The ²³¹Pa/²³⁰Th ratio of seawater and in ocean sediments is a potentially powerful tool in tracing oceanic processes such as the ocean circulation and marine primary productivity. However, ²³¹Pa/²³⁰Th reflects the combined signal of multiple controls associated with scavenging and oceanic transport, limiting its use as a paleo-proxy. Given that links between seawater and sedimentary ²³¹Pa and ²³⁰Th distributions are crucial for understanding the cycling and removal fluxes of these nuclides, we carry out analysis of ²³¹Pa and ²³⁰Th in both seawater (dissolved phase) and modern sediment samples acquired from five depth transects across the northern tropical Atlantic open ocean. Overall, the sediment data support the dominance of ²³¹Pa export in the deep Atlantic Ocean (>2.5 km) associated with the southward advection of North Atlantic Deep Water. However, the seawater data provide evidence for locally enhanced scavenging of ²³¹Pa and ²³⁰Th near the western seamounts that is likely to be associated with the influence of hydrothermal activity or episodic formation of transient nepheloid layers. At shallower depths (0.5–1.5 km), paired sediment and seawater ²³¹Pa/²³⁰Th data reveal enhanced burial of ²³¹Pa at the eastern and mid-Atlantic sites that is likely related to elevated marine primary productivity and/or influence of boundary scavenging at the African margin, and a net input of ²³¹Pa potentially maintained by the northward advection of intermediate water masses and an additional mechanism of upward diffusion. Our findings provide greater insights into the range of oceanic processes that play a significant role in the cycling of ²³¹Pa and ²³⁰Th, with implications for the controls of ²³¹Pa/²³⁰Th distribution in the Atlantic Ocean.

在²³¹帕/ ²³⁰在海洋沉积物海水和Th比是在跟踪海洋过程如海洋环流和海洋初级生产力潜在有力工具。然而，²³¹ Pa / ²³⁰ Th反映了与扫气和海洋运输相关的多种控制的综合信号，从而限制了其作为古代理的用途。鉴于海水与²³¹ Pa和²³⁰ Th沉积物之间的联系对于理解这些核素的循环通量和清除通量至关重要，因此我们对²³¹ Pa和²³⁰进行分析海水（溶解相）和现代沉积物样品中的Th均来自横跨热带北部大西洋的5个深度样带。总体而言，沉积物数据支持了与北大西洋深水向南平流有关的深大西洋（> 2.5 km）中²³¹ Pa的出口占主导地位。然而，海水数据为西部海山附近²³¹ Pa和²³⁰ Th的局部增强清除提供了证据，这很可能与热液活动的影响或短暂性星状胶体层的偶发形成有关。在较浅的深度（0.5-1.5 km），成对的沉积物和海水²³¹ Pa / ²³⁰ Th的数据表明，^231的埋藏量增加了大西洋东部和中部站点的Pa可能与海洋初级生产力的提高和/或非洲边缘的边界清除的影响有关，中间水团的北向平流和另外的补充可能使净输入为²³¹ Pa向上扩散的机制。我们的发现为在²³¹ Pa和²³⁰ Th循环中起重要作用的海洋过程范围提供了更深刻的见解，对控制大西洋中²³¹ Pa / ²³⁰ Th的分布有重要意义。