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The generation of acid mine drainage (AMD) characterized by high acidity and elevated levels of toxic metals primarily results from the oxidation and dissolution of sulfide minerals facilitated by microbial catalysis. Although there has been significant research on microbial diversity and community composition in AMD, as well as the relationship between microbes and heavy metals, there remains a gap in understanding the microbial community structure in uranium-enriched AMD sites. In this paper, water samples with varying levels of uranium pollution were collected from an abandoned stone coal mine in Jiangxi Province, China during summer and winter, respectively. Geochemical and high-throughput sequencing analyses were conducted to characterize spatiotemporal variations in bacterial diversity and community composition along pollution groups. The results indicated that uranium was predominantly concentrated in the AMD of new pits with strong acid production capacity, reaching a peak concentration of 9,370 µg/L. This was accompanied by elevated acidity and concentrations of iron and total phosphorus, which were identified as significant drivers shaping the composition of bacterial communities, rather than fluctuations in seasonal conditions. In an extremely polluted environment (pH < 3), bacterial diversity was lowest, with a predominant presence of acidophilic iron-oxidizing bacteria (such as Ferrovum), and a portion of acidophilic heterotrophic bacteria synergistically coexisting. As pollution levels decreased, the microbial community gradually evolved to cohabitation of various pH-neutral heterotrophic species, ultimately reverting back to background level. The pH was the dominant factor determining biogeochemical release of uranium in AMD. Acidophilic and uranium-tolerant bacteria, including Ferrovum, Leptospirillum, Acidiphilium, and Metallibacterium, were identified as playing key roles in this process through mechanisms such as enhancing acid production rate and facilitating organic matter biodegradation. [ABSTRACT FROM AUTHOR]

This paper studied the characteristics of the carbon emission of an industrial wastewater treatment plant (IWWTP) and a domestic WWTP (DWWTP) located in a high-tech industrial park of Shaanxi Province, China. The results showed that the total carbon emissions of the IWWTP and DWWTP were 10.13 kg/t and 1.84 kg/t in 2020, respectively. Indirect carbon emissions play a dominant role in the total carbon emission of the IWWTP, which accounts for about 97.6% of the total amount. The direct carbon emissions of greenhouse gases (e.g., CH4, N2O) account for about 62% of the total carbon emissions in the DWWTP, followed by the indirect carbon emissions generated by electricity consumption (31.06%) and chemical consumption (6.94%). Additionally, the centralized recycling and re-utilization of the wastewater could achieve 1.06 kg/t and 1.16 kg/t of carbon emission reduction in the IWWTP and DWWTP, respectively, while the carbon emissions of the DWWTP are inversely proportional to the treatment capacity. Therefore, it is of great value to collect and utilize intensively the recycled water to achieve the goal of regional carbon emission reduction and carbon neutralization of WWTPs in industrial parks. [ABSTRACT FROM AUTHOR]

At present, the life and production of our society are still accompanied by high pollution emissions. The proposal of the "double carbon" goal puts forward clearer requirements for China's energy conservation and emission reduction process. To cope with stricter green development requirements, green finance came into being, contributing a new path to the realization of the "double carbon" goal. This paper is based on the panel data of 30 provinces and cities in China (except Tibet, Hong Kong, Macao, and Taiwan) from 2011 to 2020, using the fixed effect model, threshold model, mediator model, and SDM model to study the impact of green finance on carbon neutralization capacity and its impact path based on reasonable measurement of regional green finance development level and carbon neutralization capacity. The study found that due to the existence of the "green paradox" and "forced emission reduction", China's green finance has a significant positive U-shaped impact path on carbon neutralization capacity; at the same time, informal regulation has a significant single-threshold effect in this path. When informal regulation crosses 0.47, the impact of green finance on carbon neutralization capacity will change from negative to positive, overcoming the impact of the "green paradox"; there is a nonlinear mediating effect of marketization level and technological innovation in the path of green finance affecting carbon neutralization capacity. In addition, green finance not only affects local carbon neutralization capacity but also has a positive spillover effect on neighboring regions. [ABSTRACT FROM AUTHOR]

