海底地下水排放（简称SGD）是陆源物质向海输送的重要通道，对河口等近岸海域的营养盐的分配补给和收支平衡影响显著。本研究拟以同位素示踪技术评估SGD对黄河口及其邻近海域中营养盐的含量和结构的影响。首先通过建立黄河三角洲地下水监测网，分析地下河口中的营养盐结构及其与镭氡同位素的相关关系；然后借助同位素示踪技术圈定SGD的显著排放区域，探讨不同水动力条件对SGD组成类型和显著排放区域范围的影响；在此基础上，利用同位素质量平衡模型估算SGD及其携带入海的营养盐通量，对比同期的黄河径流的输送贡献，剖析SGD对黄河口营养盐含量和结构的影响。本项目的实施将有助于深入理解黄河口及其邻近海域的陆海相互作用，丰富对高浑浊河口营养盐生物地球化学研究的认识。

Submarine groundwater discharge (SGD) has been recognized as an important partway for terrestrial materials transported into the coastal ocean. It significantly contributes to the nutrients distribution and budget in estuaries. In this study, geochemical isotopes would be used as tracers to assess the influence of SGD to the nutrient load and structure in the Yellow River Estuary (YRE). Groundwater monitoring network will be established in the Yellow River delta to better understand the nutrient structure and its relationship with radium and radon isotopes. Using isotopic tracing technique, we will locate the apparent SGD area and clarify the SGD components under different estuarine hydrodynamics. Based on Ra-Rn isotopes mass balance models, the fluxes of SGD and its associated nutrients will be quantified and compared with the contributions of the Yellow River. The information obtained here will help to understand the land-ocean interactions in the YRE, and to enrich the knowledge of nutrient biogeochemistry in high turbid estuaries.