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This work aimed to explore safe techniques for the utilization of farmland surrounding mining areas contaminated with heavy metals—specifically cadmium (Cd) and lead (Pb)—in order to achieve food security in agricultural production. A potato variety (Qingshu 9) with high Cd and Pb accumulation was used as the test crop, and seven treatments were set up: control (CK), special potato fertilizer (T1), humic acid (T2), special potato fertilizer + humic acid (T3), biochar (T4), calcium magnesium phosphate fertilizer (T5), and biochar + calcium magnesium phosphate fertilizer (T6). The remediation effect of the combined application of different passivators on the accumulation of cadmium and lead in potatoes in the contaminated soil of a mining area was studied. The results showed that, compared with CK, all passivator treatments improved the physical and chemical properties of the soil and reduced the available Cd and Pb content in the soil and in different parts of potatoes. The T6 treatment yielded the most significant reduction in the available Cd and Pb content in the soil, the Cd and Pb content in the potato pulp, and the enrichment factor (BCF) and transfer factor (TF) of the potatoes. Compared with T4 and T5, the content of available Cd in the soil decreased by 1.22% and 4.71%, respectively; the soil available Pb content decreased by 3.13% and 3.02%, respectively; the Cd content in the potato pulp decreased by 68.08% and 31.02%, respectively; and the Pb content decreased by 31.03% and 20.00%, respectively. The results showed that the application of biochar combined with calcium magnesium phosphate fertilizer had a better effect in terms of reducing the available Cd and Pb content in the soil and the Cd and Pb content in the potato flesh compared to their individual application. Biochar and calcium magnesium phosphate fertilizer can synergistically increase the content of soil available nutrients and reduce the activity of heavy metals in the soil to prevent the transfer and accumulation of cadmium and lead to potatoes, as well as improve their yield and quality. The results of this study provide technical support for safe potato planting and agricultural soil management. [ABSTRACT FROM AUTHOR]

The blooming industrialization and urbanization is leading to increased mining operations. These intensified mining activities emit heavy metals into the environment, posing serious threats to ecosystems. Hence, this study focused on assessing heavy metal pollution in mining soil, utilizing mosses as bioindicators. The ecological risk, geo-accumulation factor, and contamination factor have been calculated to know the harmful effect of heavy metals on ecosystem. The study covered three distinct mining sites of eastern India within Odisha: Jajpur's Sukinda Valley (SP1, Cr), Keonjhar's Joda-Barbil (SP2, Fe and Mn), and Sundargarh's Koira-Joda (SP3, Fe). The collection of 48 soil samples through random sampling revealed significant variations in heavy metal concentrations. SP1 recorded Cr concentration of 6572 ± 445 mg/kg and Ni of 8042.47 ± 501.38 mg/kg, surpassing eco-toxicological levels. The storage site in SP2 exhibited the highest Fe concentration at 9872 ± 502 mg/kg, and Mn levels in SP3 were at 7884 ± 432 mg/kg. Storage areas in all three regions held the highest concentrations of heavy metals. Mosses in studied area demonstrated as potential bioindicators for monitoring heavy metal pollution. EF and Igeo assessments showed Cd, Pb, Hg, and other heavy metal contamination compared to earlier investigations. This study indicated higher ecological risks for Pb, As, Cu, Ni, and Zn. The Hyophila involuta accumulates Mn, Cr, Cd, Pb, Fe, and Hg, while Barbula arcuata accumulates Mn, As, and Cu in SP1. Hyophila involuta and Trematodon longicollis accumulate Mn, Cr, Cd, Pb, Fe, Hg, and Zn in SP2. Trematodon ambiguous accumulates Cd, Fe, and Ni, while Fissidens diversifolius accumulates Mn, Cr, Hg, As, Cu, and Zn in SP3. These findings emphasize the necessity of monitoring heavy metal pollution in contaminated zones using moss as a potential bioindicator. [ABSTRACT FROM AUTHOR]

While tire wear particles (TWP) have been estimated to represent more than 90% of the total microplastic (MP) emitted in European countries and may have environmental health effects, only few data about TWP concentrations and characteristics are available today. The lack of data stems from the fact that no standardized, cost efficient or accessible extraction and identification method is available yet. We present a method allowing the extraction of TWP from soil, performing analysis with a conventional optical microscope and a machine learning approach to identify TWP in soil based on their colour. The lowest size of TWP which could be measured reliably with an acceptable recovery using our experimental set-up was 35 µm. Further improvements would be possible given more advanced technical infrastructure (higher optical magnification and image quality). Our method showed a mean recovery of 85% in the 35–2000 µm particle size range and no blank contamination. We tested for possible interference from charcoal (as another black soil component with similar properties) in the soils and found a reduction of the interference from charcoal by 92% during extraction. We applied our method to a highway adjacent soil at 1 m, 2 m, 5 m, and 10 m and detected TWP in all samples with a tendency to higher concentrations at 1 m and 2 m from the road compared to 10 m from the road. The observed TWP concentrations were in the same order of magnitude as what was previously reported in literature in highway adjacent soils. These results demonstrate the potential of the method to provide quantitative data on the occurrence and characteristics of TWP in the environment. The method can be easily implemented in many labs, and help to address our knowledge gap regarding TWP concentrations in soils. [ABSTRACT FROM AUTHOR]

The reuse of heavy-metal hyperaccumulator waste has emerged as a critical constraint in the implementation of phytoremediation to control heavy-metal pollution. Ramie (Boehmeria nivea) is a well-established arsenic (As) hyperaccumulator that has been widely used in the remediation of As-contaminated sites in recent years. To facilitate multipurpose development and the recycling of ramie straw contaminated with heavy metals, a study investigated the preparation of hydrochar (HC) at different temperatures and assessed the feasibility of reintroducing the HC into the soil. The results indicated higher yields, increased nutrient contents, and reduced As percentage levels at a hydrothermal carbonization temperature of 240°C. Treatment with a 300 mmol/L sodium hydroxide solution resulted in the removal of As from HC, ranging from 77.06% to 87.60%, effectively facilitating the reuse of HC. The application of alkali-modification HC in As-contaminated soil not only enhances soil properties but also augments the potential population of dominant microorganisms that promote soil arsenic mobilization, thereby improving arsenic mobilization capacity in mining soil. This study offers a viable strategy for enhancing the phytoremediation efficiency of As-contaminated soil and establishing a recycling system for As hyperaccumulator resources in the future. [ABSTRACT FROM AUTHOR]

Different vegetable species and topsoils were collected from different urban gardens of Seville, Cordoba, and Huelva (South Spain) and from two small towns in a mining area (Riotinto), together with topsoil close to the plants. The concentration of potentially toxic elements (PTEs) (As, B, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, and Zn) was evaluated in edible plant parts and in the soils. The same species were also purchased from Seville local markets and from a peri-urban area (domestic garden in a rural area) and also analyzed. Plant/soil pollution relation was studied and human health risk was assessed by different parameters. Soils of urban gardens from the mining area were more contaminated with As, Cr, Cu, Pb, and Zn in comparison with other locations, and generally, soils from cities showed higher values of As, Pb, and Zn than the peri-urban ones. The mean concentration of almost all potentially toxic elements was higher in leafy than in fruiting and bulbous species. Arsenic, Cd, and Pb concentrations were below health-based guidance values in all vegetables except Cd in one sample in the peri-urban area. In general, PTEs concentration in vegetables from city urban gardens did not exceed the one found in market vegetables for almost all studied elements, except in lettuce for almost elements. The hazard quotient (HQ) values were lower than the unit for all PTEs in plant species from the studied gardens, as well as the hazard index (HI), indicating that consumption of these vegetables can be considered safe and without risk to human health. Also, cancer risk values for As were below the established limits in all vegetables from the studied urban gardens, including those from the As-contaminated soils in the mining area. [ABSTRACT FROM AUTHOR]

Soil in mining wastelands is seriously polluted with heavy metals. Zero-valent iron (ZVI) is widely used for remediation of heavy metal–polluted soil because of its excellent adsorption properties; however, the remediation process is affected by complex environmental conditions, such as acid rain and freeze-thaw cycles. In this study, the effects of different pH values and freeze-thaw cycles on remediation of antimony (Sb)- and arsenic (As)-contaminated soil by ZVI were investigated in laboratory simulation experiments. The stability and potential human health risks associated with the remediated soil were evaluated. The results showed that ZVI has a significant stabilizing effect on Sb and As in both acidic and alkaline soils contaminated with dual levels of Sb and As, and the freeze-thaw process in different pH value solution systems further enhances the ability of ZVI to stabilize Sb and As, especially in acidic soils. However, it should be noted that apart from the pH=1.0 solution environment, ZVI's ability to stabilize As is attenuated under other circumstances, potentially leading to leaching of its unstable form and thereby increasing contamination risks. This indicates that the F1 (2% ZVI+pH=1 solution+freeze-thaw cycle) processing exhibits superior effectiveness. After F1 treatment, the bioavailability of Sb and As in both soils also significantly decreased during the gastric and intestinal stages (about 60.00%), the non-carcinogenic and carcinogenic risks of Sb and As in alkaline soils are eliminated for children and adults, with a decrease ranging from 60.00% to 70.00%, while in acidic soil, the non-carcinogenic and carcinogenic risks of As to adults and children is acceptable, but Sb still poses non-carcinogenic risks to children, despite reductions of about 65.00%. These findings demonstrate that soil pH is a crucial factor influencing the efficacy of ZVI in stabilizing Sb and As contaminants during freeze-thaw cycles. This provides a solid theoretical foundation for utilizing ZVI in the remediation of Sb- and As-contaminated soils, emphasizing the significance of considering both pH levels and freeze-thaw conditions to ensure effective and safe treatment. [ABSTRACT FROM AUTHOR]

