Soil In Mining Area Research Articles

The dominant microbial metabolic pathway of the petroleum hydrocarbons in the soil of shale gas field: Carbon fixation instead of CO2 emissions

In shale gas mining areas, indigenous microorganisms degrade organic pollutants such as petroleum hydrocarbons into carbon dioxide (CO2) and water (H2O) through aerobic metabolism. A large quantity of CO2 emissions will exacerbate the “Greenhouse effect”. Based on the clean sieved soil and oil-based drilling fluid in the shale gas mining area, this experiment set three concentration gradients (3523 ± 159 mg/kg, 8715 ± 820 mg/kg and 22,031 ± 1533 mg/kg) to treat the soil, and each group was disposed for the same amount of time (63 days). By analyzing the dynamic changes of microbial diversity and the abundance of key functional genes for carbon fixation, the impact of petroleum hydrocarbons on carbon fixation potential was discovered, and the natural attenuation law of petroleum hydrocarbons in contaminated soil was explored. It provided the scientific research basis of ecology for the carbon cycle, carbon allocation, and carbon fixation in microbial remediation of petroleum hydrocarbon contaminated soil. The results obtained indicated the following: i) The removal rate of petroleum hydrocarbons under high-concentration pollution (45.33 ± 3.90%) was significantly lower than low and medium-concentration pollution. The TPH concentration removal rate of each group was the largest in the early stage of culture (1-5d), and there was no significant correlation between the TPH content and the community composition (R2 = 0.0736, P > 0.05). ii) Composition and function of Carbon Fixation associated microbiota were assessed by 16S rRNA sequencing and PICRUSt (phylogenetic investigation of communities by reconstruction of unobserved states) analysis. The main carbon fixation pathway in this study is the reductive citric acid cycle, because there was no shortage of enzymes that can affect subsequent reactions.

Meta-analysis of the Effects of Metal Mining on Soil Heavy Metal Concentrations in Southwest China

Metal mining is one of the main contributors of soil heavy metals. Previous studies examining the impact of metal mining on surrounding soil have mainly focused on one or a few metal mining areas. However, such studies cannot effectively inform the management of heavy metal pollution in soil at an inter-provincial scale. As part of this study, literature was collected on soil heavy metals (i.e., As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) affected by metal mining in regions of Southwest China (i.e., Yunnan Province, Sichuan Province, Guizhou Province, Chongqing Municipality, and Tibet Autonomous Region); Next, the impact of metal mining on the soil concentrations of these metals was quantified through meta-analysis, and the relationships between the selected factors (i.e., different sub-regions, metal minerals, and land-use types) and soil heavy metal concentrations were explored. Finally, the literature data was tested for publication bias. The results showed that metal mining in Southwest China has significantly increased the concentrations of heavy metals in topsoil. The different metals were ranked according to their weight effect sizes (ES+) in the following order Cd > Pb > Hg > Zn > As > Cu > Ni > Cr. Metal mining in both Sichuan and Yunnan led to higher effect sizes of soil Cd (ES+Sichuan=4.16, ES+Yunnan=3.20) and Pb (ES+Sichuan=3.47, ES+Yunnan=2.54) than those of the other heavy metals, while metal mining in Guizhou led to a higher effect size of soil Hg (ES+=2.80). The effect size of metal mining on soil heavy metals was higher in cultivated soil (ES+=1.42) than in forested soil (ES+=0.50). The mining of lead-zinc and tin significantly increased the concentrations of soil Cd, Pb, and Zn, and the mining of copper significantly increased the concentrations of soil Cu, Cd, and Pb. Of the investigated soil heavy metals in Southwest China, Pb and Zn showed slight potential publication biases (P<0.05). The above results can provide more effective information for the environmental protection of soil in metal mining areas of Southwest China.

