Deep sea circulation of particulate materials in the Japan Sea

Otosaka, Shigeyoshi  ; Togawa, Orihiko ; Tanaka, Takayuki; Amano, Hikaru; Minakawa, Masayuki*

In order to understand biogeochemical cycles of particulate materials in the deep part of the Japan Sea, we assessed processes and a time scale of transport of particulate materials by measurements of particulate lead-210 (210Pb) and organic radiocarbon (14C) in settling particles collected in three regions of the Japan Sea; the western Japan Basin (WJB), the eastern Japan Basin (EJB) and the Yamato Basin (YB). Values of delta-14C in settling particles collected at 1 km depth ranged -1322 per mill, and there were little differences in delta-14C between sampling stations. In the YB, delta-14C values of settling particles collected in the bottom layer (about 200 m above the bottom) were similar to those in 1 km depth. On the other hand, the delta-14C values in bottom layer in the WJB and EJB were about 55 per mill smaller than those at shallower layers. These results in indicated that the deep part of the Japan Basin had a larger time scale of POC cycle than the Yamato Basin. By a comparison of mass balance of 210Pb between the WJB and EJB, it was estimated that about 60% of particulate 210Pb supplied to the WJB exported horizontally to the EJB.