[Show abstract][Hide abstract] ABSTRACT: Although climatic conditions of subtropical regions support fast biochemical degradation of soil organic matter (SOM), some of their soils reveal dark umbric horizons with considerably high organic C contents. Since such soils can reach a depth of several meters a better understanding of the processes involved in the humification of its SOM is essential for an improved elucidation of the impact of the hot and humid conditions of subtropical regions on global C cycling. Therefore, the SOM of three Umbric Ferralsols from Brazil was characterized for its quantity and chemical composition as a function of soil depth. Solid-state 13C nuclear magnetic resonance (NMR) spectra revealed an increase of the aromaticity with soil depth to exceptionally high values between 40 and 70% of the SOM. Chemical oxidation of the SOM with acid potassium dichromate confirmed that a major part of this C group is attributable to pyrogenic organic matter (PyOM). High carboxyl-C contents between 13 and 21% of the total organic C in the subsoils showed that their PyOM is strongly oxidized, most likely due to previous intense biochemical reworking. Since the latter improves the water solubility of the formerly hydrophobic charcoal residues, such oxidized PyOM can be transported with the soil solution into deeper soil horizons. As indicated by the pattern of the 13C NMR spectra and the high C contents of the subsoil, the partially degraded PyOM seems to have lost its attractiveness to microbial attack with ongoing downward movement and accumulation. Correlating parameters of organic matter with those of soil mineralogy suggested that in addition to stabilization by the mineral phase other mechanisms must have contributed to the persistence of PyOM in the studied soils. Considering that in soils, microbial degradation of aromatic structures is mainly performed by lignolytic and aerobic organisms, we suggest that increasing oxygen depletion and unfavorable living conditions in the deeper soil regions decreased the activity of those organisms. This enhanced the biochemical recalcitrance of the aromatic PyOM whereas non-pyrogenic SOM was still subjected to degradation although most likely at a slower rate. As a consequence, the selective preservation of PyOM shifted not only the quality of the subsoil SOM toward higher aromaticity but also increased its quantity. Based on our results, we concluded that downward translocation of partially degraded PyOM and its subsequent accumulation represent important processes in soil systems which are frequently affected by fires.
[Show abstract][Hide abstract] ABSTRACT: The aimof this studywas to explore the effects of plants on the underlying substrate and the possible environmental implications of such effects in an extreme environment. For this purpose, we sampled the rhizosphere soil of Bolax gummifera, which is one of the most characteristic vascular plants in the Martial Mountains (Tierra del Fuego, Argentina) where plant cover is typically sparse. Superficial (0–5 cm, Rh5) and subsuperficial (5–15 cm, Rh15) samples of B. gummifera rhizosphere and bulk soil were collected from a small homogeneous area, and the following parameters were analyzed: particle size, pH, total organic carbon (TOC), total nitrogen (TN), total Fe (TFe), Fe and Al associated with organic matter (soluble in sodium pyrophosphate, Cpyro), amorphous Fe oxyhydroxides (extracted with ammonium oxalate, Feoxa), crystalline Fe oxyhydroxides (extracted with sodium dithionite, Fedit), bioavailable plant nutrients (soluble in Mehlich 3 extractant) and claymineralogy. Several differences were found between rhizosphere soil (RS) and bulk soil. The TOC was 8 times higher and the TN and Cpyro were 4 times higher in the rhizosphere than in the bulk soil. Mineralogical results suggest a slightly higher degree of chemical weathering (mainly affecting biotite and amphibole minerals) in the RS than in bulk soil, consistent with significantly higher nutrient bioavailability in RS (Ca, Mg, K, Co, and Fe). On the other hand, the higher concentrations of C and metals extracted with sodium pyrophosphate suggest the formation of more metal–organic complexes in the rhizosphere than in the bulk soil. This metal fraction is considered as readily mobilizable and available and can be leached from the soil to continental and coastal waters. This effect will be enhanced in cold climates by expansion of plant cover due to the increased temperature expected under climate change.
