Abstract: Deposition of organic carbon forms the final net effect of the ocean carbon sink in a certain time scale, and the organic carbon deposition of Arctic shelf plays a particularly important role in the global carbon cycle due to its broad shelf area. In order to determine the organic carbon deposition flux at the north margin of Chukchi shelf, 210Pb dating method was applied to analyze the age and deposition rate of sediment samples from station R17 of the 3rd Chinese National Arctic Research Expedition. The results show that the deposition rate was 0.6 mm/a, the apparent deposition mass flux was 0.72 kg/m2/a, and the organic carbon deposition flux was 517 mmol C/m2/a, respectively. It was estimated that 29 % of the export organic carbon flux out of the euphotic zone was transferred and chronically buried into the sediment, which was much higher than the average ratio (~ 10 %) of the low-/mid-latitude region, indicating a highly effective carbon sink at the north margin of Chukchi shelf.

Key words: organic carbon deposition, ²¹⁰Pb dating, Chukchi Shelf