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Understanding the relationship between suspended particulate matter (SPM), sediment organic C, N stable isotopes, and lake trophic state index (TSI) is essential for managing lake pollution and eutrophication. According to the δ 13 C, δ 15 N, and C/N we found that the organic C in SPM and sediment of Caohai Lake primarily originated from macrophytes, while N was sourced from chemical fertilizers, phytoplankton, and aquatic plants. Total nitrogen, total phosphorus, NO3 - -N, oxidation reduction potential, and Chl.a were identified as key factors influencing the sources and variations of SPM and sediment organic C and N stable isotopes in Caohai Lake, with a significant linear correlation observed between C, N stable isotopes, and TSI in sediments. To mitigate eutrophication in Caohai Lake, it is recommended that farmers apply fertilizers judiciously to minimize nutrient loss and that aquatic plants be regularly harvested to reduce N release from plant residues., 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.)

Hypolithic communities, which occupy highly specialised microhabitats beneath translucent rocks in desert and arid environments, have assembly mechanisms and ecosystem functions are not fully understood. Thus, in this study, we aimed to examine the microbial community structure, assembly, and function of light-accessible (under quartz, calcite, and hypolithic lichen-dominated biocrusts) and light-inaccessible microhabitats (under basalt and adjacent soil) in the Qaidam Desert, China. The results showed that hypolithic communities have different characteristics compared with microbial communities of light-inaccessible microhabitats. Notably, hypolithic bacterial communities were dominated by Cyanobacteria, whereas light-inaccessible microhabitats showed a predominance of Bacteroidetes and Proteobacteria. Although the class Dothideomycetes (phylum: Ascomycota) dominated the fungal communities between the two microhabitat types, Sordariomycetes were more prevalent in light-accessible microhabitats. Network and robustness analyses showed that hypolithic communities were less complex and more resilient than microbial communities in light-inaccessible microhabitats. Our results indicated that deterministic processes, specifically homogeneous selection, govern the establishment of bacterial and fungal communities in light-accessible and light-inaccessible microhabitats. The hypolithic community showed an increased frequency of phylotypes that exhibited increased tolerance to functional stress response pathways. In contrast to light-inaccessible microhabitats, light-accessible microhabitats showed a slight decrease and a notable increase in the prevalence of carbon fixation pathways in prokaryotes and carbon fixation in photosynthetic organisms, respectively. For fungi, light-accessible microhabitats enriched saprotrophic and ectomycorrhizal groups. These results highlight the importance of complex and diverse microhabitats in desert regions, which serve as vital shelters for microbes. Combining future research on interactions between hypolithic communities and environments may enhance our current understanding of their pivotal roles in sustaining desert ecosystems. This knowledge then be applied to design and implement informed conservation efforts to preserve these unique rock-associated microhabitats in desert ecosystems., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Yanfei Sun reports financial support was provided by National Natural Science Foundation of China. Yanfei Sun reports a relationship with National Natural Science Foundation of China that includes: funding grants. 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. Published by Elsevier Inc.)

Understanding PAH and OCP distributions and sources in lakes is necessary for developing pollutant control policies. Here, we assessed the occurrence, risk, and sources of PAHs and OCPs in the sediment of Caohai Lake. The PAHs were predominantly high-molecular-weight compounds (mean 57.5 %), and the diagnostic ratios revealed that coal, biomass burning, and traffic were the sources of PAHs. HCHs (6.53 ± 7.22 ng g -1 ) and DDTs (10.86 ± 12.16 ng g -1 ) were the dominant OCPs and were primarily sourced from fresh exogenous inputs. RDA showed that sediment properties explained 74.12 % and 65.44 % of the variation in PAH and OCP concentrations, respectively. Incremental lifetime cancer risk (ILCR) assessment indicated that hazardous PAHs in Caohai Lake sediment posed moderate risks to children and adults (ILCR>1.0 × 10 -4 ), while the risk from OCPs was low; however, the recent influx of HCHs and DDTs requires additional attention., 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.)

Data on selenium (Se) transformation, specifically the mineralization or activation of Se bound by microorganisms in natural Se-enriched soil, is limited. Therefore, this study investigates the effects of microorganisms on Se availability of Se-enriched lateritic red soil and Se uptake by pak choi. Following the incubation of Stenotrophomonas maltophilia S1 and arbuscular mycorrhizal (AM) fungi agent, the available Se content of soils increased from 35 to 66.69-117.04 μg/kg, corresponding to an increase of 90.50-234.40%. The Se bioconcentration and translocation factors in pak choi increased after adding the AM fungi agent and strain S1. The soil acid phosphatase activity, and pak choi root length, surface area, and diameter also increased. Moreover, the soil acid phosphatase activity showed a significant positive correlation with soil available Se and phosphorus content (p < 0.01). Overall, the AM fungi agent and strain S1 increased Se bioavailability by enhancing soil acid phosphatase and promoting root activity, ultimately increasing pak choi's ability to absorb available Se., 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 The Authors. Published by Elsevier Inc. All rights reserved.)

