partially Ni are mainly of geogenic, i.e. pedogenic, origin. The variations in concentrations of the investigated elements are thus of both natural and anthropogenic origins. The variations in the main soil constituents, particularly Fe and Mn, are determined primarily by the composition of different regolithic substrates of the fluvial origin in recent pedogenesis. High concentrations of nickel are also related to morphogenetic characteristics of the wider region, primarily basic and ultrabasic magmatic rocks of the surrounding mountain range. It is, however, assumed that the anomalous nickel concentrations in the vicinity of the highway and the airport are of anthropogenic origin, i.e. caused by fuel combustion. Copper is characterized by strongly scattered anthropogenic influence, which is related particularly to uncontrolled solid waste disposals or discharges of liquid waste from households or agricultural enterprises. With Zn, Pb and Cd, there are two possible ways of diffuse pollution. The Sava River, which drains the area and feeds the abundant Quaternary aquifer spreading below the major part of the investigated agricultural areas, has been exposed to intensive pollution by mining, industry and cities in the recent history. The part of the area with the highest determined concentrations of Zn, Pb and Cd was repeatedly flooded as recently as the previous decade; therefore, the recent sedimentation of the river deposits exposed to pollution is a very probable cause of the accumulation of metals in this until recently inundation area. The other way is atmospheric deposition of particles from urban sources (industrial emission, traffic, waste disposals, heating plants, etc.). In addition to agricultural enterprises, several economically important, but ecologically risky, facilities are situated in the vicinity of the water-protection area. The area is intersected by a very busy ring road, while a marshalling yard, the city dump, pharmaceutical and chemical industry, the district-heating plant and the airport are all located in close proximity. The geochemical maps show a clear relationship between human activities and metal concentration gradients.
This study addresses the spatial and temporal variability of soil properties before and after the application of organic and inorganic amendments in a trace-element-polluted soil using statistics and geostatistical methods. The experiment took place in a plot (20×50 m) affected by the acid toxic pyritic sludge from the Aznalcóllar mine (Seville, Spain) in April 1998. Soil samples from 0- to 15-cm depth were collected within 48 locations, on a 14×45 m grid in 2002 and 2003, respectively. The samples were analysed for pH, total organic carbon, total sulphur and total, available and soluble As, Cd, Cu, Pb and Zn concentrations. Classic statistical and geostatistical methods were used to assess variability in contamination levels.
The kinetic behaviour of pyrite oxidation in carbonate-buffered solution was investigated in the laboratory. Oxygen concentration, surface area and temperature were varied while pH values were limited to the range of 6.7–8.5. The rate experiments were performed on crushed and sieved size-fractions of pyrite that were carefully cleaned and mixed with similar-size silica sand. Oxidation occurred in a moisture-suction device that maintained partially-water-saturated conditions. Dilute NaHCO3 solution and a CO2-O2-N2 gas mixture were passed continuously through the pyritic sand. The reaction rates were monitored by sulphate mass balance in the effluent solutions.The initial rate of oxidation was found to be a linear function of surface area. The rate-dependence on oxygen concentration is non-linear and the data fit a heterogeneous kinetic model in which the surface decomposition reaction, not sorption of oxygen, is the rate-determining step. This decomposition model explains the range of linear to non-linear models reported in the literature when different values of the adsorption constant are applied. The temperature dependence follows Arrhenius behaviour with an equivalent activation energy of about 88 kJ mole−1 in the temperature range of 3 to 25°C, showing that diffusion was not rate limiting. The oxidation rates of five pyrite specimens obtained from various locales exhibited maximum differences of only about 25%.
A system is described for the automatic measurement of electrical resistivity pseudo-sections. This comprises a linear array of up to 32 electrodes connected through a multicore cable to a computer controlled switching module and a resistivity meter. The processing of the measured sections to produce two-dimensional true resistivity images of the subsurface is briefly described. Some account is given of the capabilities and limitations of the technique. This is illustrated by a series of computed constant separation traverses for models of simple subsurface structures. Examples of processed images derived from sections measured in areas of relatively complex geology follow, a comparison being made of the interpretations obtained using an automatic imaging method and a manual iterative approach. It is concluded that with the equipment and software so far developed, in areas of modest subsurface geological complexity where some control is available and where the structures are essentially two-dimensional, then good approximations to the true geoelectric sections can be obtained down to depths of between 100 and 200 m.
