Thorium‐230 (²³⁰Th) produced in the water column is mostly removed to in situ sediments by sinking particles (proximal scavenging), allowing for the correction of vertical particle fluxes by normalizing accumulated 230Th recorded in marine sediments to its production. However, boundary scavenging, which causes lateral ²³⁰Th transport, potentially challenges the premise of the application of ²³⁰Th. In this study, we establish an empirical correlation between ²³⁰Th scavenging intensity and export productivity (EP), enabling the quantification of boundary scavenging effects on the global scale. The contribution of boundary scavenging is quantified to be prominent only in high‐productivity regions (EP > 130 mg C/m2 /day). Since merely 15% of the mid‐low latitude ocean (EP > 200 mg C/m2 /day; mostly marginal seas and coastal upwelling zones) experiences severe ²³⁰Th lateral transport (>30% of the seawater production), boundary scavenging exerts a negligible impact on ²³⁰Th normalization in most of the pelagic ocean. The deficits and excesses of observed ²³⁰Th in the water column relative to predictions are also quantified, in line with the pathways of deep ocean circulation. Our work places important constraints on the lateral transport of ²³⁰Th in the ocean, and verifies its limited impact on the application of ²³⁰Th normalization in the mid‐low latitude pelagic ocean.

暂无