Bigumditlevsen0143

nd metabolism, as well as coenzyme transport and metabolism. These results can provide a good foundation for the evaluation of vegetation restoration in the Loess Plateau, as well as a scientific basis for the rational management of plantations.Soil archaeal communities play an essential role in the biogeochemical cycles of agricultural ecosystems. However, the response and mechanisms of soil archaeal community structure and assembly processes to heavy metal pollution remain poorly understood. This study examined the archaeal community composition and assembly process and their relationships with environmental factors in arable soils around high geological background areas, metal enterprises, and mining areas, based on high-throughput sequencing. The arable soils within the study area exhibited high spatial heterogeneity of heavy metal content, as well as severe cadmium pollution. The ecological risk levels were high in some soil samples from mining areas, but low to moderate in other soil samples. Crenarchaeota (62.7%-98.3%) was the dominant phyla in all soil samples, followed by Halobacterota (1.1%-23.2%). The pH, organic matter, arsenic, and lead contents of the soil were significantly correlated with the archaeal community (P less then 0.05), making them the main driving factors of archaeal community structure. The null-model analysis showed that the assembly process of the archaeal community was mainly influenced by heterogeneous processes, including heterogeneous selection (deterministic process) and dispersal limitation (stochastic process). Heterogeneous selection played a vital role in our study areas, while homogeneous selection only occurred in samples around the metal enterprises. Therefore, environmental selection was the ultimate driver of the archaeal community assembly process in this study, and its relative importance varied according to habitat type. Environmental heterogeneity increased the contribution of heterogeneous selection to community assembly, thus enhancing the community's resistance to environmental stress, and contributing to the stability and sustainability of the agricultural ecosystem.The combination of endophytes and hyperaccumulator plants can significantly improve the efficiency of heavy metal phytoremediation in contaminated soil. A plant endophyte named Herbaspirillum R-13 was isolated from rice roots in a cadmium (Cd) contaminated paddy field. This strain exhibited a strong tolerance to Cd2+ and could grow on a solid medium with a Cd2+ concentration of 300 mg·kg-1. The R-13 strain was able to produce siderophores and Indole acetic acid (IAA), through color reactions. In addition, Pikovskaya's and Ashby's solid medium tests showed that the R-13 strain had a lower capacity for dissolving phosphorus but a higher capacity for fixing nitrogen. In the pot experiment, high-throughput sequencing technology was used to track the colonization of the R-13 strain in Solanum nigrum L. roots. Three days after inoculation, the relative abundance of Herbaspirillum in the root of Solanum nigrum L. had increased by 201.88% compared to the blank control (CK) and after two inoculations, the relative abud with Cd.A rice pot experiment was conducted to study the effects of four soil conditioners, namely polyacrylic acid (PAA), polyacrylamide (PAM), polyvinyl alcohol (PVA), and humic acid (HA), on rice growth and heavy metal uptake from paddy soil contaminated with copper and cadmium. The results showed that the height and straw weight of rice in the conditioned soil treatments increased by 7.34%-22.0% and 10.0%-32.2%, respectively, compared to the control treatment. The increased height and straw weight was generally proportional to the amount of soil conditioners used in each treatment. Application of 0.4% soil conditioners led to a slight reduction in rice yield, with the grain weight decreasing by 6.70%-32.6% relative to the control treatment. Soil conditioners had no effect on soil pH, but significantly reduced the concentration of soil available Cu (5.38%-39.7%) and Cd (6.98%-59.6%). Similarly, concentrations of Cu in rice root, straw, and grain were decreased by 0.88%-27.2%, 8.50%-45.2%, and 3.41%-31.2%, respectively, while concentrations of Cd were decreased by 5.93%-20.5%, 10.0%-51.4%, and 3.12%-50.7%, respectively. The largest and smallest decreases occurred in the PAA and PVA treatments, respectively. Application of PAA, PAM, and HA significantly decreased the translocation factor of Cu from root to straw by 11.2%-27.1%, whereas the translocation factor of Cu from straw to grain increased by 17.9%-33.6%, respectively, compared with the control treatment. D-AP5 purchase Application of PAA, PAM, and HA significantly decreased the translocation factor of Cd from root to straw by 15.2%-38.5%, compared with the control treatment, but with the exception of HA, had no effect on Cd translocation from straw to grain. In general, the application of soil conditioners promoted rice growth, inhibited the uptake of Cu and Cd by rice, and had a certain remediation effect on heavy metal contaminated soil.A field experiment was conducted in moderately and severely Cd contaminated paddy fields in Beishan Town, Changsha City, Hunan Province. This study examined the effects of LS amendment (limestone+sepiolite), in combination with soil application and foliar spraying of Zn fertilizer, on Cd uptake in early and late rice plants. The results showed that ① the application of LS (2250 kg·hm-2 and 4500 kg·hm-2) significantly increased pH and CEC values in paddy soil during the early and late rice seasons, but the addition of Zn fertilizer (90 kg/hm2) to soil and through foliar spraying (0.2 g·L-1 and 0.4 g·L-1) had no significant effects on the pH or CEC of the soil. ② LS application decreased concentrations of TCLP-Cd and CaCl2-Cd in the soils, by 11.5%-38.8% and 24.0%-81.0%, respectively, while neither of the treatments involving the addition of Zn fertilizer to soil or through foliar spraying had any significant effects on the concentrations of TCLP-Cd and CaCl2-Cd. ③Single treatments