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Map of the Rio Tinto system showing the locations of mining and polluting industries, surface sediment samples, short pound cores and the long core
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Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the
pollution of the Rio Tinto fluvial-estuarine complex, the site of Columbus' departure for the New World in 1492. Additional
sources of potential pollution include the large industrial complex at Huelva near the lower portion of...
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... of these massive sulfide deposits has been going on for about 5000 years, beginning with the Iberians and Tartessans who developed the first mine about 3000 b.c. near the present community of Nerva (Fig. 2). This un- derground, small-scale operation was followed by that of the Phoenicians (2800-2600 b.p.) and the Romans (2000-1800 b.p.). The area is the site of the beginnings of the Copper Age and the Bronze Age ( Coles and Harding 1979), and the Romans made some of their first coins from materials mined here, especially the silver and ...
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... of the Huelva area beginning in 1967. Within only a few years, operations began of (1) a huge phosphate beneficiation plant which processes raw ore from nearby Morocco and other locations, (2) a plant for processing Australian hea- vy minerals such as magnetite and ilmenite ("black sand") and (3) a large paper mill located at San Juan del Puerto (Fig. 2). Each of these industries is contributing huge volumes of pollutants to the local estuaries. The phosphate plant has produced millions of tons of phos- pho-gypsum which is piled along the west margin of the Rio Tinto estuary (Fig. 2). Tailings of the pyrite plant are similarly located and the paper plant discharges a large volume of ...
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... minerals such as magnetite and ilmenite ("black sand") and (3) a large paper mill located at San Juan del Puerto (Fig. 2). Each of these industries is contributing huge volumes of pollutants to the local estuaries. The phosphate plant has produced millions of tons of phos- pho-gypsum which is piled along the west margin of the Rio Tinto estuary (Fig. 2). Tailings of the pyrite plant are similarly located and the paper plant discharges a large volume of contaminated ...
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... Rio Tinto drainage system includes an area of 1670 km 2 and the river/estuary extends for 95 km to the mouth near Huelva. The headwaters of the river are in the area of intense mining from which the river descends from elevations near 400 m down to about 40 m at the town of Niebla (Fig. 2) below which meandering begins with a modest flood plain. The annual discharge of the Rio Tinto, as gauged at Niebla, has ranged from almost nothing to about 350 Hm 3 over the period of record (Fig. 3a). There is great variation in discharge during the hydrological year with most taking place during the wint- er whereas during the ...
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... during the hydrological year with most taking place during the wint- er whereas during the summer it is almost nothing (Fig. 3b). Floods have played a major role in the Rio Tin- to with the most recent taking place in 1995 ( Schell and others 1996). Tidal influence begins a few kilometers upstream from the community of San Juan del Puerto (Fig. 2). The es- tuarine portion of this system consists of extensive inter- tidal and supratidal flats with marsh fringes typically just above neap high tide. Mean tidal range is 2.2 m at the mouth of the estuary with some decrease upstream (Fig. 4). Water quality of this estuary is extremely poor with low tide pH values typically at 2.0-2.5. ...
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... scientific literature on the Rio Tinto is quite sparse until about 1990. During the 1990s, there was an explo- sion of research effort invested into this region, much of Hydrologic data for a long-term discharge and b annual discharge patterns over the period of 1966-1992 for the Rio Tinto taken at the town of Niebla (see Fig. 2 for location) it aimed at the pollution of the Rio Tinto and the adja- cent Odiel River. Efforts have included analyses of both the water and the sediments of the estuary but none have been very comprehensive. Although there had been considerable effort directed to- ward the ore body itself (e.g. others 1977, 1981; Klau and Large 1980) ...
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... assemblage of bacte- ria, algae and fungi inhabiting these very acidic waters. Water chemistry of the Rio Tinto has been well docu- mented and the database is growing rapidly. The local environmental authorities have been collecting water samples on a weekly basis from a single station in the middle of the estuary near the phospho-gypsum stacks ( Fig. 2) since 1977. They measure pH, dissolved oxygen and salinity, but their sampling is weekly, regardless of the tidal situation, thus giving a great range in these pa- rameters depending on tidal stage. Most of the data on water samples are from the river and estuary and few from the mining region. Published data of the analyses and the ...
