Impact Of Acid Mine Drainage Research Articles

Impacts of acid mine drainage on karst aquifers: Evidence from hydrogeochemistry, stable sulfur and oxygen isotopes

The pollution of karst aquifers by acid mine drainage (AMD) waters is increasing. Major and minor ions (Ca2+, Mg2+, HCO3−, SO42−, F−, and Fe), stable sulfur and oxygen isotopes of dissolved sulfates (δ34SSO4 and δ18OSO4) and oxygen isotope of water (δ18OH2O), were analyzed in rainwater, surface water, groundwater, and AMD water sampled from the Babu subterranean stream watershed, in Southwest China. The principal aim of this study was to explore the impact of AMD waters on the evolution of karst aquifers. Based on hydrogeochemistry and stable isotopes (δ18OH2O, δ18OSO4 and δ34SSO4): (1) the chemistry of AMD waters was primarily controlled by pyrite oxidation, karst conduit water by AMD waters and mixing with calcite and dolomite dissolution, and spring water by atmospheric precipitation and carbonate dissolution; (2) contamination of the karst conduit water was mainly attributed to the input of AMD waters, resulting in a shift of δ34SSO4 towards more negative values (from 3.4‰ to −13.2‰); (3) the quality of karst conduit water changed from suitable to unsuitable for irrigation and drinking, particularly due to the increase in total Fe, SO42−, and F− concentrations, reflecting the cumulative effect of AMD waters derived from tailings dumps; this influence was enhanced during rainstorm/drought and anthropogenic activities; and (4) the flow of contaminated groundwater through the conduit promoted the dissolution of carbonates, especially during the dry season due to the greater proportion of AMD in the groundwater. This released more CO2 to the atmosphere. We believe that analysis of stable isotopes (δ18OH2O, δ18OSO4, and δ34SSO4), combined with hydrogeochemistry, is effective for exploring the impact of AMD on karst aquifers. Therefore, reasonable treatment methods should be taken to reduce the negative impacts of tailings dumps on karst aquifers.

Effects of Fe-rich acid mine drainage on percolation features and pore structure in carbonate rocks

Acid mine drainage (AMD) poses significant ecological, environmental and geological challenges worldwide, especially in more vulnerable karst areas. However, the impact of AMD on percolation features and pore structure of carbonate strata is poorly understood, despite its importance for the evolution of carbonate aquifer as well as karst groundwater quality. To fill this knowledge gap, field investigations, core-flooding experiments, reactive transport modeling and pore structure studies [mercury intrusion porosimetry (MIP) and nitrogen physisorption analysis] were conducted to understand the geochemical processes and associated pore development in carbonate strata exposed to Fe-rich AMD. Our field investigation shows that the AMD is characterized by low pH values (2.4–3.8), high contents of sulfate (1457–4217 mg/L), Fe (100–830 mg/L, Fe3+/Fe2+) and heavy metals, that can potentially leak into carbonate strata. The major findings of this study include: (1) core-flooding experiments reveal that the interaction of carbonate rock with AMD causes a rapid elevation of solution pH and simultaneous precipitation of Fe3+/Fe2+ as iron (oxy)hydroxides or (oxy)hydroxy sulfates within the rock; (2) the results of reactive transport modeling suggest that ferrous iron has a longer transport distance than ferric iron in the carbonate core plug, and then it precipitates to fill the pore space; and (3) despite the precipitation, the flooding of AMD increases the overall permeability of cores by creating large numbers of pores with throat diameter between 0.001 and 10 μm. We also found that the interaction of AMD with the carbonate rock might stimulate the formation of preferential flow channel(s). Our results have been incorporated into a conceptual model, built to illustrate the geochemical processes and mechanisms involved. Our research has important applications in AMD treatment for coal-mining industries, and for local governments devising strategies for karst water resource protection and management.