In northern Chile, economic activities related to mining and thermoelectric energy have existed in the city of Tocopilla since the early 1900s and metal concentrations in soils have likely been altered by historic anthropogenic activities. To assess the concentrations of Cu, Zn, Pb, Ni, Co, and Cr in urban soils of Tocopilla, a total of 70 superficial (2 cm) and 70 deep (20 cm) soil samples were collected in 2014. Furthermore, to analyze concentration changes in soils over time, 18 superficial (5 cm) samples were collected in 2020–2021. A numerical evaluation (geoaccumulation index, and enrichment factor), principal component analysis, and spatial distribution approach were applied to infer geogenic and anthropogenic influence on the concentrations of these elements. The main conclusions of this research indicate that urban soils of Tocopilla contain geogenic Cu, Zn, Pb, Ni, Co and Cr. However, elevated concentrations of Cu, Zn, and Pb cannot be attributed to a geogenic origin alone, as a proportion of their enrichment is considered to be anthropogenically sourced. The contamination of anthropogenic elements has been found to be related to historic copper mining and thermoelectric energy production. Furthermore, when compared to other sites globally, median concentrations of Cu (945 mg/kg in 2014 and 823 mg/kg in 2020) and Zn (305 mg/kg in 2014 and 196 mg/kg in 2020) in superficial urban soils are among the highest worldwide. Regarding 2020–2021 sampling, Zn and Pb concentrations have increased, while Cu, Cr, Co, and Ni have remained similar to the 2014 samples. [ABSTRACT FROM AUTHOR]

The mining and processing of copper in the Kilembe area, Western Uganda from 1956 to 1982 left behind several tailing sites containing cupriferous and coralliferous pyrites. A study was conducted to establish the concentrations of trace elements in point sources (tailings) within Kilembe mine and the distribution of trace elements within catchment soils. Mine tailings and catchment soils were sampled, acid digested and tested for elemental concentrations using ICP-MS. Tailings appeared to be the main sources of trace element contamination of soils with very high concentrations (mg kg−1) of Cu (240–11500), Co (101–180) and Ni (140–248) compared with average world crust concentration of Cu (20–75), Co (1–15) and Ni (20) mg kg−1. The concentration (mg kg−1) of Cu (3.5–975), Co (4.9–110) and Ni (5.3–180) in soils along the mine zone and downstream were significantly higher than upstream trace element concentrations and in many samples exceeding recommended agricultural thresholds. Positive and significant correlations were observed between Fe and Mn with all trace elements in soil, suggesting adsorption and co-precipitation processes. The major factors influencing trace element distributions in the soils were distances and locations relative to point sources of contaminants, with soils close to and downhill of tailing sites more contaminated with trace elements. Remediation of soils to reduce trace elements is recommended in addition to containment of tailing erosion. [ABSTRACT FROM AUTHOR]

The dam failure of the Córrego do Feijão Mine (CFM) located in Minas Gerais State, Brazil, killed at least 278 people. In addition, large extensions of aquatic and terrestrial ecosystems were destroyed, directly compromising the environmental and socioeconomic quality of the region. This study assessed the pollution and human health risks of soils impacted by the tailing spill of the CFM dam, along a sample perimeter of approximately 200 km. Based on potential ecological risk and pollution load indices, the enrichments of Cd, As, Hg, Cu, Pb and Ni in soils indicated that the Brumadinho, Mário Campos, Betim and São Joaquim de Bicas municipalities were the most affected areas by the broken dam. Restorative and reparative actions must be urgently carried out in these areas. For all contaminated areas, the children's group indicated an exacerbated propensity to the development of carcinogenic and non-carcinogenic diseases, mainly through the ingestion pathway. Toxicological risk assessments, including acute, chronic and genotoxic effects, on people living and working in mining areas should be a priority for public management and mining companies to ensure effective environmental measures that do not harm human health and well-being over time. [ABSTRACT FROM AUTHOR]

The study was carried out to define the distribution of mercury in surface soils in the Mitrovica region, Republic of Kosovo and to assess the level and extent of contamination. A total of 156 soil samples were collected from a depth of 5 cm at each grid point of 1.4 × 1.4 km in an area of 301.5 km2. The mercury content was found to be between 0.02 mg/kg and 11.16 mg/kg. The average Hg content (0.49 mg/kg) exceeded the mean content in European (0.037 mg/kg) and world (0.06 mg/kg) soils by 13.2 and 8.2 times, respectively. From the calculated enrichment factors (EF) and the geo-accumulation index (I-geo), as well as from the distribution map of Hg content, it is evident that the soils of the study area are highly contaminated with mercury, with extremely high enrichment of Hg in the soils of Zone I, which was classified as the most contaminated zone with Hg and other potentially toxic elements in the study area as well as in the towns of Zveçan and Mitrovica. The higher Hg content is of anthropogenic origin, mainly due to lead and zinc mining and metallurgical activities in the study area. The mercury levels were also found to exceed the New Dutch List target value (0.3 mg/kg) in 90 km2 of the study area. [ABSTRACT FROM AUTHOR]

In the Ecuadorian Amazon, the challenges for identifying, phytoremediation species that reduce heavy metal contamination resulting from mining activity are increasing every day. The objective of this work was to evaluate the bioaccumulator potential of heavy metals of three fast-growing forest species (Ochroma pyramidale, Piptocoma discolor and Bambusa vulgaris) in a mining extraction area, in the Yutzupino community, Napo for restoration. Leaf and soil samples were collected to determine the concentration of heavy metals (Cd, Pb, Fe and Ni) using atomic absorption spectrometry and the bioconcentration factor (BCF) was calculated. Leaf analyzes showed that B. vulgaris presented a higher concentration of Ni (6.89 mg kg-1) and Fe (156.33 mg kg-1) and P. discolor contained Cd (0.35 mg kg-1) and Pb (55.67 mg kg-1). Soil analyzes showed a pattern of variation in B. vulgaris superior in Cd, Ni and Pb and in O. pyramidale for Fe. The bioconcentration factor allowed identifying the accumulating capacity of the species, which suggests that P. discolor may be used as a phytoremediation species for sites contaminated by Cd and Pb, O. pyramidale for Ni and B. vulgaris for Fe. [ABSTRACT FROM AUTHOR]

Alteration of wet and dry periods affects soil geochemical properties that drive contaminant availability and mobility. Consequently, the efficiency of soil remediation may vary, and thus soil management needs to consider these variations. This study reveals the effect of soil moisture manipulation on the behaviour of the toxic metalloids antimony (Sb) and arsenic (As) and the immobilisation efficiency of nanoscale zero-valent iron (nZVI), biochar (BC) and BC modified by iron or iron/ferrous sulphide (nZVI-BC and Fe/FeS-BC). Soil samples from an abandoned Sb mining site were tested under laboratory conditions. Two distinct (organic and mineral) soil layers were incubated with each of the amendments (2% w/w application rate) at 50% and 100% water holding capacity (WHC) of the soils for 10 weeks, and subsequently extracted with demineralised water and rainwater. The immobilisation efficiency of the tested amendments was significantly influenced by the different soil moisture regimes and type of contaminant. Sorption onto secondary Fe minerals was the dominant Sb/As immobilizing mechanism. The iron-based amendments showed up to 97% efficiency for Sb and up to 96% for As. However, Sb/As release was generally higher at 100% WHC and in the rainwater extracts compared to the other conditions, indicating that heavy rainfall and flooding of soils in-situ may increase contaminant availability and mobility. In the organic layer, enhanced formation and leaching of metalloid-DOC complexes and sorption competition of the negatively charged Sb/As species and DOC can be expected. Also, reductive dissolution of Sb or As-bearing metal oxides could lead to the observed higher Sb/As release under flooded conditions, resulting in exacerbated environmental and health risks. Therefore, it is crucial to (1) improve the sorption characteristics of the tested amendments and/or develop other effective amendments for Sb/As immobilisation in different water regimes in soil; (2) test the amendments under real field conditions to evaluate the long term wet/dry exposure; and (3) develop proper risk assessment and soil remediation strategy for the study area and similar sites. [ABSTRACT FROM AUTHOR]