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... sediment samples for geochemical analysis were taken from throughout the fluvial-estuarine system (Fig. 2). Effort was made to include sites within the min- ing area, from an apparently pristine stream near the headwaters of the Rio Tinto and from throughout the flu- vial-dominated portion of the system. Samples were also taken of the country rock in the mining area. Some limi- tations were posed by access, especially in the area of high ...
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... vial-dominated portion of the system. Samples were also taken of the country rock in the mining area. Some limi- tations were posed by access, especially in the area of high relief just below the mining areas. The estuarine portion of the system where current industry is located was sampled so as to include material from both sides of the estuary (Fig. 2). Short pound cores were taken from the channel margins of the estuary and near its upper limits. Geochemical analyses and radiometric dating were done for three vi- bracores taken from various locations in the estuary (Fig. 2). Initial geochemical analyses included the sand fraction of the samples but it was apparent that there were ...
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... of the system where current industry is located was sampled so as to include material from both sides of the estuary (Fig. 2). Short pound cores were taken from the channel margins of the estuary and near its upper limits. Geochemical analyses and radiometric dating were done for three vi- bracores taken from various locations in the estuary (Fig. 2). Initial geochemical analyses included the sand fraction of the samples but it was apparent that there were very low concentrations of pollutants in this portion of the sedi- ment, a conclusion also reached by Nelson and Lamothe (1993). The mud fraction (~63 mm) of the surface sam- ples and of two of the pound cores was analyzed for ...
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... is not present in elevated levels in the upper reaches of the Rio Tinto but it is in the estuary (Table 1). The huge beneficiation plant in the Huelva industrial complex produces both large volumes of phospho-gyp- Plots of Pb-210 analyses for four short-pound cores taken from along the tidal portion of the estuary. See Fig. 2 for locations of the cores. Note that there is no stratigraphic trend for core no. 4 and thus, no sedimentation rate was obtained for it sum waste adjacent to the estuary and discharges fluids into it. The geographic distribution of the elevated phos- phate concentrations (Table 1) extends to almost the tidal limit of the estuary at ...
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... locations of the cores. Note that there is no stratigraphic trend for core no. 4 and thus, no sedimentation rate was obtained for it sum waste adjacent to the estuary and discharges fluids into it. The geographic distribution of the elevated phos- phate concentrations (Table 1) extends to almost the tidal limit of the estuary at sample site 13B (Fig. 2). This indi- cates that the phosphate industry is polluting the Rio Tinto throughout the entire estuarine portion. It should also be noted that the analyses of the long core in the Odiel estuary adjacent to the Huelva industrial complex did not show any high levels of phosphate indi- cating that Rio Tinto waters do not travel into the ...
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... more than 100 years of the accumulation of sediment in the Rio Tinto system. The lowermost sample analyzed in each of the two cores accumulated in 1830 (2) and 1810 (3), well before the large-scale mining operations began Fig. 8 Stratigraphic geochemical data from three vibracores taken from various locations in the Rio Tinto estuary. (see Fig. 2 for locations) in the headwaters area. These data compare with the dates of large-scale copper production in the early 1880s (Harvey 1981) and the first occurrence of excess zinc in shelf cores as determined by van Geen and others (1997). Of significance is the fact that the geochemical analyses of the push-core samples show that ...
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Citations
... This river presents extreme conditions, with very high concentrations in solution of metals and metalloids and low pH values. Mining activities in the upper part of the watershed of the Río Tinto have been documented since historical times and a huge amount of widespread acid-producing mine residues exist in this area (Olias et al., 2020;Olias and Nieto 2015;Gomez-Ortiz et al., 2014;Nocete et al., 2005;Davis et al., 2000;Leblanc et al., 2000). Nevertheless, there is no consensus among the scientific community as to whether the extreme conditions of the Río Tinto are the result of natural processes or the intense mining activity in the region. ...
