Search

Hydrazine, a compound recognized for its carcinogenic and genotoxic properties, presents a significant threat to human health via environmental exposure and drug metabolism. The detection of hydrazine is essential for safeguarding human health. However, a tool capable of accurately detecting hydrazine across diverse sample types, such as soil, water sources, and plant specimens contaminated by hydrazine leakage, as well as cells and live mice containing endogenously generated hydrazine from drug metabolism, is still lacking. In this study, we have designed and synthesized a ratiometric fluorescent probe utilizing the fluorescence resonance energy transfer mechanism. Upon exposure to hydrazine, the probe exhibits an increased fluorescence ratio (F 485 nm /F 650 nm ) accompanied by a color change from orange to light blue-green. The fluorescence sensing mechanism has been validated through high resolution mass spectrometer and density functional theory. This probe demonstrates significant potential for practical applications in detecting hydrazine within water and soil samples, as well as for imaging exogenous and drug-metabolized endogenous hydrazine in cellular and murine models., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Arsenic and chromium, common polyvalent heavy metals found in soil, are a growing environmental concern, yet research on soil threshold values for these metals is limited. This study presents a method for deriving soil guidelines based on published literature, considering two land types (parkland and industry), two exposure pathways (direct contact and food chain for mammalian and avian), and two toxicity levels (NOEC/LOAEL and EC50/LC50). Soil guidelines for inorganic arsenic (III & V) and chromium (III & VI) were derived separately for parkland and industry, factoring in direct contact and food chain exposures (applicable only to parkland) and both lower and upper toxicity levels from available data. The study discusses the similarities and differences between the proposed guideline values and international standards. Additionally, a new method is introduced for deriving soil guidelines for total arsenic and chromium, applicable to naturally occurring mixed valence states. Future research should refine these guidelines by addressing sample limitations, soil properties, and regional variations to enhance their accuracy and applicability in environmental management. Both methods can serve as references for managing other pollutants. These soil guideline values, particularly the total soil guidelines, offer valuable guidance for the Chinese government in managing arsenic and chromium levels in soil., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2025 Elsevier B.V. All rights reserved.)

This study reviewed the recovery of humic substances (HS) from anaerobic digestate of sludge as a potential fertilizer, focusing on the quantification of HS, the efficiency of HS recovery, and its interaction with pollutants. The potential pitfalls of current misunderstanding for HS quantification in sludge were pointed out. HS present in sludge showed potential to be used as a fertilizer, which solubilized insoluble phosphates for enhanced soil fertility. Pretreatment prior to anaerobic sludge digestion and composting of anaerobic digestate of sludge (ADS) improved the amount of HS in anaerobic digestate. But the amount of HS extracted from the retentate of ADS was much lower than the level required for the common HS fertilizer. Therefore, an additional concentration was required to process the retentate of ADS into HS liquid fertilizer. The quinone moieties in HS accepted electrons from anaerobic microbial respiration and their role in the degradation of organic pollutants were summarized. By binding with HS, the speciation of metals in sludge was changed from water-soluble and exchangeable to organic- and sulfide-bound fractions. Future research should focus on the novel application of machine learning for quantifying HS within sludge, offering a practical approach to interpret complex fluorescence data and enhance understanding of HS characteristics and distribution. Further studies should explore the application of hydrothermal humification to enhance HS content in ADS, offering an energy-efficient method for rapid fertilization in sustainable agriculture. This study offers a window into HS recovery from ADS., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are hazardous organic pollutants prevalent in soil ecosystems. Bacteria and fungi play important roles in the degradation of PAHs in the soils. However, little is known about the differences between the bacterial and fungal community assemblies in PAH-contaminated soils. In this study, soil bacterial and fungal community distributions were investigated in maize farmlands and roadside barelands around nine coking plants in Shanxi, China. Most of the soil samples were severely polluted with PAHs. A clear microbial biogeographic pattern was observed. Bacterial communities are primarily affected by environmental factors, whereas fungal communities are primarily affected by spatial factors. Null modeling showed that homogeneous selection (deterministic processes) and dispersal limitation (stochastic processes) dominated the bacterial and fungal community assemblages, respectively. PAH concentrations were closely linked to community assembly processes, and influenced microbial co-occurrence by mediating specific network modules. Overall, the effects of PAHs on bacterial community assembly and co-occurrence relationships were greater than those on fungal communities. Some microbial taxa associated with PAH degradation can be considered potential biomarkers that reflect the degree of PAH pollution. These results expand the understanding of the mechanisms underlying the assembly and maintenance of soil microbial communities in response to PAH contamination., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Microplastic accumulation in soil ecosystems poses significant environmental concerns, potentially impacting nitrogen cycling processes and ecosystem health. This meta-analysis of 147 studies (1138 data points) assessed the impact of microplastics (MPs) on soil nitrogen-acquisition enzymes. We found that MPs exposure significantly increased soil urease (UE) and leucine aminopeptidase activities by 7.6 % and 8.0 %, respectively, while N-acetyl-β-D-glucosaminidase activity was not significantly affected. Biodegradable MPs showed more pronounced effects compared to conventional MPs. Enzyme activities were influenced by MPs properties (e.g., polymer type, size, concentration), experimental conditions (e.g., field or laboratory setting, temperature, nitrogen fertilization), and soil properties (e.g., clay content, pH, organic carbon, total nitrogen). For instance, acidic soils enhanced UE activity, while neutral soils reduced it. These findings emphasize the complex interactions between MPs and soil ecosystems, highlighting the need for context-specific environmental management strategies and policy-making approaches to mitigate the impacts of MPs pollution on soil health., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Coal combustion at power plants is a significant source of environmental pollution, with the deposition of heavy metals in soils leading to extensive ecosystem contamination and exacerbating the harmful impacts of human activities. This study presents a field investigation of heavy metal concentrations in soils around a coal-fired power plant, with monitoring sites located 1.7 to 15.2 km from the plant. Data collection occurred in 2015, 2020, and 2024 across 11 monitoring sites. X-ray fluorescence analysis was used to assess heavy metal concentrations in soil. A life cycle assessment (LCA) with ReCiPe method was conducted to evaluate the impacts on both ecological and human health. The results revealed that the concentrations of Pb, Zn, Cu, Ni, Mn, Cd, and Cr exceeded threshold levels set by both the World Soil Average and the Regional Geochemical Background. The correlation analysis shows that organic matter and clay content play vital roles in reducing the mobility of heavy metals in soil through adsorption. Notably, strong correlations between Pb and Cd suggest a common origin from coal seam minerals. The LCA shows that freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity, and human toxicity increased by over 30 % compared to the World Soil Average pollutant levels. Nickel was identified as the primary contributor to marine and freshwater ecotoxicity, while manganese had the most significant impact on human toxicity. This study provides a better understanding of the long-term consequences of heavy metal accumulation in soils near coal-fired power plant. The data on anthropogenic impacts are crucial for developing effective strategies to mitigate environmental risks associated with pollution., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The ongoing weathering of metal sulfides has substantially posed threats to the eco-systems. For remediating metal sulfides-contaminated soils, phytostabilization is a promising nature-based technique that immobilizing heavy metals (HMs) that dissolved from metal sulfides in the rhizosphere, preventing their leaching and migrating into soil and groundwater. However, the underlying mechanism regarding the mineral-root interaction involving primary metal sulfides such as galena (PbS) during the remediation processes has yet been well studied. This study aims to investigate the geochemical alterations, mineralogical transformations, and microbial community reshaping of galena-added soils during plants colonization using two representative plants, ryegrass (Lolium perenne L.) and alfalfa (Medicago sativa.). After 11 weeks of plants colonization, the morphology of galena surface was altered, as massive erosion pits (ca. 200 nm) were visualized by SEM (Scanning Electron Microscope). The microspectroscopic analyses indicated that the PbS may have transformed to PbCO 3 and PbSO 4 during the plants colonization. Additionally, the chemical sequential extraction revealed that the plants colonization could promote the soluble Pb to be associated with carbonates and amorphous Fe/Al (oxyhydr)oxides, thus limiting their bioavailability and mobility. Moreover, the key driving factors of microbial community alteration have shifted from pH and bioavailability Pb to cation exchange capacity (CEC) during the plants colonization process. These findings have uncovered the (bio)geochemical behaviors of PbS in soils during the phytostabilization processes, which may develop an integrated mechanism of mineralogical and geochemical stabilization of HMs for non-pollution outcomes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study investigates the co-occurrence of per- and polyfluoroalkyl substances (PFASs), petroleum hydrocarbons (TPHs) and benzene, toluene, ethylbenzene, and xylene (BTEX) and their effects on the indigenous microbial communities in soils at a contaminated site with a history of petroleum refinery operations. PFASs concentrations were in the range of 5.65-6.73 ng/g, and fluorooctane sulfonate (PFOS) and perfluorobutane sulfonic acid (PFBS) were the dominating compounds. No significant difference was observed in the PFASs concentration profiles between the site and background locations, indicating that PFASs detected in the soil samples were mainly contributed from non-point sources, due to the long-distance transport of PFASs in the region. The concentrations of TPHs and BTEX ranged from 227 to 72,360 mg/kg and 0.06-2109.77 mg/kg, respectively, mainly contributed by the historical refinery activities. The presence of PFASs, TPHs, and BTEX significantly impacted soil microbial community diversity and abundance, altering microbial compositions and enriching bacteria with higher resistance or metabolic capabilities against contamination. Strong correlations were observed between TPHs and its degraders such as Pseudomonas, Azoarcus, and Polaromonas. Significant positive relationship between PFASs and Trichlorobacter implied the potential defluorination capabilities of Trichlorobacter, warranting further investigation. Moreover, the higher energy metabolism including carbon, nitrogen and sulfur metabolisms and higher abundance of metabolic enzymes for alkane, cyclohexane and toluene in the refinery site revealed the potential occurrence of natural biodegradation of contaminants with indigenous microbial community. These findings highlight the complexity of sites contaminated with a mixture of traditional and emerging contaminants, providing valuable insights into the potential for biodegradation of mixed contaminants and underscoring the need for integrated approaches in environmental remediation strategies. This study contributes to understanding the ecological impacts of co-occurring contaminants and emphasizes the importance of considering multiple contaminant types in environmental risk assessments and remediation efforts., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Despite evidence of the uptake of soil microplastics (MPs) by crops, there is a paucity of knowledge regarding the contamination of vegetables in real-world environments with microplastics. This study establishes a correlation between the presence of microplastics in farmland and the concentration of microplastics in crops. The soil samples were found to contain Polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC). The proportions of PE and PP in the soil were considerable, with values ranging from 35 % to 70.6 % and 19.3 % to 50 %, respectively. The levels of PVC, PS and Polymethyl methacrylate (PMMA) in vegetables ranged from 3.64 to 17.37 μg g -1 , 0.67 to 2.45 μg g -1 and 0.02 to 0.27 μg g -1 , with Chinese cabbage exhibiting the highest concentration at 19.84 μg g -1 . The highest level of PMMA was found in eggplant at 0.27 μg g -1 . Vegetables sampled, including aubergine, lettuce and Chinese cabbage, contained more than two types of plastic. A correlation coefficient of 0.579 was observed between microplastics in vegetables and soil. This study provides insight into the contamination of environmental soils and different types of vegetables, and the data serve as a reference point for future studies., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Monitoring heavy metals in vegetation near mining or industrial sites is crucial for detecting plant contamination; requiring discrimination between metals adhered to foliar surfaces from the internal concentrations. We investigated key factors that might contribute to lead (Pb) accumulation in leaves of local vegetation near a Pb mine: (i) distance from the pollutant source, (ii) morphological characteristics of leaf surfaces, (iii) their susceptibility to Pb loss by washing, and (iv) the effect of contrasting washing reagents in Pb removal. Native plant species were sampled at three field locations, possessing different leaf surface morphologies: glabrous (smooth), resinous (waxy) and hirsute (hairy). After washing with Citranox, EDTA or deionised water, Pb contents were assessed by ICP-OES and SEM-EDX. We observed an order of Pb (and other metals) retention from hirsute > resinous > glabrous, and found: i) greater Pb accumulation in leaves near the mine due to particulate matter (PM) deposition; ii) hirsute leaves retain the highest PM-Pb; iii) higher Pb removal (10-fold) by Citranox and EDTA compared to water; and iv) hirsute leaves retained considerable PM-Pb underneath trichomes despite washing, leading to Pb overestimation. Therefore, for accurate Pb monitoring, washed glabrous leaves are best indicated due to their negligible PM retention., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Decades of research demonstrated that microbes can remediate petroleum-contaminated environments through biodegradation of hydrocarbons. Recent studies have applied signature metabolite analysis to investigate hydrocarbon-contaminated sites, focusing primarily on aquifer systems and metabolites of relatively water-soluble monoaromatic hydrocarbons. However, the number of studies involving non-targeted analysis and identification of individual metabolites in environmental samples is limited. In addition, metabolite patterns in crude oil-contaminated samples are rarely compared to those in the unaltered crude oils. In this study, we identified metabolites in complex environmental samples and crude oils from a former oil sands mining site using non-targeted gas chromatography-mass spectrometry. Based on these results, we suggest potential biodegradation processes that may account for the formation of the observed metabolites. The non-target results from water samples contaminated with crude oil showed that aromatic acids were the dominant metabolites. We observed that arylacetic acids were particularly abundant in the water samples when the metabolite patterns were compared with those found in crude oil and oil sands samples formerly produced at the site, as well as those found in oil-contaminated soil samples. The dominance of arylacetic acids is evidence that the microbial communities have a limited capacity for α-oxidation, i.e. an enzymatic attack on the methylene group, which is necessary to further degrade these compounds. Therefore, aromatic acids may be enriched at sites with long-term exposure to crude oil. Our study demonstrates that non-targeted metabolite analysis can provide an insight into the prevalent pattern of carboxylic acid metabolites and degradation processes in hydrocarbon-contaminated habitats., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.)

