The East China Sea (ECS) is a complex marginal sea with potential sources and sinks of trace metals. In this study, we investigated the distributions of dissolved Cd, Cu, Zn, and Cu-binding organic ligands in the ECS. Concentrations of Cd and macronutrients were below detection limit in the surface Kuroshio waters. Surface Zn concentrations increased along the Kuroshio Current, which may be attributed to atmospheric deposition. We detected two classes of Cu-binding organic ligands in those waters, classified as L₁ (log K = 13.6–15.2) and L₂ (log K = 11.2–13.1), respectively. L₁ could be related to biological production while L₂ distributions appeared to be controlled by water mass mixing. Particularly, the Kuroshio Surface Water had relatively low L₂ concentrations. There were no significant sources of Cu-binding organic ligands in the intermediate waters. Cd, Cu, and Zn exhibited strong positive relationships with phosphate in the intermediate waters, suggesting that phytoplankton uptake and subsequent regeneration were the dominant controls of these elements at these depths. In deep waters, the distributions of Cd, Cu, and Zn were mainly controlled by water mass mixing. This was apparent from the unique trace metal to macronutrient ratios propagating from the South China Sea and West Philippine Sea to the ECS, according to water mass mixing patterns. Cd/phosphate, Zn/phosphate, Zn/silicate, and Cu/silicate ratios in the ECS were comparable with those in the North Pacific region. This implies the absence of additional supplies of Cd, Cu, Zn, and macronutrients from marginal sources in the ECS.

中文翻译：

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东海溶解Cd、Cu、Zn和Cu结合有机配体分布的控制

东海 (ECS) 是一个复杂的边缘海，具有潜在的痕量金属源和汇。在这项研究中，我们研究了溶解的 Cd、Cu、Zn 和 Cu 结合有机配体在 ECS 中的分布。表层黑潮水域中 Cd 和常量营养素的浓度低于检测限。沿黑潮海流，地表锌浓度增加，这可能归因于大气沉积。我们在这些水中检测到两类与铜结合的有机配体，分别归类为 L ₁ (log K  = 13.6–15.2) 和 L ₂ (log K  = 11.2–13.1)。L ₁可能与生物生产有关，而 L ₂分布似乎受水团混合控制。特别是黑潮地表水的 L ₂相对较低浓度。在中间水域中没有重要的铜结合有机配体来源。Cd、Cu 和 Zn 与中间水域中的磷酸盐表现出强烈的正相关关系，表明浮游植物吸收和随后的再生是这些深度的这些元素的主要控制因素。在深水区，Cd、Cu和Zn的分布主要受水体混合控制。根据水团混合模式，从南海和西菲律宾海传播到 ECS 的独特的痕量金属与常量营养素的比率很明显。ECS中的Cd/磷酸盐、Zn/磷酸盐、Zn/硅酸盐和Cu/硅酸盐比率与北太平洋地区的比率相当。这意味着没有额外的 Cd、Cu、Zn、