(1) Acidification of colliery spoil, caused by the oxidation of iron pyrites, often results in the dieback of vegetation after land reclamation. (2) There is no reliable method of predicting the acid-producing potential of spoil and therefore it is impossible to estimate the lime-requirement for permanent pH control. (3) Chemical analyses of spoil from twenty sites showed a considerable range of variation in pyrite content and acid neutralizing capacity (calcium carbonate equivalent). (4) The acid-producing behaviour of nine spoils was related to their iron pyrites (FeS) contents and acid neutralizing capacities. (5) Most spoils were compacted with a high clay content and pyrite oxidation occurred in a shallow surface zone resulting in a material of low pH and low pyrite content. The underlying unoxidized zone exhibited high pH and high pyrite levels. (6) It is recommended that spoils be analysed for pyrite content and acid neutralizing capacity immediately after regrading. The lime-requirement for permanent pH control can then be estimated. (7) Assuming complete oxidation, 1% pyrite in spoil can give rise to a lime-requirement of 40 t ha for pH control to 15 cm depth. 1% of acid-neutralizing capacity is equivalent to 23 t ha of limestone applied, for 15 cm of spoil. Limestone should be incorporated to 45-50 cm depth and the application rate increased accordingly. (8) High pyritic spoils may have lime-requirements in the range 100-400 t ha for pH control to 45 cm depth.
Mining activity in the Iberian Pyrite Belt, on the south-west of the Iberian Peninsula, has generated a great amount of mine tailing ponds, which once the extractive activity is finished, are abandoned and become a serious environmental problem. Here we present the results of applying the electrical resistivity tomography (ERT) technique to characterize the abandoned mine ponds in two sites: Monte Romero and Mina Concepción. ERT has allowed us to determine both the general geometry of the pond’s base and the maximum thickness of the mine tailings. In all cases, the resistivity contrast between the infilling and the bedrock is high enough to clearly define the bottom pond boundary. The low-resistivity values (lower than 5 Ωm) obtained for the infilling are explained by the high concentration of pyrite in the tailings and the occurrence of acid waters. Whereas the Monte Romero mine pond is almost completely saturated with water, in Mina Concepción it has been possible to identify the presence of inner acid water flows, the outlet of which through the damaged dyke originates a spilling of acid waters to the Odiel River. No low-resistivity water flows through the base of the ponds into the bedrock have been observed, indicating a good isolation of the base of the studied mine ponds.
The Guadalquivir River is the major water source of the south of Spain. In this work, we have selected an area, about 115 km long, from Alcalá del Rı́o to the mouth of the river, to study the effects caused by human activities on water quality. The area under study includes several sensible points as the town of Seville, the Guadiamar River (where an important mine spill took place on April 1998) and the Doñana National Park.We measured several physico-chemical variables in the 26 sampling stations located along the river, and in three different campaigns from 2001 to 2002. With the results we built the data matrix, which was analysed by factor analysis/principal components analysis (FA/PCA) and cluster analysis (CA). This analysis allowed the identification of four different zones in the river, with different water quality. The first zone (zone 1A) comprised from Alcalá del Rı́o to Seville. The second zone (zone 1B) was the city of Seville, and as a consequence, presented higher concentrations of several variables such as nitrite, ammonium or manganese. The third zone (zone 2) included from Seville to the Guadiamar River. In this area, agriculture is the main activity, and then, higher concentrations of suspended solids and phosphate were measured. In terms of water quality, this zone was partially similar to zone 1A, and partially similar to the fourth zone, starting in the Guadiamar River and finishing in the mouth of the Guadalquivir River. The water in this last zone (zone 3) is mainly estuarine water. Thus, its quality is influenced by seawater input, and also by the inputs from the Guadiamar River (coming from a mining area), and presented higher copper concentration.Three principal components were extracted, explaining the 79.1% of the data variance. PC1 (46.9% variance) was mainly associated with nitrite, ammonium and manganese. PC2 (22.5% variance) was mainly associated with suspended solids and phosphates. PC3 (9.7% variance) was mainly correlated to nitrate and copper concentration.