Selenium (Se) is an indispensable trace element to human health, yet its biological tolerance threshold is relatively narrow. The potential application of machine learning methods to indirectly predict the Se content in crops across regional areas, thereby validating the reasonableness of soil health thresholds, remains to be explored. This study analyzed the factors influencing Se absorption in crops from longevity regions and employed machine learning models to predict the bioconcentration factor of Se, thereby obtaining selenium content in these crops and ultimately estimated the Se threshold for healthy soils. The results indicated that the Artificial Neural Network (ANN) model demonstrated the best predictive performance for the bioaccumulation factor (BAF) of Se in crops. The maximum permissible concentration of Se in rice was 0.17 mg/kg, while the minimum was 0.03 mg/kg; for maize, the maximum permissible concentration was 0.25 mg/kg, and the minimum was 0.04 mg/kg. Approximately 68 % of the arable land in the study area was suitable for cultivating Se-rich crops, providing important insights for the optimization of crop cultivation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Paddy fields contaminated by arsenic-containing acid mine drainage (AMD) may also have rich iron in soil. Whether this iron can be loaded onto biochar to passivate the dissolved arsenic is worth further exploration. Soil was mixed with biochar prepared at 400, 550, and 700 °C and incubated under alternating anaerobic and aerobic conditions. Soil, soil solution and biochar samples were analysed using ICP-MS, FTIR, SEM, XPS, etc. The results showed that biochar prepared at lower pyrolysis temperatures contained a higher number of functional groups. Under the combined action of microorganisms, primarily from the Firmicutes phylum, biochar promoted the dissolution of arsenic-containing iron oxides in soil, with the residual arsenic also undergoing transformation. The biochar rapidly loaded dissolved iron onto its surface, likely in the form of Fe 3 O 4 and FeOOH, and adsorbed arsenic primarily as As(III). Although the iron oxides detached over time, they were more stable on the biochar prepared at 400 °C compared to those prepared at higher pyrolysis temperatures. Meanwhile, the arsenic content on the biochar increased, raising the As/Fe molar ratio to above that of the soil. This study lays the foundation for further exploring the long-term use of biochar in AMD-contaminated paddy fields., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

