东海陆架边缘海域水团结构及其向黑潮的物质输出研究

Processes within the East China Sea Shelf Edge Area (ECSSEA) control the exchange of material between the East China Sea Shelf (ECSS) and Processes within the East China Sea Shelf Edge Area (ECSSEA) control the exchange of material between the East China Sea Shelf (ECSS) and the adjoining Kuroshio. These processes in this area influence not only supply and transport of the nutrients from the Kuroshio to the ECSS, but also the terrigenous and anthropogenic material transport from East Asia to the West North Pacific via the Kuroshio. Kuroshio water is composed of Kuroshio Surface Water, Kuroshio Tropical Water, and Kuroshio Intermediate Water etc, wherein only Kuroshio Intermediate Water is enriched in nutrients. Current studies are lack of information to discern these Kuroshio water sources that have already mixed with East China Sea water. However, multi-geochemical tracers could be very useful tools to differentiate various water sources and provide high-resolution water mass structure. So far, most of studies have used numerical modeling and physical oceanography methods to study the water mass movement and flux. There are few studies that have paid attention to the material transport from the East China Sea continental shelf to the Kuroshio. The continental run-off is one of the key themes in GEOTRACES. In this study, the high-resolution water mass structure in the ECSSEA will be characterized by using multi-geochemical tracers, and the nutrient sources and the contributions of each source will be determined. The results will provide the direct scientific basis for the assessment of the contribution of the Kuroshio to the ECSS primary productivity and the terrigenous and anthropogenic material transport from the East Asia to West North Pacific via the Kuroshio.

东海陆架边缘海区是黑潮与东海大陆架相互作用关键带。黑潮水主要为黑潮表层水、黑潮次表层水和黑潮中层水，其中只有黑潮中层水富含较多营养盐。已有研究未能辨别这些与东海水混合的黑潮水的来源，多元地球化学示踪法可以提供直接证据进行区分，提供高精度水团解析。现有研究较少关注东海陆架向黑潮的物质输出，这对于定量估算陆架区与黑潮间物质输送至关重要，边缘海向大洋的物质输出也是国际GEOTRACES（An International Study of Marine Biogeochemical Cycles of Trace Elements and their isotopes）计划的主要研究内容。本项目拟采用以稀土元素为核心的多元地球化学示踪法高分辨率解析东海陆架边缘区域水团结构，研究东海陆架与黑潮间的物质交换，聚焦东海陆架向黑潮的营养物质输送的量化，为准确评估东亚陆架向西北太平洋的物质输出提供科学依据。

东海陆架边缘海区是黑潮与东海大陆架相互作用关键带。黑潮水主要为黑潮表层水、黑潮次表层水和黑潮中层水，其中只有黑潮中层水富含较多营养盐。已有研究未能辨别这些与东海水混合的黑潮水的来源，多元地球化学示踪法可以提供直接证据进行区分，提供高精度水团解析。现有研究较少关注东海陆架向黑潮的物质输出，这对于定量估算陆架区与黑潮间物质输送至关重要，边缘海向大洋的物质输出也是国际GEOTRACES（An International Study of Marine Biogeochemical Cycles of Trace Elements and their isotopes）计划的主要研究内容。本项目采用以稀土元素为核心的多元地球化学示踪法高分辨率解析东海陆架边缘区域水团结构，研究东海陆架与黑潮间的物质交换，聚焦东海陆架向黑潮的营养物质输送的量化。主要研究结论包括（1）稀土元素、Nd同位素、Al、U同位素等多元地球化学参数是研究中国近海水团及陆架边缘海物质输运的有力工具。（2）夏季，长江冲淡水（CDW）对济州岛西南部的贡献量约为20%，对中国沿岸的贡献量超过60%；黑潮对中国东海东部的影响比例超过60%；东海北部，黄海水团的影响比例超过40%，在济州岛西南有最大值，这可能受到反气旋的影响；黑潮的流经是引起中国东海影响邻近海域的一个重要途径，CDW对日本海的贡献量约为10±3%，黑潮和黄海的贡献量约为62±2%和28±7%；约为6±3%的东海陆架水影响到西北太平洋。（3）浙、闽沿岸底层高浓度的Al 以平流输送的方式通过次表层（23.3~ 24.0 kg/m3）向黑潮进行输送，东海陆架沿密度面23.5 kg/m3的跨陆架输送较为显著。溶解态Al起源于浙、闽沿岸底层，然后向东北延伸，随之通过东海陆架往西南移动，在北纬30度附近进入黑潮水。以上研究证实了东海陆架水的输出过程是西北太平洋潜在的物质来源。