||Second Institute of Oceanography, SOA,China
||Jianfang Chen, Yanpei Zhuang, Zhongqiang Ji,
Second Institute of Oceanography, SOA,China
||Theme 1: Vulnerability of Arctic Environments
||1.1 Climate Change and Environmental Management in the Arctic
||The Arctic is facing the rapid and severe changes in recent decades. With the temperature rising and ice retreating, Arctic Ocean became warmer and fresher. Such kind of changes have the critical influence to the maine primary production and the phytoplankton community strucures. In consequence, it changed on-site carbon flux efficiency. Furthermore, the inputs of terrestrial organic carbon were also changed due to increasing river runoff, thawing permafrost and coastal erosion. Nutrients, photosynthetic pigments and bulk organic carobn index were investegated based on 4 Chinese Arctic Research Expedition(CHINARE) Cruises since 2008. The change of the primary production and the phytoplankton community in upper layer of the Ocean, as well as the composition of sedimentary organic carbon were studied compared with the collected reference historical data. Pigments induced phytoplankton communities showed that diatom dominated in shelf area, and with the continuously nutrients support by Pacific inflow water, the pelagic ecosytem would be lasted much longer than before. while in the deep basin, the phytoplankton were dominated by nano- and pico-phytoplankton (with relative abundance increasing of prasinophytes and crysophytes) due to ice retreating and freshening caused oligotrophic conditions.This would affect the marine origen organic carbon sinking flux. The result indicated that the biomass of ice algae was decreased while the pelagic ecosystem dominated and phytoplankton biomass was increase with the ice retreating. The marine origine organic matter in the sediment was mainly influenced by the nutrient level and the primary production in the upper ocean. The contribution of terrestrial organic carbon was also evaluated based on a ternary model including N/C ratio, δ13C and BIT index parameters.