The use of lithium (Li) in decarbonization strategies has positioned it as a central component of modern technological advances, particularly in battery applications. However, the increasing demand for Li has raised concerns about its environmental consequences, which are poorly documented. This study aimed to fill this knowledge gap by examining the impact of Li on soil bacterial/fungal communities. Using a microcosm approach, we explored the impacts of increasing Li concentrations on both microbial community structure and activities. Our results revealed significant changes in bacterial/fungal communities, particularly in the bacterial communities. Most of the indicator species were negatively correlated with the Li gradient, reinforcing the harmful effect of Li. Proteobacteria dominated at low concentrations, whereas Firmicutes were the most abundant at high concentrations. OTUs affiliated with the genus Alicyclobacillus represented >29 % of the total affiliated OTUs at the highest Li concentrations. Moreover, Alicyclobacillus fastidiosus showed resilience and specific adaptation to Li. Fungal communities showed less pronounced changes, with Mucoromycota remaining the dominant phylum at all concentrations. Nevertheless, some genera presented correlations with Li concentration, particularly the plant mutualists Leptodontidium, Oidiodendron, and Solicoccozyma. In addition, rapid decreases in several enzymatic activities crucial for the functioning of the carbon, nitrogen and phosphorus cycles were noted. Accordingly, microbial respiration was also impacted by high Li concentrations. Finally, a correlative analysis linked the decreases in enzyme activity to decreases in the abundances of both Proteobacteria and Ascomycota. These results underline the multiple impacts of Li on bacterial/fungal communities, highlighting both structural alterations and changes in microbial activities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Polychlorinated naphthalenes (PCNs) and polychlorinated biphenyls (PCBs) are toxic contaminants that were produced and used in large quantities for their stability, inertness, and other desirable electrical, cooling, and lubricating properties. Due to their environmental persistence and improper disposal, these contaminants have become broadly distributed in the environment. This study examines the levels, composition, distribution, and potential sources of these compounds in surface soils and street dusts collected at 19 residential and industrial areas in Detroit, Michigan. Each sample was analyzed for 32 PCN and 37 PCB congeners using gas chromatography/mass spectrometry. The geometric mean concentrations of total PCNs and total PCBs were 61 (range:11-1933) and 432 (range: 32-18,637) ng/g, respectively. The most common PCNs were tetra- to hexacongeners and PCN-59 was most prevalent individual congener. For PCBs, hexaPCBs were most common and PCB-158 was dominant. PCN and PCB levels in soils at most sites exceeded health-based guideline levels. Given the short half-lives of PCNs and restrictions on PCN and PCB production, our results imply ongoing or recent releases. Emission sources identified by principal components and other analyses include industrial thermal processes included fuel combustion and electrical waste handling at a scrap metal processor for PCNs and PCBs, respectively. The presence of sources and "hotspots" of these toxic "legacy" contaminants in urban settings like Detroit highlight the potential for human exposure and the need to identify and control sources to prevent further environmental dispersal, exposure and risk., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

The presence of heavy metal(loid)s in sewage sludge is a cause of concern and an obstacle to its agricultural valorisation. This study analysed the elemental composition of sewage sludge from 42 Portuguese wastewater treatment plants (WWTPs) during summer and winter, investigating heavy metal(loid) contamination, nutrient content, and potential risks related to sludge application to agricultural soils. Levels of 8 heavy metal(loid)s were investigated, ranging from not detected (Hg) to 5120 mg kg -1 dw (Zn), decreasing in the order Zn > Cu > Cr > Ni > Pb > As>Cd > Hg. The legal requirements for agricultural use of sludge were overall met, but elevated levels of Zn and Cu, linked to industrial sources, exceeded the permitted limits in 3 WWTPs. On average, N, P, K, Mg, and Ca comprised 80 % of the sludge nutrient profile. No seasonal variations were found, but sludge composition varied with WWTP size, wastewater origin, and between thickened and digested samples. Environmental hazard indicators showed significant sludge contamination with Zn, Cu, and Cd. However, the geoaccumulation index, potential ecological risk indicators, and risk characterization ratios showed no significant risks to sludge-amended soils, assuming a single application of 5 tons ha -1 . Human health risk assessment for workers handling sewage sludge identified dermal contact as the main route of exposure, with non-carcinogenic risk for Cr and carcinogenic risk for Ni and Cr at the highest reported levels. Sewage sludge produced in Portugal was considered suitable for agricultural use, provided that it is closely monitored and well-managed to meet the needs of crops and receiving soils, while mitigating environmental risks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.)

Heavy metal (HM) pollution in agricultural areas seriously threatens food security and ecological health. In this study, based on different soil parent materials, the HMs enrichment in the soil-crop systems of two typical eastern Chinese agricultural lands was compared and analyzed. Multivariate linear stepwise regression analysis, influence index of comprehensive quality and HHRA model were used to understand the bioaccumulation and to evaluate the soil-crop-human system. The study showed that HMs exhibited different enrichment characteristics in the two soil parent material areas. Cd faced a higher risk control rate and was a priority pollutant in the soil environment. The acidification soils in the granitic parent material area led to more widespread Ni pollution in wheat grains. The HM absorption model clarifies that driving factors such as the HM content, physicochemical properties and the distance to the river can well explain the enrichment ability of HMs in wheat grains. The synergistic evaluation revealed that only 13.04% of soil and crops were at a clean level. Soil contamination is more prevalent in the metamorphic rocks area, while crop contamination is more severe in the granitic parent material area. Probabilistic health risk assessment indicated that HMs primarily impact health through the ingestion of contaminated wheat, so residents of the granitic parent material area face a slightly higher HI. This information will be crucial for understanding the translocation and accumulation of HMs within soil-crop-human health systems of agricultural land in different soil parent material areas and for developing effective pollution prevention and control programs., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

The creation of defects in crystalline structures can tune metal-organic frameworks (MOFs) properties, such as improving their adsorptive and catalytic performance with producing more porosity and active sites. In this work, the bimetallic UiO-66 containing Zn and Zr was prepared. And then UiO-66 with missing cluster defects (UiO-66-1/3) were obtained by acid washing to remove the Zn nodes. UiO-66-1/3 was used as sorbent of dispersive solid-phase extraction (dSPE) to extract and enrich (BUs). Combination with high-performance liquid chromatography-diode array detector (HPLC-DAD) was developed to detect trace BUs in soil samples. Adsorption equilibrium can be reached in 3 min. The method possesses high enrichment factor (202-325), low detection limit (0.005-0.04 ng·mL -1 ), and wide linear range (0.02-200 ng·mL -1 ). In addition, the recovery rate of UiO-66-1/3 as an adsorbent was still higher than 95% after reused for 16 times. This work provides a new material for the enrichment and detection of benzoylurea insecticides in the environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

Applying amendments to contaminated soil has been considered a successful strategy to control lead (Pb) pollution. In this study, four different types of amendment (calcium hydrogen phosphate, CHP; hydroxyapatite, HA; ordinary Portland cement, OPC; lime, LI) at two treatment levels were used to immobilize Pb in three contaminated soils. The effectiveness of Pb immobilization was assessed by coupling a sequential extraction procedure (fraction) with in vivo mouse model (Pb relative bioavailability, Pb RBA) and in vitro gastrointestinal assays (bioaccessibility). For all four amendments, Pb RBA generally decreased in YNGJ and HNZZ, with a stronger effect at a high treatment level, but less effective in HNJY. In contrast, when in vitro gastrointestinal simulation tests were used, Pb bioaccessibility determined by SBRC and PBET was generally reduced in most cases, especially in soils treated with phosphate amendments. Sequential extraction procedure demonstrated that the addition of 4 amendments generally decreased the proportion of E1 + C2 compared to untreated soils, while increasing R5, O4, or F3. The relationship between Pb fractions and RBA/bioaccessibility indicated that the bioavailable Pb is primarily from the sum of E1 and C2. The finding of this study highlighted reducing E1 + C2 was a primary strategy to further decrease bioavailable Pb in amended soils, and monitoring Pb fractions may provide a concise and alternative method for comprehending the oral bioavailability of Pb to humans., Competing Interests: Declarations. I hereby declare that the contents of this manuscript are original and have not been published elsewhere in whole or in part. The corresponding author has received permission from all authors to submit this manuscript. All authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors. Ethical approval: All authors have read and understood the declaration on “the ethical responsibilities of authors” and have complied where appropriate with the declaration on “ the ethical responsibilities of authors” indicated in the instructions to authors. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In households and greenhouses, fuel combustion generates ashes that are sometimes deposited on the of soil surface. The consequences of the deposition of such wastes on soil properties are not well known. Therefore, this study determines these geochemical processes (effects of the deposition of household and greenhouse ashes on buried sandy soils) and soil-forming processes. The study reveals that the deposition of household ashes increases the pH of buried Arenosols, while greenhouse ashes do not raise the pH of buried soil. The increased pH of buried soils caused by household ashes arises from calcite dissolution, Ca and K mobilisation, and Ca and K trapping by coatings on quartz grains. In turn, pozzolanic reactions and the crystallisation of gypsum (or a mixture of calcite and gypsum) on the surface of coke in greenhouse ashes limit Ca leaching downwards in the soil profile. Soil horizons with household and greenhouse ashes are characterised by relatively high contents of metal(loid)s. Furthermore, the mobilisation of metal(loid)s is evidenced from horizons containing both types of combustion wastes downwards in the soil profiles. The contents of Mn, Ti, Zn, Cd, Sr, As, Cr, V, and Ba in sandy horizons buried by household ashes are higher than the contents of these elements in soils, reflecting the local geochemical background. For sandy horizons buried by greenhouse ashes, the enrichment of Cd, Sr, As, Cr, and Ba is noted as being relative to soils from a local geochemical background. Therefore, this study demonstrates that household and greenhouse ashes need special attention because of their potential negative environmental effects. The incineration of household ashes (and greenhouse ashes) with municipal wastes, and metal(loid)s recovery from the resulting ashes is a promising management strategy for these types of combustion wastes instead of storing them around households., Competing Interests: Declarations. Conflict of interest: The author declares no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

