Mine Tailings Ponds Research Articles

Accelerated solvent extraction combined with GC–MS: A convenient technique for the determination and compound-specific stable isotope analysis of phthalates in mine tailings

A reliable, simple and fast method was developed to detect four phthalic acid esters (PAEs) including dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and diethylhexyl phthalate (DEHP) in mine tailings based on the accelerated solvent extraction (ASE) combined with gas chromatography-mass spectrometry (ASE/GC–MS). Evaluation of extraction parameters including choice of extraction solvent, temperature, extraction time, and number of extraction cycles showed that dichloromethane, 120 °C, 3 min, and 2 cycles were optimal, respectively. Under these conditions, the limit of detection (LOD) and limit of quantitation (LOQ) values were in the range of 1.2–2.0 µg kg–1 and 3.0–4.6 µg kg–1, respectively, and precision of the analytical data, RSD ≤ 7.0% were determined. This method was used to analyze the PAEs-spiked mine tailing samples (100 µg kg–1 of each analyte). Acceptable recovery values of 71.3–77.1%, 100–110%, 105–116%, and 101–115% were obtained for DMP, DEP, DBP and DEHP, respectively. The technique was also successfully applied for the extraction of the PAEs in real samples collected from mine tailing pond. Finally, stable C and H isotope analyses were conducted using GC coupled to isotope ratio MS to investigate effect of the ASE method on H and C isotopic compositions of the target analytes. Results showed that the ASE procedure did not lead to significant isotope fractionation of the compounds. Overall, the major advantages of this method are: automated operation, high sensitivity, short extraction time, less solvent consumption, and compatibility with a variety of detecting equipment. Combined with CSIA, it could be used to study the degradation mechanisms of target PAEs in mine tailing environments.

A Bayesian Network-based risk dynamic simulation model for accidental water pollution discharge of mine tailings ponds at watershed-scale

Mine tailings ponds that contain heavy metals are sources of potential risk to human security and ecosystem health. China particularly faces challenge of accidental water pollution risk from more than 8869 mine tailings ponds in serve by 2015, some of which are close to residential areas and other important infrastructures within 1 km downstream. To address watershed-scale risk assessment of accidental water pollution from mine tailings ponds, a Bayesian Network-based Risk Dynamic Simulation (BN-RDS) model was proposed to simulate “sources/stressors-receptors-endpoints” risk routes. An accidental water pollution convection-diffusion simulation was coupled to Bayesian Networks to perform the risk dynamic simulation and risk evolution quantification at watershed-scale. This method was applied to the risk assessment of 23 tailings dams in 12 sub-watersheds covering the Guanting Reservoir basin (the major backup drinking water source for Beijing) in Zhangjiakou City, China. The result indicated that ecosystem health and property security were the endpoints at the highest risk in the overall watershed. Spatially, the combined risk distribution map showed the risk was higher in the downstream of the Guanting Reservoir Watershed and in its two tributary basins (the Qingshui River and the Longyang River). This research highlighted a probabilistic approach to accidental water pollution risk assessment of tailings ponds with verifiable and tangible results for risk managers and stakeholders.

Could the rhizoplane biofilm of wetland plants lead to rhizospheric heavy metal precipitation and iron-sulfur cycle termination?

