Geochemical characteristics of black carbon in surface sediments of the East Siberian Arctic Shelf and their environmental implications

Pyrogenic black carbon (BC) is closely related to climate change and human activities. In the context of global warming, the BC emission and transfer from land to sea and the environmental fate provide important scientific clues for understanding the source-sink course of terrigenous organic carbon and its climate and environmental effects under rapid climate change in the Arctic area. The East Siberian Arctic Shelf is the widest and shallowest shelf in the world, receiving a large amount of terrestrial material input from runoff and coastal erosion. Especially in recent years, frequent occurrence of wildfires around the Arctic makes it an ideal area for studying the course and route of source-sink of BC deposited in the Arctic waters. Based on the data of samples collected from the East Siberian shelf, the content, composition, spatial distribution, and influencing factors of BC in surface sediments were studied. Preliminary results show that the content of BC is 0.1～2.3 mg/g, on average of 0.99 mg/g. Among them, char from biomass combustion contributed more than 70% on average. The spatial distribution of BC is very heterogeneous. BC in the Laptev Sea and the western part of the East Siberian Sea is high, which is closely related to coastal erosion and river input. The eastern part of the shelf (including the Chukchi Sea) has less terrigenous input and relatively low BC content. The spatial variability of different types of BC is obvious. In the nearshore region, runoff and coastal erosion is probably the main input pathway of char.