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Paddy soil is recognized as a hotspot for mercury (Hg) transformation. Soil acid-base property (expressed as pH) plays a crucial role in Hg methylation and accumulation in paddy systems. However, it is challenging to study this process in soils with varying pH values due to the rarity of a single soil type spanning a wide pH range. Purple paddy soil, vital for rice cultivation in southwestern China, occurs naturally in three types based on pH: acidic, neutral, and calcareous. This variation makes purple paddy soil an ideal subject for these studies. Thus, this study investigated Hg transformation and bioaccumulation across these three purple soil types. The results showed that during the rice growing seasons, both methylmercury (MeHg) concentration and methylation potential were higher in acidic purple paddy soil than in neutral and calcareous types. In addition, total mercury (THg) and MeHg concentrations in plant tissues grown in acidic purple paddy soil were significantly higher than in other two purple soil types. These results suggest that acidic purple paddy soil was conducive to Hg methylation and accumulation in rice plants. Given that soil acidification is becoming a serious global issue, the findings could offer fundamental data on the potential risk of Hg exposure due to soil acidification.
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http://dx.doi.org/10.1016/j.envres.2024.120475 | DOI Listing |
Environ Pollut
September 2025
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Key Laboratory of Groundwater Pollution Simulation and Control Ministry of Ecology and Environment, Chinese Research Academy of Environmental Sciences, Beiji
Paddy soil represents a critical sink for microplastics (MPs), where frequent redox oscillations from wet-dry alternation can accelerate MPs aging, and alter dissolved organic matter (DOM) composition in paddy soil. However, this process remains poorly understood to date. Here, we systematically investigated the aging of three MPs and their structural effects on DOM in paddy soil during wet-dry alternation.
View Article and Find Full Text PDFJ Environ Manage
September 2025
College of Resources, Sichuan Agricultural University, Chengdu, 611130, China; Key Laboratory of Investigation and Monitoring, Protection and Utilization for Cultivated Land Resources, Ministry of Natural Resources, Chengdu, 611130, China. Electronic address:
While organic manure application effectively increases soil organic carbon (SOC) content, it may elevate greenhouse gas emissions. Crop straw, a widely available agricultural residue, enhances SOC through gradual decomposition. The effect of organic manure combined with crop straw on the organic carbon components of paddy soil is still unclear.
View Article and Find Full Text PDFEnviron Sci Process Impacts
September 2025
Nebraska Water Center, Part of the Robert B. Daugherty Water for Food Global Institute 2021 Transformation Drive, University of Nebraska, Lincoln, Nebraska 68588-6204, USA.
Rice is consumed by ∼50% of the global population, grown primarily in flooded paddy fields, and is susceptible to arsenic accumulation. Inorganic arsenic, particularly in reduced form (As(III)), is considered the most toxic and is more likely to accumulate in rice grains under flooded systems. We postulate that increased levels of highly reactive iron minerals, such as ferrihydrite, in paddy soils can regulate the bioavailability of arsenic and reduce its uptake by priming iron plaque formation.
View Article and Find Full Text PDFEnviron 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).
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