[Show abstract][Hide abstract] ABSTRACT: Purpose São Domingos mine area (Portuguese Iberian Pyrite Belt) contains several mine wastes with different environmental hazard which are disposed irregularly over a large area. This study aimed to evaluate the following: (1) soil enzymatic activities, chemical quality of leachates and Cistus ladanifer germination in Technosols composed of gossan or sulfide wastes from the mine and amendment mixtures (organic and inorganic); (2) the efficiency of a layer of gossan over sulfide wastes to improve rehabilitation of the more hazardous waste. Materials and methods Technosols were composed of gossan or sulfide wastes and amendment mixtures, at 12 and 30 g/kg, containing organic/inorganic wastes from agriculture and distilleries in equal proportion. Three microcosm assays, under controlled conditions, were carried out: Gossan/sulfide wastes and respective Technosols (assays 1-2); (assay 3) Sulfide wastes, with/without amendments, incubated during 4 months and then with an application of a thin overlayer of gossan with/without the same amendments. Cistus ladanifer was sown in half of the pots from each treatment while the remainder was left bare. After 3 and 9 months of incubation, composite samples of the materials were collected and dehydrogenase, acid phosphatase and β-glucosidase activities were determined. In same sampling periods, percolation leachates were analysed for anions and cations concentrations, pH and electrical conductivity. Results and discussion Technosols with gossan wastes were significantly different (p 4) in leachates from Technosols with sulfide wastes were reduced (>50 % of EC and 23-99 % depending on element, Technosol and sampling period), the amendments did not prevent sulfide oxidation and acid generation, improve enzymatic activities or allow seed germination. Higher elements concentrations in leachates were obtained with the overlapping of two Technosols or mine wastes, compared to the leachates from assays with a single mine waste. Application of a gossan/Technosol layer over sulfide wastes allowed C. ladanifer germination but plants died after ≈50 days. Conclusions The use of Technosols derived from gossan or sulfide wastes may be an efficient solution for rehabilitation of these mine wastes. However, the results with sulfide wastes were not encouraging. The use of a Technosol obtained from gossan wastes seems be a promising approach to isolate sulfide wastes from air and initiate their revegetation, but this technology requires further improvements, namely to prevent the ascension of salts by capillarity.
No preview · Article · Mar 2015 · Journal of Soils and Sediments
[Show abstract][Hide abstract] ABSTRACT: La mina de Touro, está ubicada entre los municipios de O Pino y Touro, en la provincia de A Coruña, en la Comunidad Autónoma de Galicia, al Noroccidente de España. Fue explotada para la extracción de Cobre, a partir del yacimiento de sulfuros metálicos, definiendo las cortas de Bama, Brandelos, Arinteiro y Vieiro. Debido a la presencia de minerales como la pirita, pirrotina y calcopirita se generaron drenajes ácidos. Para la recuperación de la mina se desarrolló un proyecto innovador, aplicando el concepto de Tecnosoles "a la carta" y humedales reactivos. Estos Tecnosoles son diseñados técnicamente y elaborados a partir de residuos no peligrosos, con la finalidad de recuperar los suelos contaminados y las aguas ácidas. En la actualidad (2014) en la mina de Touro, la aplicación de los Tecnosoles han permitido que existan poblaciones animales y vegetales, así como también se han reducidos al mínimo las zonas con aguas ácidas.
[Show abstract][Hide abstract] ABSTRACT: The potentially hazardous effects of rock wastes disposed at open pit in three different areas (Pr: Ore processing; Wr: Waste rock and Bd: Border) of an abandoned copper mine were evaluated in this study, with emphasis on acid drainage generation, metal contamination and copper geochemical dynamics in soils. Samples of waste rock were analyzed by Energy dispersive X-ray fluorescence (XRF), scanning electron microscopy with microanalysis (SEM-EDS) and X-ray diffraction (XRD). Soil samples were analyzed to determine the total metal contents (XRF), mineralogy (XRD), pH (H2O and H2O2), organic and inorganic carbon, % of total N, S and P, particle size, and a sequential extraction procedure was used to identify the different copper fractions. As a result of the prevalence of carbonates over sulphides in the wastes, the soil pH remained close to neutral, with absence of acid mine drainage. The geochemical interaction between these mineral phases seems to be the main mechanism to release Cu(2)(+) ions. Total Cu in soils from the Pr area reached 11,180mg.kg(-1), while in Wr and Bd areas the values reached, on average, 4683 and 1086mg.kg(-1), respectively, indicating a very high level of soil contamination. In the Pr and Wr, the Cu was mainly associated with carbonates and amorphous iron oxides. In the Bd areas, the presence of vegetation has influenced the geochemical behavior of copper by increasing the dissolution of carbonates, affecting the buffer capacity of soils against sulphide oxidation, reducing the pH levels and enhancing the proportion of exchangeable and organic bound Cu. The present findings show that the use of plants or organic amendments in mine sites with high concentration of Cu carbonate-containing wastes should be viewed with caution, as the practice may enhance the mobilization of copper to the environment due to an increase in the rate of carbonates dissolution.
