Resolving distribution and controls of terrigenous and marine particulate organic matter across an energetic shelf

Abstract. We assess the sources, distribution and controls of particulate organic matter (POM) across the northeastern Taiwan Strait, where monsoonal forcing, water-mass mixing, riverine inputs and sediment resuspension modulate particle dynamics. By integrating lignin biomarkers, bulk geochemistry, and sedimentary constraints within a two-step quantification approach, we demonstrate the influence of river discharge, plume intrusions, and seafloor resuspension on the distribution of terrigenous POM. Terrigenous particulate organic carbon (POC_terr) represents a minor component in most water samples but becomes substantial in resuspension-dominated layers. Combining estimated POC_terr with modeled current velocities yields an export flux of ~243 ± 56 kt C yr^‒1, consistent with the regional imbalance between riverine input and sedimentary burial. After correction for terrigenous influence, bulk POM properties exhibit features reflecting nutrient supply, photoacclimation, and temperature-dependent variation in stable carbon isotopic (δ¹³C) composition. Comparisons with co-sampled surface sediments show that biomarker signals are preserved more faithfully than δ¹³C of organic matter, which is strongly modulated by lateral transport. This study provides a practical framework for quantifying terrigenous and marine POM in continental-shelf settings and offers improved constraints for interpreting source-to-sink processes and sedimentary archives.