Sustainable Reuse of Coal Mine Waste: Experimental and Economic Assessments for Embankments and Pavement Layer Applications in Morocco

This paper deals with the potential reuse of coal mine waste rocks (CMWR) as an alternative material for road construction to conserve the natural resources and sustainable management of mining waste. The investigation was conducted through the determination of the chemical, mineralogical, geotechnical properties, and acid mine drainage formulation of CMWR as well as economic feasibility. This waste was used either alone for embankments and mixed with stabilizing agents fly ash (FA) and hydraulic road binder (HRB) for pavement applications. The experimental results confirmed that weathered CMWR can be successfully used alone as a sustainable alternative material for the embankment. Furthermore, the use of stabilizing agents in the following ratio CMWR:FA:HRB = 80:20:5 allow the use of CMWR in road sub-base layers for high-traffic pavements. Also, the environmental investigations showed that CMWR does not present any potential contaminating risk on the surrounding environment and most of the pyrite particles were already oxidized. Therefore, the environmental impact of acid mine drainage produced by pyritic waste throughout its life cycle can be neglected. Finally, an economic case study confirmed the workability of CMWR reuse in a radius of 29 km around their dumps by resulting in a lower cost compared with conventional materials.

Coal mining and the environmental impact of Acid Mine Drainage(AMD): A review

In spite of the growing global initiatives towards achieving clean energy, coal remains a dominant source of electricity generation, a fuel for iron and steel production, an important entity among road construction materials and a commodity for foreign exchange earnings for many nations. Coal mining from old and active sites remains a source of an environmental problem described as acid mine drainage (AMD). AMD is produced when sulfide present in waste rocks or tailings in coal mines reacts with air and water in a microbes facilitated oxidation to form solutions with high acidity. The acids formed by these chemical and biological conditions further release heavy metals present in the host rock in concentrations higher than are acceptable by environmental standards (pb;0.01, Zn;5, Cu;2, Fe;0.3 mg/l as prescribed by WHO and Encyclopedia of Environmental Science,2000) such that soils, surface and underground waters are contaminated. Consequently, the human population which derives her livelihood in the mine zones, in form of crop production and fishing/modern aquaculture is endangered by terminal health diseases. This article aims at bringing forth, the urgent need to work towards achieving goal six of the United Nations Sustainable Development Goals, 2030 (SDGs-6) which is clean water and sanitation while enriching the knowledge repository of the environmental problem for the purpose of teaching, research, community services and policy making. An overview of AMD menace, variables which influence its formation, selected areas that have been impacted, and a brief analysis of its treatment cost have been discussed with a list of concluding remarks in the paper.
 Keywords: Coal, Mining, Environmental , AMD

Natural Attenuation of Acid Mine Drainage by Various Rocks in the Witbank, Ermelo and Highveld Coalfields, South Africa

In the Karoo coalfields, mining operations that release acid mine drainage (AMD) are threatening groundwater resources. An important parameter controlling the extent and severity of AMD impact is the natural attenuation of rocks in response to AMD. Very little is known about such response of Karoo rocks in saturated and unsaturated conditions, a research gap filled by this paper. Laboratory column leach experiments were used to study the responses of different rock types from the Witbank, Ermelo and Highveld coalfields of South Africa. The results of the experiments show that rock samples with high quartz mineral content offered little attenuation of AMD and those consisting of plagioclase and clays offered some attenuation, while those with high carbonate mineral content, neutralized and reduced the concentration of heavy metals from AMD. The presence of oxygen increased the rate of heavy metal removal from AMD. For all rock samples under saturated and unsaturated conditions, the sulfate and chloride concentrations of AMD remained unchanged after the leaching process, showing that these parameters are conservative and can be used as potential natural tracers of AMD movement in the subsurface. The research shows that laboratory leach tests may be used to rank the various rock types in the Karoo coalfields in terms of their capacity to buffer the impacts of AMD. Such a ranking could inform policy and decision makers in regard to handling and storage of AMD-generating wastes, as well as to location and design of AMD waste storage facilities.

