高砷地下水是人类面临的最为严峻的环境问题之一，沉积物中天然有机质（NOM）组成（特别是其生物可利用性）是控制地下水中砷释放的关键因素。本项申请以江汉平原为工作区，研究不同沉积环境下NOM的组成与分布，利用新型NOM生物可利用性特征指标-名义碳氧化态（NOSC），从微观尺度识别NOM驱动下含水层中砷迁移转化的生物地球化学过程，揭示洪泛平原地下水系统中NOM对砷空间分布异质性的影响机制，建立基于“沉积环境-NOSC-砷含量”链式关系的饮水型砷暴露风险预测模型，为区域高砷地下水的预测与防控提供科学依据。本项申请以NOM为纽带，从沉积环境的视角，结合新型测试技术，研究地下水中砷分布的空间异质性，具有重要的科学意义，同时又可为与碳元素相关的其他有害物质迁移转化的类似研究提供经验和借鉴，具有重要的实用价值。

High arsenic groundwater is one of the most serious environmental issues humankind facing, and the natural organic matter (NOM) in the sediments, especially its bioavailability, is the key factor controlling the release of arsenic from sediment into groundwater. In this study, the Jianghan Plain will be selected as the study area to identify the spatial distribution and characterization of NOM under different sedimentary conditions. Moreover, the nominal oxidation state of carbon (NOSC), as a new NOM bioavailable indicator, will be used to figure out the biogeochemical processes of NOM driving the arsenic migration and transformation in the aquifer matrix, thereby identifying the correlation between the NOM and arsenic spatial heterogeneity. Understanding the linkage among sedimentary environment, NOSC and groundwater arsenic will help to build a risk prediction model on evaluating the arsenic exposure to residents, which further provides scientific fundament for the future prediction on the occurrence of high arsenic groundwater. Generally, in this study, the NOM in the groundwater system will be fully studied to explain the heterogeneity distribution of groundwater arsenic via the application of several new measurement technologies. Moreover, the full understanding of the groundwater NOM will also provide some new insights on studying the mobilization of the carbon-related hazardous substances in the groundwater system.