Distribution and stoichiometry of Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in the Seas of Japan and Okhotsk

Abstract

Trace metals play an important role in marine biogeochemistry. However, the detailed distribution of trace metals in the Seas of Japan and Okhotsk remain unknown. Herein, we report the full-depth and section distributions of the dissolved (d), total dissolvable (td), and labile particulate (lp) phases of Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in seawater samples collected from the Seas of Japan and Okhotsk during the GEOTRACES-Japan program. High lpM/tdM ratios suggest active scavenging in the Seas of Japan and Okhotsk. The lpAl and lpFe species were dominant in tdAl and tdFe, showing a strong positive correlation to each other in the both the Seas of Japan and Okhotsk. The maximum lpAl, lpFe, lpMn, and lpCo concentrations were observed at σ0 = 26.8–27.0 for dense shelf water (DSW) in the Sea of Okhotsk, implying that a metal source is laterally transported to the western subarctic North Pacific. The high enrichment factors of dMn, dCo, dNi, dCu, dZn, dCd, and dPb in the surface water of the Sea of Japan were attributed to anthropogenic emissions of these metals. In addition, temporal variations of the trace metals were examined in the Sea of Japan. The distribution of dCd did not change significantly during 1984–2010; however, data suggest that lpMn and lpFe exhibited dynamic temporal and spatial variations.