Particulate Organic Carbon fluxes in Prydz Bay, Southern Ocean during the 22nd CHINARE Nov.2005 - Mar. 2006

Dissolved and particulate 234Th, particulate organic carbon in the upper 150m of water columns from five stations in the Prydz Bay, Southern Ocean were determined during the 22nd CHINARE (Chinese National Antarctic Research Expedition) (Nov.,2005 - Mar., 2006). The disequilibria between 234Th and its parent 238U in upper layer was used to derive the average residence time of 234Th, which decreased along with the latitude toward south with minimum values, respectively 1～8d for particulate 234Th and 29～48d for dissolved 234Th, appeared at the medium latitude station, and the export fluxes of 234Th were calculated too and max values, respectively 0.35～0.63 Bq/（m3•d）for particulate 234Th and 0.44～0.65 Bq/（m3•d）for dissolved 234Th, appeared at the same station. The export fluxes of particulate organic carbon at different water columns were derived by two methods with irreversible scavenging model, and the average value were 104.7 mmol/(m2•d)(E method) and 120.6mmol/( m2•d)(B method), respectively, which meant in summer relatively high new production existed in the Prydz Bay where it would play a significant role as a CO2 sink.Key Words: POC fluxes, 234Th/238U disequilibria, Prydz Bay, Southern Ocean