... Therefore, it can be classified as an extremely acidic environment. Acidic waters and mineral precipitates in the river were used by ancient civilizations as an indicator for the presence of mineral ores, as the Río Tinto area was the source of metal extraction for Phoenicians and Romans [18]. ...
... Although, for many years, it was believed that the extreme conditions of Río Tinto were due to mining activities in the area [18][19][20], there have recently been geophysical, geological, and hydrogeological studies that reported the existence of an underground bioreactor [21][22][23][24] in which the metal sulfides of the Iberian Pyrite Belt are the source of microbial energy, feeding the river with acidic waters. ...
This report describes acidic microbial mats containing cyanobacteria that are strongly associated to precipitated minerals in the source area of Río Tinto. Río Tinto (Huelva, Southwestern Spain) is an extreme acidic environment where iron and sulfur cycles play a fundamental role in sustaining the extremely low pH and the high concentration of heavy metals, while maintaining a high level of microbial diversity. These multi-layered mineral deposits are stable all year round and are characterized by a succession of thick greenish-blue and brownish layers mainly composed of natrojarosite. The temperature and absorbance above and below the mineral precipitates were followed and stable conditions were detected inside the mineral precipitates. Different methodologies, scanning and transmission electron microscopy, immunological detection, fluorescence in situ hybridization, and metagenomic analysis were used to describe the biodiversity existing in these microbial mats, demonstrating, for the first time, the existence of acid-tolerant cyanobacteria in a hyperacidic environment of below pH 1. Up to 0.46% of the classified sequences belong to cyanobacterial microorganisms, and 1.47% of the aligned DNA reads belong to the Cyanobacteria clade.
... Limestone can be used as an alternative for the removal of sulphate in mine waters having 1,200-2,000 mg/L (Silva et al., 2012). Brahaita et al. (2017) and Davis et al. (2000) reported in their study that limestone is composed of CaCO3 when used as a means for AMD treatment due to its cheaper and can also reduce heavy metals, but the materials cannot treat AMD with high iron content because they can scale and prevent the solubility process (Skousen et al., 2017). ...
Acid Mine Drainage (AMD) is a major environmental problem due to low pH, high sulphate content, and dissolved metals. The aim of this study was to investigate the potential of limestone materials for the primary treatment of AMD water. Different doses of limestone were used in this study in the ratio of 0 g/1,000 mL as control, 20 g/1,000 mL, 40 g/1,000 mL, 60 g/1,000 mL, 80 g/1,000 mL, 100 g/1,000 mL, 200 g/100 mL (limestone/AMD) in a batch experiment of 1,500 mL plastic container. The results showed that the pH of AMD water improved to 8.6 at a dose of 100 g/1,000 mL, and the sulphate concentration decreased from 2,277 mg/L to 506 mg/L at a dose of 200 g/1,000 mL. The removal of Fe, Cu, Zn, Mn, and Ni at 200 g/1,000 mL was 99%, 92%, 68%, 96%, and 99%, respectively. The results of this study also showed that the Mn content decreased slowly as the limestone dosage increased. In addition, this study showed that limestone is a good neutralizing agent for increasing the pH of AMD water and reducing sulphate and dissolved metal concentrations. The results of this study indicated that limestone is suitable as a primary treatment agent for AMD water treatment in gold mines in Tanzania.
... Insensitively operated mines will pollute watercourses as soon as they begin operation, and ore processing activities are often very water-intensive, requiring careful planning for the use of water and its storage or treatment before release (Thomashausen et al., 2018). Greatly elevated concentrations of elements of concern in water and sediments as a result of mining activities and wastes have been recorded globally (Hudson-Edwards et al., 2011, Luckeneder et al. 2021, Zheng et al. 2020, including sites in Asia (Bhuyan andBakar, 2017, Giri andSingh, 2019), Africa (Edet andOffiong, 2003, Nduka andOrisakwe, 2011), South America (Lattuada et al., 2009, Smolders et al., 2003, North America (Gunter, 2017, Nordstrom, 2009, Oceania (Rufaut et al., 2020, Wright et al., 2017, and Europe (Davis et al., 2000, Mullinger, 2004. ...
