||The Second Institute of Oceanography, SOA, China;
36# Baochubei Road, Hangzhou 310012, China
||Youcheng Bai, The Second Institute of Oceanography, SOA, China;
Haiyan Jin, The Second Institute of Oceanography, SOA, China;
Hongliang Li, The Second Institute of Oceanography, SOA, China;
Jianfang Chen, The Second Institute of Oceanography, SOA, China;
Zhongqiang Ji, The Second Institute of Oceanography, SOA, China.
||Theme 1: Vulnerability of Arctic Environments
||1.1 Climate Change and Environmental Management in the Arctic
||Surface sediment samples (multi cores) and gravity core were taken on RV XueLong in 2008. Organic carbon and δ13Corg, biogenic silica, calcium carbonate and lipids in these sediments were determined in order to understanding “rain ratio” of biological pump, the distribution patterns of marine and terrestrial organic matter and phytoplankton community of the western Arctic Ocean. The δ13C values indicated that the sediment organic material was mainly derived from marine algae. In general, the spatial patterns of organic carbon, biogenic silica were similar, but the calcium carbonate was reversely, suggesting that biological pump was mainly dominated by siliceous phytoplankton. This was supported by phytoplankton community structure biomarkers. The higher values were in the middle of shelf than Alaska coast, but lowest concentration was observed in the south of the Chukchi Sea near Bering Strait. The large opal/CaCO3 and Corg /Cinorg ratio, which were 5.26 and 4.25 averaged respectively, indicated a high efficiency of biological pump in Chukchi Shelf. A 4.2kyr core located in central Chukchi Sea indicated that during the first stage (4200-250yr BP), the δ13C ratio and biomarkers suggested only 40% organic matter derived from marine algae. In contrast, the proportion of marine algae derived organic matter markedly increased in the second stage (250yr – present), especially in the last several decades marine algae contributed as much as 95% of total organic matter.