The attenuation of particulate organic carbon (POC) flux with depth is a fundamental control on the efficiency of the marine biological pump and ocean carbon sequestration. ²³⁰Th normalization provides a powerful approach for estimating vertical POC flux profiles, but this method assumes that excess ²³⁰Th is primarily supplied through vertical scavenging from the overlying water column. However, this assumption may be violated in regions characterized by strong lateral particle transport, including boundary currents, nepheloid layers, and enhanced horizontal redistribution of particle-reactive elements. The potential influence of lateral ²³⁰Th scavenging on reconstructed POC flux profiles remains poorly quantified.

The eastern equatorial Pacific (EEP) provides an ideal setting to evaluate this effect because of pronounced gradients in particle export and intense lateral transport associated with deep-water circulation. Here, we apply a recently developed lateral scavenging correction approach to previously published ²³⁰Th-normalized POC flux profiles measured along the GP16 transect in the EEP. By incorporating lateral scavenging effects into the ²³⁰Th normalization framework, we compare conventional and corrected estimates of POC flux attenuation, evaluate implications for reconstructed particle transfer efficiency, and assess the spatial variability of lateral scavenging effects along the transect.

Our results reveal that lateral scavenging corrections introduce systematic spatial and depth-dependent changes in reconstructed POC flux profiles. The magnitude of the correction exhibits pronounced spatial variability among stations. The largest corrections occur within the upper and mesopelagic ocean, whereas reconstructed deep-water fluxes are comparatively less affected. Corrected POC flux profiles show modified attenuation patterns compared with conventional ²³⁰Th-based estimates, indicating that neglecting lateral ²³⁰Th transport may bias assessments of particle transfer efficiency. These findings highlight the importance of accounting for lateral scavenging when applying ²³⁰Th normalization to quantify vertical POC flux attenuation and particle transfer efficiency.