The oxidative dissolution of the sulphide mineral pyrite (FeS2) has been of significant interest since it affects global geochemical cycles, generates acid mine drainage, and is used in industrial metal extraction. Several different groups of prokaryotes are known to catalyze the dissolution of pyrite and use the free energy generated from the oxidation, which may result in the dissolution of the mineral and the precipitation of the secondary ferric iron minerals either on the cell surface or is separated from the cells. However, straightforward evidence for such metabolic process in the ancient sediments is rare. Here we report pyrite crystals from the Lower Cambrian oolitic limestones that show indications of microbial erosion in various degrees. Erosion pits and tubular micro-tunnels with characteristic shapes and sizes in our samples are generally similar to those obtained from the laboratory studies on the oxidative dissolution of pyrite by ironoxidizing bacteria. Diagenetic examination demonstrates that the bioerosion predates the consolidation of the limestone. In addition, bacillus-sized and -shaped microfossils encrusted with iron oxides are present in our samples, which are very likely to be fossilized sheaths produced by iron-oxidizing bacteria. Our findings indicate that the microbial oxidative dissolution of pyrite existed in the Cambrian shallow marine carbonate sediments. Furthermore, we suggest that characteristic pitting patterns on the pyrite crystals from ancient sediments are an important clue to trace the evolution of life, in particular, the evolution of metabolism like microbial iron oxidation in the remote past on our planet, independent of biomarkers, isotopic signals and body fossils as well. [ABSTRACT FROM AUTHOR]

Coal mining has serious impacts on local environment, including damage to the land and soil by subsidence, damage to ground-water systems through the fracturing and subsiding of overlying rocks, contamination of surface waters with acid mine drainage, and pollution of the atmosphere by release of toxic gases. The damage to ground water and its consequent impacts on the regional environment is the core of research of the coal mining from the perspective of environment protection. The present paper focuses on the changes of surface vegetation coverage, the pollutants released from pit coal power plants, and the damages to the ground aquifers induced by mining activities in arid Eastern Junggar coalfield of China. At first, the authors investigated the changes of surface vegetation coverage, since mining began in the 2000s using Landsat data. Results show that the low surface vegetation coverage (grade 1 plus grade 2) in the southern part of the region decreased from 11.62 × 108 m2 in 2003 to 9.57 × 108 m2 in 2017 (−17.6%), while it increased from 11.58 × 108 m2 in 2003 to 12.70 × 108 m2 in 2017 (+ 9.7%) in the eastern part. The high surface vegetation coverage (grade 3 plus grade 4) in the southern part increased from 1.94 × 108 m2 in 2003 to 4.00 × 108 m2 in 2017 (+ 106.2%), while it decreased from 4.39 × 108 m2 in 2003 to 3.26 × 108 m2 in 2017 (−25.74%) in the eastern part. The data of annual precipitation during the same period in this area show that the changes of surface vegetation coverage have less relationship with the annual precipitation, which indicates that the mining activities is probably the major factor for that. Second, a statistic of air pollutants generated from pit coal power plants was made based on data of references. Results show that the estimated gaseous pollutant emissions increased as 865.23 tons of smoke particles, 5940.73 tons of SO2, and 7584.48 tons of NO2 in 2013, which increased rapidly with 9.73 times the smoke particle, 21.69 times the SO2, and 9.24 times the NO2 than that of 2007. And then, the physical and numerical simulation of the damage of mining activities to aquifers was made to show the permeability of the reference points of overlying aquifers varies associated with mining activities. Results show that the porous rock matrix permeability has a negative relationship with fluctuation during mining, while the fracture permeability shows a positive one. Finally, a case investigation in southern area surrounding this coalfield was illustrated. Result shows that the local ground-water level decreased by 16 m difference from the altitude level of + 774 m in 2003 to + 758 m in 2013. Data and results from this study presented the already and the potential pollutions and damages to local environment induced by the mining activities in this region. [ABSTRACT FROM AUTHOR]