Assessing the Risk of Total and Available Potentially Toxic Elements in Agricultural Soil in Typical Mining Areas in Xiangjiang River Basin, Hunan Province

In this study, soil and rice samples from 85 sites in six cities in Hunan Province were analyzed for Cu, Zn, Pb, Cd, Hg, Mn, and Co (total and bioavailable concentrations for soil) in July 2014. The results indicated that the total concentrations of Cu, Zn, Pb, Cd, and Hg in soil had increased significantly compared with the 1980s, and were correlated with their bioavailable concentrations in soil positively. The total concentrations of Cd and Co in soil were correlated with those in rice. Bioavailable concentrations of Cd, Mn, Co, Pb, and Cu represented 64.4%, 33.2%, 12.0%, 11.6%, and 6.1% of the total soil concentrations, respectively. The bioavailable concentrations of Cd and Co in soil had a extremely significant (p &lt; 0.01) positive correlation with those in rice, suggesting that bioavailable concentrations was a better indicator for soil potentially toxic elements contamination. The pH values had a significant influence on the bioavailability of Cd and Cu and the amounts taken up by rice. The Cd contamination in 27.0% rice samples exceeded World Health Organization recommended thresholds. The results added basic pollution distribution data, further revealing the relationships of metals in soil and crops and would offer great help to the metallic pollution control in these areas.

Assessing toxic metal chromium in the soil in coal mining areas via proximal sensing: Prerequisites for land rehabilitation and sustainable development

The rapid and accurate determination of soil chromium (Cr) is crucial for preventing toxic element pollution in soils and ensuring ecological security. Proximal sensing technology uses visible and near-infrared (Vis-NIR) diffuse reflectance spectroscopy, which has been demonstrated to be a viable approach for monitoring soil Cr concentrations. However, at trace levels, soil Cr is not especially spectrally active, thus limiting the practical application of using corresponding spectral data for quantifying soil Cr concentrations. In this study, we hypothesized that fused proximal sensing and soil auxiliary attributes (including organic matter (OM) and pH) could improve estimation of Cr concentrations in the soil. Additionally, the introduction of best-fit variogram models was theoretically possible to improve spatial visualization. To address these hypotheses, we collected 168 soil samples from the open coal mine area in the Eastern Junggar Basin, China. Fractional-order derivative (FOD) pretreatment and optimal band combination methods were implemented for spectral data mining and the derivation of spectral parameters, respectively. Soil Cr estimation models were calibrated with a partial least squares (PLS) approach through four designed strategies with different predictors: (I) full Vis-NIR variables, (II) effective three-band spectral indices (TBIs), (III) the effective TBIs and OM, and (IV) the effective TBIs, OM, and the pH. The results suggest that FOD could identify abundant spectral variability. Compared with full Vis-NIR variables, the effective TBIs can effectively magnify the subtle spectral signals concerning soil Cr. The optimal estimation model was determined as Strategy IV, indicating that the introduction of soil auxiliary attributes (pH and OM) can improve the estimation performance of the model; notably, the coefficient of determination (R2) and ratio of performance to interquartile distance (RPIQ) were 0.87 and 2.68, respectively. Based on the optimal semivariance model, we used kriging interpolation to map regional soil Cr. In the study area, the soil Cr distribution features strong spatial dependence and strong associations. Our study might inspire further research on soil contamination mapping based on proximal Vis-NIR sensors.

Study on the mechanism and kinetics of manganese release from waste manganese ore waste rock under rainfall leaching

Manganese released from the piled manganese ore wastes is a great threat to the local ecosystem and human health. The mechanism and dynamic characteristics of manganese release from the manganese ore wastes were studied based on the static and dynamic experiments. The concentration of manganese in the leaching solution under the intensive state is twice that resulted from the static state; the manganese release from the waste rock increased with the increase of the solid-liquid ratio and reached 922.3 mg/L when the solid-liquid ratio was 1:5. When the particle size of waste rock was less than 180 μm, the release amount of manganese was the largest and reached 491.3 mg/L. When the pH was 7 and the rainfall intensity was 80 mL/h, the increase of leaching time contributed to the rapidly decreased amount of manganese released, and the leaching process reached equilibrium gradually. The cumulative release of manganese increased with the increase of rainfall duration. In the dynamic leaching process, the change of pH and EC of the leachate had nothing to do with the initial pH of leaching agent but has a close relationship with the hydrolysis of minerals in waste. According to the experimental results, it was found that the double constant equation model fitted the kinetic process of release process better. The purpose of this study was to provide a scientific basis for the assessment and control of manganese pollution in soil and groundwater in manganese mining area.