Sorption of rare earth elements onto basaluminite: The role of sulfate and pH

Abstract Scandium, yttrium and lanthanides (REE) are critical raw materials in increasing demand for modern technology, so identifying and developing new sources of REE has become a pressing need. REE concentrations in acid mine drainage (AMD) are several orders of magnitude higher than those in natural water, and their recovery is of economic interest. Passive remediation systems designed to minimize AMD impact on the ecosystem retain REE in solid waste, where basaluminite, Al4SO4(OH)10·5H2O, is the mineral responsible for the scavenge. However, no information about the retention mechanisms of REE is currently available in the literature. The objective of the present work is to study the adsorption of lanthanides, yttrium and scandium onto synthetic basaluminite over a pH range of 4–7 at room conditions. Since sulfate is ubiquitous in AMD, the adsorption has been investigated with variable sulfate concentrations. Experimental results show that sorption onto basaluminite is strongly dependent on pH, starting at pH 5 for lanthanides and yttrium and at pH 4 for scandium. At any given pH values, sorption increases with sulfate concentration. Distribution coefficients, defined as KD = [REEsorbed]/[REEsolution], are higher for Sc, and across the lanthanide series, the distribution coefficients increase from La to Lu according to decreasing ionic radius, where yttrium is considered close to Ho. Experimental results were modeled using a sorption model that considers mass law equations where the strong sulfate aqueous complex, MSO4+, is adsorbed by exchanging a proton with the mineral surface. The dependence of the experimental results on pH suggests the formation of monodentate binding for Y and lanthanides. The bidentate complex for Sc is deduced by the two proton exchange per mol of Sc extracted from the experiments. The thermodynamic constants for the surface complexation reactions were obtained from experiments with high sulfate concentration and were successfully applied to the experiment with low sulfate content and different solid-liquid ratios. Therefore, the model can be applied to interpret the REE geochemistry in natural systems with variable pH and sulfate concentrations.

Chemical mobility of inorganic elements in stream sediments of a semiarid zone impacted by ancient mine residues

Water availability is a worldwide issue, particularly in semiarid zones. Therefore, it is necessary to know the geochemical processes involved in the mobility of contaminant sources to ensure adequate quality for this resource. Some mining areas of México are of economic importance; however, they are also the sources of large quantities of mine residues, such as the site included in this study. As an important aspect of understanding contaminant mobility in sediments and water, a thorough mineralogical characterization is paramount to identify sources and sinks for relevant elements, in this case, potentially toxic elements (PTEs) such as arsenic (As), lead (Pb) and cadmium (Cd); hence, scanning electron microscopy (SEM), X-ray diffraction (XRD) and chemical analysis were used. The total geochemical distribution was established by means of a modified selective sequential extraction procedure. The results showed that sediments constitute an effective attenuation substrate for mobilized PTEs to groundwater. Hence, arsenic and cadmium were stabilized in the sediments and/or the vadose zone, and although Pb and Zn were identified in groundwater with concentrations above the background values, they were below drinking water standards. Sulfate and total hardness concentrations in the groundwater confirmed the impact of acid mine drainage (AMD) infiltration. Considering that similar sites in Mexico are found along the Sierra Madre Oriental, the methodology of this study could be applied to understand the mobility of PTEs in the sediments and waters of semiarid environments.

Addressing Quality and Usability of Surface Water Bodies in Semi-Arid Regions with Mining Influences

Water resources management has considerable importance, specifically in the context of climate change. This subject has introduced new challenges in semi-arid regions with water quality problems, such as the Iberian Pyrite Belt, which is one of the largest metallogenetic provinces in the world and one of the driest regions in Europe. Positioned in the Mediterranean context, the region has a high density of polymetallic sulphide mines that promote the degradation of water systems. The present study aims to assess the water quality in the Pyrite Belt, considering a total of 34 surface water bodies, including constructed reservoirs, permanent and ephemeral streams, and mining facilities with accumulated water (e.g., pit lakes and mining dams). The water samples were analysed for physico-chemical properties, including field parameters (pH, electrical conductivity), alkalinity/acidity, hardness, anions, and potential toxic elements. The results were used for hydrochemical classifications and the assessment of suitability for public uses. Statistical methods, such as hierarchical cluster analysis and nearest centroid classifier, were used for grouping and evaluating the similarity between water bodies. Two groups were generated from the analysis: i) constructed lakes with alkaline and sodium signatures; and ii) waters suffering from the influence of mining wastes, e.g., showing high acidity, sulphate and metal contents. Therefore, the loss of water quality in the vicinity of mines reflects the impact of acid mine drainage. The methodological approach used may be applied to the integrated management of water resources in regions with mining influences and where it is necessary to combat drought and water scarcity scenarios.