The breakthrough of DOC from aquifer columns was the result of complex adsorption reactions between DOC and the aquifer material. Breakthrough curves (BTCs) of the DOC were characterized by an initial rapid concentration increase followed by extended tailing to long times. The extensive tailing of the BTCs was attributed primarily to the slow adsorption kinetics of DOC to the aquifer material and the nonlinear nature of the adsorption isotherm. The time required to saturate the aquifer material with organic C was dependent on the influent DOC concentration, with lower organic influent levels requiring longer pulse durations to fully saturate the aquifer sediment with organic C. Hydrophobic constituents of the DOC were preferentially adsorbed while hydrophilic components were rapidly transported through the aquifer columns. Spectral analysis (light absorbance at 260 nm) of the column effluents confirmed that the composition of the moboile organic C changed during the breakthrough of DOC. Data from this investigation demonstrate that DOC can be mobile in soil systems, and emphasizes the need to evaluate the co-transport of pollutants by DOC. -from Authors
This study deals with the experimental determination of the rate of weathering and As release from Au-bearing sulfide ores of the Mokrsko-West deposit (Czech Republic). The elevated As contents in the ore and the possible As mobilisation must be taken into account due to the close proximity of the deposit to the Vltava River, a source of drinking water for Prague. Crushed and homogenized ore material was divided into four grain-size fractions showing uniform chemical and mineralogical composition and subjected to batch and column leaching experiments. The most important reactions controlling metal leaching include (i) oxidation of sulfides, (ii) carbonate equilibrium and (iii) precipitation of hydrated ferric oxides (HFO). Hydrated ferric oxides were found to be important sorbents of mobilized As. The highest concentration of As in the leachates was obtained from the 64–1000 μm fraction. The oxidation rate in the agitated batch experiment calculated on the basis of sulfate concentrations is an order of magnitude higher (3.8×10−9 to 4.4×10−8 mol SO42− h−1 g−1) than in the static column experiment (9.6×10−10 to 7.4×10−9 mol SO42− h−1 g−1). The higher oxidation rate of batch experiments is explained by abrasion of oxidation products (mainly HFO) and by further exposition of reaction surfaces of the sulfide grains.
Mediterranean climates are characterized by winter rains — with some months of excess rainfall over evatranspiration, warm and dry summer months with moisutre deficits — drying out soils and their annual vegetation (xeric moisture regime). They are found on western parts of all continents, between the cooler temperature zone and the hot dry desert zone. The largest Mediterranean region, surrounding the Mediterranean Sea extends over 4,300,000 km2 and exhibits a wide variety of soils and geo-ecosystems.
Characteristics landscape attributes are the high proportion of mountains with sleep slopes, significant additions of Saharan desert dust to practically all soils of the region, and a large proportion of limestone and other calcareous rocks as soil parent materials. Characteristics soil behavior features are moderate weathering with pervection (leaching, lessivage) of mostly 2:1 clays into B horizons (Xeralfs:Luvisols), hematite-induced reddening of the clays due to summer dehydration of free iron oxyhydroxides, carbonate dissolution and reprecipitation with prevalence of calcic horizons (Xerolls; Calcisols) in semiarid regions, and development of Vertisols, mostly in lowlands, where deep layers of swelling/cracking clays have sedimented. Shallows soils on nearly bare slopes, mostly a result of erosion subsequent to deforestation, are frequent (Leptosols, Cambiosols; Inceptisols, Entisols). Red (or Brown) Mediterranean soils are no longer used as a separate classification group in modern, well defined, soil property-controlled taxonomies (Soil Taxonomy; FAO system), but were partially replaced by Duchaufour's term Fersiallitic soils in some classification systems. Terra Rossa continues to be used in some classification for hard limestone derived red soils, mostly shallow.
The effects of man's past and current interference with the lanscape are pervasive in most regions, and predictions for possible future effects on the soils and ecosystems, due to greenhouse gas induced warming and rainfall change, are partly negative, partly still too uncertain.