The influence of mining activities on groundwater quality is a growing concern due to highly toxic metals in the tailings. Carbonate rocks are common in the surrounding rocks of ore deposits. But such mining districts generally do not have the conditions to construct traditional tailings impoundments due to the different degrees of karstification. This paper utilises field investigations, chemical analyses, and permeability tests, etc. to study the effect of tailings impoundments on the underlying karst water systems in the Gejiu world-class Sn-polymetallic mine located in a typical karst region in southern China, with samples collected from both karst springs deriving from the mining area and tailings porewater. Because of the abundance of sulphide minerals in the ores, acid mine drainage is expected to pose a high risk. However, the results indicate that the tailings porewater is moderately neutral and is characterized by the SO4–Ca–Mg hydrochemical type. This can be attributed to the substantial buffering capacity of carbonate minerals. Pollution elements in the tailings porewater mainly include SO42− and toxic metals including As, Cd, Mn, Pb, and Hg. The type of pollution factors and the degree of contamination are not consistent in the different tailings impoundments. The hydrochemical classification of four karst springs distributed in the south of the mining area is HCO3–Ca–Mg. The concentrations of SO42− and the toxic constituents in the springs are far below the national standards for drinking water. The spring water not being contaminated may be attributed to the operation mode of the tailings impoundments (peripheral discharge and reuse of ponded water), the residual clay between the tailings impoundments and the carbonate bedrocks and the sufficient buffering capacity of the underlying karst systems. The tailings disposal at the Gejiu tin mine within the natural karst depressions is able to provide a reference for the operation of karst mines in China and elsewhere. [ABSTRACT FROM AUTHOR]

This work aims to understand the distribution and migration mechanisms of U and Mo between surface sediment and water in acid mine drainage (AMD) regions near a molybdenum mining region. A series of river sediment and water samples near the Jinduicheng mining area, one of the largest deposits of molybdenite ore in Asia, were collected and analyzed. Our results indicate that: (1) The pH value of river water samples increases with distance from upstream to downstream, while the pH has poor correlation with Mo and U; (2) The content of Mo and U in the sediment are significantly higher than the background value, which suggests potential pollution; (3) The content of Mo and U in the water and sediments in the lower reaches of the Wenyu river is significantly linearly related with the distance from the mining area, suggesting that AMD is a potential source; (4) BCR analysis shows that Mo in river sediments mainly existed as the residual, while U mainly existed as the non-residual; (5) The distribution coefficient Kd(Mo) exceeds Kd(U), indicating that Mo is enriched in sediments while U is more prone to porewater. [ABSTRACT FROM AUTHOR]

