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

Tatsuya Tsuboi, Hiroshi Iwata, Hideki Wada, Hiroyuki Matsuzaki, Rumi Sohrin, Yutaka Hiroe, Tadafumi Ichikawa, Kiyotaka Hidaka, Tomoo Watanabe


We present the water column profiles (surface to 2000 m depth) for dissolved inorganic radiocarbon (14CDIC) from 2 stations in the Kuroshio region including the Kuroshio large meander (LM) of 2004–2005. Surprisingly, the Δ14CDIC value varied up to 125‰ in the intermediate layer, especially near 600 m depth. In addition, the Δ14CDIC value was approximately –150‰ at 200 m depth at the northern station of Kuroshio in August 2005. This value is ~100‰ less than other Δ14CDIC values for the same depth. In comparison, the Δ14CDIC 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 Δ14CDIC water column profiles in the study region.

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