... Notably, the Tinto River marshes stand out as one of the most contaminated estuarine systems globally, largely attributed to historical mining activities, particularly large-scale open-pit mining practices dating back to the late 19th century. The geo-biodynamics along the Iberian Pyrite Belt (IPB) further contribute to the pollution of this system [45][46][47][48]. ...
(1) Background: This study provides novel insights into the elemental content and biomineralization processes of two halophytic species of the genus Arthrocnemum Moq. (A. macrostachyum and A. meridionale). (2) Methods: Elemental content was analyzed using ICP-MS, while biominerals were detected through electron microscopy (SEM and TEM) and X-ray diffraction. (3) Results: The elemental content showed significant concentrations of macronutrients (sodium, potassium, magnesium, and calcium) and micronutrients, especially iron. Iron was consistently found as ferritin in A. macrostachyum chloroplasts. Notably, A. macrostachyum populations from the Center of the Iberian Peninsula exhibited exceptionally high magnesium content, with values that exceeded 40,000 mg/kg d.w. Succulent stems showed elemental content consistent with the minerals identified through X-ray diffraction analysis (halite, sylvite, natroxalate, and glushinskite). Seed analysis revealed elevated levels of macro- and micronutrients and the absence of heavy metals. Additionally, the presence of reduced sodium chloride crystals in the seed edges suggested a mechanism to mitigate potential sodium toxicity. (4) Conclusions: These findings highlight the potential of Arthrocnemum species as emerging edible halophytes with nutritional properties, particularly in Western European Mediterranean territories and North Africa. They offer promising prospects for biosaline agriculture and biotechnology applications.
... Furthermore, Witwatersrand (South Africa) established a daily discharge of 350,000 m 3 of AMD [37,38]. Without appropriate technologies and practices, mining and mineral processing waste generation could persist in the environment for centuries [39]. ...
The main objective of this study was to evaluate current mining waste management practices and their challenges. This study aimed to identify existing technologies and practices, and to present improvement needs and options for environmentally sustainable practices for mining operations. Other researchers have reported many practices and technologies for managing mining waste, but the efficiency, applicability, and need for customization were not specifically addressed for developing countries. This study used field observations, measurement methods, and laboratory analysis to collect data. This study showed a large amount of mine waste rock compared to the tailings wastewater from gold processing plant produced annually. This comprises approximately 5.2 million m3 of mine contaminated water generated by leaching from the waste rock dump (WRD) and 2.3 million m3 from the tailings storage facility (TSF). The study also identified the use of TSF cut-off trenches for seepage collection, the use of lime to treat acid mine drainage (AMD), the discharge of AMD into the TSF, and the recycling of TSF water as the best practices for managing mining waste. Furthermore, the study also found that the most common environmental problems were caused by TSF water and AMD water. However, mining waste management can be improved by modifying existing practices and adopting cost-effective technologies and practices to control and treat excess mining water.
... The Tinto River is a small stream that flows through the southwest of Spain and forms a large estuary together with the Odiel River at its mouth in the Atlantic Ocean, surrounded by Neogene-Pleistocene formations ( Figure 1A,B). The hydrodynamics of this estuary are tidally dominated, as river discharges are very rare and vary from minimum flows during very dry years to about 350 Hm 3 in rainy years [27]. The tidal regime is mesotidal (2.1 m), with a low diurnal inequality [28]. ...