This study constitutes a first stage of the elaboration of a concept for setting up capillary barriers composed of reactive tailings and alkaline industrial wastes. The aim of this barrier is (1) short-term mitigation by neutralising acid produced by Fe sulfides and (2) long-term mitigation by stabilisation of secondary products. The alkaline industrial wastes, cement kiln dust (CKD) and red mud bauxite (RMB), are used to produce neutral conditions. A series of time-controlled static leaching experiments were performed. Samples of reactive tailings were prepared containing 0, 2, 5, and 10% alkaline material. The water:solid ratios were also varied (3:1, 6:1, and 20:1) in order to characterise the geochemical balance between liquid and solid phases. The data are used to discern whether mineral solubility controls exist for particular ions. The pH results show that the use of 5% CKD, 10% CKD and 10% (CKD+RMB) allows neutral pH conditions to be maintained in the reactive layer. At these percentages, the concentrations of Al, Fe, Cu, Zn and SO4 in solution are significantly reduced compared with those obtained with the reactive tailings only. Aluminum concentrations are principally controlled by secondary phases like boehmite and gibbsite; Fe, by goethite and ferrihydrite; Cu and Zn, by hydroxides. Calcium and SO4 concentrations are controlled by precipitation of gypsum. The concentrations of Na and K are found not to be controlled by mineral solubility.
Electrical resistivity tomography (ERI) and ground-penetrating radar (GPR) surveys have been combined to investigate different volcanic materials, their contacts (lava flows, pyroclastic deposits, dykes) and structures (lava tubes, faults) in Tenerife (Canary Islands). The EM waves mean velocities estimated for the different rocks range from 0.075 to 0.1 m ns−1. Non-consolidated materials such as hydromagmatic, pyroclastic and airfall deposits display the lowest EM mean velocities, whereas massive and consolidated materials, mainly lava flows, show the fastest ones. The higher resistivity values (>800–1000 Ω m) correspond to lava flows, the intermediate resistivity values (∼100–800 Ω m) are related to different types of non-consolidated deposits (pyroclastic or explosive deposits), and the lower resistivity values (5–50 Ω m) correspond to fine grained volcanic materials (altered ignimbrite and hydrovolcanic). ERI usually provides a good definition of the boundaries between the volcanic units, shows a better performance than GPR to locate structures such as lava tubes and faults, and also gives a direct estimation of depth. The resistivity models are better defined if two different datasets obtained from dipole–dipole and Wenner arrays are combined prior to the inversion procedure. On the other hand, due to its greater horizontal and vertical resolution, the GPR technique is the most effective to characterize the internal structure of the volcanic deposits. However, a very strong attenuation of the EM waves has been observed in relation to the pyroclastic deposits, which makes the GPR unable to locate internal boundaries at depths as shallow as 2 m. This problem may also derive from the choice of the frequency antennae. If this is correct, then different antenna frequencies would have produced different results.
Burgos, Pilar Madejon, Engracia Perez-de-Mora, Alfredo Cabrera, Francisco
Geoelectrical methods are applied to map the resistivity structure of the underground. Rock resistivity is of special interest for hydrogeological purposes: it allows, e.g., to discriminate between fresh water and salt water, between soft-rock sandy aquifers and clayey material, between hardrock porous/fractured aquifers and low-permeable claystones and marlstones, and between water-bearing fractured rock and its solid host rock. These applications are discussed in Chaps. 14 – 19. In this chapter, the basic principles, the field techniques, and the data evaluation and interpretation procedures of resistivity measurements are shown.
When sewage sludge is applied to land for disposal or intended beneficial use, heavy metals accumulate in the soil. Because of the concern about the environmental danger that these sludge-borne metals could represent if mobilized, many studies have been undertaken in an attempt to clarify the different factors that contribute to metal solubility, plant uptake, and leachability. The objectives of this study were to determine if two independent factors - soluble organic chelators and preferential flow paths - enhance metal mobility through soil.