Dietary uptake is the main pathway of exposure to polycyclic aromatic hydrocarbons (PAHs). However, there is no data regarding the pollution and health risks posed by PAHs in Lilium davidii var. unicolor. We measured the concentrations of 16 PAHs in lily bulbs from Lanzhou; analyzed the bioaccumulation, sources, and pollution pathways of PAHs; assessed the influence of baking on PAH pollution in the bulb; and assessed the cancer risks associated with PAH exposure via lily consumption. The total PAH concentrations in raw bulbs were 30.39-206.55 μg kg-1. The bioconcentration factors of total PAHs ranged widely from 0.92 to 5.71, with a median value of 2.25. Pearson correlation analysis revealed that the octanol-water partition coefficients and water solubility values played important roles in the bioaccumulation of naphthalene, fluorene, phenanthrene, pyrene, and fluoranthene in the raw bulb by influencing PAH availability in soil. Correlation analysis and principal component analysis with multivariate linear regression indicated that biomass and wood burning, coal combustion, diesel combustion, and petroleum leakage were the major sources of PAHs in the raw bulbs. The paired t-test showed that the PAH concentrations in the baked bulbs were higher than those in the raw bulbs. PAH compositions in lily bulb changed during the baking process. Baked bulbs exhibited a higher cancer risk than raw bulbs. Local adults had low carcinogenic risks from consuming lily bulbs. This study fills the knowledge gap about PAH pollution and the related health risks of PAHs in the Lanzhou lily., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Sun et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Microplastics (MPs) are an emerging environmental issue that might endanger the health of agricultural soil. Even though several research on the particular toxicity of MPs to species have been carried out, there is little information on MPs' impacts on soil physicochemical properties and heavy metals (HMs) availability of HMs contaminated and without contaminated soils. This study examined the changes in soil characteristics for both HMs contaminated and without contaminated soils by five distinct MPs, including Polyethylene (PE), Polyethylene terephthalate (PET), Polystyrene Foam (PS), Polyamide (PA), and a combination of these four types of MPs (Mixed MPs), at two different concentrations (0.2% and 1%; w/w), where soil incubation experiments were setup for this studies and the standard analytical techniques employed to measure soil characteristics and toxic metal availability. After the ending of soil incubation studies (90 days), significant changes have been observed for physicochemical properties [bulk density, porosity, water holding capacity, pH, electrical conductivity (EC), organic carbon (OC), and organic matter (OM)]. The soil nutrients change in descending order was found as NH4+ -N> PO43+ > Na > Ca > NO3- > Mg for lower concentrations of MPs compared to higher concentrations. The HMs availability is reducing with increasing MPs concentration and the descending order for metal availability was as follows Pb > Zn > Cd > Cr > Cu > Ni. Based on MP type, the following descending order of MPs PS > Mix (MPs) > PA > PET > PE, respectively act as a soil properties influencer. Usually, effects were reliant on MPs' category and concentrations. Finally, this study concludes that MPs may modify metal movements, and soil quality; consequently, a possible threat will be created for soil health., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Chakraborty et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Certain neonicotinoid metabolites (mNEOs) are causing widespread concern because they are equally or even more toxic than the parent NEOs. Currently, there is limited information on the distribution of mNEOs in soil. Especially, it is unknown that the effects of agricultural factors, such as plastic filming, plowing, irrigation, and fertilization, on mNEOs. This study is the first to reveal that mNEOs were commonly found in agricultural topsoil in China, with a geometric mean concentration of ΣmNEOs of 0.298 μg/kg. Among 31 provinces in Mainland China, Fujian had the highest mNEO residues, whereas Shanghai had the lowest. Among topsoil of various crop types, that of fruits and vegetables were found the highest mNEO residues. Furthermore, higher levels of film cover were associated with higher mNEO residues. Microplastics (MPs, serving as contaminant carriers) were positively correlated with mNEOs under field conditions, which was related to the adsorption capacity of microplastics and its influence on the soil conditions and the years of film cover. Alternatively, this study shows for the first time that irrigation water and manure might be sources of mNEO input into the soil, and that the plowing frequency might also influence on mNEOs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Although the relative bioavailability (RBA) can be applied to assess the effects of Pb on human health, there is no definition and no specific data of Pb-RBA to different soil sources and endpoints in vivo. In this study, we estimated the Pb-RBA from different soil sources and endpoints based on machine learning. The Pb-BAc and Pb-RBA in soils were found to be mostly in the range of 20-80 %, which is different from the USEPA Pb-RBA of 60 % in soils. The mean Pb-RBA for different biological endpoints in vivo predicted using the RF model were 49.94 ± 18.65 % for blood; 60.15 ± 26.62 %, kidney; 60.90 ± 21.51 %, liver; 50.70 ± 17.56 %, femur; and 62.89 ± 16.64 % as a combined measure. Pb-RBA of shooting range soils was 88.21 ± 16.92 % (mean), spiked/aged soils 77.11 ± 14.05 % and certified reference materials 73.70 ± 20.31 %; agricultural soil 68.28 ± 18.93 %, urban soil 64.36 ± 21.82 %, mining/smelting soils 53.99 ± 17.66 %, and industrial soils 47.71 ± 20.35 %. This study is first to define the Pb-RBA according to various soil sources and endpoints in vivo with the objective of providing more accurate Pb-RBA data for soil lead risk assessment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study focuses on the determination of dioxins and related compounds (DRCs) in sediment and soil samples gathered from craft villages and industrial zones in Bac Ninh province, northern Vietnam. The PCDD/Fs and DL-PCBs levels in sediment samples ranged from 8.34 to 1302 pg/g and 34.5 to 3186 pg/g, respectively, and total equivalent toxicity (TEQ) of DRCs ranged from 0.596 to 88.1 pgTEQ/g. The total mass concentration of DRCs in the soil samples varied from 14.2 to 4857 pg/g, with corresponding total TEQ values ranging from 0.387 to 2.61 pgTEQ/g. Risk assessment based on sediment quality guideline indicators shows that DRCs at paper recycling village had moderate adverse biological effect. Some soil samples collected in industrial clusters have total carcinogenic risk (CR) values close to the threshold (1.0 × 10 -6 ). Based on the results, it is necessary to continue monitoring and evaluating DRC compounds in craft village and industrial cluster environments and have remediation solutions to reduce these contaminated compounds., Competing Interests: Declarations. Competing Interest: The authors have no competing interests to declare that are relevant to the content of this article. Ethical Approval: Not applicable. Consent to Participate: Not applicable. Consent for Publication: Not applicable., (© 2025. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Monitoring the distribution of nutrient and beneficial elements (NBEs) in topsoils is important for assessing agricultural and ecological risks and for promoting human health. In order to understand their distribution effectively, it is critical to clarify their sources and main influence factors. In this study, a total of 272 topsoils and 46 soil parent material samples and some samples along 4 vertical profiles were collected in the Mentougou area of Beijing. Then, 12 NBEs were determined for each sample, including elements of N, P, S, Se, Zn, Mn, V, Ge, K, F, Ca, Mg. The mean content of 12 NBEs was statistically calculated and their spatial distributions were mapped. NBEs in topsoils were mainly influenced by the background of parent materials and the subsequent surficial processes. To address the weathered background, the study area was divided into 4 units, including igneous rocks, clastic rocks, carbonate, and loess units. For each unit, cluster analysis was performed to identify the relationship between 12 NBEs in topsoils. Furthermore, the changes in characteristics of 12 NBEs along vertical soil profiles of 4 units were individually analyzed by comparison with the weathered background. Therefore, the main factors influencing the distribution of 12 NBEs in topsoils were identified respectively. According to each element's main influencing factors, 12 NBEs were divided into 5 groups. The main influencing factors were same for elements in each group but different each other for 5 groups. Besides the weathered background, the distribution of NBEs in topsoils was significantly influenced by subsequent surficial processes, such as organic enrichment, leaching, and calcification. In addition to these natural surficial processes, the influence of human activities, a special surficial process, was also observed on the distribution of N, P, S, and Zn in topsoils in farming areas by interpreting normalized difference vegetation index (NDVI). This study provides a semi-quantitative method to determine the role of weathered background and subsequent surficial processes in the distribution of NBEs in topsoils, which helps to understand the current situation and evolution trend., Competing Interests: Declarations. Conflicts of interest: The authors declare no competing interests. Author statement: All authors have read, understood, and have complied as applicable with the statement on "Ethical responsibilities of Authors" as found in the Instructions for Authors., (© 2025. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This study assessed the risks of soil pollution by heavy metals in Chilmari Upazila, northern Bangladesh, using the static environmental resilience (Pi) model of soil. Geostatistical modeling and self-organizing maps (SOM) identified pollution areas and spatial patterns, while a positive matrix factorization (PMF) model revealed pollution sources. The results showed that the average concentrations of Cr, Pb and As were well above background levels. Agricultural and industrial soils were mainly contaminated with Cr, Pb and As according to the Nemerow Pollution Index (NPI), Ecological Risk (ER) and Pi Index. Over 70% of the sites were contaminated with Pb and Cr, while co-contamination was particularly high. A one-way ANOVA showed significant correlations between Pb, Cu and Zn levels and human activities. The PMF analysis revealed that industrial effluents, agrochemicals and lithogenic sources were the main contributors to soil contamination with 16%, 41% and 43%, respectively. The SOM analysis revealed three distinct spatial patterns (Pb-Zn, Cr-Cu-Ni and Co-Mn-As), which are consistent with the PMF results. These results emphasize the need for stringent measures to reduce industrial emissions and remediate soil contamination in order to improve soil quality and food security., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Al Yeamin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Currently, there is a lack of a comprehensive understanding of the behavior of polycyclic aromatic hydrocarbons (PAHs) in complex multimedia urban environmental systems. Taking Urumqi City as a case study, we developed an integrated multimedia urban environmental model to simulate the inter-media transport processes of PAHs across air, water, soil, sediment, vegetation, and impervious surfaces. The predictive results of this model were in good agreement with the actual monitoring data from 2021, confirming its accuracy. Notably, the simulated data for 2021 indicate that the total amount of PAHs in the soil reached 1.06 × 10 6 kg, accounting for 97.44% of the total PAHs in Urumqi City, highlighting soil as the primary sink for PAHs. Further analysis of transport fluxes revealed that atmospheric transfer pathways to soil and vegetation are the main mechanisms driving the distribution of PAHs in urban environments. Additionally, sensitivity analysis identified temperature, soil, and vegetation-related parameters as the primary factors influencing PAHs. Based on the simulated concentration, the risk assessment results showed that soil PAHs had a higher risk of carcinogenesis to human body. This study deepens our understanding of the behavior of PAHs in urban environments and provides insights into how human activities affect the fate and transformation of these contaminants in multimedia urban systems., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Pyrrolizidine alkaloids (PAs) and their N-oxides (PANOs) are phytotoxins produced by various plant species and have been emerged as environmental pollutants. The sorption/desorption behaviors of PAs/PANOs in soil are crucial due to the horizontal transfer of these natural products from PA-producing plants to soil and subsequently absorbed by plant roots. This study firstly investigated the sorption/desorption behaviors of PAs/PANOs in tea plantation soils with distinct characteristics. Sorption amounts for seneciphylline (Sp) and seneciphylline-N-oxide (SpNO) in three acidic soils ranged from 2.9 to 5.9 µg/g and 1.7 to 2.8 µg/g, respectively. Desorption percentages for Sp and SpNO were from 22.2% to 30.5% and 36.1% to 43.9%. In the mixed PAs/PANOs systems, stronger sorption of PAs over PANOs was occurred in tested soils. Additionally, the Freundlich models more precisely described the sorption/desorption isotherms. Cation exchange capacity, sand content and total nitrogen were identified as major influencing factors by linear regression models. Overall, the soils exhibiting higher sorption capacities for compounds with greater hydrophobicity. PANOs were more likely to migrate within soils and be absorbed by tea plants. It contributes to the understanding of environmental fate of PAs/PANOs in tea plantations and provides basic data and clues for the development of PAs/PANOs reduction technology., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