Optimization and Simulation of Process Parameters in Biosorption of Heavy Metals by Alcaligenes faecalis Strain UBI (MT107249) Isolated from Soil of Local Mining Area in North-West Nigeria

ABSTRACT The use of biological molecules to control pollutants, especially heavy metals that pollute our atmosphere, is gaining traction. In this study, simulation and optimization of process parameters using one-factor-at-a-time and response surface methodology (RSM) were employed to assess conditions for heavy metal tolerant bacteria isolated from local mining area employed in biosorption of heavy metals. Morphological, biochemical, and molecular characteristics of the isolate was determined using standard procedures. The agar plate method was used to determine heavy metal tolerance of the bacterial isolate. The effect of factors affecting biosorption of heavy metals was assessed using one-factor-at-a-time and response surface methodology respectively. The Gram-negative Alcaligenes faecalis strain UBI isolated in this study was capable of tolerating 27.0ppm of Pb2+. Optimum temperature and pH recorded were 35°C and 5 respectively. Similarly, optimum metal concentration indicated 2.5ppm with 12 hours contact time and at 7% of Inocula size (v/v) respectively. Simulation by RSM showed that the model is significant (p = .0013). The statistical accuracy of the model was elaborated by the non-significant lack of fit. The R2 (0.98) value highlights a perfect model likewise the low value of the coefficient of variance (CV = 3.09%). This study supports the idea of using bacteria as a panacea to heavy metal pollution under-regulated process parameters.

Effects of Vegetation Restoration on Soil Enzyme Activity in Copper and Coal Mining Areas.

Mining areas are suffering from serious environmental hazards, such as soil erosion, water pollution as well as land degradation. In this study, two types of mining areas in Anhui Province, China-one a copper mining area and the other a coal mining area-were selected to compare the soil properties under different vegetation restoration conditions, which can be generally classified into reclaimed and non-reclaimed areas. Soil catalase and urease activities and soil chemical properties were chosen to be the main indicators of soil quality. Principal component analysis was used to evaluate the overall soil fertility in the copper and coal mining areas. Results showed that in the copper mining area soil catalase activity was between 12.36 and 19.17 μg g-1 h-1 and urease activity was between 0.03 and 12.05 μg g-1 h-1. And in coal mining area, soil catalase activity was between 3.52 and 9.72 μg g-1 h-1 and urease activity was between 2.71 and 10.81 μg g-1 h-1. Moreover, soil catalase and urease activities in degraded areas were lower than those in reclaimed areas. Soil catalase activity and soil urease activity were significantly correlated with total potassium and total nitrogen, respectively. Soil quality in land types with vegetation restoration was higher than in non-reclaimed areas and old subsidence areas, while soil quality in the copper mining area was generally higher than in the coal mining area. Thus, the optimum measure in this region to ameliorate these degraded soils is vegetation restoration, which helps not only to improve the environment, but also to enhance soil quality in these degraded lands.

Feasibility Study on the Application of Microbial Agent Modified Water-Jet Loom Sludge for the Restoration of Degraded Soil in Mining Areas.

Open-pit mining causes soil damage and affects the health of the ecosystem. In the arid grassland mining areas, the soil is severely sanded, water-starved, and saline, thus making it difficult for plants and microorganisms to survive. Water-jet loom sludge can be used to improve the quality as it contains a lot of clay and is rich in organic matter, which provides a material basis for microorganism activity. To explore the effects of microbial agent-modified water-jet loom sludge on the restoration of degraded soil in grassland mining areas, four pot trials were set up, i.e., for untreated soil, the application of a microbial agent alone, the application of water-jet loom sludge alone, and the combined application of water-jet loom sludge and the microbial agent. The results show that (1) microbial agent-modified sludge can improve soil water-holding capacity and aggregate stability; (2) the nutrient content of the restored soil fraction increased significantly, and the pH of the original saline soil decreased from 9.06 to 7.84; (3) this method significantly increased plant biomass and microbial biomass carbon and enhanced the abundance and diversity of fungi and bacteria. The three treatments had different results in different soil properties, and the effect of the combined water-jet loom sludge and microbial agent treatment on soil remediation was significantly better than the individual application of either.

A Combined Remediation Strategy of Arsenic and Cadmium in the Paddy Soil of Polymetallic Mining Areas.

