Comparison of microbial communities in petroleum-contaminated groundwater using genetic and metabolic profiles at Kyonggi-Do,South Korea

This research has been performed to determine the differences in microbial communities according to physicochemical properties such as concentrations of volatile aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX), dissolved oxygen (DO), electron acceptors, etc., in oil-contaminated groundwaters at Kyonggi-Do, South Korea. The properties of bacterial and microbial communities were analyzed by 16S polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) fingerprinting method and community-level physiological profiling (CLPP) using Eco-plate, respectively. Based on the DGGE fingerprints, the similarities of bacterial community structures were high with similar DO levels, and low with different DO levels. Whereas the dominant bacterial groups in GW13 (highest BTEX and lowest DO) were acidobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and spirochetes, those in GW7 (highest BTEX and highest DO) were actinobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and sphingobacteria. Based on the CLPP results, the groundwater samples were roughly divided into three groups: above 4 mg/L in DO (group 1: GW3 and GW7), below 4 mg/L in DO (group 2: GW8, W1, W2, W3, and BH10), and highly contaminated with BTEX (group 3: GW13). Shannon index showed that the microbial diversities and equitabilities were higher in shallower aquifer samples. Overall, this study verified that the greatest influencing factors on microbial/bacterial communities in groundwaters were DO and carbon sources, although BTEX concentration was one of the major factors.     

Bioavailability of jarosite for stimulating acid mine drainage attenuation

Biological reduction of iron-sulfate minerals, such as jarosite, has the potential to contribute to the natural attenuation of acid mine drainage (AMD) sites. Previous studies of AMD attenuation at Davis Mine, an abandoned pyrite mine in Rowe Massachusetts, provided evidence of iron and sulfate reduction by indigenous bacteria. Jarosite is a large component of the sediment at Davis Mine and may play a role in AMD attenuation. In this study, microcosms were constructed with groundwater and sediment from Davis Mine and amended with glycerol, nitrogen and phosphorus (GNP) and naturally formed natrojarosite. Over time, higher total iron, sulfate, pH and sodium concentrations and lower oxidation–reduction potentials were observed in microcosms amended with GNP and jarosite, compared with unamended microcosms and killed controls. Geochemical modeling predicted jarosite precipitation under microcosm conditions, suggesting that abiotic processes were unlikely contributors to jarosite dissolution. SEM imaging at the jarosite surface showed microbial attachment. Microbial community composition analysis revealed a shift to higher populations of Clostridia, which are known to reduce both iron and sulfate. The results show that jarosite may be utilized as an electron acceptor by iron and/or sulfate reducing bacteria at Davis Mine and its presence may aid in the attenuation of AMD.     

Soil microbial community response to seawater intrusion into coastal aquifer of Donghai Island,South China

Due to the sea level rise and the excessive exploitation of freshwater, seawater intrusion is becoming a critical issue. To clarify the degree of seawater intrusion in Donghai Island and the microbial community structure and functional response to seawater intrusion, groundwater samples and sediment samples were collected at profiles A, B; the profiles were along the direction of groundwater flow, perpendicular to the coastline, a hydrogeochemical survey and soil microbial community analysis were also performed. The hydrogeochemistry analysis showed that the chemical type of groundwater was Na–Cl, brackish water was dominant in the area, and coastal groundwater was strongly affected by seawater intrusion. The effect of seawater intrusion on structural and functional diversity of soil microbes was analyzed from soil samples of the study area, by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). The results of DGGE patterns and phylogenetic tree show that the extent of seawater intrusion has directly influenced soil microbial community structure. The changes of microbial community structure might be related to the major elements’ concentrations in groundwater. Phylogenetic affiliation indicated that γ-proteobacteria were dominated in the profile A, while β-proteobacteria were mainly appeared in the profile B. The Flavobacteriaceae was only appeared at the shrimp ponds nearby.     