... Southwest Spain is part of the Iberian Pyritic Belt, one of the most important metallogenic provinces in Europe, which includes some of the largest massive sulfide deposits in the world. These giant deposits have been exploited for 5000 years within the Tinto River drainage basin [27], with important mining activity during the Roman period (2100-1700 yr BP) and especially in the last 150 years, with an intensive extraction of pyrite and minor quantities of gold and silver. Currently, the waters of the Tinto River suffer from acid mine drainage, due to this age-old mining activity and to the heavy-metal-rich inputs from the washing of the waste dumps generated [33]. ...
... Southwest Spain is part of the Iberian Pyritic Belt, one of the most important metallogenic provinces in Europe, which includes some of the largest massive sulfide deposits in the world. These giant deposits have been exploited for 5000 years within the Tinto River drainage basin [27], with important mining activity during the Roman period (2100-1700 yr BP) and especially in the last 150 years, with an intensive extraction of pyrite and minor quantities of gold and silver. Currently, the waters of the Tinto River suffer from acid mine drainage, due to this age-old mining activity and to the heavymetal-rich inputs from the washing of the waste dumps generated [33]. ...
Estuaries are excellent environments for identifying pollution episodes that have affected river basins, as their sediments are the final destination of some of the pollutants. This paper studies the geochemical evolution of five elements (As, Co, Cu, Pb, Zn) in a core extracted from the middle estuary of the Tinto River (SW Spain). The results are based on facies interpretation, ICP atomic emission spectrometry analysis, the application of a regional background to obtain the geoaccumulation index and dating. The main objective of this communication is the detection of natural or anthropogenic pollution episodes in the middle estuary of the Tinto River (SW Spain). Four pollution episodes have been detected: (1)~5.8 cal. kyr BP, probably caused by natural acid rock drainage processes derived from the oxidation of the Iberian Pyritic Belt deposits found in its drainage basin; (2) 4.7-4.5 kyr BP, coming from the first mining activities and characterized by a significant increase in the concentrations of the five elements analyzed; (3) 1850-1960 interval, coinciding with intensive mining and characterized by increasing values of As and, to a lesser extent, Pb (intensive mining); and (4) the second half of the 20th century, with high element concentrations from mining and industrial effluents. All episodes show an increase in their geochemical classes deduced from the geoaccumulation index. This communication can serve as an example for assessing the impact of different types of pollution in estuarine environments.
... The hydrodynamics of this estuary are tidally dominated, as river discharges are very rare and vary from minimum flows during very dry years to about 350 Hm 3 in rainy years [25]. The tidal regime is mesotidal (2.1 m), with a low diurnal inequality [26]. This estuary can be divided into three sectors, depending on the interaction between river and tidal inputs [27]: i) fluvial estuary, composed of numerous braided channels; ii) middle estuary, with numerous marshes that come to form small islands (e.g., Figure 1B: Bacuta Island); and iii) marine estuary, with a central island ( Figure 1B: Saltés Island), two main channels (Padre Santo channel, Punta Umbría channel) and two sandy spits (Punta Arenillas, Punta Umbría) that partially protect it. ...
Estuaries are excellent environments of identifying pollution episodes that have affected river basins, as their sediments are the final destination of some of the pollutants. This paper studies the geochemical evolution of five elements (As, Co, Cu, Pb, Zn) in a core extracted from the middle estuary of the Tinto River (SW Spain). Results are based on facies interpretation, ICP Atomic Emission Spectrometry analysis, the application of a regional background to obtain the geoaccumulation index and dating. Four pollution episodes have been detected at ~5.8 cal. kyr BP (acid mine drainage?), 4.7-4.5 kyr BP (first mining activities), the 1850-1960 interval (intensive mining) and the second half of the 20th century (intensive mining and industrial inputs). All episodes show an increase in one or more of these elements, as well as changes in their geochemical classes deduced from the geoaccumulation index.
... These geochemical values in Fene are accompanied by a pollen assemblage similar to the Holocene records. Notwithstanding that the rest of the analyzed samples (surface and core sediments) exhibit enhanced Cu, Pb, and Zn levels, the highest concentrations of these trace metals are far below those determined in other industrialized estuaries and rías of Galicia, the Cantabrian coast (Table 3), and in other Atlantic coastal areas (Davis et al., 2000). The only exception to this general trend is at 10-30 cm deep in the Xuvia core (n = 12), where sediments exhibit Zn contents exceeding the Effects Range Median (ERM) threshold established by Long et al. (1995) (Table 3), above which adverse effects on biota frequently occur. ...