The chemical characteristics, formation and natural attenuation of pollutants in the coal acid mine drainage (AMD) at Xingren coalfield, Southwest China, are discussed in this paper based on the results of a geochemical investigation as well as geological and hydrogeological background information. The chemical composition of the AMD is controlled by the dissolution of sulfide minerals in the coal seam, the initial composition of the groundwater and the water--rock interaction. The AMD is characterized by high sulfate concentrations, high levels of dissolved metals (Fe, Al, Mn, etc.) and low pH values. Ca2+ and SO4 2-- are the dominant cation and anion in the AMD, respectively, while Ca2+ and HCO3 -- are present at significant levels in background water and surface water after the drainage leaves the mine site. The pH and alkalinity increase asymptotically with the distance along the flow path, while concentrations of sulfate, ferrous iron, aluminum and manganese are typically controlled by the deposition of secondary minerals. Low concentrations of As and other pollutants in the surface waters of the Xingren coalfield could be due to relatively low quantities being released from coal seams, to adsorption and coprecipitation on secondary minerals in stream sediments, and to dilution by unpolluted surface recharge. Although As is not the most serious water quality problem in the Xingren region at present, it is still a potential environmental problem. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) from abandoned mines in karst-dominated regions in southwestern China was causing contamination of groundwater and surface streams. To avert the unwise decisions of "pollution first before treatment" during pre-mining, mid-mining and post-mining activities, this paper proposes a contaminant migration prevention technical framework covering 4 comprehensive processes. The formation mechanism of spring pollution, engineering remediation processes and contamination treatment effects were described in Longdong Spring. In 2018, the Longdong Spring water had Fe 33.83 mg/L and Mn 3.60 mg/L, exceeding the Chinese surface water standard (0.3 mg/L and 0.1 mg/L in GB 3838–2002) by 112 and 36 times, respectively. In 2020, after grout blocking, in situ treatment and wetland remediation, the highest Fe was 4.5 mg/L in a short period, and the spring water pollution days in this year were 42 days compared with the previous 320 spring water pollution days in 2018. In 2021, two years of remediation with the implementation of terminal remediation wetlands, the Fe was less than 0.03 mg/L compared with the previous 33.83 mg/L, and the water quality reached water standard (less than 0.3 mg/L). At present, Longdong Spring has become one of the most beautiful natural local landscapes. • An innovative practical prevention application of legacy AMD was described. • The AMD treatment technical framework covered 4 comprehensive processes. • Fe was 0.03 mg/L compared with previous 33.83 mg/L after 2 years remediation. • The variation trend of SO 4 2− in the whole mining life cycle was discussed. [ABSTRACT FROM AUTHOR]

Mining has brought many environmental problems to the surrounding soil, water, and air, with toxic elements contaminating surface water, threatening ecological balance and human health. This study selected the Wenyu watershed downstream from a large molybdenum mine in the Qinling Mountains as the study area, aiming to explore the impact of molybdenum mining on surface water quality. The content characteristics of Cd, Pb, Cu, Cr and Hg in surface water, sediment, and rock samples were analyzed by field sampling and chemical testing. The results showed only obvious Cd pollution. The pollution status and ecological risk level of surface water and sediment samples in the Wenyu Stream watershed were evaluated using the single pollution index method, geo-accumulation index method, and Hakanson potential ecological risk assessment method. Finally, the sources of Cd pollution and the impact of mining on Cd distribution in the Wenyu Stream were comprehensively discussed. The research results showed that Cd content in the Wenyu Stream was significantly affected by mining activity and the coefficient of variation of Cd content reached 99.44%. Among 22 surface water samples, 21 samples met the Class II water standard, indicating a clean overall water quality of the Wenyu Stream, and only one sample exceeded the Class II water standard with a mild pollution level. All 15 sediment samples were polluted to varying degrees and the most severely polluted sample had reached a moderate to strong pollution level. Most of the samples were at a moderate pollution level. The potential ecological hazard indexes of Cd content were at medium to very strong risk level, indicating that the overall sediment in the main ditch of the Wenyu Stream was under a strong ecological risk level. The main sources of Cd pollution, including acid mine drainage, regional geological background, sediment release, and atmospheric dry and wet deposition, were discussed. [ABSTRACT FROM AUTHOR]

In this paper, the partitioning of copper between surfacial sediments and overlaying water in Dawu-Le An River, which was contaminated by acid mine drainage resulted from mining activities, was studied by field investigation and acid dissolution experiment. Simulated adsorption experiments were carried out to study the adsorption of copper on amorphous iron oxyhydroxide and ore tailing particles. The results showed that it was the binding of copper onto the surface of dissolved Cu at downstream of Dawu River and its inlet Le Ann River. A significant part of adsorbed copper was likely to be associated with amorphous Fe/Al oxyhydroxides coated on the surface of ore tailing particles. A simplified surface complexation model can be used to describe the adsorption behavior in the river. [ABSTRACT FROM AUTHOR]