Dilute solutions containing CdCl2, ZnCl2, CuCl2, and Pb(NO3)2 were applied to soil columns with a rainmaker, and leachate metals and chloride concentrations were measured. For four columns, the input metal concentrations (mg L-1) were 7.25 Cd, 4.55 Zn, 3.51 Cu, and 13.85 Pb. In four other columns, the solution also contained dissolved organic matter so that the metals were organically complexed, and input metal concentrations (mg L-1) were 6.30 Cd, 4.11 Zn, 3.19 Cu, and 12.55 Pb. For each treatment, two of the four soil columns were undisturbed and two were constructed from homogenized soils. The rate of continuous solution application was approximately 3 cm/day.
The undisturbed soil columns treated with organically complexed metals had peak effluent concentrations, expressed as percent of influent, of 30, 26, 28, and 27% for Cd, Zn, Cu, and Pb, respectively. Peak effluent concentrations for undisturbed columns treated with metals in water were 30 and 23% of influent concentrations for Cd and Zn, but only 15 and 12% for Cu and Pb, respectively. However, the four homogenized soil columns retained all added metals, whether the metals were added in water or as organic complexes. The results indicate that previous laboratory metal leaching studies performed on homogenous soils might have greatly underestimated metal mobility in the field and that preferential flow, both alone and in combination with organic-facilitated transport, can accelerate metal leaching through soils.
The sorption and mobility of trace metals in calcareous soils (calcaric Fluvisols) were studied in experimental columns using nine soil samples extracted from Ap and AC horizons, under laboratory conditions. A contaminating solution with six heavy metals at identical concentrations (350 mg kg − 1 for each metal) was used to saturate the soil columns, and after the contamination assay two successive washes with de-ionized water were performed. Sorption rates were high for all the metals, higher than 90%. However, competition between metals resulted in greater retention of Cr, Cu and Pb than Ni, Zn and Cd. The data on mobility showed that Cr and Pb (values of K d 5.6 × 10 4 and 8.1 × 10 4 , respectively) were the least mobile metals, Cu and Zn had intermediate values (values of K d 6.9 × 10 3 and 4.8 × 10 3 , respectively), and Ni and Cd were the most mobile (values of K d 8.2 × 10 2 and 7.2× 10 2 , respectively). The mineralogy of the soil constituents was the main factor determining the retention of the metals applied. The differences observed between the soil samples, in both the retention and liberation phases, could not be linked to the properties used to characterize them.
ZapataEngineering, Blackhawk Division performed geophysical void detection demonstrations for the US Department of Labor Mine Safety and Health Administration (MSHA). The objective was to advance current state-of-practices of geophysical technologies for detecting underground mine voids. This paper describes the results of the geophysical demonstrations conducted at a known abandoned underground coal mine in eastern Illinois (Hanna, et al, 2006). The presence of old mine works above, adjacent, or below an active mine presents major health and safety hazards to miners who have inadvertently cut into locations with such features. In addition, the presence of abandoned mines beneath roadways has a great impact on the performance of the transportation infrastructure in terms of cost and public safety. Both are of major concern to the state Departments of Transportation (DOT's). Roads constructed over abandoned mines are subject to potential differential settlement, subsidence, sinkholes, and/or catastrophic collapse. Thus, there is a need to utilize geophysical imaging technologies to map and locate old mine works.
This publication is an introductory text describing the developing field of environmental geophysics. It contains case histories with examples from Australia, North America, Antarctica, Europe and China. Also included are chapters on detailed survey design, ground penetrating radar, electro-magnetic methods in environmental applications, electrical sub-surface imaging, spectral induced polarisation, and high resolution engineering reflection seismology. In this publication the greatest emphasis is given to the use of geophysics in civil engineering and in environmental and groundwater investigations.