Iron plaque (IP) formation via radial oxygen loss (ROL) of wetland plant has been predominantly recognized as the reason for heavy metal sequestration in the rhizosphere. However, the same contribution of the microbes living in a potential rhizoplane biofilm matrix has not been comprehensively elucidated. In this review, we proposed a conceptional model of the wetland plant rhizoplane biofilm and summarized the possible pathways therein for heavy metal precipitation and iron-sulfur cycle termination. After an introduction of the effects of IP and microbes on the phytoremediation of heavy metal-contaminated wetland, the distribution of rhizospheric bacteria and different metal speciations resulted from wetland plant ROL were demonstrated. Based on the studies of microflora in the rhizosphere and IP, coupled with the ROL nature, we proposed an existence of rhizoplane biofilm with a special structure that could contribute to the rhizospheric iron-sulfur cycle termination by the production of heavy metal precipitates (metal sulfides). The ROL leads to the diffusion of oxygen with a decreasing gradient from the root surface (rhizoplane) to the bulk soil, allowing the formation of an unconventional rhizoplane biofilm comprising an aerobic inner layer and an anaerobic outer layer. Thus, aerobic bacteria, e.g., iron-oxidizing bacteria (IOB) and sulfur-oxidizing bacteria (SOB), as well as anaerobic bacteria, e.g., iron-reducing bacteria (IRB) and sulfate-reducing bacteria (SRB), are favored in the inner layer and outer layer of the rhizoplane biofilm, respectively. In the inner layer, ferrous sulfide is oxidized by IOB and SOB to Fe3+ and SO42−. Fe3+ is thereafter bound with oxygen into iron (hydro)oxides, aggregating into a barrier of iron plaque for heavy metal sequestration and O2 diffusion. Excessive SO42− diffused to the outer layer is reduced to S2− by SRB, forming sufficient metal sulfide precipitates that on one hand immobilize those heavy metal ions released by H+, and on the other hand serve as a barrier for preventing the contact of ferrous sulfide from O2. Hence, further oxidization of ferrous sulfide is terminated. This rhizoplane biofilm co-existing with IP contributes to the rhizosphere element circulation. Further investigation and demonstration of its composition, structure, and function will help us better interpret the survival strategy and bioremediation potential of wetland plants in flooded mining areas, such as mine tailing ponds in tropical and sub-tropical regions with abundant rainfall.

Bioaccumulation of heavy metals in common reed (Phragmites australis) growing spontaneously on highly contaminated mine tailing ponds in Serbia and potential use of this species in phytoremediation

Heavy metal contamination of aquatic ecosystems directly threatens the health, production and biodiversity of aquatic and surrounding terrestrial ecosystems, and it represents a serious global problem. Metal extraction during ore processing produces large amounts of wastes that remain in tailings at the mining site. Fine waste particles represent a long-term source of potentially toxic metals that can be released into the ground and surface water as a result of their progressive chemical weathering. Aquatic macrophythes have a major role in absorption and accumulation of heavy metals and thereby in natural water purification. The presence of naturally growing plants on mine tailing ponds indicates their tolerance of heavy metal pollution and suggests a possible role for them in phytoremediation. In the present study, we analysed the concentrations of heavy metals (Fe, Mn, Ni, Zn, Pb, Cd, Co, Cu) in Phragmites australis plants growing spontaneously in shallow water of several mine tailing ponds. The aims of the study were to define chemical properties of the mine spoils, determine the concentrations of heavy metals in different plant organs and assess the phytoremediation potential of common reed. The investigated sediments were notably rich in both total and available forms of Fe, Pb, Zn and Cu, with their upper concentrations close to phytotoxic levels. The greatest amounts of almost all of the investigated metals in plants from all three mine tailing ponds were found in the roots, with their concentrations positively correlated with the amounts of their available forms in the corresponding sediment. The far higher metal concentrations in the roots in comparison with other plant organs clearly indicate that the metals were strongly sequestrated within root cortical tissues and were not transferred across the endodermis. Taken altogether, the presence of the greatest amounts of metals in roots, high bioaccumulation factor and low translocation factor show that P. australis is an excluder plant species with a good phytostabilisation potential. As such, it might be efficiently used in rhizofiltration of wastewaters.

Salinity effects on soil shrinkage characteristic curves of fine-grained geomaterials

Fine-grained clayey soils are prone to substantial volume changes during desiccation in response to the dynamics of their moisture regime, and are of critical importance in several geotechnical and geo- environmental engineering applications. As such, the complex interactions between the fraction of soil solids and the ionic pore fluid play a critical role in governing such volume changes, and have been the focus in studies dealing with marine geotechnology, mine-tailing ponds, engineered barrier systems, etc. With this in mind, the present investigation evaluates the volume changes and accompanying densification from a saturated slurry state to a constant volume state of a reference fine-grained geomaterial, kaolin, subjected to evaporative dewatering. For this purpose, several parametric studies involving determination of soil shrinkage characteristic curves (SSCCs) of kaolin under the influence of varied salt constituents and concentrations of pore fluid are performed. Furthermore, a critical assessment of SSCCs depicting progressive shrinkage and volume change behaviour of geomaterials is provided, followed by the analysis of experimentally obtained SSCCs of the kaolin to explore the impacts of pore fluid salinity. Moreover, the SSCCs are parameterised with a predictive model and the fitting parameters are used to quantitatively demonstrate the salinity-dependent volume change response of a representative fine-grained porous system.