Recent advances in environmental genomics have provided unprecedented opportunities for the investigation of viruses in natural settings. Yet, our knowledge of viral biogeographic patterns and the corresponding drivers is still limited. Here, we perform metagenomic deep sequencing on 90 acid mine drainage (AMD) sediments sampled across Southern China and examine the biogeography of viruses in this extreme environment. The results demonstrate that prokaryotic communities dictate viral taxonomic and functional diversity, abundance and structure, whereas other factors especially latitude and mean annual temperature also impact viral populations and functions. In silico predictions highlight lineage-specific virus-host abundance ratios and richness-dependent virus-host interaction structure. Further functional analyses reveal important roles of environmental conditions and horizontal gene transfers in shaping viral auxiliary metabolic genes potentially involved in phosphorus assimilation. Our findings underscore the importance of both abiotic and biotic factors in predicting the taxonomic and functional biogeographic dynamics of viruses in the AMD sediments. The biogeography of viral communities in extreme environments remains understudied. Here, the authors use metagenomic sequencing on 90 acid mine drainage sediments sampled across Southern China, showing the predominant effects of prokaryotic communities and the influence of environmental variables on viral taxonomy and function. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, geochemical characteristics of rare earth elements (REE) in acid mine drainage (AMD) from the Sitai coal mine of Shanxi Province, North China were investigated by determining concentrations of dissolved REEs and major solutes in the AMD samples, concentrations of REEs in the AMD precipitate samples and country rock samples (mudstone and coal), and modeling REEs species in the AMD. The results show that AMD in the Sitai coal mine have high REEs and SO4 2− concentrations in comparison with several terrestrial waters worldwide. The REE speciation modeling indicates that sulfate complexes (LnSO4 +, >60%) and free metal species (Ln3+, 20%–40%) are dominant REEs species in the AMD. AMD of the Sitai coal mine also shows a middle REE-enriched NASC (North American Shale Composite)-normalized pattern. The authors suggest that both REE sulfates (LnSO4 +) in the AMD and country rock of coal measures are possible reasons for middle REE-enriched NASC-normalized pattern of the Sitai coal mine AMD. Further work on the AMD precipitates is needed to obtain more information on the origin of the middle REE-enriched NASC-normalized patterns. [Copyright &y& Elsevier]

Metal contamination from base metal sulphide mines is a major environmental challenge that poses many ecological and health risks. We examined the metal concentrations in the Dabaoshan mine in South China in water, sediments, and aquatic organisms and their specific characteristics (i.e. size, body tissue, species, and habitat) along the Hengshi and Wengjiang River courses to assess acid mine drainage remediation efforts. Metal concentrations of arsenic, cadmium, chromium, copper, lead, nickel, thallium, and zinc were examined in tissues (i.e. gills, intestines, and muscles) of 17 freshwater species of fish, shrimps, and crabs. Metals in tissues followed the trend: intestines > gills > muscles; nearly all intestine samples exceeded the safe limits of metals analysed in this study. There is a positive correlation between distance from the mine and metal concentrations related to the flow of surface water and the habitat of aquatic organisms. The concentrations of arsenic, copper, and zinc were the highest in aquatic organisms, and the distribution was influenced by physical (distance from mine, currents, and seasonality), chemical (pH and competing ions), and biological (species, habitat, and predator–prey relation) factors. Large demersal fish and benthic fauna had higher concentrations of metals. Bioaccumulation and biomagnification of metals, as well as the high metal pollution index and target hazard quotient (arsenic, cadmium, copper, lead, thallium, and zinc), occurred in bottom feeders (C. aumtus, X. argentea) and fish belonging to higher trophic levels (P. fulvidraco, O. mossambicus). Lead and cadmium indicated the highest level of biomagnification from prey to predator. Health risks exist from the dietary intake of common aquatic species such as tilapia and carp besides crustaceans due to high arsenic, cadmium, lead, and thallium levels. Further reduction of metals is necessary to improve the effects of acid mine drainage in the catchment. [ABSTRACT FROM AUTHOR]