The strong pest pressure on intensive banana cultivation in the French West Indies led to the intensive use of chlordecone (an organochlorine insecticide) between 1972 and 1993. Due to its high toxicity for the population and the environment, many studies were conducted on the transfer of chlordecone over the last 20 years. However, most studies focused on the dissolved fraction of chlordecone, while the particle-bound fraction was understudied. Therefore, this study reconstructs pluri-decadal erosion rates (i.e. 1980-2023) and associated chlordecone particle-bound transfers from soil and sediment cores sampled in a cultivated headwater catchment (Saint-Esprit, Martinique). Based on sediment accumulation analyses in an agricultural reservoir, high erosion rates (i.e. 10 t ha -1 yr -1 ) were found in the investigated catchment during the study period, with values exceeding the estimated tolerable soil loss rate in tropical contexts (i.e. 2.2 t ha -1 yr -1 ). Based on the analysis of soil cores sampled along a banana plantation hillslope, this study highlights the formation of colluvial deposits with high levels of chlordecone contamination. When these areas are affected by erosion processes, this leads to massive remobilization of particle-bound chlordecone to water bodies. Indeed, in sediment sampled in the downstream reservoir, we observed a drastic increase in these transfers since 2006, synchronous with changes in agricultural practices. This study therefore highlighted the occurrence of legacy contamination at toeslope positions, which was estimated to potentially persist for 4000 to 11,000 years. Such a residence time highlights the need to implement changes in land management to effectively reduce erosion of agricultural soils, particularly in areas identified as "temporary deposition zones" for chlordecone contamination, in order to protect downstream water bodies from chlordecone transfer. To achieve this, agricultural practices that may increase soil erosion, such as herbicide application or intensive ploughing, should be minimized. Overall, this study improved our understanding of erosion and associated chlordecone transfers in tropical environments., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Remi Bizeul reports financial support was provided by the Prefecture de Martinique. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Ecological ditches serve as one of the important measures for the concentrated infiltration of stormwater in the construction process of sponge cities. Prolonged concentrated infiltration of stormwater can lead to the accumulation of pollutants and pollution risks in the substrate of ecological ditches. In this study, two different substrate ecological ditches were constructed, namely, a combined substrate ecological ditch with zeolite + ceramsite (EA), and a biological substrate ecological ditch (EB). The accumulation characteristics of pollutants and microbial mechanisms in the ecological ditches were evaluated by simulating the cumulative rainfall test for three years. Results showed that there was serious total nitrogen (TN) contamination in both EA and EB substrates, with mean values of 718.6 and 802.7 mg/kg, respectively. The average contents of potentially toxic elements (Cu, Pb, and Zn) in EA and EB substrates were higher than the background values of soil elements in China, and Cu posed considerable ecological risks to the environment. Proteobacteria was the dominant phylum and accounted for 32.85-41.33% in two ditches; the total number of denitrifying functional bacterial genera in the EB increased by 1.53% than EA, which proved that the biological substrate was more favourable for the growth of denitrifying microorganisms. The accumulation characteristics of pollutants and microbial mechanisms in the ecological ditches with different substrates above provide a reference for extending the service life of ecological ditch facilities.

