Variability of Organic Matter Sources and Phytoplankton Community Structure during the 19th Century under Global Warming Background in the Chukchi Sea

Multi-biomarker of sediment core P7200 obtained from the Chukchi Sea during the First Chinese National Arctic Research Expedition was measured to indicate changes of the source of organic matter, the primary productivity and the phytoplankton community structure through the 19th century. The results show that the organic matters in the Chukchi Sea are mainly from the terrigenous source, marine organisms and icerafted debris, and the ratio of terrigenous and oceanic inputs has increased over the 19th century. The total primary productivity has been elevated by nearly 100% in the century and the phytoplankton community structure also exhibits significant variability. The relative abundance of diatom increases dramatically, while that of cocolith decreases obviously and almost constant for the dinoflagellate. It is suggested that the changes of the source of organic matter, the primary productivity and the phytoplankton community structure are associated with global warming. However, elevated primary productivity and the altered phytoplankton community structure may strengthen the ability of CO₂ absorbing in the Chukchi Sea, which may weaken the greenhouse effect and should be regarded as one of the negative feedback mechanisms to the global warming.