Geochemical distribution and removal of As,Fe, Mn and Al in a surface water system affected by acid mine drainage at a coalfield in Southwestern China

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. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A quantitative estimation of the factors affecting pH changes using simple geochemical data from acid mine drainage

The behavior of heavy metals in acid mine drainage (AMD) is mainly controlled by pH values. Therefore, a quantitative estimation of factors affecting pH values in AMD is very important in predicting the behavior of those metals. Many different factors cause pH changes in streams affected by AMD and we quantitatively estimated those factors by making simple equations from geochemical data collected from the Dalsung mine. In a stream from that mine, the pH values decrease as the stream flows downstream from the AMD source, which is different from normal streams affected by AMD. The stream shows low pH ranges (4.04–5.96), high electrical conductivity (1,407–1,664 μS/cm), and sulfate concentration (680–854 ppm). Most ion concentrations decrease or do not show noticeable changes mainly due to dilution. The change of the iron content is most significant, even though the concentration of iron is relatively low compared with other ions. The iron concentration (13.4 ppm) becomes almost 0 ppm due to precipitation. Schwertmannite is the dominant precipitated phase downstream and whitish basaluminite is observed in the upstream. From our pH estimation, precipitation is the most important process lowering pH values from 5.96 to 4.04. The dilution factor was calculated by the concentration changes in sulfate ions. Dilution increases pH values, but compared with the precipitation factor, the contribution of the dilution factor to pH is relatively small. Alkalinity is the main factor that buffers hydrogen, which is released by precipitation. The redox changes, which were calculated from the pH and Eh values, also affect pH at each sampling site. The trend of estimated pH changes is almost identical to the observed ones, but the values are slightly different. Some errors are expected mainly due to the uncertainty in the observed Eh values and the chemistry of the added water for dilution.     

南海北部九龙甲烷礁邻区沉积物层中垂向细菌群落结构特征研究

本研究应用微生物16S rRNA-DGGE和T-RFLP技术,结合环境参数,对我国天然气水合物潜在区南海九龙甲烷礁附近973-4柱状样沉积物中3个层位12个不同深度(表层20 cm至382 cm,中层552 cm至796 cm,深层862 cm至1 196 cm)细菌群落结构及其分布进行了对比研究.其中T-RFLP实验表明,细菌丰度、香农指数和均匀度变化趋势相同,由深层到716 cm处先降后升,中层716 cm深度范围处微生物群落丰度、均匀度、香农指数相对较高,716 cm至表层先降后升.DGGE图谱和T-RFLP色谱峰聚类分析表明:表层20 cm至192 cm相似性较高,表层236 cm至382 cm与深层1 082 cm、1 196 cm群落结构相似性较高,但中层沉积物中微生物群落结构与表层及深层均有较大差异.环境参数表明中层甲烷含量较高,推测甲烷是影响微生物群落结构差异的主要因素之一.T-RFLP色谱峰与微生物数据库比对及DGGE条带测序也表明了:本区变形杆菌(Proteobacteria)为优势菌群,其中α-、γ-、δ-变形杆菌(Proteobacteria)为主要的细菌亚群,其他细菌包括放线菌(Actinobacteria)、厚壁菌门(Firmicutes)、绿弯菌门(Chloroflexi)为次优势菌群.甲烷含量较高的中层,甲烷氧化菌(Methanotrophs),硫还原菌(Sulfate-reducing bacteria)等与甲烷密切相关的细菌均有被检测到,表明该区域存在与天然气水合物的分解释放相关的微生物群落.     

Surface Mineralogy of Oxidized Pyrite by Acidithiobacillus Ferrooxidans

Sulfide oxidation by microbial activities play an important role in the release of heavy metals. An important source of contamination and formation of AMD is the heavy metals convey to soil, rivulet and groundwater. Pyrite is a commonly sulfide minerals in mine wastes, so it is vitally to prove up the microbial oxidation process.     

Hydrogeochemical processes of thallium in a rural area of Southwest Guizhou, China

The water system in a rural area of Lanmuchang in Southwest Guizhou is facing a risk of thallium (Tl) contamination due to Tl mineralization around the area. The major trace elements and Tl in the water system are studied to understand the hydrogeochemical processes of Tl constrained by Tl mineralization. The results showed that the dispersion pattern of Tl follows a descending order in concentration from mine groundwater (deep groundwater) →stream water→shallow groundwater→background water, reflecting the impact of Tl mineralization on the hydrogeochemical composition. Tl concentrations in stream water in both regimes are remarkably higher (2-30 fold) downstream than up- and mid-streams, probably caused by the unidentified discharge of deep groundwater. Low Tl levels are detected in the current drinking water, however, the highly elevated Tl in stream water and ground water may pose a potential environmental risk through daily washing and agricultural irrigation. This study suggests that human activities, such as agricultural irrigation, could intensify the environmental risk of Tl.     

