Behaviors of the organic matter of various origins in the estuarine turbidity maximum (ETM) serves as a fundamental part of global organic carbon circulation. To better understand provenance and transport processes of particulate organic matter in the ETM, we conducted an hourly-time resolution, semi-quantified study in Jiulong River Estuary (JRE), southern China. In the field, we measured on-site hourly hydrological parameters and collected hourly particulate suspended and settling organic matter by filtering waters and using sediment traps; In the lab, we analyzed the samples for grain size composition and geochemical proxies; And finally, we applied statistical methods to explore the controlling mechanisms of the ETM particulate organic matter (POC), and come with the following main finding: Both suspended and settling POC in JRE ETM are predominantly fine grained particles (< 63μm), with strong influence of sedimentary POC especially during flood tides; Concentration of suspended POC is positively correlated to tide velocity, while high settling POC flux is observed during low tide velocity periods; Provenance of both suspended and settling POC is controlled by tide velocity via its magnitude, direction and duration, through resuspension, water-mass change and the adequacy of source POC supply; Finally, a conceptual transport model of ETM POC is summarized regarding POC provenance and tide velocity changes. Findings of this study provide insight details on the controlling mechanisms of tide velocity on the transport processes of ETM POC, and will improve our understanding of POC behaviors at the land-ocean interface.

particulate organic carbon; tide velocity; resuspension; Empirical Orthogonal Function (EOF) Analysis; estuary turbidity maximum zone