Provenance and environmental risk of windblown materials from mine tailing ponds, Murcia, Spain

Atmospheric particulates play a vital role in the transport of potentially toxic metals, being an important exposure pathways of people to toxic elements, which is faster and can occur in a much larger scale than water, soil and biota transport. Windblown materials in abandoned tailing ponds have not been well examined. The objectives of this investigation were: to study the major physical and geochemical properties of the materials eroded by wind inside the tailing ponds, and to understand the relative contribution of different sources to its heavy metals concentration. Study area is located in Cartagena-La Union mining district (SE Spain), where metallic mining of Fe, Pb and Zn has been developed for more than 2500 years. Wind-eroded particulates were monthly collected at 3 different heights (20, 50, and 80 cm) from the ground for a period of a full year using 4 dust collectors. Four tailing samples and 4 surface soil samples from the surrounding hills were also taken. Dust, soil, and tailing samples were examined for pH, particle size distribution, electrical conductivity, calcium carbonate content, Pb, Cu, Zn, Cd, Mn, Co, Ni, Ti and Zr concentrations. The results indicated that very coarse textured, slightly saline, and almost neutral wind-eroded deposits were generated with a very high temporal variability throughout the year. They also showed that the concentration of Cd, Mn, Pb and Zn, in the dust samples is extraordinarily high (18, 1254, 1831, and 5747 mg kg−1 respectively), whereas Co, Ni, and Cu had concentrations into the range of background concentrations found in the Earth's crust (3.8, 12, and 60 mg kg−1 respectively). Besides, the concentration of both categories of heavy metals in the dust samples was higher than that in tailing and less than that of the soils. The barren surfaces of tailing ponds and also the surface soils of the surrounding area seem to be the major contributors to the dust collected. Therefore, abandoned mines as well as their tailing ponds should be rehabilitated by proper technologies and then well stabilized and/or covered by appropriate plant vegetation to control the transfer, particularly by air, of environmentally hazardous materials to other areas.

Effects of mine tailing and mixed contamination on metals, trace elements accumulation and histopathology of the chub (Squalius cephalus) tissues: Evidence from three differently contaminated sites in Serbia

Chub (Squalius cephalus) specimens were collected in Korenita River seven months after spillover from the waste water of antimony mine tailing pond and compared with chub living in Kruščica reservoir (intended for water supply) and Međuvršje reservoir (influenced by intense emission of industrial, urban and rural wastewater). Concentrations of 15 elements (Al, As, B, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Si, Sr, Zn) were determined in muscle, liver and gills of chub by inductively coupled plasma optical spectrometry (ICP-OES) and histopathological alterations in liver and gills were assessed. Chub specimens from Korenita River had higher concentrations of As, Ba and Pb in all three investigated tissues as well as higher total histopathological index values than chub from reservoirs. Specimens from Međuvršje reservoir were characterized by higher values for concentrations of Cu and Si in muscle tissue and higher values for regressive histopathological alterations in gills. Individuals of chub from Kruščica reservoir had the highest concentrations of Fe in liver, Hg in muscle and Sr and Zn in muscle while gills had the lowest value of total histopathological index. The results from the present study showed higher level of histopathological alterations as a result of mine tailing accident. As a result of mixed contamination on the Međuvršje site, histopathological index values of gills were in line with the index value from Korenita River. Increased values for Fe and Sr in chub tissue from Kruščica reservoir could be explained by geological structure of the site which is characterized by magmatic rock rich in Cu, Fe and Ni as well as dominant carbonate sediment complex of marine origin with increased level of Sr.

