Transport process of particulate organic matter in the Japan Sea

Otosaka, Shigeyoshi  ; Amano, Hikaru; Tanaka, Takayuki; Togawa, Orihiko ; Noriki, Shinichiro*; Kaba, Masato*; Minakawa, Masayuki*

In order to understand biogeochemical cycles of particulate materials in the deep part of the Japan Sea, the authors assessed the processes and a time scale of transport of particulate materials by measurements of organic radiocarbon (C-14) in settling/suspended particles collected in three regions of the Japan Sea; the northwestern, northeastern and southeastern regions. Isotopic ratios of C-14 in settling particles collected at 1 km depth showed little differences between the sampling regions. In the southeastern region, isotopic ratios of C-14 of settling particles collected in the bottom layer (about 0.5 km above the bottom) were similar to those in 1 km depth. On the other hand, the ratios in bottom layer of the northern regions were smaller than those at the shallower layers significantly. These results in indicated that there are different origins of POC between the northern and southeastern regions of the Japan Sea.