CARBON AND NITROGEN UPTAKE RATES OF PHYTOPLANKTON IN THE CHUKCHI SEA AND CENTRAL ARCTIC OCEAN

Abstract

As a Chinese IPY event, the 3rd Chinese National Arctic Research Expedition (CHINARE) was conducted from the Chukchi Sea to the central Arctic Ocean from late July to early September in 2008. Using a 13C-15N dual isotope tracer, the primary productivity experiments were measured at 24 stations for total, but 12 stations in the Chukchi Sea and 12 stations in the central Arctic Ocean during the period. In general, the temperature and salinity at surface were 4 to 6℃ and 30 in the Chukchi Sea and -1 to 3℃ and 25-27 in the central Arctic Ocean, respectively. The lower temperature and salinity in the central Arctic Ocean is believed to mainly due to the melting water from sea ice. The primary productivity of phytoplankton was higher in the Chukchi Sea than in Canada Basin during the cruise period. Especially in the station R03, the productivity was 199.6 mg C m-2 h-1 which was twice higher than the previous result in 2007. However, the average nitrogen uptake rate in the Chukchi Sea was lower in 2008 than in 2007. Based on high f-ratios in the study areas, nitrate uptake rates compared to ammonium uptake rates were relatively higher than those from other studies.