Full-text · Article · Sep 2014 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Greenhouse pot experiments were conducted over 13 months to evaluate the effect of two amendment mixture doses (30 and 75 Mg/ha) on the geochemical dispersion of trace elements by leaching hazardous mine wastes from the São Domingos mine. Mineralogical evolution of these materials was also evaluated. Amendment mixtures containing solid wastes from agriculture (plant remains + strawberry substrate and rockwool used for the strawberry crop) and from distillation of Ceratonia siliqua L. and Arbutus unedo L. fruits were used to improve the chemical characteristics of leachates from sulfide mine wastes. Sulfide mine wastes had acidic characteristics, as well as high electrical conductivity and total element concentrations (g/kg; Al: 54.8–61.2; Fe: 104.0–110.0; Pb: 9.0–13.8; S: 63.6–68.0; As: ≈ 1). These features contributed to the large capacity for leaching of hazardous elements during, at least, the first four months of incubation. In the seventh month of incubation, there was a significant decrease in the leachate concentration of the majority of hazardous elements. The addition of amendments minimised trace element dispersion in leachate percolation during the first seven months (25 to 99% reduction compared to control, depending on the element and sampling period). However, the leachate characteristics were not influenced by amendment doses and no significant differences were observed in leachate composition (control and amended treatments) after 13 months. Amendment application led to differences between the solid phases of the efflorescent salts formed on the surface of the control and the amended treatments. The efflorescent salts contained very soluble aluminium sulfates, together with alunite–jarosite-group solid phases in amended samples, and copiapite-group solid phases in control. In the core materials (5 to 10 cm in depth), the mineralogy was similar in both control and amended samples. The presence of various stable solid phases from alunite–jarosite-group, such as jarosite and beudantite (mainly in deeper materials), can explain the low concentrations of trace elements in the leachates after thirteen months.
[Show abstract][Hide abstract] ABSTRACT: 1. Introduction – The purpose of this research has been the application of Technosols as a complement to treatment of wastewater. The project was developed on a farm which has wine production, between 400000 and 600000 bottles per year, in addition, on weekends and holidays have social and cultural events with a maximum capacity of 350 people, generating specific increases for flows wastewater. According to the law, the Authority requires the treatment of the wastewater generated. In the area there is no public sewer system, so by mutual agreement specifies a point on a tributary to the river Umia. Treatment plant had a dosing chamber, which tries to maintain a constant flow into a digester fed by gravity settling tanks. Then the water goes to the first zone vertical flow wetland, and then goes to 3 horizontal flow wetlands. Above them were planted emergent macrophytes such as reeds (Phragmites), espadana (Typha) and bulrush (Scirpus), with a density of 3 units per square meter, all typical of wetlands. The control parameters detected early problems just start operation. Designers proposed expanding the size of the treatment plant, which is geometric and economically unfeasible. You could not have residual surface water due to the use of the farm hospitality. Neither can increase the area of wetlands, because the surrounding areas have other specific uses. According to the described problem, the main objective of the project was to contribute to the process of treatment of urban waste water by applying Technosols in horizontal flow wetlands. With previous successful experiences in which Technosols have served to improve water quality [1, 2, 3]. The proposal was to modify the configuration of the horizontal flow wetlands. For Tecnosol layer was applied, adding tifa type plants (Typha latifolia) and modified internal geometry to increase the path length and residence time, all this, in order to constantly evaluate the evolution of the parameters quality.
