高砷地下水是人类面临的最为严峻的环境问题之一，溶解性有机质（DOM）是地下水中砷释放过程的主控因素，准确判定DOM的来源并量化各种来源的贡献率是高砷地下水防治的关键和难点。本项申请以江汉平原为典型研究区，利用DOM中稳定碳氧同位素测试技术，分析不同来源DOM中稳定碳氧同位素的组成特征，通过室内实验获取DOM在砷释放过程中稳定碳氧同位素的分馏系数，结合稳定同位素混合模型，识别地下水中DOM的来源，量化不同来源DOM的贡献率及其动态变化，探析地下水中砷释放过程对DOM来源变化的响应机制。本项申请可为溶解性有机质的来源解析开辟新方法，为高砷地下水的防治提供科学依据，同时又可为环境中其他有害物质的来源解析提供经验和借鉴，具有重要的理论意义与实用价值。

High arsenic groundwater is one of the most serious environmental issues facing mankind, the release of arsenic from sediment to groundwater is mainly controlled by dissolved organic matters (DOM). Revealing the sources of DOM is the key to impede the high arsenic groundwater. Based on the study of high arsenic groundwater in the Jianghan Plain, this work plans to identify the sources of DOM in the groundwater, quantify the contribution ratios of different sources of DOM related to arsenic releasing, and understand their temporal variations. This work will be done by using the technology of carbon and oxygen isotopes in the DOM, analyzing the stable carbon and oxygen isotope compositions of the different sources of DOM, acquiring the fractionation factor of stable carbon and oxygen isotopes of DOM in arsenic releasing processes, and combining with stable isotopes mixing models. This study will provide new method to identify the source of DOM and other matters. More importantly, it will provide new scientific bases for the prevention and treatment of high arsenic groundwater.