Pine needle, pine bark, and soil samples were collected from various regions in South Korea, considering the suitability of vegetation samples as passive samplers. A total of 27 organochlorine pesticides (OCPs) were analyzed using a gas chromatograph/high-resolution mass spectrometer (GC/HRMS). The total concentrations of OCPs ranged between 650 and 3652 pg/g dw in soil, 215 and 1384 pg/g ww in pine needles, and 456 and 1723 pg/g ww in pine bark. Metabolites such as endosulfan sulfate, p,p'-DDE, and p,p'-DDD were dominant in the soil samples, whereas parent compounds were more prevalent in the pine needles. Diagnostic ratios and compositional profiles suggested that potential OCP sources were primarily related to historical use, atmospheric transport, and unintentional byproducts. OCPs that were never used or registered in South Korea were also detected in all sample types, indicating atmospheric transport from source regions. Sites closer to North Korea and China showed higher concentrations of OCPs, with levels gradually decreasing from west to east in the soil, suggesting long-range atmospheric transport from the source regions. Fugacity fractions indicated net volatilization for most compounds, while net deposition was observed for others, suggesting a dynamic equilibrium. This study concludes that atmospheric transport plays a predominant role in the distribution and fate of OCPs in the environment, with no evidence of current local sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This ecological study examines cancer mortality rates in 61 rural Greek municipalities, covering in total 7,305,554 person-years from 2000 to 2015, based on the Hellenic Statistical Authority data. Topsoil concentrations of Mn, Ni, Pb, Be, As and Cd in Greek grazing land samples were obtained from the GEMAS (Geochemical Mapping of Agricultural and Grazing land Soil) project. Municipalities of rural regions with population of up to 20,000 people were selected as the study area and were divided into four quartiles, according to their age-specific cancer mortality rates, to identify the most divergent areas of low/high mortality. Fusion of demographic data with topsoil measurements aimed to reveal their potential association. Towards a univariate analysis, comparing each element individually across the low/high mortality regions revealed significant overlaps in distributions of concentrations for all elements. Machine learning multi-element models were built to predict whether an area would have a low or high cancer mortality rate, based simultaneously and solely on the concentrations of the six elements of the region, for each group. The out-of-sample median accuracy of the model was very high (83.3%) for the 0-29 age group, high (66.7%) for the 30-39, 40-49 and 50-59 age groups, while the accuracy decreased significantly above age of 60. The interaction of Mn, As, Ni, and partially Be, contributes most to the model's prediction for the 0-29 age group, As becomes the main contributor in the 30-39 age group, while all six elements contribute almost equally for the 40-49 group, and the interaction of Ni, Mn and Be becomes important in the 50-59 age group. The findings of this study strongly suggest that topsoil elements may jointly influence the frequency and geographical distribution of cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Over the past decade, there has been an increase in small-scale gold mining in the arid southern region of Egypt. Miners extract ore from the Eastern Desert and transport it to Nile Valley farms, where ample water facilitates the processing. In Edfu, Egypt, the lack of economic opportunities prompted resource-constrained farmers to transform their agricultural lands into gold mines. The study utilized a multifaceted approach that integrated various methodologies, including remote sensing technologies, field surveys, chemical analyses, and statistical methods. The study aimed to assess the concentrations of carcinogenic agents and determine the potential human health risks associated with these agents in soil and fish samples collected within the city boundaries. The study examined correlations between various heavy metals (HMs), such as Ni, Pb, Cd, Cr, Cu, and Hg, in Soilsamples collected in 2020 and 2022. The results revealed direct proportional relationships among specific HMs. The Index of Geoaccumulation (Igeo) and Pollution Load Index (PLI) revealed significantly elevated values in both years, indicating potential environmental degradation. Although no carcinogenic hazards were identified, non-carcinogenic risks related to ingestion were observed for both adults and children exposed to mercury (Hg), copper (Cu), and arsenic (As). Contamination Factor (CF) values were also significantly high. Ecological risks were observed in both Soiland water, as well as in Nile Tilapia samples. Hazard Quotients (HQ) calculated for Nile Tilapia indicated potential risks for both adults and children, particularly associated with elevated arsenic (As) levels. This transformation elicited concerns regarding environmental and health implications, leading us to undertake a thorough investigation., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Semi-volatile organic compounds (SVOCs) are widely distributed across the globe, including polar regions. This study investigates the distribution and bioconcentration of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in soils and Colobanthus quitensis, while also estimating potential emission sources. Results indicated high concentrations of PAHs in soils and plants from the Sub-Antarctic region, while OCPs and PCBs were more prevalent in the Antarctic region, with higher contaminant concentrations found in soils than in plant tissues. Hexachlorobenzene (HCB) and dichlorodiphenyldichloroethylene (p,p'-DDE) were significantly higher in the Antarctic region, suggesting historical dichlorodiphenyltrichloroethane (DDT) use, while PCB 153 and 180 were the most representative PCBs in the Antarctic region. Phenanthrene (Phe) was the dominant PAH in both regions. The bioconcentration factor analysis from soils (BCF Soils ) revealed potential anthropogenic influences for certain contaminants, including γ-hexachlorocyclohexane (γ-HCH) and PCB 9 in the Sub-Antarctic region, and HCB, p,p'-DDE, PCB 9, and benzo-naphtho-thiophene in the Antarctic region. However, compounds with higher hydrophobicity showed lower Bioconcentration factor (BCF Soils ) values, indicating a tendency to accumulate in soil rather than plant tissues. This was consistent with the inverse relationship found between BCF Soils and the octanol-water partition coefficient (Log K OW ). Diagnostic ratios of PAHs revealed a predominantly pyrogenic source in the Sub-Antarctic region, while a mixture of sources was observed in the Antarctic region., Competing Interests: Declaration of competing interest Cristobal Galban-Malagon reports financial support and administrative support were provided by Universidad Mayor. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

In historic mining towns, where mining activities were abandoned many decades or even centuries ago, legacy contaminations can be remobilized and redispersed, representing a threat for the environment and human health. This study focuses on urban soils (n = 19) in the town of Jihlava, the Czech Republic, one of the medieval centers of silver mining in central Europe. The basic geochemical characterization of the soils was combined with mineralogical investigations to understand the solid speciation of the metal(loid) contaminants, oral bioaccessibility tests, and exposure assessment. The total concentrations of the metal(loid)s in the original soils were not excessively high (up to 45.8 mg As/kg, 19.2 mg Cd/kg; 205 mg Cr/kg; 91.8 mg Cu/kg, 163 mg Pb/kg, 253 mg V/kg, 262 mg Zn/kg), although, in some cases, they exceeded the regulatory guidelines for agricultural and/or residential soils. A substantial increase in the metal(loid)s contents was confirmed for the < 48-µm soil fraction that was later used for the bioaccessibility tests. Scanning electron microscopy and the electron microprobe showed that ore-derived primary sulfides were rare in the studied soils. Still, hydrous ferric oxides rich in Cu, Pb and Zn and fragments of metallurgical slags composed of metal-containing glass and silicates (olivine) were prone to dissolution during extraction in a simulated gastric fluid (SGF, glycine solution acidified to pH 1.5 by HCl). The maximum bioaccessible concentrations corresponded to 4.69 mg As/kg, 1.75 mg Cd/kg, 2.02 mg Cr/kg, 20.3 mg Cu/kg, 81.6 mg Pb/kg, 16.2 mg V/kg, and 233 mg Zn/kg. Exposure estimates were carried out for children (10 kg) as a target group and a conservative soil ingestion rate (100 mg/d). However, the daily intake of all the studied contaminants was far below the tolerable limits. Our results show that the human health risk based on incidental soil ingestion in the studied area seems limited., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s).)

Biodegradable polylactic acid (PLA) mulch has been developed to replace conventional polyethylene (PE) mulch in agriculture to reduce plastic pollution and the accumulation of microplastics (MPs) in soil. Cadmium (Cd) is a significant soil contaminant, and can be adsorbed by MPs. It is increasingly recognised that in the natural environment biofilms can develop on MPs and that this can affect their adsorption properties. We exposed PLA and PE mulches outdoors for 16 months. MPs were then generated from pristine and weathered mulches. Biofilms developed on the weathered plastics. Oxygen-containing functional groups were detected on the weathered, but not the pristine PE, abundance of these groups increased for the weathered PLA. After removal of the biofilm the observed increases in oxygen-containing functional groups relative to the pristine plastics remained. In adsorption experiments pristine PLA MPs had a greater maximum adsorption capacity than pristine PE MPs (106-126 vs 23.2 mg/kg) despite having a lower specific surface area (0.325 m 2 /g vs 1.82 m 2 /g) suggesting that the greater levels of adsorption were due to MP chemistry. The weathered plastics adsorbed more Cd than the pristine plastics (e.g. maximum adsorption capacities of 153-185 and 152 mg/kg for the weathered PLA and PE respectively). However, after removal of the biofilm, adsorption of Cd to the weathered MPs was no greater than for the pristine plastics. This suggests that the increased adsorption of Cd due to weathering was caused primarily by adsorption onto the biofilm., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Xiao Xiao reports financial support was provided by China Scholarship Council. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Ltd. All rights reserved.)