Risk Evaluation of Break-Dam in Mine Tailings Pond Based on GA-AHP and Cloud-Matter Element Model

Risk Evaluation of Break-Dam in Mine Tailings Pond Based on GA-AHP and Cloud-Matter Element Model

Mineralogical and chemical characteristics of the lead-zinc tailing and contaminated soil from the mine tailing pond in Hunan Province (China)

Mineralogical and chemical characteristics of the lead-zinc tailing and contaminated soil from the mine tailing pond in Hunan Province (China)

Efectos de la lombriz roja californiana (Eisenia foetida), sobre el crecimiento de microorganismos en suelos contaminados con mercurio de Segovia, Antoquia

<p>Dentro de las actividades que alteran la composición del suelo está la minería, que causa el aumento de daños visibles al suelo mediante la creación de minas a cielo abierto, escombreras, estanques de residuos y otras instalaciones de minas. El objetivo principal de este trabajo fue evaluar el efecto de la lombriz roja californiana sobre el crecimiento de microorganismos en suelos contaminados con mercurio en el municipio de Segovia, Antioquia. Estos suelos representan una problemática importante debido a la acumulación de mercurio en exceso que ocasiona la pérdida de la calidad del suelo. Para este estudio se tomaron cuatro tratamientos en diferentes concentraciones de mercurio y un tratamiento más como blanco con lombrices rojas californianas <em>(Eisenia foetida). </em>Para esto, se evaluó el crecimiento de microorganismos a través de diferentes cultivos en el laboratorio, encontrando un crecimiento satisfactorio de los mismos luego de 25 y 90 días de tratamiento. De acuerdo al comportamiento observado, se evidencia una inmovilización del mercurio y una adaptación de los microorganismos al suelo contaminado, mostrando un aumento significativo de estos con el transcurso del tiempo.</p>

Pollution characteristics and assessment of sulfide tailings from the Dabaoshan Mine, China

Sulfide at mine tailing ponds poses a source of contamination to the surrounding environment. This study was designed to investigate and assess the fresh and weathered tailings pollution in the vicinity of the Dabaoshan Mine in Guangdong Province, China for in situ rehabilitation. Characterization of the fresh and weathered tailings was performed using geochemical and mineralogical analysis. Results indicated that low sulfur weathered and fresh tailing samples still presented a relatively high acid-production potential. Cu, Zn, Pb, and Cd in fresh tailing samples mainly existed in sulfides, whereas residual silicates were the dominant chemical forms of the four metals in weathered tailing samples. According to Hakanson's ecological risk index assessment, the potential risk individual coefficients of four heavy metals similarly ranked as follows: Cd > Cu > Zn > Pb. The tailing samples in the Dabaoshan Mine presented a much high potential ecological risk. The health risk assessment showed that the carcinogenic risk and non-carcinogenic risk levels of heavy metals in tailing were both lower than 10−6 and 1.0, respectively. The main exposure route of total non-carcinogenic risk from the tailing was the ingestion of tailing particles.

Dark septate endophytes colonizing the roots of ‘non-mycorrhizal’ plants in a mine tailing pond and in a relatively undisturbed environment, Southwest China

ABSTRACTDark septate endophytes (DSEs), one of the most common fungal colonizers of roots, are considered to overlap in function with mycorrhizal fungi. However, there is little knowledge on the distribution and identity of DSEs in ‘non-mycorrhizal’ plants. In the current study, colonization and diversity of DSEs colonizing the roots of eight typically ‘non-mycorrhizal’ families were assessed. In total, 120 root samples of 31 plant species were all colonized by DSEs. Intensity of DSE colonization varied greatly among different plant species, with a range of 0.56–47.56%, 8.13% on average. Cladosporium, Cyphellophora and Phialophora were the dominant genera, with a relative abundance of more than 60% over a total of 90 isolates. Our results showed that diverse DSE species colonized the roots of ‘non-mycorrhizal’ plants, especially they were more common in degraded mine tailings than in the undisturbed site, but their integral roles to the functional roots are in need of further experimental demonstration.