The combined pollution of arsenic (As) and cadmium (Cd) are quite common in the polymetallic mining areas located in southern China. In the present study, field experiments were established for the purpose of exploring a simultaneous remediation strategy of rice variety-water management-contaminant immobilization on the As and Cd contamination in paddy soil. The obtained results revealed that the Maba Yinzhan was the best low-accumulation rice variety, with As and Cd concentrations of 0.54 and 0.16mgkg-1, respectively, in the rice grains. On the basis of water management during heading stage, the treatment using 0.15wt% lime plus 0.5wt% ferro-ferric oxide (FO) decreased the As and Cd concentrations by 64.02% and 34.78%, respectively, in the grains. The results of this study potentially provide an effective remediation solution for the As/Cd contaminated soils in polymetallic mining areas.

Ecological risk assessment of heavy metal contamination of mining area soil based on land type changes: An information network environ analysis

In this study, a grid-based network environ analysis (FEM-NEA) framework was developed to identify the ecological risks of the internal components within a landscape scale mining ecosystem with multiple land types. In this framework, an information-based network analysis is applied for addressing ecological risk assessments (ERA) based on control allocation (CA) and energy flow matrix, which can quantificationally reflect the relationship between soil ecosystems and ecological communities. In order to improve the computational accuracy and efficiency, the FEM and information-based network analysis are combined to further quantify the flow risk among different components within each grid as well as the whole ecosystem. Compared with the existing NEA-ERA model, various risk factors and receptors are compatible with the proposed FEM-NEA framework and both direct and indirect effects can be taken into consideration altogether. By taking an abandoned mining area of the Yanshan mountain as an example, risk propagation between all component of the ecosystem concerning both direct risk and integral risk dynamic were quantified. The results showed that contaminated soil normally poses risks to surrounding ecological environment, thereby affecting local vegetation and microorganisms. Afterward, the risks are passed throughout the ecosystem, forming threats to herbivores and predators via the food chain. Here, the probability of risk is ranked as follows: village> farmland> bare land> woodland. Moreover, the influence of input energy and data attributes on the prediction results are also discussed. When the input energy rises by 50%, the control allocation (CA) from herbivores to soil microorganisms correspondingly increases by 1.00% but the value from herbivores to carnivores decreases by 0.71%. This highlights the robustness of the proposed ecological risk assessment framework (FEM-NEA). In general, the FEM-NEA results not only presents the macro-scale risk distribution caused by the interaction of each component, but also reflects the potential migration direction of the risk center. Findings can provide a new perspective and method for assessing ecological risks and also help support remediation techniques for contaminated areas with different land types.

Geochemical Characterization and Trace-Element Mobility Assessment for Metallic Mine Reclamation in Soils Affected by Mine Activities in the Iberian Pyrite Belt

The geochemical characterization of the mine deposits and soils in metal mining areas is essential in order to develop an effective mine reclamation strategy. The determination of total potentially toxic element (PTE) content, together with the application of chemical extraction procedures, can give insight into the behavior of contaminants after the application of different mine reclamation solutions, as well as identify the areas where urgent action is needed. This work presents a practical application to the evaluation of the pollution potential of trace elements in soils affected by mining activities, to be used in metallic mine reclamation. The PTE behavior was assessed by single extractions in order to simulate four environmental conditions: PTE mobility under rainfall conditions, acid mine drainage, reducing conditions, and plant uptake. The spatial distribution of contaminants in the study area was evaluated by determination of PTE total content in soil samples. Trace elements with high natural mobility, such as Zn, appeared concentrated at water and sediment discharge areas, while As, Pb, and Cu contents were higher near the mine wastes. The results obtained after the extractions suggested that the highest PTE content was extracted in the complexing–reducing medium, due to the dissolution of secondary sulfates and Fe3+ oxyhydroxides and the subsequent release of PTEs associated with those mineral phases. Reclamation strategies applied in the study area should promote efficient water drainage, infiltration, and subsuperficial water circulation in order to maintain oxidant conditions in the soil. The methodology applied in this study may constitute a valuable tool to define the geochemical constraints in metal mining areas, as well as help to develop appropriate mine reclamation solutions.