Because of the high degree of automation in the coal mining industry in the Ruhr area, Germany, about 1 metric ton of crushed rock/colliery spoil is brought to the surface for every metric ton of coal. Most of the colliery spoil disposed of must be dumped. These colliery spoil dumps are anthropogenic geological sediment bodies, which have a characteristic facies resulting from geological, technical, and economical factors connected with the formation of the dumps. The relation between the facies of the dumps and these factors, for example, is examplified with the pyrite content within the colliery spoil. Pyrite content within the dumps is dependent both on the conditions during sedimentation and (early) diagenesis and the techniques used for mining and processing. Thus, this geologic-technical facies of the dumps controls the weathering processes on and in dumps. These humaninduced processes are mainly responsible for the environmental impact on soil and groundwater. Oxidation of pyrite as well as alteration of pyrite under anoxic conditions yields dissolution of carbonates, accompanied by gypsum formation, by acid attack and strong acidification takes place.
This paper contributes to increase the knowledge of the contents and sources of heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni,
Pb and Zn) to agricultural soils in Castell??n province (Spain), a representative area of the European Mediterranean region.
The surface horizons of 77 agricultural soils under vegetable crops were sampled and heavy metals were analysed by atomic
absorption spectroscopy (AAS) after microwave extraction using the USEPA 3051A method. Mean heavy metal contents were similar
to those obtained in other areas of this region. However, heavy metal contents (e.g. Cr, Pb) in some soils were above the
maximum limit set in the 86/278/CEE Directive. Multivariate analysis (correlation analysis and principal component analysis
??? PCA) was performed so as to identify the sources of heavy metals to soils. Co, Fe and Ni were highly correlated amongst
them (r???>???0.800; p??? ???0.500; p??? ???0.200; p??? ???0.400; p??? ??????0.400; p??? ??????0.300; p???<???0.01) were observed. Anthropogenic elements were less correlated with soils properties, since these elements are generally
more mobile because they form more soluble chemical species associated to anthropogenic sources. Particularly, no correlation
was found between Cd and Zn and soil properties. These findings extend results achieved in other parts of the region, highlighting
the need to set soil quality standards in order to declare soils affected by anthropogenic pollution, particularly in the
case of anthropogenic metals such as Cd, Cu and Pb, and also Cr and Zn in some areas. Further knowledge from other areas in
this region would improve the basis for proposing such standards at regional level, which is a priority objective in Europe
according to the European Thematic Strategy for Soil Protection.
The remediation of contaminated sites, legacies of past industrial activities, requires more or less complex and costly measures depending on the nature and extent of contamination, the environmental protection legislation currently in force, the anticipated future use and the commercial value of the land. Remedial action involves implementing techniques capable of removing or containing the contaminants to prevent them from migrating to surrounding areas. Here we explore the possibility of using red muds, bauxite ore processing waste, and/or fly ash produced by coal fired power stations for immobilizing the heavy metals contained in severely contaminated soils. The results of laboratory column leaching demonstrate that relatively small additions of fly ash or red muds, or a combination of the two, to the contaminated soils drastically reduces the heavy metal content in the effluent.
Limestone addition is a commonly applied technique to prevent acid generation from sulphidic wastes containing 1–10% S. In the present paper, the effectiveness of small amounts, lower than the stoichiometric requirement, of this alkaline additive in inhibiting acid generation from a pyrite concentrate material is studied. Long term laboratory column tests were conducted on a partially oxidised pyrite concentrate, where limestone was added by thoroughly mixing. The amount of alkaline additive ranged from 6.4 to 29% wt. corresponding to 5–30% of the stoichiometric quantity. The performance of the pyrite-limestone mixtures was evaluated by monitoring the drainage quality of the columns. Furthermore, a detailed geochemical characterisation of the column solid residues was performed after a monitoring period of 270 days. The effect of secondary oxidation-neutralisation products on the hydraulic conductivity of material was also examined. Dissolution of previously formed oxidation products occurred in the control column during the monitoring period, resulting in the release of a significant amount of Fe, Zn, Mn, Cd, As and SO4 and to a lesser extent Pb. However, due to the presence of secondary products, further oxidation of pyrite particles was delayed. The experimental results showed that homogeneous mixing of pyrite with limestone amounting to only a fraction of the contained acidity inhibited the generation of acidic drainage and significantly reduced the dissolved amount of metals and sulphates for a test period of 270 days. Under the alkaline conditions prevailing in the limestone amended columns, secondary precipitation of ferric hydroxides and gypsum occurred. A ten fold decrease of hydraulic conductivity was observed for the material amended with 207 kg CaCO3/t, corresponding to 15% of the contained acidity.
