Decadal change of particulate flux in the Japan Sea/East Sea

Otosaka, Shigeyoshi  ; Oku, Shunsuke*; Minami, Hideki*; Minakawa, Masayuki*; Noriki, Shinichiro*

The Japan Sea is regarded as a miniature of the ocean because of its bowl-like topography and unique seawater circulation. Recent studies have suggested that biogeochemical processes in the Japan Sea correspond with the global climate change. In this study, we assessed decadal changes in particulate flux and elemental composition of sinking particle in the Japan Sea by comparing results of a sediment trap experiment in September 1984 with those in 1999-2001. Total mass flux did not show remarkable temporal change, however, biogenic opal/carbonate ratios observed recently were lower than those from the previous observation. In addition, relative content of scavenging elements such as manganese and cobalt also showed a decrease between the 15 years. These results may indicate decadal changes in ecological characteristics at the surface and transport processes of particulate materials in the deep water.