Transport processes of particulate materials and biogeochemical cycle of trace elements in the western North Pacific and the Japan Sea

Otosaka, Shigeyoshi  ; Minakawa, Masayuki*; Noriki, Shinichiro*

Sediment trap experiments in the Japan Sea are useful in order to know trends of transport processes of particulate materials in the world's ocean, because the Japan Sea is known as a "miniature" of the ocean. In this study, results of sediment trap experiments in the Japan Sea that were carried out by JAEA, Hokkaido University and Fishery Research Association of Japan from 1999 to 2002 were summarized. Particulate fluxes in the Japan Sea were larger in the western Japan Basin where nutrients were effectively supplied to surface layers. Using elemental composition of rare earth elements in settling particles as a indicator of the origin of lithogenic particles, three source materials of lithogenic particles to the Japan Sea were defined. It was also suggested that about 60% of particulate materials supplied to the deep part of the western Japan Basin were transported horizontally to the eastern Japan Basin through the deep layers. The biogeochemical cycle of particulate materials in the "model-ocean" such as Japan Sea would strongly help the study on global cycles of major/trace materials in the ocean by combining long-term observations of particulate flux in the North Pacific.