Water Column Profiles of Dissolved Inorganic Radiocarbon for the Kuroshio Region, Offshore of the Southern Japanese Coast

Abstract

We present the water column profiles (surface to 2000 m depth) for dissolved inorganic radiocarbon ([delta]14CDIC) from 2 stations in the Kuroshio region including the Kuroshio large meander (LM) of 2004–2005. Surprisingly, the [delta]14CDIC value varied up to 125‰ in the intermediate layer, especially near 600 m depth. In addition, the [delta]14CDIC value was approximately -150‰ at 200 m depth at the northern station of Kuroshio in August 2005. This value is ~100‰ less than other [delta]14CDIC values for the same depth. In comparison, the [delta]14CDIC water column profiles for the southern station of Kuroshio and GEOSECS station 224 decrease down to 600 m depth and were similar below 600 m depth. Our results suggest that strong upwelling associated with the Kuroshio LM has a powerful influence on the [delta]14CDIC water column profiles in the study region.