Colloid mobilization and transport in response to freeze-thaw cycles: Insights into the heavy metal(loid)s migration at a smelting site.

Smelting sites often exhibit significant heavy metal(loid)s (HMs) contamination in the soil and groundwater, which are inevitably subjected to environmental disturbances. However, there is limited information available regarding the migration behaviors of HMs in a disturbed scenario. Thus, this work explored the migration of HMs-bearing colloids in response to freeze-thaw treatments by laboratory simulation and pore-scale study.

Standardized framework for assessing soil quality at antimony smelting site by considering microbial-induced resilience and heavy metal contamination.

Antimony smelting activities damage the soil and vegetation surroundings while generating economic value. However, no standardized methods are available to diagnose the extent of soil degradation at antimony smelting sites. This study developed a standardized framework for assessing soil quality by considering microbial-induced resilience and heavy metal contamination at Xikuangshan antimony smelting site.

The heterogeneous distribution of heavy metal(loid)s at a smelting site and its potential implication on groundwater.

The downward migration of soil heavy metal(loid)s (HMs) at smelting sites poses a significant risk to groundwater. Therefore, it is requisite for pollution control to determine the pollution characteristics of soil HMs and their migration risks to groundwater. 198 soil samples collected from a Pb-Zn smelting site were classified into 6 clusters by self-organizing map (SOM) and K-means clustering.

Polymetallic contamination drives indigenous microbial community assembly dominated by stochastic processes at Pb-Zn smelting sites.

Indigenous microbial communities in smelting areas are crucial for maintaining fragile ecosystem functions. However, the community assembly process and their responses to polymetallic pollution are poorly understood, especially the taxa in each bin from the amplicons that contributed to the assembly process. Herein, microbial diversity, co-occurrence patterns, assembly process and the intrinsic mechanisms across contamination gradients at a typical PbZn smelting site were systematically unravelled by high-throughput sequencing.

Pb/As simultaneous removal from soil leachate of Pb/Zn smelting sites by magnetic biochar.

Lead (Pb) and arsenic (As) contaminated soils, caused by Pb and zinc (Zn) smelting activities, pose an urgent environmental issue. Magnetic biochar (MB) has been regarded as an increasingly appealing candidate for the remediation of multi-metals in contaminated soils or their leachate. Finding economically feasible preparation methods for MB and demonstrating its remediation potential is desperately required for the remediation of such complex smelting sites.

Pollution characteristics and quantitative source apportionment of heavy metals within a zinc smelting site by GIS-based PMF and APCS-MLR models.

The abandoned smelters present a substantial pollution threat to the nearby soil and groundwater. In this study, 63 surface soil samples were collected from a zinc smelter to quantitatively describe the pollution characteristics, ecological risks, and source apportionment of heavy metal(loid)s (HMs). The results revealed that the average contents of Zn, Cd, Pb, As, and Hg were 0.

Enhancement of nitrogen on core taxa recruitment by Penicillium oxalicum stimulated microbially-driven soil formation in bauxite residue.

Microbially-driven soil formation process is an emerging technology for the ecological rehabilitation of alkaline tailings. However, the dominant microorganisms and their specific roles in soil formation processes remain unknown. Herein, a 1-year field-scale experiment was applied to demonstrate the effect of nitrogen input on the structure and function of the microbiome in alkaline bauxite residue.

The formation of multi-metal(loid)s contaminated groundwater at smelting site: Critical role of natural colloids.

The occurrence and migration of colloids at smelting sites are crucial for the formation of multi-metal(loid)s pollution in groundwater. In this study, the behavior of natural colloids (1 nm-0.45 µm) at an abandoned smelting site was investigated by analyzing groundwater samples filtered through progressively decreasing pore sizes.

Driving factors for distribution and transformation of heavy metals speciation in a zinc smelting site.

