Biogeochemical properties of sinking particles in the southwestern part of the East Sea (Japan Sea)

Abstract

This study investigates the biological pump system in the East Sea (Japan Sea) by conducting an analysis of the total particle flux, biogenic material composition, and carbon isotope ratios of sinking particles. The samples were collected for one year starting from March 2011 using time-series sediment traps deployed at depths of 1040m and 2280m on bottom-tethered mooring at Station EC1 (37.33°N, 131.45°E; 2300m water depth) in the Ulleung Basin (UB), southwestern part of the East Sea. The temporal variation in the particulate organic carbon (POC) flux at 1000m shows a good relationship with the primary production in the corresponding surface water. The ratio of POC flux at 1000m to satellite-based primary production in the corresponding region in the UB was ~3%, which is comparable to the values of 2 to 5% estimated from previous studies of other part of the East Sea. The lithogenic material accounted for >17% of the sinking particles at 1000m and for a larger fraction of 40 to 60% at 2280m. The radiocarbon contents of the sinking POC at both trap depths imply the additional supply of aged POC, with a much greater contribution at 2280m. Overall, the particle flux in the deep interior of the East Sea appears to be controlled by the supply of complex sources, including aeolian input, the lateral supply of resuspended sediments, and biological production in the surface water.