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

In this study, we investigated the distributions of sea-surface suspended particulate organic carbon(POC) and its stable isotope(δ13CPOC) in Prydz Bay, Antarctica, and examined the factors infl uencing their distribution, sources, and transport. We used measurements collected from 61 stations in Prydz Bay during the 29 th 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 δ13CPOC value ranged from-29.68‰ to-26.30‰, with an average of-28.01‰. The concentration of suspended POC was highest in near-shore areas and in western Prydz Bay. The POC concentration was correlated with chlorophyll a concentration and sea ice coverage, suggesting that POC was associated with phytoplankton production in local water columns, while the growth of phytoplankton was obviously affected by sea ice coverage. The δ13CPOC value in suspended particles decreased gradually towards the outer waters of Prydz Bay, while in eastern Prydz Bay the δ13CPOC value become gradually more negative from nearshore to deep-water areas, suggesting that δ13CPOC was mainly infl uenced by CO2 fixation by phytoplankton. The δ13CPOC value in suspended particles near Zhongshan Station was significantly negative, possibly as a result of the input of terrigenous organic matter and changes in the phytoplankton species composition in the nearshore area.