Heavy metals are of public concern in aquatic ecosystems due to their growing release from industries and mining activities. This study investigated the sources, temporal-spatial distributions and water quality of dissolved heavy metals (Mn, Co, Al, Ni, Ba, V, Sb, Fe, Sr) in the Lake Aha watershed, an area under the influence of sewage and acid mining drainage. These heavy metals displayed significant spatial and temporal variabilities. The water quality index results (WQI values ranged from 3.21 to 15.64) and health risk assessment (all hazard indexes are below 1) indicated that dissolved heavy metals in this study pose a low risk for human health. Correlation analysis and principal component analysis indicated that Fe and Sr mainly presented a natural geological feature in the study area, and Mn, Co, Al and Ni were influenced by the acid coal mine drainage, whereas Ba, V and Sb were under the impact of local industrial or medical activities. This study provides new insights into the risk assessment of heavy metals in small watersheds. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) lake of Xiang Mountain in Anhui Province, China, was characterized by acidic waters (pH around 2.8) containing high concentrations of soluble metals and sulfate. To investigate the function and dynamics of this extreme ecosystem, four water samples were collected from the lake in the fall of 2010. The acidophilic community structure was analyzed by molecular approaches, and bacterial and archaeal clone libraries of 16S rRNA genes were constructed. In contrast to dominance of chemolithotrophic acidophiles in typical AMD environments, autotrophic iron/sulfur-oxidizing bacteria were detected in only one sample with low abundance. Unexpectedly, the Cyanobacteria group was the predominant in all four samples (54.9%−77%). Chemoheterotrophs Acidiphilium and Acidisphaera were also abundant. These two heterotrophic groups contain bacteriochlorophyll that can perform photosynthesis, an advantage to grow and survive in such oligotrophic acidic environments. Only two clone sequences related to Legionella (2.8% of the total clones) were recovered from one sample in sharp contrast to its higher abundance (12.7%) in the summer of 2009. All archaeal sequences were affiliated to the phylum Crenarchaeota. The results of statistical analysis suggested that the water chemistry of the AMD lake controlled microbial composition of the AMD ecosystem. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is a common pollution in mining areas due to the oxidation of pyrite and associated sulfide minerals at mines, tailings and mine dumps. Elevated metals (Fe, Mn, Al) and metalloids (As, Hg) in AMD would deteriorate the local aquatic environment and influence the water supply. A carbonate basin with deposits of high-arsenic coal in Xingren County, southwestern China, was chosen to study the behavior of As and other chemical constituents along a river receiving AMD. Heavy metals (Fe, Mn) and major ions such as (Ca, Mg, Cl, SO) in surface water, and As in sediment and surface water were analyzed. It was found that high concentrations of SO (1,324-7,560 mg/L) and Fe (369-1,472 mg/L) in surface water were mainly controlled by the interactions between water and rocks such as the oxidation of pyrite in the local coal seams, precipitation and adsorption of iron minerals. Although ubiquitous carbonate minerals in the bedrock and the riverbeds, low pH (<3) water was maintained until 2 km downstream from the AMD source due to the Fe(hydro)oxide minerals coating on the surface of carbonate minerals to restrain the neutralization of acidic water. Moreover, the formation of Fe(hydro)oxide precipitations absorbed As was dominated the attenuation of As from water to sediment. Whereas, the dilution also played an important role in decrease of As in river water. [ABSTRACT FROM AUTHOR]

The article presents a study on the archaeal diversity in three acid mine drainage (AMD) samples from Dabaoshan Mine in China. It employs amplified ribosomal DNA restriction analysis (ARDRA) to describe the genetic level of the diversity and community structures of the archaeal communities. It evaluates nine different ARDRA patterns from 146 clones and were analyzed as operational taxonomic units (OTUs). It presents the sequence data and phylogenetic analysis of the clones associated to the Thermoplasmatales. It identifies the existence of one OTU assigned to Ferroplasma and the isolation of the clones in two similar units. It explains the reciprocality of Simpson's index in these diversities and the correlation of the concentrations of ferrous ions and toxic ions in the AMD samples.