Per- and polyfluoroalkyl substances (PFAS), often termed "forever chemicals," are a diverse group of persistent fluorinated compounds, including the well-known perfluorooctanesulfonic acid (PFOS), which has been identified as lethal to bee larvae. However, the risk of PFAS exposure through pollen, a bee's primary food source, has not been thoroughly investigated. In controlled greenhouse experiments, Cannabis sativa L. (hemp) plants were cultivated in soil contaminated with eight PFAS compounds. Phytoremediation potential was assessed by measuring bioconcentration factors (BCF) in both the total above-ground biomass and pollen. The study found that BCF for total PFAS in hemp pollen was significant (>20.8), with over 45% of the total PFAS uptake of around 3248 μg/kg concentrated in the pollen. Based on these figures, the estimated daily intake (EDI) of PFOS for western honeybees (Apis mellifera) was found to be about 124.5 μg/kg body weight per day. These findings underscore a critical global threat to pollinator health, with significant implications for agriculture and biodiversity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2024. Published by Elsevier Ltd. All rights reserved.)

PAH extraction methods have been widely studied over the last decades. However, there is still no consistent method for contaminated soils. Here, for the first time, PAH source characteristics in soils were considered for the investigation of different pretreatment methods, extraction techniques and solvents in nine petrogenic to primarily pyrogenic urban soils. Sources were identified by macroscopic identification of source substrates and analysis of 71 PAH and alkylation patterns. The comparison of extraction solvents revealed that a combined sequential extraction using dichloromethane (for petrogenic PAH) and toluene:methanol (6:1) led to the highest extraction efficiencies for all samples and is therefore best suited for PAH analysis of unknown samples. Acetone:n-hexane led to the lowest extraction efficiencies for all samples and is not recommended as extraction solvent. The comparison of extraction techniques showed that Pressurized Solvent Extraction is more efficient than ultrasonic extraction especially for petrogenic PAH, but also for pyrogenic PAH. Grinding increased PAH extractability considerably but mainly for petrogenic PAH from bituminous coal particles. In mixed to primarily pyrogenic samples with a smaller proportion of coal, the enhanced extractability of coal leads to a more petrogenic PAH distribution and consequently a decrease in the source identifying PAH Alkylation Index. It is concluded that PAH contents in unknown (urban) soils, where pyrogenic and petrogenic PAH can be present, cannot generally be compared if different extraction techniques, different extraction solvents and grinding or no grinding are applied. As extraction efficiency increases with more effective methods and solvents for bituminous coals, it is recommended to define a specific extraction technique and solvent mixture for improved comparability in future PAH analyses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Metolachlor is the most heavily used member of acetanilide herbicides, which are noted for forming highly soluble metabolites in root zone soils soon after field application. The two primary metabolites of metolachlor, metolachlor ethane sulfonic acid (MESA) and metolachlor oxanilic acid (MOXA), retain the same chiral chemistry as their source and are important tracers of nitrate loading from agricultural cropland. New analytical methods for separating the isomers of MESA and MOXA, enable studies assessing changes in the abundance of atropisomer pairs of the carbon chiral enantiomers in environmental samples. These changes were documented starting with the atropisomers in the parent metolachlor structure, leading to soil-degraded metabolites, and then in samples collected over 3 years from 15 subwatersheds in the Upper Choptank River Watershed. The influence of drainage differences, %hydric soil and slope, across the watershed strongly correlate with shifts in atropisomer abundance ratios, especially for those enantiomers of MOXA and MESA with axial aS rotations. The hypothesis is that differentiating atropisomer chiral shifts occur as the compounds exit to receiving waters. These findings offer a novel tool to study the transport of these important tracers of cropland-influenced groundwater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier B.V. All rights reserved.)

The waste generated from cement manufacturing is an important source of heavy metal contamination of groundwater and soil. This study investigated the concentration of toxic metals in the soil of a major cement factory and nearby groundwater. Ecological and carcinogenic risks of the metals were calculated. Potential reproductive toxicity and genotoxic effects of the samples were assessed in the sex and somatic cells of male mice using sperm abnormalities and bone marrow micronucleus (MN) assays, respectively. Also, the serum ALP, ALT, AST, total testosterone (TT), luteinizing hormone (LH), and follicle-stimulating hormone (FSH); and liver SOD and CAT activities were measured in the treated mice. Cr, Cu, Ni, Zn, Mn, Cd, and Pb levels in the soil and groundwater exceeded the allowable maximum standard. Ingestion and dermal contact were the most probable routes of human exposure with children having about 3 times higher probability of exposure to the metals than adults. Ni, Pb, and Cr presented carcinogenic risks in children and adults. In the MN result, nuclear abnormalities in the studied mice especially micronucleated polychromatic erythrocytes increased significantly (P < 0.05). Compared to the negative control, the ratio of PCE/NCE showed the cytotoxicity of the 2 samples. Data further showed a significant increase in the serum ALP, AST, and ALT while the liver CAT and SOD activities concomitantly decreased in the exposed mice. Sperm morphology results showed that the samples contained constituents capable of inducing reproductive toxicity in exposed organisms, with alterations to the concentrations of TT, LH, and FSH. Toxic metal constituents of the samples were believed to induce these reported reproductive toxicity and genotoxic effects. These results showed the environmental pollution caused by cement factories and the potential effects the pollutants might have on exposed eukaryotic organisms., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

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 soil resilience index (SRI) and soil contamination index (SCI) were calculated by Minimum Data Set and geo-accumulation model, respectively. After standardized by a multi-criteria quantitative procedure of modified Nemerow's pollution index (NPI), the integrated assessment of soil quality index (SQI), which is the minimum of SRI NPI and SCI NPI , was achieved. The results showed that Sb and As were the prominent metal(loid) pollutants, and significant correlations between SQI and SRI indicated that the poor soil quality was mainly caused by the low level of soil resilience. The primary limiting factors of SRI were Fungi in high and middle contaminated areas, and Skermanella in low contaminated area, suggesting that the weak soil resilience was caused by low specific microbial abundances. Microbial regulation and phytoremediation are greatly required to improve the soil quality at antimony smelting sites from the perspectives of pollution control and resilience improvement. This study improves our understanding of ecological effects of antimony smelting sites and provides a theoretical basis for ecological restoration and sustainable development of mining areas., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Contamination by arsenic (As) is a pressing environmental and public health issue requiring urgent remediation strategies. One cost-effective and eco-friendly method involves adding stabilizing agents to soils to reduce As mobility. However, remediation projects must also address potential ecotoxicological effects. These effects may include harmful impacts on both aquatic and terrestrial organisms, including plants, disruption of ecosystem balance, and the potential bioaccumulation of toxic substances in the food chain. Biochar from organic fraction of municipal solid waste (OFMSW) shows promise for As-contaminated soil remediation. Pot experiments were conducted with soil contaminated with As (100 mg kg -1 ) and amended with biochar produced at three different temperatures (300, 500, and 700 °C) and addition rates (1 and 5%, w/w). Chemical fractionation showed higher As concentration in a less accessible fraction (F4). Biochar amendments did not significantly differ from the control in As immobilization, but enhanced maize (Zea mays) growth and reduced As uptake, with the most promising results seen with 1% of biochar produced at 700 °C. The bioaccumulation factor (BCF) and translocation factor (TF) were both lower than 1, indicating a low absorption of As and minimal translocation from the root to the shoot. The bioaccessible percentage was higher in the samples treated with biochar compared to the control. According to the results, biochar showed no satisfactory potential for As immobilization and its approach of pretreatment/modification should be tested regarding possible improvements in the immobilization performance of As. Since most contaminations involve multiple contaminants simultaneously, it is essential to test the interactions between arsenic and other pollutants to understand the effects of biochar in such complex scenarios, which will be explored in future studies. Graphical abstract., Competing Interests: Compliance with ethical standards. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The diffusive gradient in thin films technique (DGT), with a resin gel based on Lewatit® FO 36 was used for the first time to predict arsenic (As) bioavailability in soils collected in different environmental contexts. The predicted bioavailability, determined by fluxes to DGT, was compared with the bioavailability and bioaccumulation in the plants (Calendula officinalis), where a strong correlation was observed (r = 0.8857 (C E /C roots ) and r = 0.9208 (C E /C shoots ); p < 0.05; n > 40). Arsenic, predominantly accumulated in the roots of plants from all soil samples, reached concentrations up to 507.8 mg kg -1 . To better understand the As distribution within the various soil-bearing phases, sequential extraction procedures were performed and revealed low mobility and availability of As, particularly in A and R soil samples, where As pollution is primarily caused by anthropogenic activities such as mining and industrial activities. The obtained results show that Calendula officinalis plants can be grown on soils contaminated by arsenic, while the low translocation factors indicate that accumulate arsenic predominantly in the root system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, we collected 177 soil samples from major tea-producing areas in China, systematically investigated the spatial distribution characteristics of the polycyclic aromatic hydrocarbons (PAHs) in the soil of these tea plantations and discussed the environmental factors influencing of the PAHs in tea garden soil. The feature ratio method and source analysis methods were used to determine the PAHs source in tea garden soil, and the potential risk of PAHs in tea garden soil was also evaluated. The results showed that the concentrations of the 16 PAHs in 177 samples ranged from 6.21 to 4068.91 ng g -1 , with an average of 257.00 ng g -1 . The majority of PHAs in tea garden soils predominantly contained a 5-6 ring pattern, and the highest content was indeno (1,2,3-cd) pyrene (InP, 23%) and benzo (b) fluoranthrene (BbF, 16%). In addition, 10.16% of the PAHs in tea plantation soils contained a 2-3-ring pattern, with naphthalene (NAP) having the highest content. PAH source in Chinese tea garden soil was predominantly mixed combustion, such as incomplete biomass combustion, petroleum combustion, coal combustion and wood combustion. The PAHs distribution was mainly affected by the industrial structure, geographical location of tea plantation, climatic conditions, soil properties and other factors in different regions. According to the Dutch Maliszewska-Kordybach grading standard, 79% of the soil samples from Chinese tea plantations were classified as unpolluted, 13% as mildly polluted, and 2% and 6% as moderately and severely polluted, respectively. Although the PAH pollution in tea plantations was generally low, BaP and InP pose significant ecological risk in some areas. Therefore, strategies such as effective guidelines and environmentally friendly technologies, must be developed to reduce the risk of PAH pollution in tea plantation soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

