The chemical speciation of Cu is dominated by complexation with organic ligands. However, the size fractionation of dissolved Cu and its organic ligands are not well understood. In this study, we revealed new insights into the biogeochemical cycling of Cu in the subarctic Pacific based on both chemical speciation and size fractionation analyses. Our data show that the surface waters of the subarctic Pacific contain a pool of colloidal Cu that was not observed in the subtropical South Pacific Ocean. Both soluble and colloidal Cu in the surface waters were strongly bound to organic ligands. In the intermediate waters, strong soluble Cu‐binding organic ligands were present, which could be related to the Cu uptake mechanism of methanotrophs under low oxygen environments. In deep waters, dissolved Cu concentrations increased but soluble Cu concentrations remained mostly constant, indicating that there are sources of colloidal non‐labile Cu in the benthic layer. Dissolved Cu exhibited a positive linear relationship with silicate in the upper 1500 m while soluble Cu displayed a linear relationship with silicate throughout the water column. The results of this study show that dissolved Cu is bound by organic ligands of various sizes and binding strengths throughout the water column of the subarctic Pacific, and that the characteristics of these ligands change with depth.

中文翻译：

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北极近太平洋中铜的生物地球化学循环的新见解：分布，尺寸分级和有机络合

Cu的化学形态主要是与有机配体络合。但是，对溶解的铜及其有机配体的尺寸分级还不甚了解。在这项研究中，我们基于化学形态分析和尺寸分级分析揭示了对北极亚太平洋太平洋地区铜的生物地球化学循环的新见解。我们的数据表明，亚太平洋太平洋的表层水含有一个胶态铜池，而在亚热带南太平洋则没有观察到这种胶态铜。地表水中的可溶性铜和胶体铜均与有机配体牢固结合。在中间水域中，存在强固溶性的结合铜的有机配体，这可能与低氧环境下甲烷营养菌对铜的吸收机制有关。在深水里 溶解铜的浓度增加，但可溶性铜的浓度基本保持恒定，表明底栖层中存在胶态非不稳定铜的来源。在整个水柱中，溶解的铜与硅酸盐在1500 m处呈正线性关系，而可溶性铜与硅酸盐呈线性关系。这项研究的结果表明，溶解的铜在整个南极太平洋水柱中被各种大小和结合强度的有机配体结合，这些配体的特征随深度而变化。在整个水柱中，溶解的铜与硅酸盐在1500 m处呈正线性关系，而可溶性铜与硅酸盐呈线性关系。这项研究的结果表明，溶解的铜在整个南极太平洋水柱中被各种大小和结合强度的有机配体结合，这些配体的特征随深度而变化。在整个水柱中，溶解的铜与硅酸盐在1500 m处呈正线性关系，而可溶性铜与硅酸盐呈线性关系。这项研究的结果表明，溶解的铜在整个南极太平洋水柱中被各种大小和结合强度的有机配体结合，这些配体的特征随深度而变化。