Arsenic in the Wiśniówka acid mine drainage area (south-central Poland) – Mineralogy, hydrogeochemistry, remediation

This paper summarizes different aspects of arsenic mineralogy and geochemistry in the Wiśniówka acid mine drainage (AMD) area, south-central Poland. The basic source of this metalloid in AMD water bodies is micro-grained pyrite that forms two different mineralized zones within the Upper Cambrian rock formation. Due to specific textural and geochemical characteristics, this mineral undergoes rapid oxidation on exposed quarry walls and unvegetated tailings piles, thus contributing to elevated arsenic concentrations in acid pit lakes and ponds, and locally intermittent pools. The latter were highlighted by the highest As levels reaching even 370 mg/L. Of the three AMD large reservoirs, the Podwiśniówka (eastern) lake revealed distinctly raised As concentrations varying from 7.02 to 22.2 mg/L. Another interesting water body is the Marczakowe Doły acid pond showing diverse seasonal As concentration patterns in colloids and a water column. Results of geochemical modeling showed that the saturation indices (SI) of hematite and goethite exhibited the highest values (range of 6.96 to 12.84 and 2.47 to 5.39, respectively) tending to precipitate in all the water bodies examined. In addition, the positive SI values of nanosized ε-Fe2O3 (1.64 to 4.13) and schwertmannite (0.90 to 2.10) were found only in the Wiśniówka Duża and Marczakowe Doły acid waters. Laboratory experiments revealed that the best chemical and cost-effective method (out of the limited number of options) of arsenic removal from the AMD waters examined was the use of high-grade powdered limestone (fraction 0.0–0.09 mm) or more effective although more expensive limewater (calcium hydroxide). The positive SI values of hematite, goethite, ε-Fe2O3 and schwertmannite of neutralized solutions suggest that these minerals should precipitate. Due to diverse concentrations in the examined rock series, arsenic has been used for fingerprinting “hot” places within the mining and neighboring areas, as well as for predicting the directions and effects of strip mining for quartzites. The As signature can also be applied to monitor a detrimental AMD impact on local surface and underground waters.

Impact of acid mine drainage and hydrogeochemical studies in a part of Rajrappa coal mining area of Ramgarh District, Jharkhand State of India

Groundwater quality studies of coal mining areas are very important due to coal explorations, dumping of huge quantity of over burdens, and subsequently mixing with the coal mine drainage areas. The main objective of this study was to evaluate the possible influence of acid mine drainage (AMD), in the groundwater in terms of major ions, trace elements and identifying the hydrogeochemical characteristics, in the Rajrappa coal mining area in the central part of India. The results show that groundwater is generally neutral to alkaline in nature. The major ions and trace elements concentrations in the groundwater samples were found to be below the permissible limits based on WHO guidelines and suitable for the drinking water purposes. Few wells show a higher order in certain parameters due to impact local geologic strata. The piper diagram shows two major hydrochemical water types represents, such as Ca-Mg-Cl, and Ca-Mg-HCO3 types. Based on major ion concentrations and its minor variations are indicative of the stable geochemical and hydrologic environments, which controls the groundwater chemistry in the coal mining area. Geochemical evolution of the groundwater chemistry mainly controls by the natural geochemical processes such as mineral dissolution, rock-water interactions and mineral precipitation processes. Saturation index studies show that, groundwater samples were near saturation to equilibrium conditions with the carbonate phase minerals of calcite and dolomite and undersaturated with gypsum and anhydrite. Secondary minerals of Fe and Mn – sulphate and carbonate phase species are in undersaturated conditions. The shorter residence times of groundwater in the wells, lack of acid mine drainage generating conditions and the impact of dilution during high base flows are diluting the coal mining drainage streams and making a negligible impact of acid mine drainage.

Community perceptions on the health risks of acid mine drainage: the environmental justice struggles of communities near mining fields

Environmental and social research studies have debated the impact of acid mine drainage (AMD). Solutions to the problems caused by AMD have tended towards a technocratic investment in temporary to long-term solutions. However, the health effects of AMD remain neglected in research and policy arenas because of the lack of documented evidence. As a result, this renders the problem invisible, while the impact is deleterious for poor communities. Such communities suffer the effects of AMD principally through a perpetual risk posed by water pollution. Moreover, they are voiceless and excluded from matters affecting their well-being. This study was carried out with a community in Carolina, near the Mpumalanga coal mining fields. It tested their understanding and perceptions of health risks associated with AMD. The goal was to uncover the knowledge of the research participants of the existence of AMD and of its impact on their physical health and well-being. Qualitative methods were employed to measure knowledge, attitudes, and perceptions and to analyse the diseases inventory of the study population. Findings suggest that communities located near mines are affected by mining externalities that pose a threat to their health. It was also discovered that such communities are excluded from any planning and decision-making by local mining authorities. This case study presents strong evidence in favour of empowering marginalised communities by including them in decision-making, actively facilitating their participation, and exposing them to environmental health education to increase their awareness and reduce the risks caused by mining externalities.