involving only LS amendment, nd decreasing Cd concentrations in brown rice.Heavy metals in farmland soil are one of the most hazardous pollutants in the environment, owing to their universality and irreversibility. Modified biochar has been widely used in the adsorption and immobilization of heavy metals in soil, and its applicability is mainly determined by the types of heavy metals, pollution levels, and soil environmental conditions. Soil pollution is gradually becoming more complex and diversified, and heavy metal pollutants mostly occur in the form of compound pollution. However, most studies have focused on single heavy metal pollutant or the addition of heavy metal to soil. This study used rice straw as a raw material to prepare biochar, and modified it with K3PO4, KMnO4, and NaOH. The physicochemical and structural characteristics of the modified biochars were detected using a BET accelerated surface area and porosimetry system, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and the biochars were then analyzed for the availability and foobilization efficiency of Cu and Cd in soil was achieved with K3PO4 modified biochar. With an addition of 2% K3PO4 modified biochar, the immobilization efficiency of Cu and Cd was 61.06% and 4.12%, respectively. In summary, K3PO4 modified biochar had a better immobilization effect on both Cu and Cd in compound contaminated soil.With the rapid development of electronic technology, soil heavy metal contamination caused by electronic waste dismantling activities has attracted the attention of many researchers. To investigate the contamination status and spatial distribution of Cd in soil-crop systems around an e-waste dismantling area, 171 pairs of soil and crop samples were collected for analysis. The concentrations of cadmium in root vegetable soil, leaf vegetable soil, solanaceous vegetable soil, and orchard soil were (1.292±0.647), (1.010±0.201), (0.921±0.125), and (0.861±0.135) mg·kg-1, respectively. The average values of cadmium in these four soil types were 10.0, 7.8, 7.1, and 6.3 times the background values of soil Cd in Zhejiang Province, respectively, and 4.31, 3.4, 3.07, and 2.72 times the risk screening values for soil contamination of agricultural land, clearly indicating cadmium accumulation in the soil. However, only a small percentage of crops contained cadmium levels that exceeded food safety limits. Moreover, different types of crops showed different capacities for cadmium enrichment and can be ranked accordingly leaf vegetables > root vegetables > solanaceous vegetables > fruits. The single factor pollution index and the potential ecological risk assessment revealed severe Cd contamination in the study area, with a high potential ecological risk. Cadmium exposure posed a higher health risk for children than for adults. However, the single heavy metal cadmium pollution index does not indicate a threat to local residents at this time. Moran's I index and kriging interpolation results revealed that Cd has significant spatial autocorrelation, with high values mainly concentrating around the e-waste dismantling area, indicating a significant correlation with e-waste dismantling activities.The Qinghai-Tibet Plateau is an extremely vulnerable area that is sensitive to human activities. In recent years, more and more human disturbances have been detected in this area. This study analyzed the spatial distribution and ecological risks of 7 heavy metals (Cr, Ni, Cu, Zn, As, Cd, and Pb) in two regions, namely the Bailong River and Yellow River and their two tributaries (BY region) in Gannan and the Yarlung Zangbo River and its two tributaries (YZ region) in Tibet. In terms of spatial distribution, concentrations of the seven heavy metals were higher in the east and lower in the west of the BY region. The average concentrations all exceeded the background value of the Qinghai-Tibet Plateau, especially for Cd (4.50 times) and As (2.83 times). High Pb concentrations were mainly found in water, urban and rural residential land, and industrial and construction land. In the YZ region, heavy metal concentrations were lower along the river, while high-altitude areas exhibited higher heavy metal concentrations. The average concentrations of Ni, Zn, As, and Cd exceeded the background values of the Qinghai-Tibet Plateau, especially that of Cd (3.13 times), which mostly exhibited high values in water coverage areas. The geo-accumulation index method and the potential ecological risk index method show that the degree of As and Cd pollution was relatively high in the BY region in Gannan, with the greatest potential ecological risk occurring in the water coverage area. In the YZ region in Tibet, the degree of Cd pollution was high, with the highest potential ecological risk also occurring in the water coverage area. This study provides significant guidance for the environmental protection, sustainable development, and utilization of soil under different types of land use in the Qinghai-Tibet Plateau.Metal mining is one of the main contributors of soil heavy metals. Previous studies examining the impact of metal mining on surrounding soil have mainly focused on one or a few metal mining areas. However, such studies cannot effectively inform the management of heavy metal pollution in soil at an inter-provincial scale. As part of this study, literature was collected on soil heavy metals (i.e., As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) affected by metal mining in regions of Southwest China (i.e., Yunnan Province, Sichuan Province, Guizhou Province, Chongqing Municipality, and Tibet Autonomous Region); Next, the impact of metal mining on the soil concentrations of these metals was quantified through meta-analysis, and the relationships between the selected factors (i.e., different sub-regions, metal minerals, and land-use types) and soil heavy metal concentrations were explored. Finally, the literature data was tested for publication bias. The results showed that metal mining in Southwest China has significantly increased the concentrations of heavy metals in topsoil.