[Show abstract][Hide abstract] ABSTRACT: Este estudo teve como objectivo avaliar, em ensaios em vaso, a eficiência de uma fitorremediação combinada de escombreiras de pirite e gossan através da aplicação de resíduos orgânicos e inorgânicos e desenvolvimento de Lavandula luisieri (Rozeira) Rivas-Martinez. Quatro Tecnossolos, contendo materiais de escombreira de gossan e misturas de resíduos orgânicos e inorgânicos a 75 e 150 Mg/ha, foram aplicados sobre uma camada de cinzas de biomassa e brita calcária e estas sobre materiais de escombreira de pirite em vasos de cerca de 30 cm de altura. Nos Tecnossolos foi semeada L. luisieri cujo desenvolvimento foi monitorizado durante um ano. As características químicas dos materiais dos Tecnossolos (pH, conductividade eléctrica e concentração de multielementar na fracção disponível), antes da sementeira (após um mês de incubação) e no final do ensaio, bem como as concentrações dos mesmos elementos nas raízes e parte aérea das plantas foram determinadas.
Os Tecnossolos apresentaram, relativamente ao controlo, melhor estrutura bem como maiores valores de pH e concentrações de Corgânico e nutrientes disponíveis para as plantas. Esta melhoria das características da escombreira de gossan permitiu uma maior germinação e desenvolvimento das plantas ao longo do ensaio, independentemente do Tecnossolo usado. Apesar do aumento da concentração de Al na fracção disponível dos materiais, as plantas que aí cresceram não mostraram sinais de toxicidade. Tendo em conta a concentração dos elementos químicos na planta (no geral, as raízes apresentam concentrações semelhantes às da parte aérea, ou mesmo superiores), que são inferiores ao limite tóxico para os animais domésticos, e a ausência de sintomas de toxicidade as plantas de rosmaninho mostram ser adequadas para a fitoestabilização de escombreiras de gossan da mina de São Domingos. O isolamento natural dos materiais de escombreira de pirite e o desenvolvimento das plantas nos Tecnossolos aplicados como cobertura permitiu uma diminuição da oxidação dos sulfuretos presentes na escombreira. Consequentemente, a geração de drenagem ácida e dispersão, através dos lixiviados, de elementos potencialmente contaminantes foi fortemente atenuada ou mesmo impedida. Assim, a reabilitação integrada destes dois tipos de escombreiras mostrou ser adequada e sustentável.
[Show abstract][Hide abstract] ABSTRACT: Se determinó la capacidad máxima de adsorción de fosfatos en un Tecnosol con propiedades ándicas. El Tecnosol fue diseñado, formulado y elaborado para reducir las concentraciones de P en sistemas acuáticos, contribuyendo a la reducción de la eutrofización y sus consecuencias nocivas. Después de seis meses sumergido en aguas del río Limia, la capacidad de adsorción del Tecnosol apena disminuyó. Por este motivo, se decidió realizar un ensayo de adsorción en laboratorio y someter el Tecnosol a ciclos de aporte de P. Para simular condiciones naturales en aguas eutrofizadas, los ensayos se realizaron con concentraciones de 1 mg.L-1, mientras que para monitorizar la respuesta a condiciones extremas se añadieron también dosis de 100 mg.L-1 en paralelo. Para contrastar el efecto que tuvo ese periodo sumergido en agua sobre el Tecnosol se utilizaron dos grupos de muestras: el Tecnosol usado y el mismo Tecnosol conservado sin uso. La máxima de adsorción del Tecnosol sin usar puede llegar a 7500 mg.kg-1.
