Data for Dissolved lead (Pb) and Pb isotope along the East China Sea and Kuroshio transect – evidence for isopycnal transport and particle exchange

Lead (Pb) isotopes are widely used in tracing processes that transport Pb within the environment due to the globally-spread Pb pollution. In today’s ocean, Pb is mainly sourced from anthropogenic emissions and is removed by particle scavenging. However, recent efforts involving Pb isotopes started to point that sediments at ocean boundary, either suspended or benthic, as a previously underestimated source and sink of Pb to the seawater dissolved pool. To assess the contributions of Pb from seawater-sediment boundary, we measured the dissolved Pb concentrations and isotopic compositions in seawater from the outer East China Sea (ECS) and along the Kuroshio. Along the Kuroshio, depth profiles exhibit highly similar Pb concentrations across constant density planes, suggesting isopycnal transport. Pb isotope ratios in most of the samples show strong contributions of aerosol Pb, except for seawaters from the East China Sea and deep Okinawa Trough (>800m), which show evidences of crustal Pb contribution. The Okinawa Trough deep water has overlapping Pb isotope ratios with East China Sea water, where the suspended particulate matter is abundant. Our data on Pb isotopes in the East China Sea and the Okinawa Trough deep water, together with data from previous studies at other continental margins suggest that the seawater-sediment boundary along the continental shelves may be an important source and sink in marine Pb cycling.

铅（Pb）同位素因全球范围内广泛分布的铅污染，被广泛应用于示踪铅在环境中的迁移过程。当前海洋中的铅主要来自人为排放，并通过颗粒清除作用得以去除。然而，近期针对铅同位素的研究表明，海洋边界处的悬浮或底栖沉积物，此前被低估了其作为海水溶解态铅库的源与汇的作用。为评估海水-沉积物边界贡献的铅占比，我们测定了东海外陆架及黑潮沿线海水中的溶解态铅浓度与同位素组成。在黑潮区域，深度剖面显示等密度面上的铅浓度高度相似，表明存在等密度输运过程。多数样品的铅同位素比值显示出气溶胶铅的显著贡献，但东海及冲绳海槽800米以深的海水样品除外，这些样品表现出地壳来源铅的贡献特征。冲绳海槽深层海水的铅同位素比值与东海海水重叠，而东海区域悬浮颗粒物丰富。我们针对东海及冲绳海槽深层海水的铅同位素数据，结合其他大陆边缘的已有研究数据，表明大陆架沿线的海水-沉积物边界可能是海洋铅循环中重要的源与汇。