Heavy metal pollution at an abandoned smelter pose a significant risk to environmental health. However, remediation strategies are constrained by inadequate knowledge of the polymetallic distribution, speciation patterns, and transformation factors at these sites. This study investigates the influence of soil minerals, heavy metal occurrence forms, and environmental factors on heavy metal migration behaviors and speciation transformations.

Sb/As immobilization and soil function improvement under the combined remediation strategy of modified biochar and Sb-oxidizing bacteria at a smelting site.

Antimony (Sb) and arsenic (As) lead to soil pollution and structural degradation at Sb smelting sites. However, most sites focus solely on Sb/As immobilization, neglecting the restoration of soil functionality. Here, we investigated the effectiveness of Fe/HO modified biochar (Fe@HO-BC) and Sb-oxidizing bacteria (Bacillus sp.

[Research Progress on Solidification and MICP Remediation of Soils in Heavy Metal Contaminated Site].

Heavy metal pollution in soils of smelting sites is an important environmental problem to be solved urgently. Solidification technology has become one of the mainstream technologies for heavy metal remediation in contaminated sites owing to its shorter remediation time, low cost, and high treatment efficiency. On the basis of summarizing the latest research progress on the remediation of heavy metal pollution in sites by solidification in the past 10 years, this study focused on the mechanisms of solidification technology and analyzed the advantages and disadvantages of different mechanisms (mechanism of inorganic materials, mechanism of organic materials, mechanism of mechanical ball milling, and mechanism of microbial-induced carbonate mineralization (MICP)) and their scope of application.

Geochemical fractionation and potential release behaviour of heavy metals in lead‒zinc smelting soils.

The lack of understanding of heavy metal speciation and solubility control mechanisms in smelting soils limits the effective pollution control. In this study smelting soils were investigated by an advanced mineralogical analysis (AMICS), leaching tests and thermodynamic modelling. The aims were to identify the partitioning and release behaviour of Pb, Zn, Cd and As.

Ecological restoration affects the dynamic response of alkaline minerals dissolution in bauxite residue.

Regulating alkalinity is the key process to eliminating environmental risk and implementing sustainable management of bauxite residue. Nevertheless, continuous release of free alkali from the solid phase (mainly sodalite and cancrinite) is a major challenge for long-term stability of alkalinity in amended bauxite residue. In order to understand the dissolution behavior of sodalite and cancrinite, their dissolution kinetics under simulated pH conditions of 8, 9 and 10 were investigated.

Using Fe/HO-modified biochar to realize field-scale Sb/As stabilization and soil structure improvement in an Sb smelting site.

Antimony (Sb) and arsenic (As) released from the Sb smelting activities pose a major environmental risk and ecological degradation in Sb smelting sites. Here the effects of Fe/HO modified biochar (Fe@HO-BC) on the synchronous stabilization of Sb/As and the improvement of soil structure in a typical Sb smelting site in Southern China based on a 1-year field experiment were studied. Application of ≥1 % (w/w) Fe@HO-BC could stably decrease the leaching concentrations of Sb and As of the polluted soils to Environmental quality standards for surface water Chinese Level III (GB3838-2002).

Groundwater heavy metal(loid)s risk prediction based on topsoil contamination and aquifer vulnerability at a zinc smelting site.

Groundwater pollution is a recurrent problem in abandoned non-ferrous metal smelting sites, and its severity is influenced by topsoil contamination, hydrogeological characteristics, and hydrogeochemical conditions. In such unique areas, traditional methods for evaluating groundwater pollution risk are biased, as the long production history of these sites have led to highly polluted and heterogeneous soil and groundwater. Herein, based on a typical lead-zinc smelting site, As, Pb, Zn, Cd, Mn, and Ni were found to be the predominant heavy metal (loid)s in groundwater, with respective exceedance rates of 44.

Microbially-driven alkaline regulation: Organic acid secretion behavior of Penicillium oxalicum and charge neutralization in bauxite residue.

Microbially-driven alkaline neutralization in bauxite residue by functional microorganisms is a promising approach for the ecological rehabilitation on alkaline disposal areas. However, the alkali resistance and acid secretion mechanism of functional microorganisms are still unknown, which limits their application. Here, saline-alkaline resistance, acid production performance, and differentially expressed genes of Penicillium oxalicum (P.

