Seasonal cycling of zinc and cobalt in the Southeast Atlantic along the GEOTRACES GA10 section
Seasonal cycling of zinc and cobalt in the Southeast Atlantic along the GEOTRACES GA10 section
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DOI：
10.5194/bg-2020-42
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
N. Wyatt;A. Milne;E. Achterberg;T. Browning;H. Bouman;E. Woodward;M. Lohan
中科院分区：
文献类型：
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作者：
N. Wyatt;A. Milne;E. Achterberg;T. Browning;H. Bouman;E. Woodward;M. Lohan
抽象的。我们报告了 2010 年南半球春季和 2011/2012 年夏季东南大西洋亚热带和亚南极水域溶解锌 (dZn) 和钴 (dCo) 的分布。在亚热带地表水中观察到强烈的季节性信号，早春混合层 dZn 和 dCo 浓度分别为 3.16 ± 1.35 nM 和 39 ± 9 pM，而夏季值因生物活动而远低于这些水平。春季混合层 dZn 浓度升高是由于 20-50 m 深度的 dZn 明显近海迁移造成的，而这些升高的 dZn 源自厄加勒斯浅滩的成岩输入。相比之下，公海亚南极地表水表现出基本一致的季节间混合层 dZn 和 dCo 浓度，分别为 0.11 ± 0.08 nM 和 11 ± 5 pM。上层水体中 dZn 和 dCo 的垂直分布与磷酸盐 (PO43−) 的垂直分布相似，在每个季节和整个动态生物地球化学范围内都具有正线性关系，表明该区域这些金属的表面生物下降和浅层再矿化在很大程度上影响了它们的分布。根据 PO43− 的线性回归计算得出的 dZn 和 dCo 的生态化学计量表明，在东南大西洋上层水体中，相对于 dCo，dZn 的总体使用量更大，季节间 Zn:Co 比率在 9 到 29 之间。发现亚热带地表水 Zn:Co 比率在春季和夏季之间下降，表明在季节之间 dZn 相对于 dCo 优先去除。在本文中，我们研究了东南大西洋两个不同生态系统中外部输入和浮游植物演替的季节性影响如何与 dZn 和 dCo 的分布以及 Zn:Co 生态化学计量的变化相关。
Abstract. We report the distributions of dissolved zinc (dZn) and cobalt (dCo) in sub-tropical and sub-Antarctic waters of the Southeast Atlantic Ocean during austral spring 2010 and summer 2011/12. A strong seasonal signal was observed in sub-tropical surface waters with early spring mixed-layer dZn and dCo concentrations of 3.16 ± 1.35 nM and 39 ± 9 pM, respectively, compared with summer values depleted well below these levels by biological activity. The elevated spring mixed-layer dZn concentrations resulted from an apparent offshore transport of elevated dZn at depths between 20–50 m, derived from lithogenic inputs from the Agulhas Bank. In contrast, open-ocean sub-Antarctic surface waters displayed largely consistent inter-seasonal mixed-layer dZn and dCo concentrations of 0.11 ± 0.08 nM and 11 ± 5 pM, respectively. The vertical distributions of dZn and dCo in the upper water column were similar to that of phosphate (PO43−), with positive linear relationships during each of the seasons and across dynamic biogeochemical regimes, suggesting surface biological drawdown and shallow remineralisation of these metals in this region largely influences their distribution. The ecological stoichiometries for dZn and dCo, calculated from the linear regression with PO43−, suggest a greater overall use of dZn relative to dCo in the upper water column of the Southeast Atlantic with an inter-seasonal Zn:Co ratio ranging between 9 and 29. Sub-tropical surface water Zn:Co ratios were found to decrease between spring and summer indicating a preferential removal of dZn relative to dCo between seasons. In this paper we investigate how the seasonal influences of external input and phytoplankton succession may relate to the distribution of dZn and dCo, and variation in Zn:Co ecological stoichiometry, across two distinct ecological regimes in the Southeast Atlantic.