Given their ephemeral nature, eddies have proven difficult to study, with contrary results from field observations that typically sample at the center during a specific stage of an eddy lifespan. Using the natural occurring radionuclide ²³⁴Th, we examined particle fluxes within two cyclonic eddies (CEs) at different evolutionary stages (mature stage eddy, C2, and a decay stage eddy, C1) in the oligotrophic western South China Sea (SCS). Using a 1‐D steady state model, ²³⁴Th derived particulate organic carbon (POC) and opal fluxes at 100 m were determined. Both POC and opal fluxes were significantly higher at the eddy edges relative to the eddy cores, with integrated eddy POC and opal fluxes of 6.2 (2.1) mmol C m⁻² day⁻¹ and 1.5 (0.28) mmol Si m⁻² day⁻¹ in C2 (C1). When compared to non‐eddy regimes, both POC (by 2.6‐fold) and opal fluxes (by 7.5‐fold) in C2 were enhanced; they were reduced and decoupled (0.9‐fold and 1.4‐fold) in C1. The difference in enhancement of particle fluxes and the coupling/decoupling between POC and opal flux likely reflects changes in phytoplankton community structures resulting from eddy evolution. Scaling these results to the entire SCS basin suggests that CEs contribute <4% of the net POC flux but >15% of the opal flux. Therefore, CEs may regulate the biogeochemical cycling of silica to a much greater extent than carbon in the ocean.

中文翻译：

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旋风涡流中碳和蛋白石出口的瞬态增强和解耦

考虑到涡流的短暂性，涡流已经难以研究，而现场观测的结果却相反，涡流寿命通常在涡流寿命的特定阶段在中心采样。使用天然存在的放射性核素²³⁴ Th，我们在贫营养型南海西部（SCS）中检查了两个旋风涡（CE）中处于不同演化阶段（成熟期涡C2和衰减期涡C1）内的粒子通量。使用一维稳态模型，确定了100 m处的²³⁴ Th衍生颗粒有机碳（POC）和蛋白石通量。相对于涡流核心，POC和蛋白石通量在涡流边缘处均显着更高，涡流POC和蛋白石通量的总和为6.2（2.1）mmol C m ^-2天^-1在C2（C1）中为1.5（0.28）mmol Si m ^-2 day ^-1。与非涡流相比，C2中的POC（增加了2.6倍）和蛋白石通量（增加了7.5倍）都得到了增强；它们在C1中减少和解耦（分别为0.9倍和1.4倍）。颗粒通量的增强以及POC和蛋白石通量之间的耦合/去耦的差异可能反映了涡流演变引起的浮游植物群落结构的变化。将这些结果扩展到整个南海盆地，表明CE贡献的净POC通量<4％，但蛋白石通量> 15％。因此，与海洋中的碳相比，CE可以更大程度地调节二氧化硅的生物地球化学循环。