The article presents the study conducted regarding the use of culture-independent 16S rRNA gene under cloning approach on determining the microbial diversity of mine water at Zhong Tiaoshan copper mine in Shanxi province, China. The study based on the Principal Component Analysis (PCA) of the Operational Taxonomic Units (OTU) and biogeochemical data shows that the diversity of microbial communities in water is affected by the biogeochemical properties. The different concentrations and temperature of several elements also influenced the structure and composition of microbial communities.

Cultivation-based and molecular approaches were used to characterize the phylogenetic composition and structure of the microbial community in an extremely acidic (pH 2.0) acid mine drainage (AMD) associated with Pb/Zn mine tailings that were undergoing vigorous acid generation. Acidophilic bacteria were isolated and enumerated on solid media, and were found to be restricted to isolates related to Acidithiobacillus ferrooxidans and Acidiphilium cryptum. By contrast, cloning and phylogenetic analysis of 16S rRNA genes revealed that, although low in total taxonomically distinct groups, the tailings AMD ecosystem harbored a wide range of phylogenetically diverse microbes. Of the 141 clones examined, 104 were phylogenetically affiliated with the recently discovered, iron-oxidizing Leptospirillum group III within the Nitrospira. It thus appears that iron serves as the major electron donor in this habitat. Thirty clones were affiliated with the Proteobacteria, half of which belonged to organisms related to Alphaproteobacteria species capable of ferric iron reduction. Other clones were grouped with Betaproteobacteria and Gammaproteobacteria (six clones each), and even with Deltaproteobacteria (three clones), a subdivision with anaerobic sulfate or metal (iron) reduction as the predominant physiological trait of its members. Finally, four clones were clustered within the Firmicutes and the Acidobacteria. Approximately half of the sequence types representing the majority of the total clones fell into lineages that are poorly represented by cultured organisms or have thus far been represented by only a few environmental sequences. Thus, the present study extends our knowledge of the biodiversity of microorganisms populating highly acidic AMD environments. [ABSTRACT FROM AUTHOR]

The article presents abstracts of several studies on environmental geochemistry. Some of the abstracts presented include "Biogeochemical Cycling of Nutrients in Karstic Catchments, Southwestern China: Linkages to Changes of Eco-Environments," by Congqiang Liu and "Emerging Organic Contamination in China," by Guibin Jiang and colleagues.

Acid mine drainage (AMD) from abandoned coal mines can lead to serious environmental problems due to its low pH and high concentrations of potentially toxic elements. In this study, soil pH, sulfur (S) content, and arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), zinc (Zn), iron (Fe), manganese (Mn), and mercury (Hg) concentrations were measured in 27 surface soil samples from areas in which coal-mining activities ceased nine years previously in Youyu Catchment, Guizhou Province, China. The soil was acidic, with a mean pH of 5.28. Cadmium was the only element with a mean concentration higher than the national soil quality standard. As, Cd, Cu, Ni, Zn, Mn, Cr, and Fe concentrations were all higher than the background values in Guizhou Province. This was especially true for the Cd, Cu, and Fe concentrations, which were 1.69, 1.95, and 12.18 times their respective background values. The geoaccumulation index of Cd and Fe was present at unpolluted to moderately polluted and heavily polluted levels, respectively, indicating higher pollution levels than for the other elements in the study area. Spatially, significantly high Fe and S concentrations, as well as extremely low pH values, were found in the soils of the AMD sites; however, sites where tributaries merged with the Youyu River (TM) had the highest Cd pollution level. Iron originated mainly from non-point sources (e.g., AMD and coal gangues), while AMD and agricultural activity were the predominant sources of Cd. The results of an eco-risk assessment indicated that Cd levels presented a moderate potential ecological risk, while the other elements all posed a low risk. For the TM sites, the highest eco-risk was for Cd, with levels that could be harmful for aquatic organisms in the wet season, and may endanger human health via the food chain. [ABSTRACT FROM AUTHOR]