Integrated treatment of acid mine drainage using cryptocrystalline magnesite and barium chloride

This study endeavours to report the efficiency of a hybrid approach in the treatment of acid mine drainage. Cryptocrystalline magnesite was used to pre-treat acid mine drainage and barium chloride was used to remove the residual sulphate through the formation of barium sulphate. Batch experimental approach was adopted and the documented optimum conditions for both cryptocrystalline magnesite and barium salts were used. This was 60 mins for pre-treatment and 60 mins for polishing the residual sulphate. Water quality was assessed using ICP-MS and IC. Mineralogical composition was done using XRD, elemental composition with XRF, morphology with SEM and transmission electron microscope. Magnesite removed >99% of heavy metal species and 40% sulphate except for base cations. Barium managed to remove 99% of residual sulphate from an aqueous system. This indicate that the water meet the industrial, discharge and irrigation standards as stipulated by the water quality guidelines. As such, it can be concluded that this integrated approach can be used to treat acid mine drainage to useable standards as defined in the water quality guidelines. This will be a pragmatic approach for mining houses to curtail the impact of acid mine drainage by using natural and locally available materials such as cryptocrystalline magnesite and polish the water with barium salts.

Paleolimnological Fingerprinting of the Impact of Acid Mine Drainage After 50 Years of Chronic Pollution in a Southern Finnish Lake

Acid mine drainage (AMD) is acknowledged to have long-lasting impacts on aquatic environments. Hence, mines have also been detected to pose problems years after closure due to the leaching of toxic drainage initiated by sulfide oxidation. To assess the effects of chronic but relatively low volume acid mine drainage derived from the Haveri copper–gold mine operating between 1938 and 1960 on a freshwater bay in southern Finland, we compared cladoceran assemblages from the pre-mining period with contemporary populations using paleolimnological approaches and multiple sediment cores. The cladoceran community of the pre-mining era differed significantly from the contemporary community of the lake (ANOSIM R = 0.91; p = 0.0001), but closely resembled the contemporary community of a nearby non-polluted reference site. Our results suggest that the differences in species compositions between pre-mining and contemporary samples are most likely caused by eutrophication and not by the AMD impact. Because AMD at our study site is most intense during the spring snowmelt period, cladocerans may avoid seasonal pollution peaks through winter dormancy. Possible pollution peaks resulting from heavy rains during the summer may have negative impacts on the cladoceran community, but such short-term impacts are probably rapidly counteracted by immigration from cleaner areas of the lake.

Geochemistry and microbial community composition across a range of acid mine drainage impact and implications for the Neoarchean‐Paleoproterozoic transition

AbstractStreams impacted by acid mine drainage (AMD, also known as acid rock drainage) represent local environmental and ecological disasters; however, they may also present an opportunity to study microbial communities in environments analogous to past conditions. Neoarchean continents had streams and rivers replete with detrital pyrites. Following the emergence of oxygenic photosynthesis, Cyanobacteria colonized streams and rivers on continental surfaces. The combination of labile detrital pyrite grains and locally produced O2 generated by Cyanobacteria produced ideal conditions for pyrite oxidation similar to that found at modern AMD‐impacted sites. To explore the connection of modern sites to ancient conditions, we sampled sites that exhibited a range of AMD‐impact (e.g., pH from 2.1 to 7.9 [Fe2+] up to 5.2 mmol/L [SO42−] from 0.3 to 52.4 mmol/L) and found (i) nearly all analytes correlated to sulfate concentration; (ii) all sites exhibited the predominance of a single taxon most closely related to Ferrovum myxofaciens, an Fe‐oxidixing betaproteoabacterium capable of carbon and nitrogen fixation, and (iii) signs of potential inorganic carbon limitation and nitrogen cycling. From these findings and building on the work of others, we present a conceptual model of continental surfaces during the Neoarchean and Paleoproterozoic linking local O2 production to pyrite oxidation on continental surfaces to sulfate production and delivery to nearshore environments. The delivery of sulfate drives sulfate reduction and euxinia—favoring anoxygenic photosynthesis over cyanobacterial O2 generation in near‐continent/shelf marine environments.