The concentration and bioaccessibility of potentially toxic metals, including As, Cd, Cr, Cu, Mn, Ni, Pb and Zn, were determined in surface soil samples from a mining community (Kenyasi) and a non-mining community (Sunyani) in Ghana, to investigate the contribution of mining activities to the environmental burden of potentially toxic metals. The study found significant differences in metal concentrations (p < 0.05) in As, Cd, Cu, Mn, Ni, and Zn, but no significant difference (p > 0.05) in Pb and Cr between the two communities. The study found a moderate correlation between pH and metal concentrations in the mining community and a moderate positive correlation with As, Cd, Cr, Cu, Ni, and Zn in the non-mining community. The distribution pattern revealed elevated levels of toxic metals in the southeastern corridor of the mining community, which is close to a gold mine. Most heavy metals were concentrated in the commercial community's southern zone, with more residents and private elementary schools. Metal bioaccessibility was variable, and except for Cu and Zn, the mean bioaccessibility was less than 50% for a given metal. Contamination factor, geoaccumulation index, and soil enrichment factor suggested very high contamination of Cd, and a considerable to moderate contamination of As, Ni, Zn, and Cu at both the mining and non-mining communities. The above observations and the pollution and risk indices employed in this study confirmed that the mining community was more polluted (PLI = 2.145) than the non-mining community (PLI = 1.372). The total metal hazard (HI) exceeded thresholds by three and four times at non-mining and mining sites. Regular monitoring is necessary, especially in the mining community, to prevent soil metal accumulation. [ABSTRACT FROM AUTHOR]

Coal mining activities are causing an extensive range of environmental issues at both operating and abandoned mine sites. It is one of the most environmentally destructive practices, with the capability to eliminate fauna and flora, impact the groundwater system, and pollute the soil, air, and water. The Czech Republic relies almost exclusively on coal as its primary domestic source of energy. The combined reserves of hard and brown coals in this country are 705 million tons. About 50 million tons of coal is produced annually, making it the 14th biggest producer in the world. Soil degradation is an inevitable outcome of the coal production from surface coal mining procedures in the Czech Republic. Significant changes have taken place in soil productivity, hydraulic characteristics, horizon, and texture as a result of soil pollution, bioturbation, compaction, and weathering. The current review has evaluated the impact of reclamation and coal mining on soil characteristics, including biological, chemical, and physical properties. Additionally, the study has outlined the process of soil formation in reclamation areas in the Czech Republic. In nutshell, research gaps and future directions in understanding coal mining areas and their influences on soils in the Czech Republic are identified. [ABSTRACT FROM AUTHOR]

Modifications of sludge biochar with metal-based materials can enhance its fertilizing efficiency and improve safety. To elucidate the effects of ferrous sulfate modification on the fate of phosphorus in sludge biochar and its effect on phosphorus fractionation in soil, we investigated the changes in fractionation and bioavailability of phosphorus in modified sludge biochar and studied the changes in soil characteristics, microbial diversity and response, bioavailability, plant uptake of phosphorus, and heavy metals in contaminated soils after treatment with ferrous sulfate modified sludge biochar. The results demonstrated that ferrous sulfate modifications were conducive to the formation of moderately labile phosphorus in sludge biochar, and the concentrations increased by a factor of 2.7 compared to control. The application of ferrous sulfate-modified sludge biochar to alkaline heavy metal-contaminated soils enhanced the bioavailable, labile, and moderately labile phosphorus contents by a factor of 2.9, 3.0, and 1.6, respectively, whereas it obviously reduced the leachability and bioavailability of heavy metals in soils, exhibited great potentials in the fertilization and remediation of actual heavy metal-contaminated soils in mining areas. The biochar-induced reduction in soil pH, enhancement of organic matter, surface oxygen-containing functional groups, the abundance of Gammaproteobacteria, and its phosphonate degradation activity were primarily responsible for the solubilization of phosphorus from modified biochar in heavy metal-contaminated soils. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) poses a serious challenge to the ecosystem due to its disastrous effect on soil and water resources which contributes to the pollution and reduction of the accessibility of potable water and arable land for agricultural activities. The treatment of contaminated soils using physical, chemical, or thermal methods requires some improvements to meet the required remediation purpose. The purpose of this study is to investigate the application of bioattenuation, wastewater, and air-injection for the remediation of AMD polluted soils. A microcosm comprising 1 kg of polluted soil was amended with varying loadings of domestic and brewery wastewaters for biostimulation treatments, and the bioattenuation received no amendment while the bioventing treatment was supplied with wastewaters and atmospheric air at 3 L/min for 30 mins intervals every 48 h. The investigation conducted under the ambient condition for 28 days recorded average metal removal efficiencies of 12-31% (bioattenuation), 50-66% for all heavy metals (iron, aluminum, copper and zinc) except manganese (28%) (biostimulation) and 56-70% (bioventing) while 32%, 35% and 52% sulfate removal efficiencies were recorded for bioattenuation, bioventing and biostimulation respectively. The study revealed that wastewater and bioventing systems can be efficiently utilized as an eco-friendly approach for the treatment of acid mine contaminated soils and pollution mitigation in the mining environments. In addition, from a comparative point of view, the results of the study further showed that the amendment of wastewater is more effective for sulfate removal while air injection enhanced metal removal from acid mine drainage contaminated soils. The synergetic effects have also been observed; the current study demonstrates that the combined application of biostimulation and bioventing system requires constant monitoring to ensure the provision of appropriate anoxic conditions for biosulfidogenic activity by enhancing sulfate removal while promoting an oxic environment for the oxidation process to facilitate metal removal for the effective treatment of acid mine drainage contaminated soil. [ABSTRACT FROM AUTHOR]

Due to the obvious potential hazards it poses to the environment, animals, and human health, Mn (II) contamination has become worrisome. The broad aim of the study was to examine the contamination levels of soil in the Shivrajpur Mn mine site, physicochemical tests such as pH and heavy metal analyses were done. Later 16S rRNA sequencing was used to characterize bacterial species isolated from different colonizer plant samples. The bacterial strains recovered from Mn mine rhizospheric soil exemplified morphological and molecular diversity. It was discovered that all seven bacterial isolates could survive Mn salt concentrations up to 2000 mg/l, whereas only one, Staphylococcus capitis (GenBank OP861008), could withstand concentrations up to 10,000 mg/l. The three isolates, Staphylococcus capitis, Bacillus albus (GenBank OP861099), Bacillus tequilensis (GenBank OQ135205), have the ability to sustain the Mn tolerance as the agar wells were surrounded by growth expanse. The findings imply that the Staphylococcus capitis could be used to create a biosorbent that is both effective and environmentally benign, and it can aid in the bioremediation of contaminated soil. [ABSTRACT FROM AUTHOR]

This study was conducted in the territory of the industrial site of the Udachny Mining and Processing Division (Yakutia, northeast Russia). The objects of study were permafrost soils and two species of shrubs (Betula middendorffii T. and Duschekia fruticose R.). Soil and plant samples were analyzed using atomic absorption spectrometry for the presence of PTEs (Pb, Ni, Mn, Cd, Co, Cr, Zn, Cu, and As). The bioaccumulation factor (BAF), frequency of occurrence (Hi), pollution index (PI), and pollution load index (PLI) were calculated. The PI and PLI are calculated for both soil and two plant species for the first time in this study. The results showed that the soils have a high Ni, Cr, Co, As, and Mn content. It has been established that high soil pollution naturally leads to an increase in the concentration of elements in the leaves of shrubs. The soils and vegetation are dominated by elements associated with trap magmatism—Cr, Co, Cu, and dolerite dikes—Mn and Zn. For Betula middendorffii, the PLI was classified as unpolluted to moderately polluted, and Duschekia fruticosa. was classified as unpolluted. The high level of contamination is typical for areas located near industrial sites, such as waste dumps, kimberlite pipes, tailings ponds, and roads. The BAF results confirmed that the leaves of Betula middendorffii are able to accumulate more PTEs and have the highest level of resistance to PTE contamination in mining environments. This analysis showed that the consistent application of the PI, PLI, and BAF indices is very efficient in the ecological and biogeochemical assessment of the situation in industrial development areas. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a hazardous heavy metal that poses several problems to human health and the environment requiring remediation to reduce such risks. In situ remediation is a promising, low-cost strategy for immobilizing heavy metals in soil. Using soil materials from a natural forest and from a mining area near the forest, Cd released kinetics (by the stirred flow method) combined with sequential chemical extraction as a function of the application of rates of biochar, phosphate, calcite, and biosolids were investigated through a series of laboratory experiments. Among the amendments, biochar and biosolids were more effective in reducing Cd desorption kinetics in forest soil than in mine soil. Both treatments increased the Cd associated with organic matter (OM), which suggests that part of the Cd was immobilized by the organic compounds that were applied to the soil. Phosphate application to both soils reduced Cd desorption kinetics. Column leaching carried out using the mine soil showed that a quarter and a half of the phosphorus (P) rate increased Cd leaching, while the higher rate decreased Cd leaching compared to untreated forest soil. Treatment with calcite was more effective in decreasing desorption kinetics of Cd in the mine soil in the initial time period (30 min), while the same was observed in the forest soil only after 120 min. In both soils, the Cd associated with OM increased after the addition of calcite as a result of the increase in the negative charge on the surfaces of the OM. [ABSTRACT FROM AUTHOR]

