Variations in organic carbon loading of surface sediments from the shelf to the slope of the Chukchi Sea, Arctic Ocean
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Variations in organic carbon loading of surface sediments from the shelf to the slope of the Chukchi Sea, Arctic Ocean LI Zhongqiao1, WANG Xinyi2, JIN Haiyan1, 3, JI Zhongqiang1, BAI Youcheng1, CHEN Jianfang1, 3* 1 Laboratory of Marine Ecosystem and Biogeochemistry, Second Institute of Oceanography, State Oceanic
Administration, Hangzhou 310012, China 2 Laboratory of Marine Chemistry and Environment, Ocean College, Zhejiang University, Zhoushan 316021, China 3 State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic
Administration, Hangzhou 310012, China Received 30 March 2016; accepted 8 August 2016 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2017
Abstract
The content of organic carbon (OC) normalized to the specific surface area (SSA) of sediment is widely used to trace variations in OC loading (OC/SSA). This study presents observations of OC/SSA of surface sediments collected in the Chukchi Sea, a typical Arctic marginal sea. Shelf sediments exhibit much higher OC/SSA values than slope sediments in the study area. Compared with OC/SSA values reported from the East Siberian Shelf and Mackenzie River, the slope sediments possess lower OC loading. This abrupt decrease in OC/SSA is mostly related to the lower primary production on slope as well as possible oxidization processes. The results of linear regression analysis between OC and SSA indicate a sedimentary source rock for the OC in the Chukchi Sea sediments. Moreover, shelf sediments with low SSA possess a larger rock OC fraction than slope sediments do. The dataset of the present study enables a more thorough understanding of regional OC cycling in the Chukchi Sea. Key words: Chukchi Sea, Arctic, surface sediments, organic carbon loading, carbon cycle Citation: Li Zhongqiao, Wang Xinyi, Jin Haiyan, Ji Zhongqiang, Bai Youcheng, Chen Jianfang. 2017. Variations in organic carbon loading of surface sediments from the shelf to the slope of the Chukchi Sea, Arctic Ocean. Acta Oceanologica Sinica, doi: 10.1007/s13131-017-1026-y
1 Introduction The Arctic Ocean possesses the largest continental shelf in the world and plays a key role in the global organic carbon (OC) cycle (Chen et al., 2015; Stein and Macdonald, 2004). Under the impact of global warming effect, the Arctic Ocean and surrounding areas are showing greater sensitivity to changes than the other regions (Chen et al., 2015). Global warming will lead to the thawing of permafrost and enhanced the export of soil OC and minerals into aquatic systems. During the transportation and burial of terrestrial OC, a certain fraction of the carbon is converted into CO2; thus, permafrost thawing is a source of atmospheric CO 2 . In addition to affecting the terrestrial environment, warming will also reduce the sea ice extent and keep the water warm (Chen et al., 2015), thus leading to higher oceanic productivity. The oceanic productivity in the Arctic stems mainly from large diatoms (>20 μm; Li et al., 2007), which are more easily tra
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