Migration and distribution characteristics of soil heavy metal(loid)s at a lead smelting site.

Heavy metal(loid)s contamination is a constant issue at smelting sites. It is essential to investigate the spatial distribution and migration characteristics of heavy metal(loid)s in the soil for environmental management and remediation strategies of non-ferrous smelting sites. In this study, 203 soil samples from 57 sites were collected in a typical lead smelting site.

Straw addition increases enzyme activities and microbial carbon metabolism activities in bauxite residue.

Recovery of microbial functions is one of the critical processes in the nutrient cycling of bauxite residue for improving revegetation. Straw is considered to be effective to increase microbial diversity and drive the development of the microbial community, but its effect on microbial carbon metabolism has not been illustrated. The present study evaluated the effects of phosphogypsum (PG), straw (SF) and phosphogypsum plus straw (PGSF) on physicochemical properties, enzyme activities, and microbial carbon metabolism activities in bauxite residue.

Multi-technological integration in a smelting site: Visualizing pollution characteristics and migration pattern.

Heavy metal(loid)s pollution of industrial legacies has become a severe environmental issue worldwide. Linking soil pollution to groundwater contaminant plumes would make invisible pollution features visible across the site, but related studies are lacking and require the convergence of multiple technologies. This study uniformly managed the soil and groundwater data in a 3D visualization model to pellucidly assess the spatial distribution of critical contaminants beyond simple drilling information.

Remediation potential of magnetic biochar in lead smelting sites: Insight from the complexation of dissolved organic matter with potentially toxic elements.

Magnetic biochar has been widely used in potentially toxic elements (PTEs) polluted soils due to its magnetic separation capability and synchronous immobilization for multiple metals. However, the contribution of magnetic biochar to soil dissolve organic material (SDOM) and its binding behavior with PTEs needs to be further clarified prior to its remediation application on lead smelting sites. In this study, multi-spectral techniques of excitation-emission matrix (EEM) fluorescence spectroscopy and two-dimensional FTIR correlation spectroscopy (2D-FTIR-COS) were used to explore the evolution characteristics of SDOM in the lead smelting site under the remediation of magnetic biochar, and to further analyze its affinity and binding behavior with Pb and As.

The assembly process and co-occurrence patterns of soil microbial communities at a lead smelting site.

The potential toxic elements of the site are diverse and complex, seriously threatening the land utilization potential and soil ecological function. Microbial community is critical to maintaining ecosystem function, their assembly processes and diversity play an essential role in predicting changes in soil ecological function. However, our understanding of the mechanisms that shape community composition and successional direction in complex polluted environments is very limited.

Long-term weathering difference in soil-like indicators of bauxite residue mediates the multifunctionality driven by microbial communities.

Long-term weathering enhances the stability of ecosystem services and alters the microbiome, however, its influences on the relationship between microbial diversity and multifunctionality are still poorly understood. Hereby, 156 samples (0-20 cm) from five artificially divided functional zones including central bauxite residue zone (BR), the zone near residential area (RA), the zone near dry farming area (DR), the zone near natural forest area (NF), and the zone near grassland and forest area (GF) were collected in a typical disposal area to determine the heterogeneity and development of biotic and abiotic properties of bauxite residue. Residues in BR and RA exhibited higher values of pH, EC, heavy metals, and exchangeable sodium percentage compared to those in NF and GF.

Effect of potentially toxic elements on soil multifunctionality at a lead smelting site.

Contaminated soil at smelting sites affects land utilization and environmental regulation, resulting in soil degradation. However, the extent to which potentially toxic elements (PTEs) contribute to site soil degradation and the relationship between soil multifunctionality and microbial diversity in the process remains poorly understood. In this study, we investigated changes in soil multifunctionality and the correlation between soil multifunctionality and microbial diversity under the influence of PTEs.