MOE Key Laboratory of Groundwater Quality and Health, China University of Geosciences, Wuhan, Hubei 430078, China; School of Environmental Studies, China University of Geosciences, Wuhan, Hubei 430078, China.
College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
J Hazard Mater. 2024 Nov 5;479:135684. doi: 10.1016/j.jhazmat.2024.135684. Epub 2024 Aug 28.
Arsenic (As) mobilization in paddy fields poses significant health risks, necessitating a thorough understanding of the controlling factors and mechanisms to safeguard human health. We conducted a comprehensive investigation of the soil-porewater-rice system throughout the rice life cycle, focusing on monitoring arsenic distribution and porewater characteristics in typical paddy field plots. Soil pH ranged from 4.79 to 7.98, while porewater pH was weakly alkaline, varying from 7.2 to 7.47. Total arsenic content in paddy soils ranged from 6.8 to 17.2 mg/kg, with arsenic concentrations in porewater during rice growth ranging from 2.97 to 14.85 μg/L. Specifically, arsenite concentrations in porewater ranged from 0.48 to 7.91 μg/L, and arsenate concentrations ranged from 0.73 to 5.83 μg/L. Through principal component analysis (PCA) and analysis of redox factors, we identified that arsenic concentration in porewater is predominantly influenced by the interplay of reduction and desorption processes, contributing 43.5 % collectively. Specifically, the reductive dissolution of iron oxides associated with organic carbon accounted for 23.3 % of arsenic concentration dynamics in porewater. Additionally, arsenic release from the soil followed a sequence starting with nitrate reduction, followed by ferric ion reduction, and subsequently sulfate reduction. Our findings provide valuable insights into the mechanisms governing arsenic mobilization within the paddy soil-porewater-rice system. These insights could inform strategies for irrigation management aimed at mitigating arsenic toxicity and associated health risks.
砷在稻田中的迁移对人体健康构成重大威胁，因此需要深入了解其控制因素和机制，以保障人类健康。本研究在水稻全生育期内对土壤-孔隙水-水稻系统进行了全面调查，重点监测了典型稻田土壤中砷的分布和孔隙水特征。土壤 pH 值范围为 4.79-7.98，而孔隙水 pH 值呈弱碱性，范围为 7.2-7.47。稻田土壤中总砷含量范围为 6.8-17.2 mg/kg，水稻生长期间孔隙水中砷浓度范围为 2.97-14.85μg/L。具体而言，孔隙水中亚砷酸盐浓度范围为 0.48-7.91μg/L，砷酸盐浓度范围为 0.73-5.83μg/L。通过主成分分析（PCA）和氧化还原因子分析，我们发现孔隙水中砷浓度主要受还原和脱附过程的相互作用影响，两者共同作用占比 43.5%。具体而言，与有机碳相关的氧化铁的还原溶解对孔隙水中砷浓度动态变化的贡献率为 23.3%。此外，土壤中砷的释放遵循硝酸盐还原、铁离子还原和硫酸盐还原的顺序。本研究结果为深入了解稻田土壤-孔隙水-水稻系统中砷迁移的机制提供了重要线索。这些发现可为灌溉管理策略提供参考，以减轻砷毒性和相关健康风险。