Mercury levels in Oryza sativa cultivated in Philippine small-scale mining villages

Soil physico-chemical parameters and total mercury concentrations were measured in soil and rice plant samples collected over a cropping period grown in areas near mine tailings ponds in two Philippine small-scale mining (SSM) communities. Step-wise regression analysis relating environmental parameters to Hg uptake showed that pH has a highly significant effect on Hg content in the samples (p < 0.001) while temperature, contrary to previous studies, had no significant effect. The mean total Hg concentrations appeared to be significantly lower in rice plant parts sampled in control sites than in the contaminated sites in both SSM communities: 0.020 and 2.832 mg/kg, respectively in Aroroy, Masbate and 0.004 and 0.016 mg/kg, respectively in Fidelisan, Sagada. Harvested rice grains from the Masbate sampling sites further revealed total Hg concentration at 0.1331 mg/kg, exceeding the maximum permissible limit of 0.02 mg/kg Hg contamination. The study shows that Hg use in SSM activities and the cumulative effects of prolonged exposure to the metal through regular consumption of the village-cultivated rice may put the local residents at risk of health problems related to mercury.

Ecological restoration alters microbial communities in mine tailings profiles.

Ecological restoration of mine tailings have impact on soil physiochemical properties and microbial communities. The surface soil has been a primary concern in the past decades, however it remains poorly understood about the adaptive response of microbial communities along the profile during ecological restoration of the tailings. In this study, microbial communities along a 60-cm profile were investigated in a mine tailing pond during ecological restoration of the bare waste tailings (BW) with two vegetated soils of Imperata cylindrica (IC) and Chrysopogon zizanioides (CZ) plants. Revegetation of both IC and CZ could retard soil degradation of mine tailing by stimulation of soil pH at 0–30 cm soils and altered the bacterial communities at 0–20 cm depths of the mine tailings. Significant differences existed in the relative abundance of the phyla Alphaproteobacteria, Deltaproteobacteria, Acidobacteria, Firmicutes and Nitrospira. Slight difference of bacterial communities were found at 30–60 cm depths of mine tailings. Abundance and activity analysis of nifH genes also explained the elevated soil nitrogen contents at the surface 0–20 cm of the vegetated soils. These results suggest that microbial succession occurred primarily at surface tailings and vegetation of pioneering plants might have promoted ecological restoration of mine tailings.

不同植物群落下铜尾矿废弃地生物结皮中真菌群落结构的比较

PDF HTML阅读 XML下载 导出引用 引用提醒 不同植物群落下铜尾矿废弃地生物结皮中真菌群落结构的比较 DOI: 10.5846/stxb201507181512 作者: 作者单位: 安徽大学资源与环境工程学院,安徽大学资源与环境工程学院,安徽大学资源与环境工程学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（41171418） Comparing the fungal community structure in biological soil crusts obtained under different plant communities in a copper mine tailings Author: Affiliation: School of Resources and Environmental Engineering,Anhui University,School of Resources and Environmental Engineering,Anhui University,School of Resources and Environmental Engineering,Anhui University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:分布于铜尾矿废弃地的裸地表面及维管植物群落中的生物土壤结皮在尾矿废弃地生态恢复过程中扮演重要角色。利用分子生物学技术探讨了不同维管植物下以及不同演替阶段的生物土壤结皮中真菌的多样性及其群落结构的变化。结果表明：生物土壤结皮中的真菌主要包括子囊菌门（Ascomycota）、担子菌门（Basidiomycota）和壶菌门（Chytridiomycota），其中子囊菌门占绝对优势，其相对丰度为55.12%-87.73%，其次为担子菌门相对丰度为12.27%-43.86%；不同样本真菌群落结构在门、纲、目以及属的水平存在显著差异；生物土壤结皮中真菌群落结构和多样性的差异与维管植物群落类型以及演替阶段不同的生物土壤结皮的类型有关，与基质化学性质之间无显著的相关性。 Abstract:Biological soil crusts (BSCs) found on the surface of bare wasteland and beneath the tracheophyte communities in mine tailing ponds, play an important role in the processes that are involved in natural ecological restoration of copper mine tailings. Fungi are an important part of BSCs, and they adhere to the surface soil and other components stably through their fungal hypha. It is important to enhance the resilience of mine tailings against wind erosion, as well as improve their moisture holding capacity that can be beneficial for the plant colonization on loose mine tailings' surfaces. However, the structure and diversity of microbial communities (especially fungal communities) of BSCs on the surface of mine tailings are poorly investigated. In this study, the changes in the fungal diversity and community structure of BSC samples at different successional stages, as well as tracheophyte species, were investigated using molecular biotechnologies. Moss-algal crusts beneath the Hippochaete ramosissimum (YM) had the lowest diversity index (including Shannon-Wiener index, Simpson index and Pielou index), among other significant differences of diversity and evenness that were observed in the fungal communities from the BSC samples and tracheophyte species. In addition, significant differences in basic soil chemical properties, such as loss-on-ignition, total nitrogen, and available phosphorus, were also found among the BSC samples. This indicates that the fungi in the BSC samples included the phyla Ascomycota, Basidiomycota, and Chytridiomycota. The phylum Ascomycota was dominant in these samples, and displayed a higher relative abundance 55.12%-87.73%, followed by the phylum Basidiomycota with a relative abundance of 12.27%-43.86%. Significant differences in fungal community structure were found at the phylum, order, class, and genus level. In addition, a non-metric multidimensional scaling (NMDS) analysis also showed that the fungal community structure is significantly influenced by tracheophyte species and the successional stage. However, canonical correlation analysis (CCA) indicated that this variation was not mainly caused by the substrate chemical properties of the mine tailings. In addition, Pearson correlations showed no significant correlation between fungal community structure and soil chemical properties. 参考文献 相似文献 引证文献

