Distribution of Te species in the eastern Indian Ocean and its oceanographic features

Abstract

Tellurium is assigned as one of technology-critical elements (TCEs) useful for industrial products such as a DVD. Marine ferromanganese oxides on the seafloor contain high concentration of Te. In seawater, Te present as different oxidation states (Te(IV) and Te(VI)) with very low concentration below 2 pmol/kg. Redox transformation between Te(IV) and Te(VI) and variability of Te(IV)/Te(VI) ratios in marine environment are crucial for better understanding of marine biogeochemical cycles of Te. However, reliable data of Te in seawater is sparse due to difficulty in the analysis. We developed a new analytical method to obtain reliable data of Te species in seawater and clarified vertical profiles of Te species in station BD7 found in the western North Pacific. Te species showed a scavenged type distribution, high concentration in surface and decreasing with depth. These results suggested that scavenging processes controlled Te species distribution in typical oxic ocean. In this study, we perform determination of Te species in the eastern Indian Ocean having a specific anoxic environment such as oxygen minimum zone and report Te species distribution and its oceanographic features.