2:45 PM - 3:00 PM
[MIS28-09] A relationship between seawater Ba/Ca ratio and salinity in surface waters in the East China Sea
Keywords:Ba/Ca, Surface Salinity, East China Sea
In this study, we collected surface seawater samples (upper 100 m depth) in the Yellow Sea and the ECS during KH13-4 cruise in early July 2013 (R/V Hakuho-Maru), and investigated a relationship between seawater Ba/Ca ratio and salinity in the ECS. Seawater samples were filtered by 0.2 μm membrane filter onboard. Ba/Ca ratios were measured by an isotope dilution method using ICP-MS (HP4500). Analytical precision of Ba/Ca ratio was 0.9%.
Seawater Ba/Ca ratios were strongly correlated with salinity although the Yellow Sea and the ECS represented different regression lines. Freshwater sources in the Yellow Sea represented higher [Ba2+] than the freshwaters in the ECS. In the eastern part of the ECS (i.e., northern Okinawa Trough) where the eastward flowing Changjiang diluted water mixes with the Kuroshio water, we found the following relationship between seawater Ba/Ca and salinity: Ba/Ca (μmol mol-1) = 36.0—0.95×salinity (r2 = 0.87, 0-30 m, 33-34.5 psu). We will also present planktonic foraminifera Ba/Ca ratios of core-top ECS sediments, and discuss the possibility of using shell Ba/Ca ratios as an independent paleo-salinity proxy in the ECS.