摘要
高砷地下水造成的砷中毒对人体健康产生巨大威胁,砷甲基化过程可将毒性更高的无机砷转化为毒性低的甲基砷,在一定程度上可以降低砷的环境风险从而减轻对人体的毒害,有望成为调控地下水砷污染问题的有效途径.然而目前高砷地下水的研究主要侧重于无机砷的迁移转化,对于甲基砷富集的关键过程与控制因素研究还十分有限.本研究选取江汉平原长江与汉江沿岸的浅层地下水开展无机碳同位素示踪与溶解性有机质三维荧光光谱分析,解析江汉平原地下水中控制甲基砷富集的有机质降解途径,识别关键生物地球化学过程.研究发现江汉平原的甲基砷浓度范围为<0.01~444μg/L(平均值为30μg/L),长江沿岸和汉江沿岸地下水甲基砷的富集主控过程有明显差异:长江沿岸地下水中,以高分子量芳香族有机化合物降解驱动的产甲烷过程为主导,促进砷的生物甲基化过程;此外,伴随有机质发酵的硫酸盐还原过程也可导致地下水中甲基砷的富集.汉江沿岸地下水中,以小分子活性有机质发酵过程为主导,促进了砷生物甲基化过程.
Arsenic poisoning caused by high-arsenic groundwater represents a significant threat to human health.The arsenic methylation process,which converts highly toxic inorganic arsenic into less toxic methylated arsenic species,has the potential to mitigate the environmental risk of arsenic contamination and reduce its toxicity to humans.This process may provide an effective approach to managing arsenic pollution in groundwater.However,current research predominantly focuses on the migration of inorganic arsenic,with limited understanding of the key processes and controlling factors that govern the enrichment of methylated arsenic.In this study,it analyzed shallow groundwater from the Jianghan plain,located along the Yangtze and Han rivers,using inorganic carbon isotope tracing and EEMs of dissolved organic matter.The aim of this study is to elucidate the organic matter degradation pathways that regulate the enrichment of methylated arsenic and to identify the key biogeochemical processes involved.It found that methylated arsenic concentrations in the Jianghan plain ranged from<0.01 to 444μg/L,with an average concentration of 30μg/L.The processes controlling methylated arsenic enrichment differed significantly between groundwater from the Yangtze River and the Han River.Along the Yangtze River,the degradation of high-molecular-weight aromatic organic compounds drives methanogenesis,which in turn promotes arsenic biomethylation and the subsequent enrichment of methylated arsenic in groundwater.Additionally,the sulfate reduction process,associated with the fermentation of organic matter,also supports arsenic biomethylation.In contrast,in the Han River region,the arsenic biomethylation process is primarily driven by the fermentation of small-molecule reactive organic matter.
作者
袁晓芳
李林倩
张彦鹏
邓娅敏
Yuan Xiaofang;Li Linqian;Zhang Yanpeng;Deng Yamin(Geological Survey,China University of Geosciences,Wuhan 430074,China;Wuhan Center of China Geological Survey,Wuhan 430205,China;MOE Key Laboratory of Groundwater Quality and Health,School of Environmental Studies,China University of Geosciences,Wuhan 430078,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2024年第11期3917-3929,共13页
Earth Science
基金
国家重点研发计划“变革性技术关键科学问题”重点专项“劣质地下水改良的原位调控理论与技术研究”(No.2021YFA0715900).
关键词
甲基砷
地下水
碳
同位素
三维荧光光谱
江汉平原
水文地质.
groundwater
methylated arsenic
carbon
isotopes
three-dimensional excitation-emission matrix spectroscopy
Jianghan plain
hydrogeology.
