This study focuses on a decommissioned mining area of acid in-situ leaching in Xinjiang. By analyzing long-term groundwater monitoring data, a three-dimensional transient groundwater flow and contaminant solute transport model was developed to simulate the migration of contaminant species（U（Ⅵ）and ）in the ore-bearing aquifer. The study aims to provide a reasonable hydraulic control strategy to ensure the groundwater environmental safety in the decommissioned mining area. The results indicate that the post-decommissioning groundwater flow field is generally consistent with the direction of the natural flow field. High concentrations of U（Ⅵ）and remains extensively in the mining area and gradually migrate and diffuse downstream under the influence of groundwater dynamics. The constructed model successfully reproduces the observed groundwater level trends in the decommissioned mining area and accurately simulates the downstream migration and diffusion of U（Ⅵ）and from within the mining area. This demonstrates that hydraulic control is a crucial measure for ensuring the ecological safety of the downstream groundwater environment in future conditions. Analysis of three hydraulic control pumping schemes revealed that a combined internal and external pumping strategy yielded the best control results. Using a comprehensive evaluation method to quantitatively assess each scenario, the optimal solution was determined to involve installing six pumping wells downstream and three pumping wells within the mining area, each operating at a pumping rate of 60m³/day. This approach achieves effective source reduction within the site and hydraulic containment downstream, keeping contaminant migration within a 50m range at relatively low cost. By employing the developed numerical model to compare and select hydraulic control strategies under future planning conditions, this study provides a scientific basis for decision-making on groundwater environmental safety in the mining area and offers valuable insights for the remediation of similar decommissioned in-situ leaching uranium mines.

To clarify the dissolution patterns of pathogenic microorganisms in rainwater runoff, a laboratory-simulated rainfall experiment was conducted to flush soil treated with earthworm castings. Propidium monoazide（PMA）combined with quantitative PCR（qPCR）was used to investigate changes in the abundance of viable fecal indicator bacteria（FIB）. The results exhibited that after rainfall, the concentrations of electrical conductivity, ammonia, nitrate, and total phosphorus（TP）in the mixed soil matrix decreased by 51.34%, 45.20%, 99.09%, and 26.22%, respectively. In runoff water, the concentrations of ammonia, total phosphorus, and chemical oxygen demand（COD）exhibited a trend of initially rising and then falling, with peak values occurring within the first 15minutes. The qPCR quantification results for four fecal indicator bacteria—total coliforms（TC）, fecal coliforms（FC）, Escherichia coli（EC）, and Enterococcus spp（ES）—also displayed a similar trend of increasing and then decreasing. A significant positive correlation was found between the PMA-qPCR results and the culture method（Spearman r=0.723, P<0.001）. The fecal coliform counts in all runoff samples exceeded the limits specified in the "Surface Water Quality Standard"（40000CFU/L）. The study indicates that viable pathogenic microorganisms can be washed into water bodies through rainfall and are widely dispersed during initial runoff, increasing the risk of their environmental transmission.

To enhance the acid production efficiency of sludge anaerobic fermentation, based on the established evidence that the inclusion of syngas improved waste activated sludge（WAS）fermentation performance, this study investigated the effects of different chemical pretreatments combined with a syngas-mediated WAS fermentation system. The results showed that the free nitrous acid combined with peracetic acid（FNA/PAA）experimental group had the highest production of short-chain fatty acids（SCFAs）（（5520.20±204.99）mg COD/L）. However, the FNA/PAA group exhibited only 50.4% and 35.8% utilization rates for H₂ and CO, respectively. In contrast, the TAP group demonstrated efficient utilization of syngas, with H₂ and CO utilization rates reaching 99.8%and 95.8%, respectively. Moreover, the production of SCFAs in the TAP group achieved a significant level of（4663.67±163.86）mg COD/L. At the same time, the three-dimensional fluorescence spectrum showed that TAP group had better extracellular polymer stripping and WAS lysis efficiency. TAP group also enhanced the enrichment of acid-producing functional bacteria in the anaerobic fermentation process, and significantly increased the abundance of Firmicutes to 59.0%. In addition, Romboutsia, which can metabolize acetic acid, ethanol and H₂, accounted for the highest proportion in alkali pretreatment（AP）and TAP groups（19.2% and 21.3%）.