Metal-fluxes characterization at a catchment scale: Study of mixing processes and end-member analysis in the Meca River watershed (SW Spain)

Fluxes of acidity and contaminants from acid mine drainage (AMD) sources to the receiving surface water bodies were studied in a mining-impacted watershed (Meca River, SW Spain) using a novel methodology based on the joint application of EMMA and MIX codes. The application of EMMA and elemental ratios allowed delimiting the end-members responsible for water quality variations at a catchment scale. The further application of MIX quantified the significant impact of AMD on the river quality; less than 10% of AMD relative contribution is enough to maintain acidic conditions during most of the year. The mixing model also provided information about the element mobility, distinguishing those elements with a quasi-conservative behavior (e.g., Cu, Zn, Al, Co or Ni) from those affected by mineral precipitation/dissolution (e.g., K, Si, Na, Sr, Ca, Fe, Pb, or As). Floods are the main driver of dissolved and, mainly particulate, contaminants in the catchment. Thus, the first rainfall events in November only accounted for 19% of the annual Meca flow but yielded between 26 and 43% of the net acidity and dissolved metal loads (mainly, Fe, As and Pb). Concerning particulate transport, around 332tons of particulate Fe, 49tons of Al, 0.79tons of As and 0.37tons of Pb were recorded during these first floods. The particulate As concentration can be up to 34 times higher than the dissolved one during floods and between 2 and 4 times higher for Fe, Pb and Cr. This integrated modeling approach could be a promising and useful tool to face future restoration plans in derelict mines worldwide. This approach would allow prioritizing remedial measures, achieving an environmental and cost-effective restoration of degraded areas.

Mercury Bioaccumulation in Crayfish in Acid Mine-Impaired Appalachian Streams

We tested the hypothesis that mercury (Hg) bioaccumulation in crayfish inhabiting acid mine-impacted streams increases with the severity of acidification. Sixty-four sites in southeast Ohio were ranked for severity of acid mine impact using an index of six water chemistry parameters (Fe, Mn, Al, sulfate, acidity, and pH) characteristic of acid mine drainage. Macroinvertebrate communities along the acid mine drainage (AMD) gradient were sampled by kick and dip net, and the abundances of different functional feeding groups characterized to evaluate differences in dietary prey availability to crayfish inhabiting AMD-impaired streams. Mercury in crayfish (Orconectes sanbornii) was measured at 19 sites. Composite samples (N = 10) of tail tissue from these sites were analyzed for mercury, along with sediment from six sites. Sediment methyl mercury (MeHg) ranged from 0.03 to 0.479 ng/g, typical of background (uncontaminated by Hg or AMD) levels for lakes and streams in this region. MeHg concentrations in crayfish tail tissue ranged from 26.7 to 122 ng/g. Contrary to our hypothesis, total Hg and MeHg in crayfish tissue were negatively correlated with acid mine impairment (r = −0.479, p = 0.036; r = −0.049, p = 0.0293, respectively), suggesting that crayfish bioaccumulate Hg more slowly in acid mine-impaired streams. This pattern is opposite of trends for increased bioaccumulation rates in food webs of lakes acidified by atmospheric deposition. Total macroinvertebrate (prey) abundance at study sites declined with increasing AMD impact. The reduced Hg accumulation in acid mine-impacted waters may be related to a change in diet, greater reliance on detritus-based food items, and/or lower trophic status of crayfish in acidified streams.

Exploration of Diffuse and Discrete Sources of Acid Mine Drainage to a Headwater Mountain Stream in Colorado, USA

We investigated the impact of acid mine drainage (AMD) contamination from the Minnesota Mine, an inactive gold and silver mine, on Lion Creek, a headwater mountain stream near Empire, Colorado. The objective was to map the sources of AMD contamination, including discrete sources visible at the surface and diffuse inputs that were not readily apparent. This was achieved using geochemical sampling, in-stream and in-seep fluid electrical conductivity (EC) logging, and electrical resistivity imaging (ERI) of the subsurface. The low pH of the AMD-impacted water correlated to high fluid EC values that served as a target for the ERI. From ERI, we identified two likely sources of diffuse contamination entering the stream: (1) the subsurface extent of two seepage faces visible on the surface, and (2) rainfall runoff washing salts deposited on the streambank and in a tailings pile on the east bank of Lion Creek. Additionally, rainfall leaching through the tailings pile is a potential diffuse source of contamination if the subsurface beneath the tailings pile is hydraulically connected with the stream. In-stream fluid EC was lowest when stream discharge was highest in early summer and then increased throughout the summer as stream discharge decreased, indicating that the concentration of dissolved solids in the stream is largely controlled by mixing of groundwater and snowmelt. Total dissolved solids (TDS) load is greatest in early summer and displays a large diel signal. Identification of diffuse sources and variability in TDS load through time should allow for more targeted remediation options.

