Linkage between coastal and shelf system in the western Arctic Ocean

Abstract

Arctic Ocean waters are strongly affected by biogeochemical processes occurring over the surrounding Arctic shelves. A fundamental understanding of these processes is essential for predicting global climate change. In terms of shelf-basin interaction processes, organic matter export is important to the Arctic Ocean ecosystem, where heterotrophic production reportedly exceed autotrophic production in the central Arctic Ocean. In the present study, source and distribution of organic matter were investigated in the shelf and slope regions of Chukchi and Beaufort Seas during the Arctic Ocean cruise of R/V Mirai (JAMSTEC). Distribution of particulate organic carbon (POC) concentration along the observational line (162°W - 138°W) on the slope, showed a significant increase in the both surface mixed water and cold halocline water on the slope of near Barrow Canyon (155°W) and eastward upto150°W. This POC distribution may be due to the eastward flow of dense shelf waters (containing high concentrations of organic matter such as POC and Chl. a and DOC) off Barrow Canyon on the slope. There was no significant abundance of organic matter in cold halocline water of Canada Basin. On the other hand, distributions of stable isotope ratio of particulate organic matter (δ13C and δ15N) and particulate C/N ratio in the surface water on the slope indicate the influence of terrestrial organic matter through the Mackenzie River runoff.