Galician rías provide several ecosystem services of great ecological and economic significance in the northwestern Iberian margin, requiring a good environmental quality for sustainable harnessing. More paleoenvironmental reconstructions extending to their preindustrial state are needed to predict their evolution under natural and human-induced perturbations, such as ongoing anthropogenic global warming. This study's aim is twofold: first, characterize the current environmental conditions governing the inner Ría of Ferrol (Galicia, NW Spain) and address its recent natural and anthropogenic evolution. Therefore, a multiproxy approach (benthic foraminifera, grain size, pollen content, trace metals, Al, total organic and inorganic carbon contents, total nitrogen content, δ13C, magnetic susceptibility, 210Pb and 137Cs radiotracers, and microplastics) has been applied to intertidal surface and sediment core samples. The benthic foraminiferal results exhibit typical inner ría assemblages, primarily driven by natural ría-estuarine dynamics, with a higher dominance of brackish species (H. germanica, A. morphogroup tepida), fewer living individuals and marine allochthonous taxa toward the continental end-member. The foraminiferal standing crops and surface trace metal concentrations do not reflect strong anthropogenic impacts, although areas with elevated magnetic susceptibility have been detected, probably associated with nearby industrial activities. The recent sedimentary deposits reveal anthropogenic impacts at local and regional scales, with different environmental shifts. Local impacts were triggered by physical interventions in the inner ría, with the construction of the As Pías Bridge in 1968 and the great urban-industrial development of Ferrol city and surrounding localities experienced since the late 19th century. Land-use changes have driven regional scale changes, corresponding to reforestation plans with the introduction of anthropogenic vegetal species for industrial purposes initiated in the 1940s. The stratigraphic analysis of sediment cores has unveiled high levels of contaminants (Zn and microplastics) in the innermost sector as the primary environmental concerns. In this sediment-infilling and restricted area, potential dredging activities could release them leading to their possible bioavailability. Although past adverse environmental conditions cannot be discarded, sedimentary intervals with negligible presence of microfauna in the innermost area have mostly been attributed to taphonomic processes involving calcareous dissolution and disaggregation of agglutinated tests, likely caused by carbonateundersaturated conditions and organic matter metabolization by microbial activity respectively.
... This is a widely described environmental problem in the Iberian Pyritic Belt (IPB) at the Iberian Peninsula, affecting southwest Spain and southeast Portugal. This mining district has been exploited for 5000 years [13], and it has more than 1500 million tons of polymetallic sulfides [14]. ...
Currently, only 50% of concrete produced from construction and demolition waste is being recycled in Europe. This falls short of the European Union’s target of 70% by 2020. Moreover, this figure only considers coarse fractions (>4 mm), as technical issues arise when using fine fractions. In pursuit of a complete circular life for recycled concrete, this investigation explores the potential use of fine fractions to enhance the physicochemical conditions and reduce the element concentration of acid mine drainage. Two trickling sets were prepared using a filter holder, with acidic waters passing through a layer of recycled concrete aggregates. Results revealed an immediate increase in water pH to neutral levels, a reduction in solution oxidation, and the complete, or near-complete retention, of potentially toxic elements by the substrate (with retention percentages of over 99.9% for Al and Fe, between 43.1% and 61.1% for S, over 91.1% for Zn, and over 99.1% for Cu). The experiment also showed a significant increase in Ca levels (tripling the initial value) and some Mg in the water, which could promote the subsequent precipitation of carbonates and the retention of trace metals. In summary, this study demonstrates the effectiveness of using recycled concrete aggregates in a laboratory setting. Further investigation is necessary to evaluate the feasibility of implementing this technique at the pilot scale.
