Charcoal distribution in surface sediments of the East Siberian Shelf and its controlling factors
Charcoal is a direct indicator of fire events.In the context of global warming and frequent circumpolar Arctic wildfires,the generation,migration and burial of charcoal are key elements contributing to the under-standing of the environmental effects of Arctic climate change and the source-sink trajectory of terrestrial carbon.However,there are few studies on charcoal in the Arctic Ocean.The East Siberian Shelf(ESS)is the largest continental shelf in the world,receiving and sequestering large amounts of terrestrial carbon.It is also one of the Arctic regions where the melting of sea ice,coastal erosion,and wildfires are the most pro-nounced,making it a favorable area to study the charcoal record in the Arctic.On the basis of the surface sediment samples obtained from the first Sino-Russian joint Arctic research expedition in 2016,the distribu-tion,concentration,relative abundance,transport process,and the controlling factors of charcoal on the ESS of different sizes were studied.The results show that the total concentration of charcoal in the ESS surface sediments lies between 4.4×104 and 4.1×106 grains·g-1,with an average of 9.3×105 grains·g-1.Coarse char-coal particles were found near shore and fine particles were found offshore.As a result of long-distance transport by hydrodynamics and wind,charcoal particles in the study area are dominated by ultrafine grains(83%on average).River input,coastal erosion,atmospheric transport,sea ice and current processes may jointly influence the cross-shelf pathway of charcoal.
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