Hydrochemistry of superficial waters in the Adoria mine area (Northern Portugal): environmental implications

The purpose of this work is to characterize the hydrochemical behavior of acid mine drainages (AMD) and superficial waters from the Adoria mine area (Northern Portugal). Samples of superficial and mine drainage water were collected for one year, bi-monthly, with pH, temperature, Eh, conductivity and HCO₃ determined in situ with chemical analyses of SO₄, Ca, K, Mg, Na, Cl, Ag, As, Bi, Co, Cu, Fe, Mn, Ni, Pb, Zn and Cd. In the mine, there are acidic waters, with low pH and significant concentrations of SO₄, and metals (Fe, Mn, Zn, Cu, Pb, Cd and Ni), while in the superficial natural stream waters outside the mine, the pH is close to neutral, with low conductivity and lower metal concentrations. The stream waters inside the mine influence are intermediate in composition between AMD and natural stream waters outside the mine influence. Principal Component Analysis (PCA) shows a clear separation between AMD galleries and AMD tailings, with tailings having a greater level of contamination.     

Evaluation of fertility indicators associated with arsenic-contaminated paddy fields soil

Emerging environmental issues related to heavy metal contamination in rice draw great concern about the soil quality of paddy farming lands irrigated with groundwater. Investigating the functioning of soil microorganisms exposed to heavy metal contamination is imperative for agricultural soil manipulations. The current study accentuates the influence of heavy metals on microbial activity and community composition in arable soil of West Bengal State of India. The result revealed that the fertility indicators (activity of all soil enzymes) and growth-limiting factors (soil N and P) were negatively correlated with the heavy metal stress except the soil total organic content which demonstrated significant positive correlation with the heavy metals. In case of functional diversity of soil, all the considered diversity indices exhibited no specific pattern along with the availability of heavy metals. Further, despite the heavy metal contamination, we observed a very complex and indifferent pattern of bacterial community composition along the heavy metal contamination sites. Overall, we found that γ-Proteobacteria had been the most abundant bacterial community followed by Actinobacteria, Firmicutes, β-Proteobacteria and α-Proteobacteria. Commemorating all the results, we can infer that arsenic and other heavy metal contamination is deteriorating the soil quality and hence warrants immediate attention of concerned soil scientist and agronomists.     

Pollution of a water course impacted by acid mine drainage in the Imgok creek of the Gangreung coal field,Korea

The purposes of this study are to (i) determine the geochemical characteristics of Imgok creek impacted by acid mine drainage (AMD) generated from abandoned coal mines, (ii) to assess the pollution of heavy metals in the stream sediments and soils, and (iii) to identify the chemical form of Fe precipitates collected in the study area where there are 4 abandoned coal mines, which belong to the Grangreung coal field at the eastern part of Korea. AMD generated from mine adits and coal refuse piles shows low pH, and high concentrations of Fe, Al and SO₄, especially in the Youngdong coal mine. In Imgok creek, pH values increased, and total dissolved solids (TDS) values decreased with distance. The concentrations of toxic heavy metals and major cations except Fe decreased by dilution, but the concentration of Fe decreased rapidly due to the formation of precipitates. The quality of groundwater samples did not exceed the Korean drinking-water standard. In the stream sediments, the concentrations of Fe are relatively high in the Youngdong tributary and Imgok creek, but the concentrations of heavy metals are similar to those of unpolluted sediments. Pollution indices of agricultural soils range from 0.28 to 0.47. Yellowish red Fe precipitates collected in the study area turned out to be amorphous or poorly crystallized minerals (determined by X-ray diffraction patterns and Fe_ox/Fe_tot ratios) and to contain chemically bonded SO₄ and OH [determined by infra-red (IR) spectral analysis]. With these, the mol ratios of Fe/S ranging from 4.6 to 6.1 determined by electron probe micro-analysis (EPMA) in precipitates strongly support the existence of schwertmannite.     