Mine tailings are ubiquitous in the landscapes of mined areas. Metal solubilities were compared in two chemically distinct mine tailings from the old Mining District of Cartagena-La Unión (SE Spain). One of the tailings was acidic (pH 3.0) with 5400 mg/kg Zn, 1900 mg/kg As and 7000 mg/kg Pb. The other was neutral (pH 7.4) with 9100 mg/kg Zn, 5200 mg/kg Pb and 350 mg/kg As. In samples from the acidic tailings, more than 15% of the Zn and 55% of the Cd were extractable with 0.1 M NaNO3, and distilled water. In the neutral tailings, using the same reagents, less than 1% of the metals were extractable. A sequential extraction procedure revealed that the sum of the residual and the Fe oxide fractions of Cu, Zn and Pb comprised 80–95% in the acidic tailings and 70–90% in the neutral tailings. The acidic mine tailings had a higher metal solubility, resulting in more metal leaching in the short-term, but also a higher fraction of inert metal. In contrast, in the neutral tailings, the metals were evenly distributed between, oxides and the residual fraction. This implies lower metal mobility in the short-term, but that metal mobility may increase in the long-term. When applied to mine tailings, sequential extractions may provide misleading results because the strong cation exchange capacity of some extractants may induce pH changes and thereby significantly change metal solubility.
This paper deals with the behaviour in a tailings pond of the residues produced during the flotation of a complex sulphide ore. The composition of the tailing was essentially pyrite (63.4%) with minor amounts of Cu, Pb and Zn sulphides (1.4, 0.5 and 0.8, respectively). In addition, sulphite ion and other thiosalts were present in the liquid phase. These reducing products were added at the flotation plant in order to prevent undesirable oxidations. The presence of these reducing products controlled the redox potential of the system, inhibiting oxidation reactions. A laboratory column was used to simulate the evolution of the tailings in the pond. Distilled water was added at the top of the column; the water flowed across the tailings and finally was collected at the bottom for its chemical and microbiological analysis. The actual situation in the industrial site was reproduced by a model consisting of tow columns: one (column S) was the part of the ore under water, and the other (column H–S) was the part of the ore subject to humidity and dryness cycles. These two tests reproduced the system very well: the submerged pyrite did not produce acidic water but the ore exposed to humidity and dryness cycles generated drainages with pH near to 2. The metal and sulphate concentrations were consistent with this.The influence of two other factors was also studied: bacterial activity and the height of solid residue inside the columns. The tests showed that the presence of active bacteria intensified the weathering of the residue and that, when the height of the ore in the column decreased, solid weathering also intensified.Finally, a third factor taken into account was the presence of products with reducing activity associated with the ore as a consequence of the flotation process. This combined action affected the behaviour of the residue, which was also reproduced successfully with the assayed laboratory columns.
Cadmium (Cd) is of no known essential biological function and is toxic to plants and animals. Leaching of Cd through soil profiles has implications for both its accumulation in subsoil or contamination of ground-water. We measured adsorption and transport of Cd in the presence of Ca and Na salts of varying ionic strengths using batch and miscible displacement techniques. Two variable charge soils, an Oxisol and an Alfisol, were used in this study. The Alfisol, despite its lower clay content, showed an adsorption coefficient (K) that was four times higher than the clay-rich Oxisol. Such a difference in adsorption was attributed to the presence of 2 : 1 layer silicate minerals in the Alfisol and the consequent high surface negative charge density. In column experiments, a marked effect of ionic strength on the breakthrough curves (BTCs) of Cd was observed when the concentrations of NaNO3 were increased from 0.03 M to 0.15 M in the background solutions. This increase caused nearly four times faster movement of Cd through the Oxisol soil column. The effect of increasing Ca(NO3)2 concentration on Cd adsorption and transport was relatively less pronounced than that recorded for the NaNO3 solution. In the Alfisol, the increase in Ca(NO3)2 ionic strength from 0.05 M to 0.25 M resulted in four-fold smaller adsorption coefficient. For both soils, the movement of Cd at a constant ionic strength was, however, an order of magnitude faster in the presence of Ca(NO3)2 than that in the presence of NaNO3. To describe the combined effect of ionic strength and pH, we used the K values calculated from the BTCs with CXTFIT model to develop a simple theoretical relationship between Cd adsorption and [H+], [Ca2+] and [Cd2+] in solution. The relation was found to be consistent with other published studies. The study demonstrated that Cd mobility in soils is strongly affected by the soil solution composition (ionic strength and type of cations).
