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The efficiencies of neutral salts, strong acids, and chelates were tested for extracting cadmium (Cd) from three paddy soils. The higher the selectivity of the cations of the added neutral salts toward soil adsorption sites, the lower the pH in the extracts and the more soil Cd could be extracted. In addition, soil carbon and nitrogen contents and mineral composition were closely associated with the amount of Cd extracted. Calcium chloride and iron(III) chloride were selected as wash chemicals to restore Cd-contaminated paddy soils in situ. Washing with calcium chloride led to the formation of Cd chloride complexes, enhancing Cd extraction from the soils. The washing also substantially decreased soil levels of exchangeable and acid-soluble Cd, which are the major forms of bioavailable Cd for rice (Oryza sativa L.). The optimum conditions for in situ soil washing were also determined for calcium chloride.
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http://dx.doi.org/10.1016/j.envpol.2006.01.017 | DOI Listing |
Environ Sci Technol
September 2025
Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Iron plaque (IP) on rice root surfaces has been extensively documented as a natural barrier that effectively reduces contaminant bioavailability and accumulation. However, its regulatory mechanisms in rhizospheric methane oxidation and biological nitrogen fixation (BNF) remain elusive. This study reveals a previously unrecognized function of IP: mediating methanotrophic nitrogen fixation through coupled aerobic methane oxidation and IP reduction (Fe-MOX).
View Article and Find Full Text PDFJ Hazard Mater
September 2025
State Key Laboratory of Regional and Urban Ecology, Ningbo Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China; Zhejiang Key Laboratory of Pollution Control for Port-Petrochemical Industry, CAS Haixi Industrial Technology Innovation
Reactive oxygen species (ROS) are critical mediators of soil biogeochemical processes. While the production of ROS with biochar (BC) in the rhizosphere has not been explored. We demonstrate that BC and Fe-modified biochar (FeBC), prepared at 400°C and 600°C, influence ROS generation in paddy soil containing biodegradable (polybutylene succinate: PBS) and conventional (polystyrene) microplastics (MPs).
View Article and Find Full Text PDFJ Hazard Mater
August 2025
Hubei Key Laboratory of Microbial Transformation and Regulation of Biogenic Elements in the Middle Reaches of the Yangtze River, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan 430205, China; State Key Laboratory of Green and Efficient Development of
Microplastics (MPs) have been shown to enhance nitrous oxide (NO) emissions and soil salinization potentially amplifying this effect. This study investigated the individual and combined impacts of polyethylene (PE) MPs and salinity on NO emissions from paddy soils, while simultaneously analyzing related microbial parameters. MPs significantly increased cumulative NO emissions by 9.
View Article and Find Full Text PDFJ Environ Manage
September 2025
Institute of Biological & Environmental Sciences, University of Aberdeen, 23 St. Machar Drive., Aberdeen, AB24 3UU, UK.
Integration of diverse fertilisation strategies with water-saving irrigation techniques presents a promising sustainable agricultural practice, offering the potential to reduce greenhouse gases (GHGs) emissions, enhance carbon sequestration and boost crop yields. However, existing research on the influence of soil microorganisms on biogeochemical processes of GHGs is limited. Herein, we explored the microbial mechanisms influencing GHGs emissions through a 3-year field experiment and metagenomic sequencing conducted in southeastern China.
View Article and Find Full Text PDFJ Hazard Mater
August 2025
Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China. Electronic address:
Environmental remediation strategies for cadmium (Cd)-contaminated rice paddies often face challenges due to reliance on time-consuming field trials and limited pre-assessment of intervention efficacy. Here, we propose a machine learning and causal inference-integrated framework to enable proactive decision-making, using iron plaque-mediated Cd immobilization as a model system. By analyzing 76 paired soil-rice samples, extreme gradient boosting (XGBoost) and SHapley Additive exPlanations (SHAP) identified six critical drivers of grain Cd accumulation from 31 physicochemical and microbial indicators.
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