Using Taihu algal mud as the research subject, two common flocculants, polymeric ferric sulfate（PFS）and polyacrylamide（PAM）, were selected to prepare different hydrochars at 180°C, 220°C, and 260°C. The results demonstrated that as the hydrothermal temperature increased, the carbon content in the algal mud hydrochar increased, while the hydrogen and nitrogen contents decreased. Decarboxylation and hydrolysis reactions were identified as the dominant processes during the hydrothermal conversion. The incorporation of PFS significantly enhanced the iron content in the hydrochar by 519.6% to 748.3%, and the rise in hydrothermal temperature facilitated the transformation of iron from Fe（III）to Fe（II）, thereby improving its reducibility. PAM exhibited degradation at lower temperatures, generating oxygen-containing functional groups, while PFS promoted the degradation and carbonization of organic matter. The hydrochar prepared at 180°C showed higher nutrient retention. Rice cultivation experiments indicated that the application of algal mud-based hydrochar did not adversely affect rice growth；notably, PAM-based hydrochars increased rice plant biomass by 9.0%. Based on field survey data, it was estimated that converting Taihu algal mud into hydrochar could annually recover 3077.7 tons of total nitrogen and 776.7 tons of total phosphorus. The recovered total phosphorus accounted for 43.1% of the external phosphorus load input into Taihu Lake.

In this study, a pot experiment was conducted to simulate soil contaminated with varying levels of cadmium（Cd）, arsenic（As）, and lead（Pb）to investigate the changes in biomass, the absorption and accumulation of mineral nutrients, as well as the accumulation characteristics of heavy metals under different contamination conditions. Furthermore, soil threshold for Cd, As, and Pb in acidic soil were derived to ensure the safe production of cherry radish. The results indicated that cherry radish exhibited significant toxic effects when heavy metals content added in soil reached the risk control threshold. The contents of iron（Fe）, copper（Cu）, and zinc（Zn）in root of cherry radish increased initially and then decreased as the level of heavy metals contamination increased, while manganese（Mn）content continuously increased. The root of cherry radish had the highest enrichment and translocation ability for Cd, with average bioconcentration factors（BCF）being 18.6 and 115 times higher than those for As and Pb, respectively. The average translocation factors（TF）for Cd were 4.02 and 2.41 times higher than those for Pb and As, respectively. Based on the National Food Safety Standard（GB2762—2022）, and considering the safety of both the roots and shoots of cherry radishes, the derived soil threshold values for safe cherry radish production in acidic soil were 0.30mg/kg for Cd, 171.1mg/kg for As, and 27.5mg/kg for Pb.

In this study, fly ash, blast furnace slag, desulfurization gypsum, sludge, straw, and sawdust were utilized as raw materials. These materials were mixed at varying ratios, and Solanum nigrum was selected as the experimental plant for indoor pot trials. Farmland soil and contaminated soil from a metal mining wasteland were employed as controls. Variance analysis and Mantel tests were employed to analyze the effects of substrate ratios on Solanum nigrum growth characteristics, physicochemical properties of reconstructed soil, and relationships between substrate materials. A minimum dataset（MDS）for soil quality evaluation and entropy-weighted TOPSIS were applied to identify optimal substrate ratios. The results demonstrated that reconstructed soils formed by different solid waste ratios exhibited loose textures and enhanced water retention. Organic matter content was measured within a range of 39.01~70.03g/kg. All solid waste-based reconstructed soils were found to support Solanum nigrum growth, with biomass ranging from 0.11 to 3.18g/pot. A minimum dataset for soil quality assessment was established based on four critical indicators: chlorophyll content, plant height, pH, and water stability of 0.5~1mm aggregates. Subsequently, the entropy-weighted TOPSIS model was applied to systematically evaluate the comprehensive quality of the reconstructed soils. The optimal combination ratio, identified as fly ash: blast furnace slag : desulfurization gypsum : sludge : straw at a mass ratio of 4:2:1:1:2, demonstrated superior performance in both plant growth and soil functionality.

The remediation effect of Robinia pseudoacacia L. intercropped with Solanum nigrum L. and Pteris vittate L. on Cd and As contaminated soil was studied through a pot experiment. The results showed that the intercropping of R. pseudoacacia L. could promote the growth and the uptake of Cd and As in S. nigrum L. and P. vittate L., and reduce the content of Cd and As in soil, as well as enhance soil enzyme activities. Compared with the monocultures of S. nigrum L. and P. vittate L., the whole biomass of S. nigrum L. and P. vittate L. was significantly enhanced（P<0.05）by 50.4% and 86.2% when intercropped with R. pseudoacacia L. Meanwhile, the contents of Cd and As in the leaves of S. nigrum L. were significantly enhanced（P<0.05）by 78.4% and 260.7%, respectively. The total accumulation of As in aboveground parts of all plants under the intercropping of R. pseudoacacia L. with S. nigrum L. and P. vittate L. was significantly enhanced（P<0.05）by 1.11 and 2.17 times compared with the monocultures of R. pseudoacacia L. or S. nigrum L., and the total accumulation of Cd was significantly enhanced（P<0.05）by 1.89 and 15.72 times compared with the monocultures of R. pseudoacacia L. or P. vittate L. Moreover, the contents of available Cd and As in soil under the intercropping of R. pseudoacacia L. with two hyperaccumulators were significantly reduced（P<0.05）by 23.6% and 17.0% compared with the control, respectively. Meanwhile, the contents of soil organic matter and alkaline hydrolysis nitrogen were significantly enhanced（P<0.05）by 46.2%~83.2% and 18.5%~26.4% as compared with the monocultures, the activities of soil catalase was significantly enhanced（P<0.05）by 43.7%~53.0% compared with the monocultures of R. pseudoacacia L. or P. vittate L., the soil sucrase and urease activities were also significantly enhanced（P<0.05）by 11.5%~28.4% and 20.6%~36.4% compared with the monocultures of R. pseudoacacia L. and S. nigrum L., respectively. The results suggested that the intercropping of R. pseudoacacia L. with two different types of hyperaccumulator could effectively uptake and accumulate Cd and As to reduce the bioavailability of Cd and As in the contaminated soil, and effectively improve the soil environmental quality, which could be considered as a promising intercropping model for the simultaneous remediation of Cd and As contaminated soil in mining areas.