Co-remediation of PTEs contaminated soil in mining area by heat modified sawdust and herb

Exploring efficient remediation technologies to remediate potentially toxic element (PTE) in soil around the mining area has become a trendy research topic. This study conducted material composed of sawdust ash (SA) and sawdust biochar (SB) with mass ratio of SA:SB = 1:2 in combination with Medicago sativa L. and Festuca arundinacea to remediate soil contaminated by zinc (Zn), cadmium (Cd), and arsenic (As) in a mining area. The result showed that the removal rates of Zn, Cd, and As were the highest under the treatment of Festuca arundinacea combined with 5% material with values of 22.15%, 22.05%, and 12.47%, respectively. Festuca arundinacea had the most potent ability to absorb and tolerate composite PTEs, and the co-remediation process could remarkably improve soil enzyme environment and microbial community diversity. The distribution of PTEs in plant subcellular showed that the accumulation of Zn, Cd, and As in the cell wall of Festuca arundinacea root was significantly increased by adding 2% materials. The concentrations of Zn, Cd, and As in the cell wall were 4486.25, 33.59, and 124.15 mg/kg, respectively. The combination of 2% material and Festuca arundinacea could effectively remove PTEs in soil and enhance the detoxification ability of the plant, thus effectively improving the soil environment and remediating PTEs pollution. This study provided insights into the remediation of PTE-contaminated soil in mining area by combining materials and plants.

Microfluidically supported characterization of responses of Rhodococcus erythropolis strains isolated from different soils on Cu-, Ni-, and Co-stress

We present a new methodological approach for the assessment of the susceptibility of Rhodococcus erythropolis strains from specific sampling sites in response to increasing heavy metal concentration (Cu2+, Ni2+, and Co2+) using the droplet-based microfluid technique. All isolates belong to the species R. erythropolis identified by Sanger sequencing of the 16S rRNA. The tiny step-wise variation of metal concentrations from zero to the lower mM range in 500 nL droplets not only provided accurate data for critical metal ion concentrations but also resulted in a detailed visualization of the concentration-dependent response of bacterial growth and autofluorescence activity. As a result, some of the isolates showed similar characteristics in heavy metal tolerance against Cu2+, Ni2+, and Co2+. However, significantly different heavy metal tolerances were found for other strains. Surprisingly, samples from the surface soil of ancient copper mining areas supplied mostly strains with a moderate sensitivity to Cu2+, Ni2+, and Co2+, but in contrast, a soil sample from an excavation site of a medieval city that had been covered for about eight centuries showed an extremely high tolerance against cobalt ion (up to 36 mM). The differences among the strains not only may be regarded as results of adaptation to the different environmental conditions faced by the strains in nature but also seem to be related to ancient human activities and temporal partial decoupling of soil elements from the surface. This investigation confirmed that microfluidic screening offers empirical characterization of properties from same species which has been isolated from sites known to have different human activities in the past.

Spatial Distribution Characteristics of Heavy Metals in Surface Soil of Xilinguole Coal Mining Area Based on Semivariogram

Heavy metal pollution is a major environmental problem facing humankind. Locating the source and distribution of heavy metal pollutants around mines can provide a scientific basis for environmental control. The structure effect and random effect of a semivariogram can be used to determine the reason for spatial differences in the heavy metal content in surface soil, and the coefficient of variation and regression analysis can be used to confirm that the verification accuracy meets the geostatistical requirements. According to the maximum difference method, the content of heavy metals in the surface soil of the mining area is higher than that of the surroundings, and Cu and Zn levels are higher than the background values for Inner Mongolia. In the present case, Zn, Mn, Pb, Cr, Ni, and Cu levels exceeded the background values for the surroundings of the study area by 65.10%, 53.72%, 52.17%, 46.24%, 33.08%, and 29.49%, respectively. The results show that human activities play a decisive role in the spatial distribution of heavy metals, leading to their spatial distribution in the form of “core periphery”. This distribution pattern was significantly affected by the slope, NDVI value, and the distance from the mining area, but the spatial distribution of Pb was significantly related to high-grade roads. The research methods and conclusions have reference significance for the sources and spatial distribution characteristics of heavy metal pollution in similar mining areas and provide a target for the prevention and control of environmental pollution in the study area.

Health risk assessment of heavy metals in soils and screening of accumulating plants around the Wanshan mercury mine in Northeast Guizhou Province, China.

