To estimate the risks and developing remediation strategies for the mercury (Hg)-contaminated soils, it is crucial to understand the mechanisms of Hg transformation and migration in the redox-changing paddy fields. In present study, a Hg-spiked acidic paddy soil (pH 4.52) was incubated under anoxic conditions for 40 d and then under oxic conditions for 20 d. During anoxic incubation, the water-soluble, exchangeable, specifically adsorbed, and fulvic acid-complexed Hg decreased sharply, whereas the humic acid-complexed Hg, organic, and sulfide-bound Hg gradually increased, which were mainly ascribed to the enhanced adsorption on the surface of soil minerals with an increase in soil pH, complexation by organic matters, precipitation as HgS, and absorption by soil colloids triggered by reductive dissolution of Fe(III) oxides. By contrast, after oxygen was introduced into the system, a gradual increase in available Hg occurred with decreasing soil pH, decomposition of organic matters and formation of Fe(III) oxides. A kinetic model was established based on the key elementary reactions to quantitatively estimate transformation processes of Hg fractions. The model matched well with the modified Tessier sequential extraction data, and suggested that large molecular organic matter and humic acid dominated Hg complexation and immobilization in acidic paddy soils. The content of methylmercury increased and reached its peak on anoxic 20 d. Sulfate-reducing bacteria Desulfovibrio and Desulfomicrobium were the major Hg methylating bacteria in the anoxic stage whereas demethylating microorganisms Clostridium_sensu_stricto_1 and Clostridium_sensu_stricto_12 began to grow after oxygen was introduced. These new dynamic results provided new insights into the exogenous Hg transformation processes and the model could be used to predict Hg availability in periodically flooded acidic paddy fields.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.envpol.2023.121335 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The Effect of Cysteine on the Removal of Cadmium in Paddy Soil by Combination with Bioremediation and the Response of the Soil Microbial Community.
Toxics
December 2024
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
Bioremediation is widely recognized as a promising and efficient approach for the elimination of Cd from contaminated paddy soils. However, the Cd removal efficacy achieved through this method remains unsatisfactory and is accompanied by a marginally higher cost. Cysteine has the potential to improve the bioleaching efficiency of Cd from soils and decrease the use cost since it is green, acidic and has a high Cd affinity.
View Article and Find Full Text PDFPhenol-Quinone Redox Couples of Natural Organic Matter Promote Mercury Methylation in Paddy Soil.
Environ Sci Technol
January 2025
National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
Methylmercury in paddy soils poses threats to food security and thus human health. Redox-active phenolic and quinone moieties of natural organic matter (NOM) mediate electron transfer between microbes and mercury during mercury reduction. However, their role in mercury methylation remains elusive.
View Article and Find Full Text PDFUtilizing conductive materials for reducing methane emissions in postharvest paddy rice soil microcosms.
Sci Total Environ
January 2025
Program of Sustainability in Biosystems, Institute of Agrifood Research and Technology (IRTA), Caldes de Montbui, Barcelona, Spain. Electronic address:
Paddy fields are a major anthropogenic source of global methane (CH) emissions, a powerful greenhouse gas (GHG). This study aimed at gaining insights of different organic and inorganic conductive materials (CMs) - biochar, fungal melanin, and magnetite - to mitigate CH emissions, and on their influence on key microbial populations, mimicking the postharvest season throughout the degradation of rice straw in microcosms under anaerobic conditions encompassing postharvest paddy rice soils from the Ebro Delta, Spain. Results showed that fungal melanin was the most effective CM, significantly reducing CH emissions by 29 %, while biochar amendment also reduced emissions by 10 %.
View Article and Find Full Text PDFA root system architecture regulator modulates OsPIN2 polar localization in rice.
Nat Commun
January 2025
State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.
Ideal root system architecture (RSA) is important for efficient nutrient uptake and high yield in crops. We cloned and characterized a key RSA regulatory gene, GRAVITROPISM LOSS 1 (OsGLS1), in rice (Oryza sativa L.).
View Article and Find Full Text PDFRice-Fish Farming Improved Antioxidant Defences, Glucose Metabolism, and Muscle Nutrient of in Sichuan Province.
Metabolites
December 2024
Fisheries Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu 611730, China.
Rice-fish farming is an ancient and enduring aquaculture model in China. This study aimed to assess the variations in digestive enzymes, antioxidant properties, glucose metabolism, and nutritional content between reared in paddy fields and ponds. Notably, the levels of amylase and trypsin in from rice paddies were considerably higher compared to those from ponds.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!