Microbial sulfate reduction and metal attenuation in pH 4 acid mine water

Sediments recovered from the flooded mine workings of the Penn Mine, a Cu-Zn mine abandoned since the early 1960s, were cultured for anaerobic bacteria over a range of pH (4.0 to 7.5). The molecular biology of sediments and cultures was studied to determine whether sulfate-reducing bacteria (SRB) were active in moderately acidic conditions present in the underground mine workings. Here we document multiple, independent analyses and show evidence that sulfate reduction and associated metal attenuation are occurring in the pH-4 mine environment. Water-chemistry analyses of the mine water reveal: (1) preferential complexation and precipitation by H₂S of Cu and Cd, relative to Zn; (2) stable isotope ratios of ³⁴S/³²S and ¹⁸O/¹⁶O in dissolved SO₄ that are 2–3 ‰ heavier in the mine water, relative to those in surface waters; (3) reduction/oxidation conditions and dissolved gas concentrations consistent with conditions to support anaerobic processes such as sulfate reduction. Scanning electron microscope (SEM) analyses of sediment show 1.5-micrometer, spherical ZnS precipitates. Phospholipid fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analyses of Penn Mine sediment show a high biomass level with a moderately diverse community structure composed primarily of iron- and sulfate-reducing bacteria. Cultures of sediment from the mine produced dissolved sulfide at pH values near 7 and near 4, forming precipitates of either iron sulfide or elemental sulfur. DGGE coupled with sequence and phylogenetic analysis of 16S rDNA gene segments showed populations of Desulfosporosinus and Desulfitobacterium in Penn Mine sediment and laboratory cultures.     

Behavior of rare earth elements in acid coal mine drainage in Shanxi Province, China

Rare earth element (REE) concentrations were determined in acid mine drainage (AMD), bedrock, pyrite, and coal samples from the Sitai coal mine and the Malan coal mine in Shanxi province, China. The AMD displayed high REE concentrations with typical convex shale-normalized patterns. The REE concentrations in the bedrock samples are one order of magnitude higher than those found in pyrite and coal samples. The high REE concentrations in AMD most likely come from the acidic solution leached out REE in bedrock. Results from laboratory and field experiments show that pH is the most important factor controlling the fractionation of REE; but Fe, Al, and Mn colloids and secondary minerals also affects their fractionation. As the pH increased from 4 to 6, the concentrations of total dissolved REE decreased from 520 to 0.875???g?L^?1. Fe and Al in AMD has less influence on the fractionation of dissolved REE than low concentrations of Mn. HREE were preferentially removed by secondary minerals and colloids, followed by MREE. Rare earth element??s speciation modeling indicates that sulfate complexes (LnSO₄ ⁺ and Ln(SO₄) ₂ ^? , 79?C91%) and free-metal species (Ln³⁺, 8.8?C21%) are the dominant REE species in the AMD, but the REE-sulfate complexation could not explain the MREE-enriched patterns.     

In situ biotreatment of acidic mine drainage using straw as sole substrate

Feasibility of using straw as sole substrate for in situ bioremediation of acidic mine drainage (AMD) was studied. The result showed that straw was more suitable than woodchips, which had been successfully used for bioremediating AMD at the source, for establishing bioremediation layer. The sulfate removal rate of rice straw treatment was almost two times higher than that of the woodchips treatment when the initial pH of the synthetic AMD was set to 3.0. Straw treatment may be more efficient at reducing sulfate than woodchips treatment under stressful conditions. The sulfate removal rate of the rice straw treatment increased from 8.67 to 21.77 mg L⁻¹ day⁻¹ when initial pH increased from 1 to 7 while the removal rate of woodchips treatment increased from 3.80 to 11.95 mg L⁻¹ day⁻¹. The sulfate removal rate of the rice straw treatment decreased from 13.93 to 9.91 mg L⁻¹ day⁻¹ when temperature decreased from 25 to 5°C while the removal rate of woodchips treatment decreased from 7.43 to 4.98 mg L⁻¹ day⁻¹. Differences in soluble organic carbon release between rice straw and woodchips led to the differences in bioremediation efficiency. Concentrations of Cu²⁺ maintained at low level in the column effluent during the whole bioremediation period. Cu²⁺ was removed by forming sulfide precipitates. Microbial community analysis showed that sulfate reducing bacteria in the bioremediation layer together with microorganisms capable of degrading rice straw caused the bioremediation of AMD. These findings have significant environmental implications in terms of in situ bioremediation of AMD using straw as sole substrate.     

