Deep sea circulation of particulate organic carbon in the Japan Sea

Otosaka, Shigeyoshi  ; Tanaka, Takayuki; Togawa, Orihiko ; Amano, Hikaru; Karasev, E. V.*; Minakawa, Masayuki*; Noriki, Shinichiro*

Transport processes of particulate organic carbon (POC) were inferred from sediment trap experiments in the three regions of the Japan Sea (western and eastern Japan Basin and Yamato Basin) and radiocarbon measurement. Annual mean C/C isotopic ratio decreased with depth and the vertical changes in the isotopic signature were considered to indicate mixing of two fractions; labile POC produced in the surface and refractory POC. From seasonal variations of POC flux of the two fractions, transport processes of POC in the Japan Sea were summarized as follows: (1) In the Japan Basin, both labile and refractory POC were supplied in spring and a reservoir of refractory POC was formed, and (2) in the Yamato Basin, larger amount of refractory POC were carried the interior and accumulated rapidly.