982 / 2024-09-19 23:32:38
local sources of cadmium, nickel, zinc, copper, and iron in the western South Pacific
trace metals,seawater,the western South Pacific Ocean
Session 10 - The biogeochemistry of trace metals in a changing ocean
Abstract Accepted
Linjie ZHENG / Kyoto University
Tomoharu Minami / Kanazawa University
Cheuk-Yin CHAN / Kyoto University
Shotaro Takano / Kyoto University
Yoshiki Sohrin / Kyoto University
The western South Pacific Ocean is interconnected with the Southern Ocean, the Tasman Sea, and the Coral Sea. Numerous active hydrothermal vents have been documented in the North Fiji and Lau Basins and along the Tonga-Kermadec Arc (Auzende et al., 1991; Hart et al., 2000). Nevertheless, studies on trace metals in this region are limited. In this study, we present a comprehensive dataset detailing the full-depth sectional distributions of Cd, Ni, Zn, Cu, and Fewithin the total dissolvable (td), dissolved (d), and labile particulate (lp) fractions in the western South Pacific Ocean, obtained during the GEOTRACES Japan KH-14-6 research cruise (Zheng et al., 2024)

Among these five trace metals, only dCd exhibits a strong correlation with phosphate, while dNi, dZn, and dCu concentrations increase independently of phosphate in waters exceeding 1500 m depth. This divergence indicates that the distribution of dCd is primarily influenced by ocean circulation and biogeochemical cycling in the western South Pacific Ocean. The variations of dNi, dZn, and dCu can partly be attributed to reversible scavenging, benthic release from sediments in the Fiji Basins and the Southwest Pacific Basin, and/or water mass mixing. While a moderate correlation exists between dFe and PO4 throughout the water column, the slope of the regression line is less than half of the Fe/P ratio observed in phytoplankton, suggesting substantial scavenging of dFe. The distribution of dFe is influenced by local sources such as hydrothermal activities and intense weathering on tropical-subtropical lands. In addition, the distribution of lpFe closely parallels that of lpAl, indicating the dominant influence of lithogenic sources.

Auzende, J.-M. et al. 1991, Marine Geology, 98(2): 259-269.

Hart, S.R. et al., 2000. Geochemistry, Geophysics, Geosystems, 1(12).

Zheng, L., Minami, T., Takano, S. and Sohrin, Y., 2024. Marine Chemistry: 104411.