Effects of iron on arsenic speciation and redox chemistry in acid mine water

Concern about arsenic is increasing throughout the world, including areas of the United States. Elevated levels of arsenic above current drinking-water regulations in ground and surface water can be the result of purely natural phenomena, but often are due to anthropogenic activities, such as mining and agriculture. The current study correlates arsenic speciation in acid mine drainage and mining-influenced water with the important water-chemistry properties Eh, pH, and iron(III) concentration. The results show that arsenic speciation is generally in equilibrium with iron chemistry in low pH AMD, which is often not the case in other natural-water matrices. High pH mine waters and groundwater do not always hold to the redox predictions as well as low pH AMD samples. The oxidation and precipitation of oxyhydroxides deplete iron from some systems, and also affect arsenite and arsenate concentrations through sorption processes.     

人工回灌过程中地下水微生物群落变化

人工回灌过程中,回灌水的注入使目的含水层地下水环境发生变化,微生物条件也会随之改变,从而影响地下水环境质量及水文地球化学作用。以上海市某人工回灌试验场为例,在分析人工回灌过程中水化学演化特点的基础上,应用DGGE技术对场地回灌过程中地下水中的微生物群落结构变化进行研究,为评价人工回灌对地下水水质安全的影响提供科学的理论依据。结果表明:人工回灌作用使目的含水层地下水中的Eh值及DO质量浓度升高,分别由64.0 mV、1.12 mg/L升至534.4 mV、1.44 mg/L;同一位置处微生物群落结构与原始地下水状态的相似性随时间降低;同一时刻距离回灌井越远的监测井的微生物群落结构越接近于原始地下水状态。随着回灌的进行,目的含水层地下水中优势菌属(种)共有7种,其中Rubrivivax gelatinosus和Candidatus Accumulibacter phosphatis clade IIA str.的反硝化能力以及Rhodoferax ferrireducens对Fe³⁺的还原能力,对地下水水化学组分产生影响。     

Distribution of reduced inorganic sulfur compounds in lake sediments receiving acid mine drainage

The sediments of Lake Anna, Virginia, act as a major sink for incoming acid mine drainage (AMD) pollutants (Fe, SO₄²⁻, H⁺) due to bacterial sulfate reduction (SR). Acid-volatile sulfide (AVS), elemental S, and pyrite concentrations in the sediments of the polluted arm of the lake are significantly greater than those in unpolluted sections of the lake. Measurements of SR using ³⁵SSO₄²⁻ showed that AVS and S⁰ are the major short-term (48 h) products of SR in these sediments. Inorganic forms of S(AVS, S⁰, and FeS₂) made up from 60 to 100% of the total sediment S concentration. Pyrite concentrations in the sediment were high but decreased exponentially with distance from the AMD source, suggesting that the pyrite was deposited as stream detritus from the abandoned mines. Iron monosulfide and elemental S concentrations were highest at a station 1 km away from the AMD inflow, indicating formation in situ. There was no evidence for the formation of organic S species. The results suggest that in Fe- and S-rich locations such as those contaminated with acid mine drainage, the distribution of end products of SR may vary substantially from those reported for more moderate environments.     