This study, which considers coal mining sites, aims to solve problems pertaining to the immense permeability, poor stability, and the environmental pollution of soil. In regard to reconstituted soil, the novel "2+1" layered construction technology entails designing a water-resisting layer, a modified layer, and an evaporation inhibition layer on the surface of the gangue hill. This technology, which entails constructing a novel type of reconstituted soil, considered four mechanical and physical soil properties, namely soil particle size, humidity, unit weight, and soil structure grade. The construction of novel reconstituted soils should consider the influence of biological factors and that of an arid environment, as well as the influence of the soil permeability coefficient, water content, density, temperature, and water-soil interaction; simultaneously, it should consider the chemical composition. With respect to the water-resisting layer, we selected loess and feldspathic sandstone that exhibited high clay content, and we utilized a 20 cm design thickness. The modified layer was composed of sandy loess, weathered coal, and feldspathic sandstone. This layer was exhibited a 60 cm design thickness, and it considered the characteristics pertaining to vegetation, soil compactness, and soil chemical composition. The evaporation inhibition layer was designed using materials such as gravel and straw checkerboard. Regional tests indicated that verified the rational robustness of the novel "2+1" reconstituted soil layered construction. The results provide a reference for ensuring the ecological sustainability of coal mining sites that characterize the arid, desert areas of Northwest China. [ABSTRACT FROM AUTHOR]

Long-term mining activities have caused serious heavy metals contamination of farmland soils. In this study, we investigated the concentrations, distributions, accumulations, potential ecological risk, and sources of eight heavy metals in farmland soils of Pb–Zn mining areas. According to the soil standard GB15618-2018, Cd was the most contaminated, followed by Pb and Zn. The geo-accumulation index showed that Pb, Zn, Cd, and Hg accumulated seriously. The potential risk index indicated that Cd, Hg, and Pb were the main environmental risk elements. An integrated approach combining multivariate statistical analysis, PMF, and GIS mapping was used to analyze the sources of heavy metals. Four main sources were identified and quantified: (1) mining activities source, the main source of Cd (71.09%) and Zn (61.88%); (2) agricultural activities source, dominated by Hg (73.01%); (3) atmospheric deposition sources, with Pb (85.11%) as the main contributor; (4) natural source, characterized by Cr (72.96%), Ni (66.04%), As (55.98%) and Cu (37.70%). This study would help us understand the pollution characteristics and sources of farmland soils in mining areas and provide basic information for the next step of pollution control and remediation. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in soils seriously threatens human health and aggravates the global pollution burden. In this study, we investigated the risk of heavy metal contamination in soils at a Zn-Pb mineral processing plant in Longnan, China, and the effects of different heavy metal contamination levels on diverse microbial communities. Statistical analysis showed that, except for Ni, the average content of all detected metals (Zn, Pb, As, Cu, Cd, Hg) in the soil was higher than the background value of soil in the study area, which was most seriously contaminated with Pb and As. Comparison of functional divisions showed that heavy metal soil contamination was most serious in the raw material stacking area and the production area. Interpolation analysis showed that areas closer to the wastewater discharge area had higher contents of each heavy metal and were more seriously polluted. From the point of pollution index, the risk of heavy metal soil pollution in the study area was very high (RI = 2845.24, i.e., > 600), with Cd and Hg being the most serious pollutants compared with other heavy metals. Microbial community abundance, diversity, and structure differed at different levels of heavy metal contamination. The community diversity of bacteria decreased with increasing heavy metal concentrations, while no significant change in fungi was observed. Evidence from variation redundancy analysis (RDA) and the Spearman correlation analysis showed that the leading factors affecting microbial community composition were Cu, Cd, Hg, and pH. Actinobacteria and Gemmatimonadetes at the uncontaminated level (CL) were significantly and negatively correlated with the concentrations of Cu, Zn, Cd, and Pb. Proteobacteria and Chloroflexi at the severely contaminated level (SL) were significantly correlated with pH and Hg. However, heavy metal contamination had less effect on most of the dominant fungi. In conclusion, microbial communities such as Proteobacteria, Actinobacteria, Chloroflexi, and Ascomycota showed greater tolerance to heavy metals. These results could be used as important references for the remediation of heavy metal-contaminated soils. [ABSTRACT FROM AUTHOR]

The present research was carried out to examine the health and environmental impacts associated with coal mining activities in the Makarwal coal mining area in Pakistan. To achieve the objectives, 41 soil samples were collected from the coalmine-affected areas and analyzed for major and toxic trace elements (TTEs) using atomic absorption spectroscopy. Most of the soil samples have extremely high concentrations of toxic metals such as Ni, Cd, Cr, Cu, Zn, and Pb. The positive correlations and high concentration of trace elements in the Makarwal coalmine-affected region suggest an analogous origin of soil contamination. The factor analysis (FA) showed two components, i.e., F1 (53.4%) and F (74.21%), of total variability for soil. The F2 was loaded with Pb, Zn, Ni, and Cr, which was similar to cluster 2, while the F1 was loaded with Cu and Cr, having a similar pattern to cluster 1. This proves that the contamination in the surrounding area is mostly associated with geological ore strata existing in the Makarwal coalfield. Based on geoaccumulation (Igeo), the elemental concentration in the studied soil sample could be categorized as follows: (1) Pb, Ni, and Zn are moderate to severely polluted and (2) Cr and Cu are in the moderately polluted category. The ecological risk indices (ERIs) of the single trace element contamination index highlighted that Cd, Pb, Ni, and Cr pose a high risk to humans and the ecosystem. Based on different statistical tools performed for the source identification and distribution of metal contamination, it seems that the exposed sedimentary rocks, including limestone, dolomite, sandstone, and coal, are responsible for the toxic metal contamination in the study area. [ABSTRACT FROM AUTHOR]

Mineral resources are considered significant material sources for economic and social development. However, during mining processes, various toxic pollutants, such as heavy metals, are released into the soil environment, which pose serious threats to the ecological environment and human health in mining areas. In addition, intricate geology, geomorphology, and changes in soil physicochemical properties, as well as complex processes comprising the migration and transformation of pollutants, complicate the remediation of soil environments. Given the lack of existing technology, such as inadequate soil remediation, we analyzed the recent achievements in the remediation of contaminated soils in mining areas and introduced the basic concept of land restoration. Moreover, we introduced the theoretical and experimental research status of five types of typical treatment technologies for heavy metals, including extraction, passivation, nanotechnology, combination, and new concept techniques in detail; subsequently, we also described the advantages and limitations of the application of existing remediation techniques. This study aims to provide directions for future research on soil pollution control, treatment technologies, and remediation practices in mining areas. [ABSTRACT FROM AUTHOR]

Soil phosphatase activity is identified as sensitive to arsenic (As) pollution and therefore, often used as an indicator to estimate As toxicity in soil. Nevertheless, the effect of As on soil phosphatase activity after its desorption by P is not adequately studied. This study employed sequential extraction procedure and ecological dose parameters to show As mobility and its toxicity to acid phosphatase (AcP). Results indicated that P application significantly increased As desorption ratio in the As ageing process. In S1 (As 2895 mg kg−1) soil, after P addition, the water‐soluble (FWS) fraction had the highest proportion of As, while for S2 (As 645 mg kg−1) and S3 (As 39 mg kg−1) it was residual (FRES) fraction. Additionally, P addition increased the As bioavailability in all soils. Generally, P addition significantly reduced soil AcP activity under all P concentrations and increased in the soil with minimum As content. The variation partitioning analysis indicated that for S1, P concentration was the major factor, for S2 and S3 soils, it was As desorption and ageing time, respectively, that influenced the AcP activity in soils. The calculated ecological dose (ED50) showed that in most cases, As toxicity increased at the end of ageing. Thus, it is essential to control the phosphorus fertilizer applications in silty soils with acid and neutral pH, since it can lead to increased As mobility and toxicity to soil AcP. Core Ideas: Increasing P concentration increased As mobility and bioavailabilityAcid phosphatase (AcP) activity decreased in high and medium As‐contaminated soilsP treatment, As desorption, and ageing greatly influenced AcP activity in soilsImportant to control P fertilizer application in managing As‐polluted soils [ABSTRACT FROM AUTHOR]

Previously conducted studies have established that soil contamination by trace elements (TEs) around coal mines affects ecological biodiversity and human health. One of the ways to protect the health of the surrounding population of coal mine sites is through the assessment of contamination impacts by accurate procedures for the establishment of relevant reclamation plan. The aim of the study is to develop an applied methodological approach to easily assess and quantify the impact of coal mining on the surrounding soils. To achieve this goal, a set of relevant geochemical indexes (enrichment factor—EF, geochemical background—GB, and geoaccumulation index—Igeo) and a geostatistical interpolation for mapping soil contamination were applied. It is experimentally established that the process of combining these techniques can be of great interest in highlighting the anomalous areas and revealing the contamination sources. A case study has been carried out on of the abandoned coal Jerada mine site in Morocco. Soils and coal mine waste rocks (CMWR) samples were collected from this site. Soil and CMWR samples were analyzed for their geochemical content. CMWRs were characterized further for their mineralogical composition and environmental behavior. Based on the EF, three TEs (As, Pb, and Zn) were targeted. The results of GB and Igeo calculations have established an evident relationship between the CMWR dump and the occurred soil contamination. TEs distribution pattern has been revealed using the obtained geochemical maps. The developed methodological approach may be in high demand when assessing soil contamination in most of abandoned coal mine sites around the word. [ABSTRACT FROM AUTHOR]