Watershed-Scale Environmental Risk Assessment of Accidental Water Pollution: The Case of Laoguan River, China

Although co-existing sources of chemicals pose major cumulative environmental threats to watersheds, few risk assessments have specifically tackled the accidental chemical pollution of rivers at watershed-scale. Herein, a Watershed-scale Accidental Pollution Risk Assessment (WAPRA) method was constructed which applied a risk ranking procedure to the whole watershed, and was based on watershed-scale stressors, exposures to and effects of water accidental pollution risk (e.g. sudden occurrences, waterway spread, and acute consequences). Multi-criteria analysis and instantaneous water quality models were used to refine the risk ranking procedure within the framework of a Relative Risk Model (RRM), a regional-scale ecological risk assessment approach. The study area comprised the Laoguan River, a tributary watershed of the Danjiangkou Reservoir, which will eventually feed into the South-to-North Water Diversion Project in China. The resultant map shows that risk is higher in the upstream and downstream reaches, and lower in the middle reaches. The map also indicates that the greatest threat to water quality arises from the upstream heavy metal mine tailings ponds. Sensitivity and uncertainty analyses were performed to validate the robustness of the WAPRA method.

Accidental Water Pollution Risk Analysis of Mine Tailings Ponds in Guanting Reservoir Watershed, Zhangjiakou City, China.

Over the past half century, a surprising number of major pollution incidents occurred due to tailings dam failures. Most previous studies of such incidents comprised forensic analyses of environmental impacts after a tailings dam failure, with few considering the combined pollution risk before incidents occur at a watershed-scale. We therefore propose Watershed-scale Tailings-pond Pollution Risk Analysis (WTPRA), designed for multiple mine tailings ponds, stemming from previous watershed-scale accidental pollution risk assessments. Transferred and combined risk is embedded using risk rankings of multiple routes of the “source-pathway-target” in the WTPRA. The previous approach is modified using multi-criteria analysis, dam failure models, and instantaneous water quality models, which are modified for application to multiple tailings ponds. The study area covers the basin of Gutanting Reservoir (the largest backup drinking water source for Beijing) in Zhangjiakou City, where many mine tailings ponds are located. The resultant map shows that risk is higher downstream of Gutanting Reservoir and in its two tributary basins (i.e., Qingshui River and Longyang River). Conversely, risk is lower in the midstream and upstream reaches. The analysis also indicates that the most hazardous mine tailings ponds are located in Chongli and Xuanhua, and that Guanting Reservoir is the most vulnerable receptor. Sensitivity and uncertainty analyses are performed to validate the robustness of the WTPRA method.