The Wanshan mercury mine, which is an abandoned mine located in northeastern Guizhou Province in Southwest China, has introduced serious Hg pollution to the local ecosystem resulting from previous mining and smelting activities. However, it is not clear to date whether soil pollution has actually improved after treatment by related departments. Therefore, the present study investigates the vegetation community and heavy metal contents of the soil and plants in the Wanshan mercury mining area. The results showed that most of Hg, Cd, As, Cu, and Zn contents in soil samples were higher than those of Soil Environment Quality Risk Control Standard for Soil Contamination of Agricultural Land in China (GB15618-2018). The observed plant species mainly consisted of Compositae, followed by Leguminosae. Unfortunately, this investigation found that heavy metal concentrations in these plants were not extremely high and far below the standard of hyperaccumulator. Despite all this, the maximum values of bioaccumulation factor for Pb, Cd, Hg, As, Cu and Zn were Serissa japonica (Thunb.) Thunb., Rhus chinensis Mill., Potentilla sibbaldii Haller f., Erigeron canadensis L., Clerodendrum bungei var. bungei. and Rhus chinensis Mill., respectively. Regardless of the carcinogenic or noncarcinogenic risk index, the potential risk to urban children is higher. Our results suggest that heavy metal pollution was indeed relieved since their contents in soil significantly decreased in comparison with those reported in other previous studies. This finding provides a reference for the long-term treatment of heavy metal pollution in the local environment and other areas employing analogous environmental protection measures.

Preface for the SUITMA10 Conference proceedings Soils of Urban, Industrial, Traffic, Mining, and Military Areas (SUITMAs) are essential resources that deserve our attention for the sustainable management of anthropized environments

Preface for the SUITMA10 Conference proceedings Soils of Urban, Industrial, Traffic, Mining, and Military Areas (SUITMAs) are essential resources that deserve our attention for the sustainable management of anthropized environments

Heavy metal pollution characteristics and health risk evaluation of soil around a tungsten-molybdenum mine in Luoyang, China

Heavy metal pollution in mining area soil and its impact on human health have been becoming one of the most important global environmental problems. This study investigated the heavy metals in the soil around the tungsten-molybdenum mining area in southwestern Luoyang, Henan Province, assessed the level of heavy metal pollution in the soil around the tungsten-molybdenum mining area, and quantified the risks of these pollutants to human health. To assess these potential threat levels, The pollution index, potential ecological hazards and health risk assessment methods recommended by the United States Environmental Protection Agency (USEPA) are applied. The results indicated that the average soil content of the heavy metals Zn, Cr, Cd and As exceeded the soil pollution risk screening value. The Nemerow comprehensive pollution index (PN) was greater than 3, which indicated severe pollution. The potential ecological risk index (RI) of each sampling point was integrated in the order $${\mathrm{RI}}_{\#7}$$ > $${\mathrm{RI}}_{\#6}$$ > $${\mathrm{RI}}_{\#5}$$ > $${\mathrm{RI}}_{\#3}$$ > $${\mathrm{RI}}_{\#4}$$ > $${\mathrm{RI}}_{\#2}$$ > $${\mathrm{RI}}_{\#1}$$ . Among the heavy metals, Cd posed the greatest ecological threat, accounting for 91.32% of RI. The effect of heavy metals in soil on the single non-carcinogenic health risk index (HQ) and non-carcinogenic total index (HI) through three exposure pathways, oral intake > skin contact > respiratory inhalation, was $${\text{HQ}}_{{{\text{Zn}}}} {\text{ < HQ}}_{{{\text{Cu}}}} {\text{ < HQ}}_{{{\text{Cd}}}} {\text{ < HQ}}_{{{\text{Pb}}}} {\text{ < HQ}}_{{{\text{Cr}}}} { < 1}$$ . The sum of $${\mathrm{HI}}_{\mathrm{Pb}}$$ and $${\mathrm{HI}}_{\mathrm{Cr}}$$ accounted for 92.96 and 92.98% of adults and children, respectively. In addition to the inhalation route $${\mathrm{CR}}_{\mathrm{Cd}}$$ , $${\mathrm{CR}}_{\mathrm{Cr}}$$ and $${\mathrm{CR}}_{\mathrm{Cd}}$$ in the study area were higher than the maximum acceptable human-level recommended by the U.S. EPA (10–6), and the CR and TCR were higher in children than in adults. Therefore, the heavy metal pollution of soils in the studied tungsten-molybdenum mine area was found to pose a serious threat to the surrounding ecological environment and residents’ health.