Mining activities in the opencast coal mines contaminate the surrounding soil by releasing coal dust containing heavy metals (HMs). The objective of the present study was to quantify the concentration of HMs like Fe, Cu, Mn, Ni, Cr, Zn, and Co in soil on profile and distance basis in the vicinity of the coal mines. This research also proposed the synthesis application of positive matrix factorization (PMF) model for the quantitative assessment of pollution sources. The results showed that the soil was more affected due to the presence of Cr in mining areas., and the contamination factor (Cf) of Cr was high at the edge of coal mine. It was observed from the study that Cf of the HMs was decreased with the increase in distance from the mine edge. The application of PMF model demonstrated that the contributions of Zn (4.2%), Ni (16.8%), and Mn (100%) were maximum in the pollution. The study concluded that soil contamination is inexorable due to opencast coal mining activities, and it can be mitigated by developing a green belt or through the process of ecological restoration and phytoremediation. [ABSTRACT FROM AUTHOR]

To investigate the heavy metal contamination of soil in a uranium mining area in northern Guangdong, a physicochemical evaluation method was used to evaluate the contaminated soil near the pit and tailings pond of the uranium mining area, determine its heavy metal content and evaluate its ecological risk using the Nemerow integrated contamination index, ground accumulation index and potential ecological risk index. The results show that the average content of nine heavy metal elements in the soil of the uranium mining area exceeds the background value of red soil in Guangdong Province. Three pollution evaluation indices all indicate that Cd, As and U have serious pollution and high ecological risk, while the remaining elements are weakly polluted and the potential ecological risk of the six sampling sites all show very strong risk. On this basis, soil ecotoxicity was evaluated using ostracods (Cypridopsis vidua and Heterocypris sp.), Vibrio fischeri and Vicia faba L. Higher concentrations of heavy metals at individual sites (T1, T2, P2) resulted in higher mortality of ostracods, higher inhibition of Vibrio fischeri luminescence and a significant reduction in germination and pigmentation of broad beans. The results of the biotoxicity evaluation were consistent with the results of the physicochemical evaluation, allowing for a more direct and comprehensive evaluation of the ecotoxic effects of uranium and heavy metals in the mine soils. [ABSTRACT FROM AUTHOR]

• Pb-Zn mining soils had toxic effects on Enchytraeus crypticus at various biological levels. • Reproduction and growth of enchytraeids were affected by metals at sublethal doses. • At sublethal doses, metals induced lipid peroxidation and DNA damage in enchytraeids. • A complementary mechanism for oxidative damage in enchytraeids exposed to metals. • MDA and DNA damage in E. crypticus could be an efficient early-warning tool for mining soils. The sub-lethal ecotoxicity of field-contaminated soils toward small soil fauna, such as enchytraeids, remains understudied but holds paramount importance in soil pollution assessment. This study employed Enchytraeus crypticus to evaluate metal-contaminated soils from a mining area across various levels of biological organization, including individual level responses (survival, growth, reproduction, Cd/Pb/Zn accumulation), cellular level effects (peroxidase (POD), superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), acetylcholinesterase (AChE), lipid peroxidation malondialdehyde (MDA)) and genetic alterations (olive tail moment (OTM) and tail DNA%). The study revealed considerable Cd and Pb accumulation, exerting adverse impacts on the reproduction and growth of the enchytraeids after a 21-day exposure. Changes in cellular and genetic parameters occurred with increasing exposure concentration and duration, indicating heightened lipid peroxidation and DNA damage in enchytraeids. A noteworthy metal detoxification process, evident at a physical level, was identified in E. crypticus , characterized by an initial escalation in toxicity followed by a subsequent decline. A distinctive complementary mechanism governing oxidative damage was detected in the enchytraeids, with an initial suppression of CAT activity, followed by inductions in SOD, POD, and GSH activity. Over the exposure duration, MDA content and DNA damage in the enchytraeids exhibited concentration-dependent shifts indicating their potential as efficient early-warning indicators for assessing the impact of Pb-Zn mining soils. This study contributes to a comprehensive understanding of the toxicological implications of metal-contaminated soils within the soil-enchytraeid framework. [ABSTRACT FROM AUTHOR]

Removal of heavymetals fromsoil bywashingwith different eco-friendly washing agents is one of the methods that has gained great interest in scientific research. As previous studies reported the potential of chitosan to be used as an eco-friendly washing agent for the removal of heavy metals from soils, in the present study, the removal of lead and copper from multi-metal contaminated soil collected from a mining area located in Zlatna (Alba County, Romania) by chitosan washing was investigated. Soil washing experiments were performed at laboratory scale by an ex-situ soil washing technique. A solid/liquid ratio (S/L ratio; g:mL) of 1:10, two concentrations of chitosanwashing solution (2 and 5%) and different stirring times (120, 240, 360, 720, 1440 and 2400 min) were the studied parameters of the washing process. The results indicated that copper and lead removal efficiency increased with increasing the stirring time and the concentration of chitosan in the washing solution (in the case of Cu). In the investigated experimental conditions, about 55%and 77%of copper and lead were removed from the soil after 2400 min of stirring with the chitosan washing solution. [ABSTRACT FROM AUTHOR]

Understanding the level of heavy metal contamination coupled with the assessment of environmental and human risks associated with mine waste dumpsites is an important step to initiating efficient measures for mine wasteland restoration, stabilization, and bioremediation. In the present study, concentration of the heavy metals; Copper (Cu), Cobalt (Co), Iron (Fe), Lead (Pb), Manganese (Mn), and Zinc (Zn) in soil from mine waste dumpsites around Kitwe (Sites: BM and TD26) and Mufulira (Site: TD10), Zambia, was assessed to determine the level of contamination, ecological risks, and progress made in reclamation. The mine waste dumpsites in the two towns are located in the vicinity of residential areas. Therefore, there is need to provide information for optimization of protocols for post-mining landscape in Zambia and elsewhere to limit soil, river, and groundwater contamination and to accelerate the restoration process. Mean values for soil pH, electrical conductivity, and organic matter varied between 5.9–8.4, 2534.8–538.6 μS/cm, and 0.90–2.75%, respectively. The mean concentrations of heavy metals of BM, TD26, and TD10 decreased in order of Fe > Cu > Co > Mn > Pb > Zn across all sites. However, the order of overall degree of heavy metal contamination computed using control soil as a baseline in BM, TD26, and TD10 was Cu > Co > Fe > Pb > Mn > Zn. The pollution load index was 0.355 at BM, 0.329 at TD26, and 0.189 at TD10, indicating high soil pollution at BM and TD26. The Potential Ecological Risk Index for all heavy metals tested at BM, TD26, and TD10 showed low ecological risk in the vicinity of the studied dumpsites. Furthermore, the present study also showed that the polluted soils around smelter sites and mine waste dumpsites are susceptible to dispersion by wind and water. Additionally, results from TD10 revealed that the initiated remediation of the tailings dam was somewhat successful. Finally, this study provided an updated status regarding the accumulation of heavy metals in mine waste dumpsites of Kitwe and Mufulira, Zambia and baseline information necessary to enhance post-mining landscape reclamation. [ABSTRACT FROM AUTHOR]

After the accident at the Fukushima nuclear power plant in Japan, a large amount of radioactive contaminated soil was generated, which brought great challenges for treating and disposing of the soil. The recycling of slightly polluted soil can reduce the amount of contaminated soil. This paper analyzes the main exposed scenes of 137Cs polluted soil used in the construction of highway subgrade, soil bag handling and paving. The Monte Carlo algorithm (MCNP) and RESRAD-ONSITE program are used to simulate the two scenes respectively, and the concentration of 137Cs is derived in the soil at the effective dose of 1 mSv per year. It is concluded that: the annual effective doses of porter and paver are 0.41 mSv per year and 0.23 mSv per year respectively caused by 1 Bqg-1 137Cs contaminated soil; the activity of 137Cs are 2.44 Bqg and 4.26 Bqg-1 respectively in the soil at 1 mSv per year for porter and paver; the calculated results are consistent with those reported by the Japan Atomic Research Agency. Also, they are lower than the activity concentration corresponding to the effective dose con- trol level of 1 mSv per year under low-probability events in IAEA No. RS-G-1.7 slightly. [ABSTRACT FROM AUTHOR]