A water exploration in a karst area can be hardly imagined without the application of electrical and seismic methods, but karst areas are very difficult environments for any geophysical exploration due to very high surface nonhomogeneities. Dual gradient mapping (measurements performed at two depth levels), two-dimensional (2-D) resistivity imaging, refraction methods and high-resolution reflection methods have been applied on a characteristic karst case in Croatia. General overview on the subsurface resistivity distribution has been reached by using the gradient mapping measurements. This revealed low-resistivity zone points of the fractured rock filled with water. Map of relative changes of apparent resistivities with depth discovers two different zones: resistivity increases with depth in the eastern part and resistivity decreases with depth in the western part of the area. Weak reflections are seen in the stacked seismic reflection section placed with the 2-D resistivity imaging profile, but they can be followed along the entire profile. By combining refraction and reflection data, faulted and fractured zones can be determined at surface as well as at greater depths, which will enable a precise definition of their extensions. Two-dimensional inverse seismic modelling have been carried out to clarify significance of the main reflection horizon, which is probably caused by a lithologic boundary, meaning a contact of dolomites and compact limestones. The model of acoustic impedancies has been derived on the basis of refraction velocities, reflection velocities and geological data from borehole. An accurate geological model has been established on the basis of all the data.Two-dimensional resistivity surveying can be used very efficiently in karst water explorations of shallow targets, but for deeper targets the seismic methods can be very useful by reason of poor resolution of the electrical resistivity methods.
Bioavailability of heavy metals in metal-contaminated soils depends on physical, chemical and biological factors. Physical (structure, penetrability) and chemical factors (Eh, pH, speciation, concentration) give the framework in which biological factors can modify the metal availability by release of oxygen, protons, and organic acids and by association with mycorrhizal fungi. With these conditions in mind, the possibilities of the use of hyperaccumulating higher plants for the decontamination of metal polluted soils, i.e. phytoremediation, are explored.By small scale experiments it has been demonstrated that at present phytoremediation is only an economically important clean-up technique for slightly contaminated soils. Heavily contaminated soils can only be revegetated using highly metal-resistant plants.
Completely revised and updated, this new edition of the popular and highly regarded textbook, Applied Geophysics, describes the physical methods involve din exploration for hydrocarbons and minerals. These tools include gravity, magnetic, seismic, electrical, electromagnetic, and radioactivity studies. All aspects of these methods are described, including theoretical considerations,data acquisition, and data processing and interpretation, with the objective of locating concentrations of natural resources and defining their extent. In the past fourteen years or so since the writing of Applied Geophysics, there have been many changes in the field of exploration geophysics. The authors give full treatment to changes in this field, which include improved techniques for calculating gravity fields, the use of proton-precession and optically-pumped magnetometers, improved quality of seismic data,magnetotelluric as a practical exploration method, new electromagnetic exploration methods, the use of gamma-ray sp
Problems associated with heavy metal characterization in the majority of sites are often due to multiple sources of pollution. This work presents the results through the use of advanced statistical techniques to identify sources of soil heavy metals in a typical Mediterranean city. The multivariable analysis performed on seven metals identified four sources controlling their variability. Cr, Mn, and Ni contents were associated to soil parent materials; Cd and Pb contents were related to anthropogenic activities, specifically industrial activities and traffic; Cu content is controlled by long-term application of inorganic fertilizers in agricultural areas. Finally, zinc concentration is associated to commercial and outdoor activities in the area. These results were supported by the fact that metals associated to parent material (Cr, Mn, and Ni) were better correlated with soil lithogenic properties, while anthropogenic metals were correlated with more variable soil constituents.