Application Géomatique Pour La Cartographie De La Vulnérabilité Environnementale Engendrée Par Les Déchets Miniers De La Mine Ferrifere De Nador (Nord-est du Maroc)

The field work has been done to study the impact of acid mine drainage on the environment. Space pollution measurement was carried out on the basis of interesting physicochemical and geomatic analyses of water and solid region outcrops. The study showed that the phenomenon under study represents an alarming problem that is attributed to the presence of huge stocks of mining waste sulphur, directly exposed to a Mediterranean climate and thus remains capable of accelerating the oxidation process. The classification of zones according to the levels of fragility is entailed by the necessity to opt for a model that is compatible with different intrinsic and extrinsic parameters. The study was concluded by the superposition of six thematic layers charting the environmental vulnerability map by the GIS. The findings demonstrated that most vulnerable zones near the points of exploitation are very oxidized in bottomlands or in places well apart from carbonate facies (pH <3.

Distribution and diversity of bacterial communities and sulphate-reducing bacteria in a paddy soil irrigated with acid mine drainage.

To investigate the effects of long-term acid mine drainage (AMD) irrigation on the change in bacterial community and sulphate-reducing bacteria (SRB) in a paddy soil. The bacterial community structures were investigated using 454 pyrosequencing, and 98931 effective sequences were selected for the bacterial diversity analysis. The known dominant phyla in the paddy soil were Acidobacteria (33·5%), Proteobacteria (19·7%), Nitrospira (2·8%) and Actinobacteria (2·7%). Higher percentage of Acidobacteria than Proteobacteria was detected. The relative abundances of the dominant bacterial lineages were more significantly correlated with the soil pH, the organic matter and the sulphate than the heavy metals. The diversity of the SRB in the surface paddy soil showed that the uncultured SRB groups might play important roles in paddy soils. The other OTUs mainly belonged to six phylogenetic divisions: Desulfobacca, Desulfovibrio, Syntrophobacter, Desulforhopalus, Desulfarculus and Desulfobulbus. The distribution of the absolute abundance and the relative contribution of the SRB along the vertical soil profile were investigated by RT-PCR assays based on the dsrB gene. The abundance of the dsrB gene copy numbers was up to 1·92×10(9) copiesg(-1) dry soil, which is slightly higher than the other non-AMD-affected paddy soil. This study demonstrated that the abundance of SRB is increased by the AMD irrigation while changing the composition and diversity of the bacterial community in the paddy soil. This is, to our knowledge, the first attempt to characterize and quantify changes in the diversity and distribution of the microbial community and SRB in the long-term AMD-irrigated paddy soil, which will further increase our understanding of the impact of AMD on sulphur biogeochemical cycling in the paddy soil.

Responses of Stream Biofilm Phospholipid Fatty Acid Profiles to Acid Mine Drainage Impairment and Remediation

Acid mine drainage (AMD) impairs many streams throughout the historical and current coal mining regions. Abandoned mines often have sulfur-rich coal that produces sulfuric acid after exposure to water and oxygen. These streams are characterized by lowered pH, increased metal load, and decreased biotic assemblage complexity in comparison to unimpaired streams. Remediation efforts using alkaline addition have been successful in reducing the impacts of AMD by improving the chemical environment and reestablishing biotic assemblages that more closely resemble unimpacted streams. We used phospholipid fatty acids (PLFA) to detect changes in biofilm fatty acid profiles, differences in specific fatty acid biomarkers, and nutritional quality among AMD-unimpaired, AMD-impaired, and AMD-remediated stream sites in southeastern Ohio (USA). In general, the physical, chemical, and biological measurements of the remediated sites were intermediate between the unimpaired and impaired streams. PLFA content was five times greater in AMD-unimpaired sites when compared to AMD-impaired and double that of AMD-remediated sites. PLFA profiles separated sites of the three categories into two statistically distinct groups: AMD-unimpaired/AMD-remediated and AMD-impaired. The results of this study showed that PLFA profiles have great promise as an additional metric to evaluate AMD impact for stream biomonitoring programs.