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The presence of potentially toxic elements (PTEs) in soil and plants is a risk factor to human well-being and the environment. Soil and leaves from a traditional medicinal plant, Vachellia karroo, known as the sweet thorn plant, were assessed to determine the extent of pollution by PTEs from gold mine tailings in a case study area of Matjhabeng Local Municipality, South Africa. A risk classification tool was developed using the different indicators of pollution quantified to describe the pollution risk at each sampling site. High concentrations of copper, cadmium, lead, nickel, and zinc were measured in the soil, which exceeded the maximum permissible soil quality limits. The enrichment factor and geoaccumulation index results also confirmed heavy soil pollution by copper, nickel, and zinc, with exceptionally heavy pollution by cadmium and selenium. The PTEs in the soil were in an exchangeable form, with the sweet thorn plant accumulating lead and selenium at toxic levels, which poses a risk to the health of the local people as the plant is used for medicinal purposes. The overall pollution risk classification tool of the sampling sites showed that 17% were high-risk areas, 53% were moderate-risk areas, and 20% of the sites were low-risk areas. [ABSTRACT FROM AUTHOR]

Background and aims: Soil quality is critical to maintaining the sustainability of vegetation reclamation. However, its variation and crucial driving factors along long-term reclamation chronosequences in metallic mine wastelands require further exploration.This study determined the variation in soil quality and its dominant drivers across a 49-year vegetation reclamation chronosequence in a vanadium titanomagnetite tailings reservoir using the minimum data set-soil quality index (MDS-SQI) method by analysing multiple soil physical, chemical, and biological properties and plant biomass.The results revealed that phosphatase (AP), soil organic carbon (SOC), heavy metal pollution (PLI), clay, and total phosphorous were retained as indicators of the MDS. The SQI values increased significantly during the first 13 years after reclamation (p < 0.01), owing to the elevated AP activities and SOC contents. They then maintained a stable and high level within the following reclamation age, which was attributable to the sluggishly increased AP activities and SOC contents and constantly increased PLI values. The aboveground plant biomass primarily drove the reclamation-age dependence of the SQI by impacting soil (microbial) nutrient turnover.Our study highlights the necessity of incorporating changes in soil heavy metal pollution into post-reclamation soil quality monitoring in metallic mine wastelands. Moreover, the results imply that aboveground plant biomass can indicate the response of soil quality to long-term vegetation reclamation at sites with a single vegetation composition.Methods: Soil quality is critical to maintaining the sustainability of vegetation reclamation. However, its variation and crucial driving factors along long-term reclamation chronosequences in metallic mine wastelands require further exploration.This study determined the variation in soil quality and its dominant drivers across a 49-year vegetation reclamation chronosequence in a vanadium titanomagnetite tailings reservoir using the minimum data set-soil quality index (MDS-SQI) method by analysing multiple soil physical, chemical, and biological properties and plant biomass.The results revealed that phosphatase (AP), soil organic carbon (SOC), heavy metal pollution (PLI), clay, and total phosphorous were retained as indicators of the MDS. The SQI values increased significantly during the first 13 years after reclamation (p < 0.01), owing to the elevated AP activities and SOC contents. They then maintained a stable and high level within the following reclamation age, which was attributable to the sluggishly increased AP activities and SOC contents and constantly increased PLI values. The aboveground plant biomass primarily drove the reclamation-age dependence of the SQI by impacting soil (microbial) nutrient turnover.Our study highlights the necessity of incorporating changes in soil heavy metal pollution into post-reclamation soil quality monitoring in metallic mine wastelands. Moreover, the results imply that aboveground plant biomass can indicate the response of soil quality to long-term vegetation reclamation at sites with a single vegetation composition.Results: Soil quality is critical to maintaining the sustainability of vegetation reclamation. However, its variation and crucial driving factors along long-term reclamation chronosequences in metallic mine wastelands require further exploration.This study determined the variation in soil quality and its dominant drivers across a 49-year vegetation reclamation chronosequence in a vanadium titanomagnetite tailings reservoir using the minimum data set-soil quality index (MDS-SQI) method by analysing multiple soil physical, chemical, and biological properties and plant biomass.The results revealed that phosphatase (AP), soil organic carbon (SOC), heavy metal pollution (PLI), clay, and total phosphorous were retained as indicators of the MDS. The SQI values increased significantly during the first 13 years after reclamation (p < 0.01), owing to the elevated AP activities and SOC contents. They then maintained a stable and high level within the following reclamation age, which was attributable to the sluggishly increased AP activities and SOC contents and constantly increased PLI values. The aboveground plant biomass primarily drove the reclamation-age dependence of the SQI by impacting soil (microbial) nutrient turnover.Our study highlights the necessity of incorporating changes in soil heavy metal pollution into post-reclamation soil quality monitoring in metallic mine wastelands. Moreover, the results imply that aboveground plant biomass can indicate the response of soil quality to long-term vegetation reclamation at sites with a single vegetation composition.Conclusions: Soil quality is critical to maintaining the sustainability of vegetation reclamation. However, its variation and crucial driving factors along long-term reclamation chronosequences in metallic mine wastelands require further exploration.This study determined the variation in soil quality and its dominant drivers across a 49-year vegetation reclamation chronosequence in a vanadium titanomagnetite tailings reservoir using the minimum data set-soil quality index (MDS-SQI) method by analysing multiple soil physical, chemical, and biological properties and plant biomass.The results revealed that phosphatase (AP), soil organic carbon (SOC), heavy metal pollution (PLI), clay, and total phosphorous were retained as indicators of the MDS. The SQI values increased significantly during the first 13 years after reclamation (p < 0.01), owing to the elevated AP activities and SOC contents. They then maintained a stable and high level within the following reclamation age, which was attributable to the sluggishly increased AP activities and SOC contents and constantly increased PLI values. The aboveground plant biomass primarily drove the reclamation-age dependence of the SQI by impacting soil (microbial) nutrient turnover.Our study highlights the necessity of incorporating changes in soil heavy metal pollution into post-reclamation soil quality monitoring in metallic mine wastelands. Moreover, the results imply that aboveground plant biomass can indicate the response of soil quality to long-term vegetation reclamation at sites with a single vegetation composition. [ABSTRACT FROM AUTHOR]

Soils close to former mines or metallurgical facilities often contain extreme concentrations of potentially toxic elements (PTEs), and among soil remediation actions needed, enhanced phytoextraction techniques using chelating agents could be a very promising option. In this context, a pot experiment was conducted to evaluate the effect of Na2-EDTA, olive mill wastewater (OMW), and their combination (EDTA + OMW) on As, Pb and Zn uptake by Helianthus annuus (sunflower), grown in a heavily contaminated soil from Lavrio, Greece. After harvest, aboveground and belowground biomass and the concentrations of As, Pb and Zn were determined. Additionally, composite soil samples of all treatments were subjected to appropriate sequential extraction procedures for each PTE. Results showed that although nonstatistically significant effects on plant growth and As concentration were observed, Pb and Zn plant concentrations increased by the EDTA addition, alone or combined with OMW. When the total bioavailability parameter was assessed, EDTA treatment was also found to significantly enhance As uptake (50% increase, p ≤ 0.05). These results were further supported by the respective sequential extraction schemes in which both Pb and As showed increased concentration in the corresponding more soluble soil fractions, probably as an outcome of partial Fe–Mn amorphous oxide dissolution. Our study thus suggests that the applied treatments of EDTA, OMW or their combined application could play a key role as reductive agents in enhancing the mobility of these PTEs in the soil environment, triggering their increased uptake by H. annuus. [ABSTRACT FROM AUTHOR]

Soil contamination by heavy metals, particularly mercury (Hg), is a problem that can seriously affect the environment, animals, and human health. Hg has the capacity to biomagnify in the food chain. That fact can lead to pathologies, of those which affect the central nervous system being the most severe. It is convenient to know the biological environmental indicators that alert of the effects of Hg contamination as well as the biological mechanisms that can help in its remediation. To contribute to this knowledge, this study conducted comparative analysis by the use of Shotgun metagenomics of the microbial communities in rhizospheric soils and bulk soil of the mining region of Almadén (Ciudad Real, Spain), one of the most affected areas by Hg in the world The sequences obtained was analyzed with MetaPhlAn2 tool and SUPER-FOCUS. The most abundant taxa in the taxonomic analysis in bulk soil were those of Actinobateria and Alphaproteobacteria. On the contrary, in the rhizospheric soil microorganisms belonging to the phylum Proteobacteria were abundant, evidencing that roots have a selective effect on the rhizospheric communities. In order to analyze possible indicators of biological contamination, a functional potential analysis was performed. The results point to a co-selection of the mechanisms of resistance to Hg and the mechanisms of resistance to antibiotics or other toxic compounds in environments contaminated by Hg. Likewise, the finding of antibiotic resistance mechanisms typical of the human clinic, such as resistance to beta-lactams and glycopeptics (vancomycin), suggests that these environments can behave as reservoirs. The sequences involved in Hg resistance (operon mer and efflux pumps) have a similar abundance in both soil types. However, the response to abiotic stress (salinity, desiccation, and contaminants) is more prevalent in rhizospheric soil. Finally, sequences involved in nitrogen fixation and metabolism and plant growth promotion (PGP genes) were identified, with higher relative abundances in rhizospheric soils. These findings can be the starting point for the targeted search for microorganisms suitable for further use in bioremediation processes in Hg-contaminated environments. [ABSTRACT FROM AUTHOR]

