Cadmium (Cd) is a trace metal whose distribution in the ocean bears a remarkable resemblance to the nutrient phosphate (PO₄³⁻). This resemblance has led to the use of Cd as a proxy for ocean nutrient cycling in paleoceanographic applications, but the processes governing the cycling of Cd in the modern ocean remain unclear. In this study, we use previously published Cd observations and an Artificial Neural Network to produce a dissolved Cd climatology that reproduces the observed subtle deviations between the Cd and distributions. We use the Cd and climatologies, along with an ocean circulation inverse model, to diagnose the biogeochemical sources and sinks of dissolved Cd and . Our calculations reveal that dissolved Cd, like , is removed in the surface ocean and has a source in the subsurface, consistent with the simultaneous incorporation of Cd and into sinking organic particles. However, there are also contrasts between the cycling of dissolved Cd and In particular, the surface export ratio varies 8-fold across latitudes, reaching highest values in the iron-limited sub-Antarctic Southern Ocean. This depletes Cd relative to in the low-latitude thermocline while adding excess Cd to deep waters by the regeneration of Cd-enriched particles. Also, Cd tends to regenerate slightly deeper than in the subsurface ocean, and the regeneration ratio reaches a maximum at 700–1,500 m. These contrasts are responsible for a slight concavity in the relationship and should be considered when interpreting paleoceanographic Cd records.

中文翻译：

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镉和磷酸盐海洋循环的全球对比

镉 (Cd) 是一种痕量金属，其在海洋中的分布与营养磷酸盐 (PO ₄ ^3- )具有显着的相似性。这种相似性导致在古海洋学应用中使用 Cd 作为海洋养分循环的代理，但控制现代海洋中 Cd 循环的过程仍不清楚。在这项研究中，我们使用先前发表的 Cd 观测和人工神经网络来生成溶解的 Cd 气候学，重现观察到的 Cd 和分布之间的细微偏差。我们使用 Cd 和气候学以及海洋环流反演模型来诊断溶解的 Cd 和 的生物地球化学源和汇。我们的计算表明溶解的 Cd，如, 在表层海洋中被移除，在地下有一个来源，这与 Cd并入下沉有机颗粒的同时结合一致。然而，溶解的 Cd 循环之间也存在对比，特别是，表面输出比率在纬度之间变化 8 倍，在铁限制的亚南极南大洋达到最高值。这会消耗低纬度温跃层中的 Cd，同时通过富含 Cd 的颗粒的再生向深水中添加过量的 Cd。此外，Cd 的再生往往比地下海洋略深，再生率在 700-1,500 m 处达到最大值。这些对比是造成轻微凹陷的原因 在解释古海洋学 Cd 记录时应该考虑这种关系。