[Show abstract][Hide abstract] ABSTRACT: Wastewater discharge from shrimp farming is one of the main causes of eutrophication in mangrove ecosystems. We investigated the phosphorus (P) geochemistry in mangrove soils affected by shrimp farming effluents by carrying out a seasonal study of two mangrove forests (a control site (CS); a site affected by shrimp farm effluents (SF)). We determined the soil pH, redox potential (Eh), total organic carbon (TOC), total phosphorus (TP), and dissolved P. We also carried out sequential extraction of the P-solid phases. In SF, the effluents affected the soil physicochemical conditions, resulting in lower Eh and higher pH, as well as lower TOC and higher TP than in CS. Organic P forms were dominant in both sites and seasons, although to a lesser extent in SF. The lower TOC in SF was related to the increased microbial activity and organic matter decomposition caused by fertilization. The higher amounts of P oxides in SF suggest that the effluents alter the dominance of iron and sulfate reduction in mangrove soils, generating more reactive Fe that is available for bonding to phosphates. Strong TP losses were recorded in both sites during the dry season, in association with increased amounts of exchangeable and dissolved P. The higher bioavailability of P during the dry season may be attributed to increased mineralization of organic matter and dissolution of Ca-P in response to more oxidizing and acidic conditions. The P loss has significant environmental implications regarding eutrophication and marine productivity.
Full-text · Article · May 2014 · Environmental Monitoring and Assessment
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to identify metal-tolerant plants with potential application in phytoremediation strategies. For this we evaluated the distribution and chemical fractionation of heavy metals in soils and their accumulation or exclusion by native plant species growing in an abandoned Pb/Zn mine in NW Spain. Mine-soils (I = 0–20 cm, II = 20–40 cm) and shoots of the dominant plants were sampled at 39 sampling points in a (100 m × 100 m) regular grid at two sites (mine zone (MZ) and tailing ponds (TP)).
No preview · Article · May 2014 · Applied Geochemistry
[Show abstract][Hide abstract] ABSTRACT: The purpose of this investigation was to test the application of Technosols for the prevention of contamination by slate. The excavation of materials, soil or rock, generates transport, treatment and disposal of material to another location, which will inevitably alter the relief, affecting air, species composition and even the water cycle. Both the exploration and exploitation of slate materials are frequent adverse effects on water, among which are increased acidity, concentration of pollutants (sulfates and potentially toxic metals and metalloids) and solid particles in cases discharge. The geology of Galicia has a large presence of slate with many variations due to the composition of the strata. Among the different types of items that may become mobilized shale holdings some potentially very dangerous, among which we highlight the Arsenic, Copper, Nickel, Manganese, Chromium and Vanadium. The research group has implemented several projects Technosols application. These have allowed the concept and application area, evolve from remediation projects until the current ones, which are intended to prevent pollution episodes. The common criterion is that the immobilized Technosol elements and compounds, potentially polluting. The hypothesis states take an evolutionary step in implementing Technosols now directed to use in preventing contamination of some potentially hazardous elements in conjunction with the slates of the geology of Galicia and avoid the presence of acid mine drainage. Waste in the exploitation of shale are analyzed. Of these, those that present the greatest potential risk are chosen, and necessarily need to be treated. Will take them to a specific area for this purpose. Monitoring the effect of Technosol, will be performed by analyzing samples of water leaving the treatment. Thus, we can distinguish two types of samples, rocks and water. The initial results of the study presented in this article, are positive, however it should be mentioned that monitoring, behavior Technosol, will run for at least the next 4 years.
[Show abstract][Hide abstract] ABSTRACT: Gossan wastes represent one of the most hazardous mine wastes in several mining areas from the Iberian Pyrite Belt. Phytostabilisation of mine wastes with Cistus ladanifer L. could be a good option, but its growth and germination are impaired by substrata conditions. To overcome these limitations, application of organic and inorganic amendments may speed up the growth of C. ladanifer while improving the mine wastes. This study evaluated the simultaneous influence of different application rates of amendments and growth of C. ladanifer on chemical and biological properties of gossan wastes.
