Source and spatial distributions of particulate organic carbon and its isotope in surface waters of Prydz Bay, Antarctica, during summer

Abstract

In this study, we investigated the distributions of sea-surface suspended particulate organic carbon (POC) and itsstable isotope (δ 13 CPOC) in Prydz Bay, Antarctica, and examined the factors influencing their distribution, sources, and transport.We used measurements collected from 61 stations in Prydz Bay during the 29th Chinese National Antarctic Research Expedition,in combination with remote sensing data on sea surface temperature (SST), chlorophyll a concentration, and sea ice coverage.The POC concentration in the surface waters of Prydz Bay was 0.28–0.84 mg·L -1 , with an average concentration of 0.48 mg·L -1 .The δ 13 CPOC value ranged from -29.68‰ to -26.30‰, with an average of -28.01‰. The concentration of suspended POC washighest in near-shore areas and in western Prydz Bay. The POC concentration was correlated with chlorophyll a concentration andsea ice coverage, suggesting that POC was associated with phytoplankton production in local water columns, while the growth ofphytoplankton was obviously affected by sea ice coverage. The δ 13 CPOC value in suspended particles decreased gradually towardsthe outer waters of Prydz Bay, while in eastern Prydz Bay the δ 13 CPOC value become gradually more negative from nearshore todeep-water areas, suggesting that δ 13 CPOC was mainly influenced by CO 2 fixation by phytoplankton. The δ 13 CPOC value in suspendedparticles near Zhongshan Station was significantly negative, possibly as a result of the input of terrigenous organic matter andchanges in the phytoplankton species composition in the nearshore area.