Sinking particles play a critical role in transferring carbon from the atmosphere to the deep ocean. However, only a small fraction of the organic carbon produced in the euphotic zone finally gets sequestrated in the deep ocean/sediment due to intensive transformations, including aggregation, disaggregation, and remineralization. Mesoscale eddies are one of the processes that can affect ocean nutrient budget, and thus affect carbon sequestration. But studies have yet to be carried out to examine how particle dynamics inside eddy-impacted regions alter carbon export efficiency. Here, we combine observed thorium isotopes (²²⁸Th and ²³⁴Th) and particulate organic carbon (POC) data at two stations (TS1 at the center of a cyclonic eddy, SEATS as a reference station is at non-eddy-impacted region) in the South China Sea with a 1D inverse model to infer particle-dynamic parameters and study how particle dynamics can impact particle export efficiency. We assume second-order kinetics for adsorption and aggregation, and first-order reaction kinetics for remineralization, disaggregation, and desorption. Our model results show that the rates of remineralization and disaggregation at TS1 were higher than at SEATS, indicating an enhanced particle fragmentation inside the eddy. The enhanced particle fragmentation counteracted the nutrient pumping effect that promoted surface ocean production and eventually led to an equivalent carbon flux compared to non-eddy impacted SEATS station.