Otosaka, S.; Hou, Y.; Wakita, M.; Yamashita, Y.; Nishioka, J.; Obata, H.; Miyairi, Y.; Yokoyama, Y., and Ogawa, H., 2023. Origin and transport of dissolved organic matter in the northwestern margin of the North Pacific inferred from radiocarbon signatures. In: Lee, J.L.; Lee, H.; Min, B.I.; Chang, J.-I.; Cho, G.T.; Yoon, J.-S., and Lee, J. (eds.), Multidisciplinary Approaches to Coastal and Marine Management. Journal of Coastal Research, Special Issue No. 116, pp. 181-185. Charlotte (North Carolina), ISSN 0749-0208.

Distribution of Δ¹⁴C (an index of radiocarbon concentration/radiocarbon dating) in Dissolved Organic Carbon (DOC) was observed at four stations, one in the subarctic gyre and three in northwest marginal regions of the western North Pacific, to track the dynamics of organic matter. At all stations, Δ¹⁴C in DOC was explained by a two-component mixing model of “fresh” DOC produced in the surface layers and “old” DOC circulating in the deep layers. In the subarctic gyre, the estimated concentration of old DOC was the highest in the intermediate layer (200–800m). On the other hand, in the marginal regions, the concentrations of old DOC were particularly high in the upper layers of the connection region with the marginal sea. These results suggest that allochthonous dissolved organic matter from the marginal region was transported to the open ocean through the intermediate layer. The transport processes of dissolved organic matter inferred in this study provide an important basis for explaining the relationship between dissolved organic matter exports from land, coasts, and the continental shelf and biological production in the northwestern North Pacific.