No preview · Article · Apr 2014 · Journal of Geochemical Exploration
[Show abstract][Hide abstract] ABSTRACT: Los problemas de calidad del agua tienen su origen en diferentes actividades como: industria, minería, aguas residuales urbanas o agricultura, entre otras. En todas ellas se evidencia el desequilibrio producido por las actividades antrópicas, que, en muchas ocasiones, queda abandonado a soluciones de atenuación natural, de acuerdo a los componentes minerales de los materiales geológicos, la actividad biológica y el papel de filtro, reactor, reactivo y sistema tamponizante de los suelos y las condiciones hidráulicas que regulan la concentración de oxidantes o los procesos de sedimentación, ente otros efectos. Este sistema de depuración natural es, en muchos casos, insuficiente para lograr la recuperación de la calidad de las aguas en el espacio y tiempo necesario, especialmente cuando se supera la carga crítica de contaminantes del sistema suelo-agua. Los Tecnosoles son suelos, que pueden ser diseñados técnicamente (Tecnosol "a la carta"), para reforzar la capacidad de atenuación de los sistemas naturales, corregir las disfunciones existentes y aumentar la capacidad de amortiguación y la carga crítica de contaminantes del sistema suelo-agua afectado. Con estos antecedentes, el grupo de investigación ha ejecutado distintos proyectos con aplicación de Tecnosoles para recuperar aguas, suelos y ecosistemas afectados por diferentes tipos de procesos contaminantes. Se hace mención aquí de tres tipos de procesos con diferentes Tecnosoles en los que se han conseguido buenos resultados: • Drenajes Ácidos de Mina • Eutrofización • Aguas Residuales Las conclusiones de los distintos estudios han servido para ampliar el campo de acción de esta línea de investigación sobre Tecnosoles en espacios contaminados. Palabras claves: calidad de agua, tecnosol "a la carta".
[Show abstract][Hide abstract] ABSTRACT: A semi-arid mangrove estuary system in the northeast Brazilian coast (Ceará state) was selected for this study to (i) evaluate the impact of shrimp farm nutrient-rich wastewater effluents on the soil geochemistry and organic carbon (OC) storage and (ii) estimate the total amount of OC stored in mangrove soils (0–40 cm). Wastewater-affected mangrove forests were referred to as WAM and undisturbed areas as Non-WAM. Redox conditions and OC content were statistically correlated (P b 0.05) with seasonality and type of land use (WAM vs. Non-WAM). Eh values were from anoxic to oxic conditions in the wet season (from −5 to 68 mV in WAM and from b40 to N 400 mV in Non-WAM soils) and significantly higher (from 66 to 411 mV) in the dry season (P b 0.01). OC con-tents (0–40 cm soil depth) were significantly higher (P b 0.01) in the wet season than the dry season, and higher in Non-WAM soils than in WAM soils (values of 8.1 and 6.7 kg m −2 in the wet and dry seasons, respectively, for Non-WAM, and values of 3.8 and 2.9 kg m −2 in the wet and dry seasons, respectively, for WAM soils; P b 0.01). Iron partitioning was significantly dependent (P b 0.05) on type of land use, with a smaller degree of pyritization and lower Fe-pyrite presence in WAM soils compared to Non-WAM soils. Basal respiration of soil sediments was significantly influenced (P b 0.01) by type of land use with highest CO 2 flux rates measured in the WAM soils (mean values of 0.20 mg CO 2 h −1 –g −1 C vs. 0.04 mg CO 2 h −1 –g −1 C). The OC storage reduction in WAM soils was potentially caused (i) by an increase in microbial activity induced by loading of nutrient-rich effluents and (ii) by an increase of strong electron acceptors [e.g., NO 3 − ] that promote a decrease in pyrite concentration and hence a reduction in soil OC burial. The current estimated OC stored in mangrove soils (0–40 cm) in the state of Ceará is approximately 1 million t.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this investigation was to test the application of Technosols for the treatment of eutrophication by capturing phosphates from eutrophic water bodies, thereby preventing or reducing the intensity of cyanobacterial blooms. A Technosol designed specifically for phosphate adsorption was placed into permeable bags to allow contact with water. These bags were mounted onto three parallel plates on a steel structure to cover the largest possible area of the riverbed. Two tributaries of the As Conchas reservoir were chosen because of their nutrient levels. The locations of the treatment structures were determined based on their accessibility to equipment and machinery. After placement, the effect of Technosol on water quality was monitored in samples taken upstream and downstream of the point of contact with the Technosol. This study obtained the first data regarding the behavior of an experimental Technosol, designed for a specific purpose (called Technosol "a la carte," or tailor-made Technosol), e.g., for the treatment of eutrophication in field conditions. The results demonstrate Technosol's high capacity for decreasing eutrophication: phosphate concentrations were reduced after contact with the Technosol, and during the implementation period, there were no cyanobacterial blooms at the As Conchas dam downstream of the test sites.