Hydrogeochemical signatures and evolution of groundwater impacted by the Bayan Obo tailing pond in northwest China

Uncontrolled leakage from mine tailing ponds can pose a serious environmental threat. Groundwater quality in a semi-arid region with extensive worries about the leakage from one of world's largest tailing ponds is studied herein through an integrated hydrogeochemical analysis and multivariate statistical analysis. Results show that elevated concentrations of NO2−, B, Mn, NH4+, F−, and SO42− in groundwater were probably caused by leakage from the tailing pond and transported with the regional groundwater flow towards downstream Yellow River. While NO2− contamination is only limited to areas close to the pond, high B concentrations persist within the contaminated plume originating from the tailing pond. Our current study shows that there is no geochemical evidence for U and Th contamination in groundwater due to leakage from the Bayan Obo tailing pond. Combining effects which includes regional variations, pond leaking and downstream mixing, mineral precipitation and dissolution, redox processes, ion exchange processes and agricultural activities, controlled groundwater hydrogeochemical signatures in the studied area. This study demonstrate that an increase in knowledge of evolution of groundwater quality by integrating field hydrochemical data and multivariate statistical analysis will help understand major water–rock interactions and provide a scientific basis for protection and rational utilization of groundwater resources in this and other tailing-impacted areas.

Biological activity of the metal-rich post-flotation tailings at an abandoned mine tailings pond (four decades after experimental afforestation).

In the spring 2012, post-flotation tailings of the inactive impoundment Lintich (Slovakia) were sampled. In the impoundment sediment and also in its surrounding, we detected concentration of Pb, Zn, Cd, Cu, and Ba exceeding limiting values. We detected low values of the microbial biomass carbon and microbial activity in the impoundment sediment (LiS) and its dam (DAM) along with potential respiration stayed relatively low and therefore also substrate availability index and metabolic quotient (qCO2) were higher in the control sample (REF) than in the LiS and the DAM. The low qCO2 level indicates that microbial community, despite of dangerously high levels of heavy metals in sediment, is still able to sufficiently utilize sources of available organic carbon. Anyway, we could doubt function of the metabolic index as universal indicator of environment conditions, regarding the anthropogenic substrates. We confirmed changes in composition of the mite communities along gradient dam-impoundment. The percentage of eudominant, recendent, and subrecendent species increased at the expense of dominants and subdominants, all together with decreasing diversity and equitability of the community. We identified species Chamobates borealis, Carabodes rugosior, Metabelba propexa, and Pergalumna nervosa with negative respond under the heavy metal stress. Species Adoristes ovatus was indifferent and Dissorhina sp., Hafenrefferia gilvipes, and Oppiella nova prospered under the loaded conditions. Forty years after experimental afforestation, we expect specific community of actively surviving microorganisms and Oribatida species detected in the DAM are usual in the greatly degraded habitats or on sites in the early succession.

Remediation of cyanide from the gold mine tailing pond by a novel bacterial co-culture

A total of 310 isolates were obtained from the gold mine tailing pond, in Khorasan-Razavi province in NE Iran. The cyanide tolerances of these strains were studied in an M9 medium supplemented by different cyanide concentrations. Nine strains showed the highest level of cyanide tolerance and could grow in up to 350 ppm of cyanide. Of these, two isolates, designated BN1 (identified as Halomonas to genus level by 16SrDNA sequencing) and DNB, capable of metabolizing cyanide as the sole source of nitrogen were selected for further analysis. The effects of different factors including pH, temperature, inoculum size and initial cyanide concentration were studied on the remediation process by OFAT (one factor at a time) experimental design. Strains BN1 and DNB showed 66% and 50% removal of cyanide at pH 9.5, temperature 25 °C, inoculum size 2.5% (v/v) and an initial cyanide concentration of 50 ppm after five days, respectively. The co-culture of strains was removed 75% of cyanide from the tailing pond after 96 h.