Multi-Isotopic approach to trace the provenance and trajectory of sinking particles in the Ulleung Basin, East Sea (Japan Sea)

The Ulleung Basin (UB), in the East Sea (Japan Sea) hosts a long-term ocean monitoring station with a time-series sediment trap. We present new 1-year sinking particle fluxes, along with organic (radiocarbon) and inorganic (detrital neodymium; ϵNd-detrital) isotopic compositions of sinking particles and surface sediments in order to constrain lateral particle advection. The εNd-detrital values of the Korean Peninsula and the Japanese Islands bedrocks differ distinctly, and the εNd-detrital values of surface sediments increase eastwards showing strong contrasts in sediment provenance. This suggests that the εNd-detrital signature of sinking particles may serve as a robust approach to trace particle provenance and transport in the UB, although the present ϵNd-detrital dataset is preliminary due to limited temporal coverage. Sinking particles collected at 1000 m and 2000 m depth in the UB exhibited a similar range in ϵNd-detrital to those of surface sediments throughout the year. The ϵNd-detrital values at 300 m depth were tended to be lower than those at 1000 m and 2000 m depths, with the lowest value observed in winter. Our observations suggest that lithogenic material accumulating in the upper sediment trap was potentially transported from the adjacent shelf area via northward transport, while those at greater depths were predominantly influenced by local sediment resuspension. Along with radiocarbon analyzes of sinking particulate organic carbon, our results highlight the importance of lateral transport and local sediment resuspension as key mechanisms regulating the supply of pre-aged organic carbon associated with lithogenic materials to the UB.