Soil heavy metal pollution evaluations are a necessary measure for mine ecological control projects. In this study, the heavy metals Pb, Zn and Cd were studied in mining areas, tailings areas, sewage plant areas, residential areas, reclamation areas, and farmland areas. Soil pollution assessments of lead-zinc ore mine soils in the countryside of China are performed based on the index of geoaccumulation (Igeo) and the improved analytic hierarchy process (AHP). Finally, the pollution sources were analyzed by positive matrix factorization (PMF). The Igeo for the heavy metals Pb, Zn and Cd in the mining area reached 5.20, 3.34, and 5.66, respectively. In addition, 80 and 65% of the mining area and tailings area reached extremely strong pollution, respectively. The numerical simulation predicts that the pollution hazard in the southeast of the mine is high and that the pollution is concentrated. The severity of soil pollution in mines derived by the index of improved analytic hierarchy process (PAHP) was as follows: mining area (70.80) > sewage plant area (35.57) > tailings area (30.64) > farmland area (28.40) > residential area (21.11) > reclamation area (10.06). Among the three categories of pollution sources, one includes reclamation area, farmland area and tailings area; one includes sewage plant area and residential area; and one includes mining area. The source contribution of Pb by the phenomenon of indiscriminate discharge of wastewater after ore smelting was as high as 90.4%; The contribution of the blind mining and tailings piling phenomenon of mines to the source of heavy metals Zn and Cd was 81.4 and 90.2%, respectively. This study proposes a reliable scientific method and technical method for evaluating mine soil pollution and provides a guiding basis for mine development and protection. [ABSTRACT FROM AUTHOR]

Increasing mining and industrial discharge of untreated wastewater, as well as excessive use of fertilizers for agricultural purposes, and heavy metal contamination in soil have become one of the serious environmental problems worldwide. In the present study, pot experiments were conducted to evaluate the influence of arsenic contamination and other factors on the growth and development of local forage grasses like Purple guinea and Ruzi grasses under controlled conditions. Influence of arsenic concentration, soil properties, and fertilizers on biosorption and withstanding potential of grasses was studied using model soil and real-time arsenic-contaminated mine soil. High arsenic contents in soil significantly affected the growth as well as biomass production of grasses and declined the overall biomass production concerning exposure durations. Purple guinea and Ruzi grasses showed growth tolerance in arsenic-contaminated soils with concentrations of 100 and 150 mg/kg respectively. Grass species, soil compositions, and properties, fertilizers, growth duration, etc. potentially influenced arsenic accumulation in grasses. Both local forage grasses showed <1 bio-accumulation factor (BAF) and bio-concentration factor (BCF) after 45 days that indicates the minimum harvesting time of 45 days, and biosorption rate was found significant to the exposure duration. Maximum translocation factor (TF) values observed in Purple guinea and Ruzi grasses were 0.65 and 0.95, respectively which are < 1, therefore, these local forage grasses could be labeled as arsenic-metallophytes and ability to tolerate high levels of heavy metals without much biosorption. The results confirmed that local forage grasses have much growth tolerance potential against arsenic in real-time mine soil with desired fertilizers and these species could be used for sustainable management of ecological health of the Thung Kum gold mine area in Thailand. [ABSTRACT FROM AUTHOR]

Drastic changes in the water regime of trace elements (TEs) contaminated soils under semiarid conditions, from completely dry to flooding situations, may alter the solubility of the contaminants and, therefore, their potential mobility and availability to plants. Certain macrophyte species have shown a promising suitability for their use in the phytoremediation of TEs contaminated soils under fluctuating flooded–unflooded conditions, as a consequence of their high resistance and tolerance to contamination. Similarly, different water conditions occur during rice (Oryza sativa) cultivation, a species often used as a model plant for TEs toxicity studies. The aim of this work was to study the tolerance and oxidative response to TEs of common reed (Phragmites australis) and rice grown in contaminated mining soils, when exposed to different water saturation conditions. Both species (common reed and rice) were cultivated in three different contaminated soils from the Sierra Minera of La Unión-Cartagena (SE-Spain) under contrasting water saturation conditions (flooded and unflooded) in a pot experiment. Soil EC and elevated metal (mainly Cd and Zn) soluble concentrations conditioned the survival of the plants. Whereas, As accumulation in the aerial part of both species influenced the most oxidative stress homeostasis. Common reed showed to be a good candidate for its use in the phytostabilization of TEs contaminated soils under both flooded and unflooded conditions. [ABSTRACT FROM AUTHOR]

In view of the influence of different soil types on the effect of chemical oxidation remediation, three typical soils in my country were selected to simulate the preparation of benzo [a] Pyrene contaminates the soil, using activated sodium persulfate in the reaction conditions: water-soil ratio 2:1, activator addition 10%, reaction temperature 25 ℃ Carry out chemical oxidation experiments. The effects of three soil types and their properties on the loading and oxidation effect of benzo[a]pyrene were explored. Research Form Ming: Among the three soil types, yellow sand soil has the worst loading capacity for benzo[a]pyrene, followed by purple soil, and black soil is the best. The degradation rate of benzo[a]pyrene in the soil after chemical conversion is the lowest in black soil, followed by purple soil, and highest in yellow sand; Cation exchange capacity and organic matter content in soil And the specific surface area is positively correlated with the loading rate of benzo[a]pyrene, and the pH value is negatively related to the loading rate of benzo[a]pyrene, and the square of the correlation coefficient is greater than 0.92, of which the content of organic matter and its specific surface area have a greater impact on the loading capacity of benzo[a]pyrene; the content of organic matter in the soil has a greater impact on its oxidation efficiency Fruit has the greatest impact. The higher the organic content, the lower the degradation rate of benzo[a]pyrene. The results of the study are useful for the repair of benzo[a]pyrene contaminated soil in different regions. The design of complex technical solutions has guiding significance. [ABSTRACT FROM AUTHOR]

Immobilisation of lead (Pb) and toxic elements in contaminated soils is of importance due to their persistence in the environment. Herein, we investigated the effects of sugarcane filter cake biochar (SFCB) and sugarcane bagasse ash (SBA) on the extractability of Pb and some toxic and potentially toxic elements (As, Cd, Cu, and Zn) in polluted mine soil samples from Lower Klity Creek, Thailand. The soil was equilibrated with the SFCB and SBA at the respective rates of 0, 1, and 5% (w/w) for 120 days at field capacity. The results revealed that both SFCB and SBA materials significantly (P < 0.05) decreased Pb extractability in the studied soil, and it stabilised after 56 days of incubation. At 120 days, the SFCB and SBA application at the rates of 5% SFCB, 5% SBA, 1% SFCB, and 1% SBA decreased the extractable Pb contents by 50.35, 40.81, 29.42, and 19.27%, respectively, compared to unamended soil. The SFCB and SBA materials also improved soil chemical properties by increasing the soil pH, available phosphorus, and extractable sulfur. At 5%, SFCB decreased As extractability and increased organic carbon in the studied soil. The Zn availability in the studied soil was also improved by SFCB and SBA addition. This study highlights the potential use of biochar and ash from the sugarcane industry to stabilise Pb and As in contaminated soils. [ABSTRACT FROM AUTHOR]

The exploitation of mineral resources is very important for economic development, but disorderly exploitation poses a serious threat to the ecological environment. However, investigations on the advantages of plant species and environmental pollution in polluted mining areas are limited. Thus, a survey was conducted to evaluate the impacts of abandoned mines on the surrounding ecological environment along rivers in polluted areas and to determine the Arsenic (As) pollution status in soil and plants. The results showed that the soil and vegetation along the river in the survey area were seriously polluted by As. The total As content of the 15 samples was significantly greater than the national soil background value (GB 15618-2018), and degree of pollution was nonlinearly related to the distance from the mine source, R2 = 0.9844. B. bipinnata, P. vittata and B. nivea were predominant with degrees of dominance of 0.01–0.33, 0.05–0.11, and 0.06–0.14 respectively. The As enrichment capacities of Juncus and P. vittata were significantly greater than those of the other plants, while the bioaccumulation factors (BCFs) were 21.81 and 7.04, respectively. [Display omitted] • The As pollution status of plants and soil in mine polluted area was evaluated by comprehensive investigation. • The degree of soil pollution was found to have a non-linear relationship with the distance from the mine source, with a high correlation (R2 = 0.9844). • B. bipinnata, P. vittata and B. nivea are dominant species in As-contaminated soils. • Juncus and P. vittata were found to have significantly higher Arsenic (As) enrichment capacity compared to other plant species. [ABSTRACT FROM AUTHOR]

