海底地下水排泄（SGD）是近岸海洋化学和生态系统演化的重要驱动因素，其携带的大量物质对珊瑚礁发育和退化起着非常重要的作用。然而，基于长时间序列的SGD动态变化记录的研究极为薄弱。本项目拟以南海北部的海南三亚，广东大亚湾和广西涠洲岛珊瑚礁区为研究对象，以地球化学为主要研究手段，利用珊瑚骨骼（常量和微量元素、稳定同位素和放射性核素）的环境记录功能，重建近百年来南海北部岸礁区SGD及其携带物质通量的年际变化记录和近十年的月际变化记录。同时，综合SGD和珊瑚生理指标在时间和空间上的变异特征、人类活动记录、近岸水文地质条件、地下水和海水化学参数研究，查明SGD对珊瑚礁发育和退化的影响机制及其关键过程，进而甄别南海北部不同海域珊瑚礁退化的主导驱动因素，并提出科学合理的应对建议。

Submarine groundwater discharge (SGD) is an significant driving factor of marine chemistry and coastal ecosystem evolution, and plays a very important role in the development and degradation of coral reefs due to supplying large loads of chemicals into the coastal ocean. Nevertheless, the studies on records of SGD dynamic changes based on long time series are rather weak. This progect plans to take the coral reef zones of Sanya in Hainan, Daya Bay in Guangdong and Weizhou Island in Guangxi in the northern South China Sea as the objects of study. Geochemistry is selected as the main approach of this study. The environmental proxy records of coral skeletons (constant and trace elements, stable isotopes and radionuclides) are applied to reconstruct the historical patterns of the annual fluxes of SGD and chemicals it carries during the past century, as well as the monthly ones during the past decades. Meanwhile, an integrated investigation of spatial-temporal variabilities of SGD and coral physiological indicators, the records of anthropogenic activities, alongshore hydrogeological conditions, and chemical parameters of groundwater and seawater will be made to exlore the mechanism and its key process impacting the development and degradation of coral reefs. Further, the dominate driving factors of different areas in the northern South China Sea will be identified, and then the scientific and reasonable advices will be offered.