The accumulation of heavy metals (i.e., As, Cu, Ni, Pb, and Zn) in soils and native plant species near copper, nickel, and pyrite mines in Vietnam was assessed. The highest soil As, Cu, Ni, Pb, and Zn concentrations recorded in mine soils were 42.3, 1570, 9870, 128, and 462 mg/kg, and those in agricultural soils were 11.4, 453, 94.9, 34.4, and 147 mg/kg, respectively. Pollution index (PI) values indicated heavy pollution (PI = 3.99-13.0) for mine soils, and unpolluted to severely polluted (PI = 0.65-2.84) for agricultural soils. Soil enrichment factors had a wide range, from minimal to extreme enrichment of heavy metals (EF = 0.03-91.4). Arsenic minerals may be the main source of high As concentrations in sulfide mines. The As, Cu, Ni, Pb, and Zn concentrations of 20 native plant species near three mines were in the ranges of 0.05-1150, 3.17-123, 0.47-291, 0.08-6.34, and 6.87-168 mg/kg (dry weight, DW), respectively. Based on the recorded hyperaccumulation levels (1150 mg/kg, DW), bioaccumulation factors (BAF = 2.4-90.0), biomass, and rapid growth, Pteris vittata L. is considered a promising plant for phytoextraction of As in soils. Bidens pilosa L. has potential for phytostabilization of sulfide-bearing soils, given its low concentrations of heavy metals in plant shoots, BAF values of <1, high biomass, and wide distribution. Integrated phytoremediation and phytomanagement are applicable to metal-contaminated soils. Phytomining, energy crops, and vegetation cover should be investigated for the phytomanagement of metal-contaminated soils in mining areas., Competing Interests: Compliance with ethical standards. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Predicting the natural distribution of heavy metals (HMs) in soil is important to understand the potential risk of pollution. However, suitable technologies are still lacking for wide scale due to the large spatial heterogeneity. In this study, we developed machine learning models for predicting natural contents of five typical HMs in soil, including As, Cd, Cr, Hg and Pb. It was found that the optional random forest (RF) model had the best performance with the R 2 up to 0.64. Based on this model, potential distribution of the five HMs explored that elevated contents were mainly concentrated in the southwest and south central of China. Feature analysis illustrated that importance of natural factors followed the order of geological attributes > soil properties > climatic conditions > ecological functions. In particular, lithology of the parent material dominated the content of metals, with the contributions of 18-25%. Moreover, soil properties of pH, cation exchange capacity, profile depth of soil and vegetation coverage had different influences on HMs, due to the variability in the properties of different HMs. This study developed a mapping relationship between natural factors and soil HMs by data science method, which may provide instructive information for pollution control and planning decisions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Straw return-to-field releases substantial dissolved organic matter (DOM), which can interact with clay minerals and influence mercury (Hg) dynamics in soil-plant systems. However, its detailed mechanisms remain poorly understood. In this study, DOM-montmorillonite (DOM-M) complexes were synthesized using DOM extracted from composted rice straw (DOM rice ) and rape straw (DOM rape ). The objective of this study was to investigate their impacts on Hg methylation in soil and the accumulation of total Hg (THg) and methylmercury (MeHg) in vegetables. The results demonstrated that straw-derived DOM significantly increased MeHg levels in the soil and water spinach. However, humified straw-derived DOM effectively suppressed this elevation by 29.0-64.5%. Specifically, humified DOM rice resulted in lower MeHg concentrations in the soil and reduced THg and MeHg levels in water spinach compared to humified DOM rape . Natural montmorillonite reduced Hg methylation in the soil but increased the accumulation of THg and MeHg in water spinach. In contrast, the humified DOM rape -M complex significantly mitigated the MeHg accumulation in water spinach that was enhanced by montmorillonite, with a reduction percentage of 25.8-52.0%, while the humified DOM rice -M complex did not demonstrate a similar advantage. This discrepancy could be attributed to certain molecular components in DOM rape , such as higher thiol-rich protein-like fractions and oxidized S species, which could promote Hg retention within mineral layers. The reduced adsorption capacity of humified DOM rice -M for Hg 2+ also emphasized the unique role of humified DOM rape -M. Overall, this study highlights the importance of humified straw-derived DOM and its interaction with soil minerals in shaping Hg dynamics within the plant-soil system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Arsenic (As) methylation in soils affects the environmental behavior of As, excessive accumulation of dimethylarsenate (DMA) in rice plants leads to straighthead disease and a serious drop in crop yield. Understanding the mobility and transformation of methylated arsenic in redox-changing paddy fields is crucial for food security. Here, soils including un-arsenic contaminated (N-As), low-arsenic (L-As), medium-arsenic (M-As), and high-arsenic (H-As) soils were incubated under continuous anoxic, continuous oxic, and consecutive anoxic/oxic treatments respectively, to profile arsenic methylating process and microbial species involved in the As cycle. Under anoxic-oxic (A-O) treatment, methylated arsenic was significantly increased once oxygen was introduced into the incubation system. The methylated arsenic concentrations were up to 2-24 times higher than those in anoxic (A), oxic (O), and oxic-anoxic (O-A) treatments, under which arsenic was methylated slightly and then decreased in all four As concentration soils. In fact, the most plentiful arsenite S-adenosylmethionine methyltransferase genes (arsM) contributed to the increase in As methylation. Proteobacteria (40.8%-62.4%), Firmicutes (3.5%-15.7%), and Desulfobacterota (5.3%-13.3%) were the major microorganisms related to this process. These microbial increased markedly and played more important roles after oxygen was introduced, indicating that they were potential keystone microbial groups for As methylation in the alternating anoxic (flooding) and oxic (drainage) environment. The novel findings provided new insights into the reoxidation-driven arsenic methylation processes and the model could be used for further risk estimation in periodically flooded paddy fields., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Bound residual (BR) fraction typically represents the "endpoint" of soil pollution risk assessment and remediation. However, it remains unclear whether the BR fraction of sulfamethoxazole (SMX) still presents a release risk after immobilized by biochar. Therefore, the SMX migration rate in different fractions were quantified. Results revealed that there are three extractable fractions of SMX in biochar-soil systems, allowing the migration of SMX among these various fractions. 1.0 % biochar could increase 8.5 %∼14.1 % BR fraction and 17.9 %∼36.9 % non-extractable fraction, respectively. Model simulations and Sobol Global Sensitivity Analysis results revealed that migration of SMX from BR fraction to labile fraction or stably-adsorbed fraction significantly affects overall fraction migration, suggesting BR fraction still poses a potential release risk. When considering the BR fraction, the half-life of SMX extended to 93.8 ∼ 132.0 days. Thus, the potential release risk of SMX in the BR fraction should not be overlooked when applying biochar for soil remediation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)