Dissolved barium and silicon isotopes at the Congo River-dominated Southeast Atlantic margin from METEOR cruise M121 (GEOTRACES cruise GA08)@en

To better understand the association between barium (Ba) and silicon (Si) at ocean margins, we collected filtered seawater samples along the Congo River plume at the coast of Congo and Gabon and along an off-shelf section at 3°S, complemented by three freshwater samples collected directly from the Congo River. The water samples from the Congo margin were collected during GEOTRACES cruise GA08 with German RV Meteor (M121) in November-December 2015 with a stainless steel CTD rosette and a towed fish for surface waters. Congo River freshwater samples were taken upstream by boat in May, July and October 2017 near the center of the river at ~6°S and ~12.5°E (stations 12.1-12.3). We determine for the first time Ba and Si stable isotopes at the Congo River-dominated Southeast Atlantic margin. Based on these data we evaluate the contribution of Congo River plume to Ba and Si budgets in the South East Atlantic Ocean, and the association between Ba and Si at the Congo margin.

为明晰海洋边缘带中钡（Ba）与硅（Si）的耦合关联，本研究沿刚果与加蓬海岸的刚果河羽流区域，以及3°S的陆架外断面采集了过滤海水样品，并补充采集了3份直接取自刚果河的淡水样品。刚果边缘带的海水样品采集于2015年11—12月，搭载于德国"流星号"（RV Meteor）M121航次执行的GEOTRACES航次GA08，采用不锈钢温盐深仪采水器阵列（CTD rosette）与表层水拖曳式采水器（towed fish）完成采样。刚果河淡水样品于2017年5、7、10月通过乘船在刚果河上游采集，采样点位位于河流主航道附近，坐标约为6°S、12.5°E（站位12.1-12.3）。本研究首次在以刚果河为主导的东南大西洋边缘带测定了Ba与Si的稳定同位素。基于上述实测数据，本研究评估了刚果河羽流对东南大西洋海域Ba、Si收支的贡献，以及刚果边缘带中Ba与Si的耦合关联。