This study investigated the functional characteristics of plant growth-promoting rhizobacteria（PGPR）isolated from the rhizosphere soil of Celosia argentea Linn., a Cd-hyperaccumulator. A strain with high tolerance to Cd^2-, Pb^2-, and Zn^2- was isolated. This strain was identified using physiological and biochemical characteristics analysis and sequence analysis of the 16S rDNA and nrdA functional genes. The effects of various culture conditions on the strain's growth and heavy metal removal capabilities, as well as its potential for promoting plant growth were examined. This strain was identified as Achromobacter sp., designated WL-37. The minimum inhibitory concentrations（MIC）of Cd^2-, Pb^2-, and Zn^2- for strain WL-37 were determined to be 600, 1800, and 1000mg/L, respectively. Under optimized conditions（e.g., pH values and inoculation amounts）, the strain achieved maximum removal rates of 69% for Cd²⁺, 95% for Pb²⁺, and 62% for Zn²⁺. Moreover, WL-37 exhibited multiple plant-promoting traits, including nitrogen fixation, ACC deaminase production, and siderophore production. In summary, the high-efficiency strain identified in this study represents a valuable resource for the remediation of multi-metal contaminated soils and supports the development of plant-microbe combined remediation technologies.

High-concentration areas of soil heavy metals exist in ecological functional protection zones of Southwest China. To investigate their potential pollution risks and influencing factors, this study selected soils in the Xuanwei region of Yunnan Province as the research subject. Combining geographical, geological, and anthropogenic activity data, the content characteristics of eight heavy metal elements were analyzed in 1487 surface soil samples and 374 deep soil samples. The geo-accumulation index and potential ecological risk index were used to assess the potential pollution risks of surface soils, while principal component analysis（PCA）and geographical detector methods were employed to identify influencing factors. The results revealed that heavy metals in both surface and deep soils were enriched compared to the A-layer and C-layer background values of Chinese soils. Most heavy metals also exhibited enrichment relative to the A-layer and C-layer background values of Yunnan Province. Cd, Hg, and Pb posed relatively high potential pollution risks, whereas Cu, Cr, Ni, Zn, and As showed lower risks. The main influencing factors for heavy metal enrichment included geological background, clay minerals, organic matter, mining activities, and topography. Synergistic effects of multiple factors could exacerbate heavy metal enrichment, while pH, CaO, Light（light index）, and WIG exhibited minimal impacts.

This study focused on the long-term AMD-contaminated paddy soils in the Dabaoshan mining area of Guangdong Province. The distribution characteristics of soil iron phases and iron-bound organic carbon were analysed, combining with high-throughput sequencing to examine the effects of AMD irrigation on soil organic carbon sequestration and the response of soil microbial community structure. The results indicated that: ① AMD irrigation led to soil acidification, with accumulation of iron, sulfur and heavy metals in paddy soils. The contents of TOC in paddy soils showed significant positive correlation with TFe, and OC_Fe. ② AMD irrigation resulted in decreases of soil microbial abundance and diversity. AMD irrigation led to a decrease in the relative abundance of Geobacter in paddy soils, whereas acid tolerant iron and/or sulfur metabolizing bacteria such as Thiobacillus and Thioifustis became the dominant bacteria in paddy soils with the most heavily AMD pollution. ③ RDA analysis identified Fe_p, TOC, and TFe were the most crucial factors influencing microbial community structure. In conclusion, AMD irrigation brought dissolved iron into paddy soils which was beneficial to soil organic carbon preservation. In addition, AMD irrigation resulted in the formation of microbial community structure that closely related to AMD pollution gradient, the form and content of iron and carbon.