This study examined the effectiveness of pristine biochar (BC) and Fe-functionalized biochar (FBC) in remediating As-Sb co-contaminated soil, and revealed the resulting impact on soil enzymatic activities and bacterial communities. Results from incubation experiments showed that the 1.5% FBC treatment reduced the bioavailable As and Sb concentration by 13.5% and 27.1%, respectively, in compared to the control, and reduced the proportion of specifically adsorbed and amorphous Fe-Mn oxide-bound metal(loid) fractions in the treated soil. Among the BC treatments, only the 1.5% BC treatment resulted in a reduction of bioavailable As by 11.7% and Sb by 21.4%. The 0.5% BC treatment showed no significant difference. The FBC achieved high As/Sb immobilization efficiency through Fe-induced electrostatic attraction, π-π electron donor-acceptor coordination, and complexation (Fe–O(H)–As/Sb) mechanisms. Additionally, the 1.5% FBC treatment led to a 108.2% and 367.4% increase in the activities of N-acetyl-β-glucosaminidase and urease in soils, respectively, compared to the control. Furthermore, it significantly increased the abundance of Proteobacteria (15.2%), Actinobacteriota (37.0%), Chloroflexi (21.4%), and Gemmatimonadota (43.6%) at the phylum level. Co-occurrence network analysis showed that FBC was better than BC in increasing the complexity of bacterial communities. Partial least squares path modeling further indicated that the addition of biochar treatments can affect soil enzyme activities by altering soil bacterial composition. This study suggests that FBC application offers advantages in simultaneous As and Sb immobilization and restructuring the bacterial community composition in metal(loid)-contaminated soil. [Display omitted] ● 1.5% Fe-functionalized biochar (FBC) addition reduced As/Sb availability in soils. ● 1.5% FBC treatment enhanced the N-acetyl-β-glucosaminidase and urease activities. ● The abundance of Proteobacteria and Actinobacteriota increased in FBC-treated soil. ● Biochar affects soil enzyme activities by altering soil bacterial composition. ● Co-occurrence analysis verified that FBC enhanced bacterial community complexity. [ABSTRACT FROM AUTHOR]

Soil monitoring in abandoned mine areas is important from the perspective of ecological and human health risk. Arsenic (As) is a predominant metalloid contaminant in abandoned mine area and its behavior has been influenced by various soil characteristics. Bioindicator can be a useful tool in terms of testing the extent to which they are uptaken by plants bioavailability. Eighteen soils near the mine tailings dam were collected to investigate the effect of As contamination on As absorption by Brassica juncea. The pH range of the experimental soils was between 4.90 and 8.55, and the total As concentrations were between 34 mg kg−1 and 3017 mg kg−1. The bioavailability of As was evaluated by Olsen method, and B. juncea was cultivated in eighteen soils for 3 weeks. Principal component analysis, correlation, and multiple regression analysis were performed to estimate a significant factor affecting As uptake by B. juncea. All statistical results indicated that As bioavailability in soil is the main factor affecting As uptake in root and shoot of B. juncea. Although translocation process, the amount of As in shoot was exponentially explained by As bioavailability in soil. This result suggests that the contamination and bioavailability of As can be confirmed only by analyzing the shoot of B. juncea , which is be easily found in environmental ecosystem, and implies the applicability of B. juncea as a bioindicator for the monitoring of As contamination and its behavior in soil ecosystem. [Display omitted] • Efficiency of Brassica juncea shown as a bioindicator for As, integral for abandoned mine soil and ecological risk assessment. • Investigation on As absorption in Brassica juncea roots and shoots relates directly to soil As bioavailability, assessed via Olsen method. • Shoot As levels correlate with soil bioavailability, indicating potential for simple As monitoring. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) has continued to be a major threat leading to the destruction of the ecosystem and contamination of soil and waterbodies. The high sulfate concentration of AMD lowers the soil pH, making the soil more acidic and less productive which contributes to a reduction in the availability of arable land for agricultural purposes. Biological treatment has offered a cost-effective and eco-friendly approach through the introduction of organic substrates, aeration, or genetically modified microorganism to stimulate the contaminated environment and enhance sulfate reduction as opposed to previously used physicochemical methods which were criticized due to their inefficient and non-ecofriendly nature. This study focused on the evaluation of biological treatment through the application of wastewater (biostimulation) and air-injection (bioventing) for sulfate removal from AMD-contaminated soils. AMD-contaminated soil was amended with brewery (BWW) and municipal wastewater (MWW) at varying loading ratios to investigate the possible synergy while atmospheric air was supplied to bioventing treatments only. All treatments were conducted at mesophilic conditions for 28 days. The inability to improve sulfate removal rate through air-injection can be attributed to biosulfidogenesis preference for anoxic as against (high) oxic conditions for optimum performance. The BST and BVT treatment resulted in 34–53% and 27–42% sulfate removal efficiency, respectively. This study showed the efficacy of wastewater biostimulations and bioventing as a promising approach for sulfate and heavy metal removal from AMD-contaminated soils. The techniques have the potentials as vital tools for the mitigation of pollution aftermath in affected communities. [ABSTRACT FROM AUTHOR]

Arsenic (As) and cadmium (Cd) are two prominent metal contaminants in mining soil, threatening food and environmental safety. The effects of Fe-loaded biochar on the accumulation and translocation of As and Cd in a soil-lettuce system were investigated to evaluate the efficiency of Fe-loaded biochar in reducing As and Cd bioavailability. Application of Fe-loaded biochar at a rate of 0.5–1.5% decreased the concentrations of porewater As and Cd by 4.2–53.0% and −0.6–21.7%, respectively. The results of sequential extraction showed that Fe-loaded biochar can promote the transfer of As and Cd in soils from the available fraction to a relatively stable fraction, thus reducing the mobility and availability of As and Cd. The concentrations of As and Cd in lettuce shoots in the Fe-loaded biochar treatment were significantly decreased by 11.4–26.0% and 4.4–12.9% compared with those in the untreated soil, respectively. Fe-loaded biochar applied at a rate of 0.5–1.0% had no obvious effect on plant biomass, and the lowest weight of lettuce shoots and roots was observed in the treatment with Fe-loaded biochar applied at a rate of 1.5%, in which they were reduced by 12.9% and 18.0%, respectively. Overall, Fe-loaded biochar as a soil amendment was effective in simultaneously reducing As and Cd bioavailability in As and Cd co-contaminated soils, and an application rate lower than 1.5% is recommended to avoid significant decreases in plant growth. [ABSTRACT FROM AUTHOR]

The removal of total petroleum hydrocarbons (TPHs) from contaminated mining soil was carried out under in vitro conditions. The aerobic consumption of TPH in the slow bioremediation stage via biostimulation with native microorganisms and biostimulation-bioaugmentation with autochthonous fungal isolates was evaluated. The initial TPH concentration was 70,880 ± 975 mg TPH/kg soil, soil was amended with nutrients at a C:N:P ratio of 100:15:1, the water content was adjusted to the soil field capacity, and batch microcosm reactors were incubated at room temperature (20.5 ± 3.1°C) for 90 days. The bioaugmentation process was tested using four hydrocarbonoclastic fungal strains isolated from the same contaminated mining soil individually and a mixed culture of the four isolates. The molecular characterization of the isolated fungi was based on sequence analysis of 18S rRNA, and the fungi were identified as Aspergillus niger MT786339.1, Aspergillus fumigatus MT786338.1, Aspergillus terreus MT786341.1, and Aspergillus flavus MT786340.1. The best TPH removal was achieved by inoculation with the fungal consortium (57 ± 1.97%) at 45 days (slow stage) after initiating the biostimulation process, followed by inoculation with Aspergillus niger (49 ± 1.2%), Aspergillus terreus (44 ± 0.67%), Aspergillus fumigatus (35 ± 0.98%), and Aspergillus flavus (32 ± 0.38%), while the degradation rate achieved with native microorganisms was only 21.6 ± 1.5%; statistical analysis of the results showed significant differences. [ABSTRACT FROM AUTHOR]

Arsenic (As) and cadmium (Cd) co-contamination has been a typical problem in Chinese agricultural land adjacent to historical metal mining and smelting activities. Remediation of As and Cd in soil has encountered many difficulties owing to the distinct nature of the two metal(loid)s. In this study, we developed a remediation scheme by adding a hexadecyltrimethylammonium (HDTMA)-modified zeolite to a mining site soil and evaluated the immobilization effect. The result of the increased surface zeta potential indicates that the HDTMA modification conferred the zeolite with adsorbability towards As through the cationic surfactant head. The addition of the highest dosage of HDTMA-modified zeolite (10%) to the contaminated soil greatly improved soil organic matter by 1.4 times, partly due to the elevated C loading on the zeolite from HDTMA. Sequential extraction results show that the addition of HDTMA-modified zeolite not only increased the residual fraction of As (by 2.7–5.9%) but also reduced the toxicity-related fraction (by 2.3–2.7%) when compared to the unmodified zeolite and blank treatments. The oxidizable fractions of Cd in the modified zeolite treatment were significantly higher than that in the blank soil. Besides, the exchangeable fractions of Cd were all significantly reduced in the zeolite treatments. Enzyme activity assays show that the HDTMA-modified zeolite treatment could greatly improve soil microbial environment. The physiologically based extraction test (PBET) also proved that the bioavailability of As and Cd was reduced after the modified zeolite treatment. [ABSTRACT FROM AUTHOR]