Integrated geophysical and geochemical study on AMD generation at the Haveri Au–Cu mine tailings,SW Finland

The Haveri tailings area contains 1.5 Mt of sulfide-bearing waste from the Au–Cu mine that operated during 1942–1961. Geophysical and geochemical methods were used to evaluate and characterize the generation of acid mine drainage (AMD). Correlations were examined among the electrical resistivity tomography (ERT) data, the total sulfide content and concentrations of sulfide-bound metals (Cu, Co, Fe, Mn, Ni, Pb and Zn) of tailings samples, and the resistivity and geochemistry of surface water. The resulting geophysical–geochemical model defines an area in the vadose tailings, where a low resistivity anomaly (<10 Ohm m) is correlated with the highest sulfide content, extensive sulfide oxidation and low pH (average 3.1). The physical and geochemical conditions, resulting from the oxidation of the sulfide minerals, suggest that the low resistivity anomaly is associated with acidic and metal-rich porewater (i.e., AMD). The lower resistivity values in the saturated zone of the central impoundment suggest the formation of a plume of AMD. The natural subsoil layer (silt and clay) and the bedrock surface below the tailings area were well mapped from the ERT data. The detected fracture zones of the bedrock that could work as leakage pathways for AMD were consistent with previous geological studies. The integrated methodology of the study offers a promising approach to fast and reliable monitoring of areas of potential AMD generation and its subsurface movement over large areas (ca. 9 ha). This methodology could be helpful in planning drill core sampling locations for geochemical and mineralogical analysis, groundwater sampling, and choosing and monitoring remedial programs.     

招远金矿区水体中硫同位素特征及其对污染来源的指示

稳定同位素因其指纹效应已成为分析矿区污染来源的重要技术手段。文章以招远金矿区为例,应用硫同位素联合水化学分析、聚类分析及氢氧同位素分析招远金矿区水污染特征和成因。通过分析可知,矿区内地表水和地下水主要接受大气降水补给,水力联系密切。水化学类型以SO₄—Ca和SO₄—Na型为主,阴离子以SO₄2-为主,地表水和地下水的NO₃-和Cl-在空间上变异性较大。地表水硫酸盐含量普遍偏高,硫酸盐污染较为严重,高值区出现在玲珑金矿、金翅岭金矿和张星镇附近;而地下水高值区都出现在玲珑金矿附近,且SO₄2-浓度沿着径流方向逐渐降低。地表水中硫酸盐δ34S值介于1.8‰~9.8‰,地下水中硫酸盐δ34S值介于2.7‰~9.6‰,地表水和地下水硫酸盐含量受玲珑金矿硫化、玲珑花岗岩和胶东岩群影响明显。在地下水径流途中,有地表水入渗污染地下水的现象。另外,工业废水的排放也是硫酸盐含量升高的主要原因。研究表明:硫同位素在金矿区硫酸盐污染的来源和特征方面有很好的指示作用,是评价矿山开采对地下水污染的有效工具。     

Contamination of water and soil by the Erdenet copper–molybdenum mine in Mongolia

As one of the largest copper–molybdenum (Cu–Mo) mines in the world, the Erdenet Mine in Mongolia has been active since 1978 and is expected to continue operations for at least another 30 years. In this study, the potential impacts of mining activities on the soil and water environments have been evaluated. Water samples showed high concentrations of sulfate, calcium, magnesium, Mo, and arsenic, and high pH values in the order of high to low as follows: tailing water > Khangal River > groundwater. Statistical analysis and the δ²H and δ¹⁸O values of water samples indicate that the tailing water directly affects the stream water and indirectly affects groundwater through recharge processes. Soil and stream sediments are highly contaminated with Cu and Mo, which are major elements of ore minerals. Based on the contamination factor (CF), the pollution load index (PLI), and the degree of contamination (C_d), soil appears to be less contaminated than stream sediments. The soil particle size is similar to that of tailing materials, but stream sediments have much coarser particles, implying that the materials have different origins. Contamination levels in stream sediments display a tendency to decrease with distance from the mine, but no such changes are found in soil. Consequently, soil contamination by metals is attributable to wind-blown dusts from the tailing materials, and stream sediment contamination is caused by discharges from uncontained subgrade ore stock materials. Considering the evident impact on the soil and water environment, and the human health risk from the Erdenet Mine, measures to mitigate its environmental impact should be taken immediately including source control, the establishment of a systematic and continuous monitoring system, and a comprehensive risk assessment.