Α comprehensive geotechnical characterisation of overburden material from lignite mine excavations

For the sustainability of lignite and coal mining, engineers need the soils' appropriate geotechnical characterisation of the excavations. This characterisation relates to the slope stability, the overall area stability, and the sustainable exploitation of mining areas during operational and post-closure eras. This work presents a novel perspective on the soil characterisation of lignite mine excavations. Rather than focusing on one particular mine, a comprehensive geotechnical characterisation provides insights about the soils of related mining areas. Additionally, slope stability representative cases guide soil characterisation and analysis rather than following it. The Greek lignite mines are used as a representative example for the illustration of this framework. Initially, the two typical slope stability scenarios for Greek lignite mines are established: a slope in the presence of a weak zone and a homogeneous slope. The crucial geotechnical parameters are then statistically examined based on an extensive database established from laboratory results of various mines. Focus is on shear strength (friction angle and cohesion), the key to slope stability, and physical properties that can provide the strength through empirical correlations. Many soil layers exhibit a low residual friction angle from 5° to 15°, corresponding to the weak zone. Peak friction angle presents a mean value of 28.4°, and a characteristic value of 25.0°; cohesion presents a wide range with a mean value of 111 kPa and a characteristic value of 84 kPa. Finally, cross-correlations between geotechnical parameters present large scatter, but relations for estimating the residual and the peak friction angle reveal general trends.

Mobility of potentially toxic elements in family garden soils of the Riotinto mining area

Agricultural soils in mining areas usually accumulate potentially toxic elements (PTEs) that can become a health risk to humans by entering the trophic chain. In this study, five small agricultural plots close to Riotinto mines (SW Spain) were studied, with the aims of comparing the concentration of PTEs with respect to the regional (South Portuguese Zone) baseline and conducting availability studies in order to determine the contamination of soils. Chemical composition, total and clay mineralogy, and edaphic parameters were determined in topsoil and subsoil samples to characterize the soils, and single extractions were conducted to assess the mobility. The mineralogy of the soils was composed of quartz and phyllosilicates, with small amounts of feldspars and occasionally containing hematite and calcite. The texture ranged from sandy to silty loam, the pH was slightly acidic, and high contents of organic matter were found. Total concentrations of trace elements correlated with the texture, the content in iron oxy-hydroxides and the pH. The values of As, Pb, Cu, and Zn exceeded the regional baseline even in sites unaffected by mining. The results suggest that a widespread sampling is necessary to determine the local background. The most water-soluble element was As, due to the competition of organic matter for sorption sites. The content of Cu, Cr and Zn extracted with different methods were higher in sandy soils with low iron oxy-hydroxides content. Monoammonium phosphate and EDTA extractions seemed to remove elements from organic matter and iron oxy-hydroxides. The extracted fractions of As and metals reached up to 10–30 wt%. Despite the high total concentrations of the element in soils, they generally showed low available proportions, especially with water and ammonium acetate extractants. The results suggest that the soils are not necessarily a risk to humans and higher investigation efforts are necessary to assess the availability of PTEs and their transfer to plants.

Potential bacteria capable of remediating mercury contaminated soils

Mercury content in ex-artisanal and small-scale gold mining areas in Cianjur District, Province of West Java, Indonesia was 7 to 36 mg L−1. It has exceeded the threshold value for industrial land. Bioremediation of mercury using mercury-resistant bacteria is attractive to remove mercury from the environment because it is more effective and less expensive. The objective of this study was to obtain potential bacteria capable of accumulating mercury to be used to remediate mercury contaminated soils in ex-gold mining areas. Potential bacteria isolates were characterized for their phenotypic and biochemical properties using the Biolog system. Thirty-two mercury-resistant bacteria were successfully isolated from the rhizosphere of Pityrogramma tartarea growing predominantly around tailings of ex-artisanal gold mining. After screening the presence of mercury, the three best isolates showing high resistances are Pseudomonas putida R2.13 and P. maculicola R4.27 that are capable to tolerate 180 mg L−1 mercury, and Enterobacter aerogenes R3.24 that is capable to survive at 170 mg L−1. Furthermore, the three bacteria also can fix atmospheric nitrogen and solubilize phosphate, but they cannot solubilize potassium. These indicate that P. maculicola R4.27, P. putida R2.13, and E. aerogenes R3.24 are potential as bioaccumulation agents on mercury-contaminated soils.