An integrated assessment of heavy metal (HM) contamination in dissolved matter, suspended particular matter (SPM) and sediments in lakes is essential. This study assessed the risks of HMs in the water, SPM and sediment of Caohai, China, and analyzed the changes in sediment HM contamination in conjunction with historical data. The HM transport was dominated by the SPM load, and the concentrations of Zn (179.07-1821.24 mg kg -1 ), Pb (53.63-181.46 mg kg -1 ), and Cd (3.68-21.31 mg kg -1 ) in SPM and sediment were 5.34-149.11 times higher than the upper continental crust (UCC) values. SPM and sediments were lightly to extremely polluted and had moderate to very high toxicity risks with Cd, Pb and Zn, and these three HMs originated from industrial and agricultural sources. The concentrations of Zn, Pb, and Cd in Caohai sediments increased by 36.7-187.9 % in 2022 compared to pre-2020. This research provides valuable reference data for the remediation of polluted karst lakes., 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 Ltd.)

The concentration and speciation of endogenous cadmium (Cd) in soil systems derived from parent materials is continuously altered by rock-soil-plant interactions. Previous studies on the distribution of Cd primarily focused on surface soil at regional scale. However, it lacks a novel approach to provide a new perspective on dynamics and redistribution of Cd in soil profile. Therefore, this study tries to establish the linkage between isotope fractionation and environmental processes of Cd in soil profiles with geogenic Cd enrichment based on Cd isotopes. High Cd concentrations were observed in the profile from forest at accumulation zone and the one from farmland at ridge in a rural area, southwest China. Soil erosion and deposition substantially influence the vertical distribution of total Cd in soil from the accumulation zone. Accordingly, distinct Cd isotope compositions were observed in different layers (δ 114/110 Cd: -0.087 ‰ to -0.066 ‰ vs -0.325 ‰ to -0.056 ‰). Mineral transformation, pedogenesis and biological activities controlled the dynamics and redistribution of Cd. The mobility of Cd increased during weathering processes, with ~40 % to 60 % of Cd residing in exchangeable fraction in the surface layers. Biological activity is a vital factor that drives Cd isotope fractionation in soil, resulting in depletion of heavy Cd isotopes in surface layers of the studied farmland profile. Contrasting fractionation effects were observed in profiles from forest and farmland due to the variance in soil-plant Cd cycling. Our study revealed the processes that control dynamics and redistribution of endogenous Cd in soil profiles, and proved that Cd isotope is a useful tool to investigate the bio-geochemical processes of Cd in soil systems., 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 © 2022 Elsevier B.V. All rights reserved.)

This study investigated the pollution, fractionation and potential risks of heavy metals in soils from a mountainous area with black shale outcropping, with emphasis on Cd and Zn. Elevated concentrations of heavy metals in black shales reflected high geochemical baseline in the study area. Metals released from oxidative weathering were redistributed and retained during pedogenic processes, leading to enrichment of Cd, Cu, Cr, Ni, V and Zn in soils. As a highly concerned metal pollutant, the content of Cd in all collected samples (N = 112, Cd: 0.44-16.1 mg/kg) exceeded the risk screening value for Chinese agricultural land. Metals in local soils were retained through adsorption onto soil constituents clay minerals and FeMn oxides and/or precipitation within secondary minerals. Based on sequential extraction, Cd and Zn fractionated in soils, with Cd mainly occurring in the mobile fraction (47.9% to 78.7%) as adsorbed, FeMn oxides and carbonate associated phases, whereas residual fraction (67.1%) dominated for Zn, followed by FeMn oxides coagulation (17.9%). Metals in residual soils from slopping location were highly related to metals in the parent rocks distributed more heterogeneously than metals in alluvial soils from flat location. High levels of heavy metal pollution in soils posed potential risks to the local eco-environmental systems and community, and Cd was highly concerned due to its high mobility. Cultivation in alluvial soils from valleys poses less risk than in residual soils, but appropriate approaches to reduce the risk in local soils is still necessary. The findings from this study provide basic knowledge and insight for risk control and targeted management of soils with geogenic heavy metal pollution in black shale outcropped mountainous 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 © 2020 Elsevier B.V. All rights reserved.)

In this paper, FTIR microspectroscopy was used to compare Cortex Eucommiae from Anhui Province (A), Henan Province (B) and Sichuan Province (C) of China. High-resolution spectra were obtained with good reproducibility. From IR spectra, some obvious differences in band frequency could be observed among Cortex Eucommiae A-C. Curve fitting result indicated that polysaccharides' structures and contents were different among Cortex Eucommiae A-C. To distinguish Cortex Eucommiae from different producing areas, the A1245/A1328 ratio might be an exceptionally practical factor. Additionally, FTIR microspectroscopy could identify Cortex Eucommiae A-C with 89.5% accuracy in combination with hierarchical cluster analysis. The results suggest FTIR microspectroscopy is very easy and efficient for distinguishing Cortex Eucommiae from different areas, and also indicate FTIR microspectroscopy may be practical for TCM research., (Copyright © 2015 Elsevier B.V. All rights reserved.)