Elution characteristics of metal from sulfide minerals and environmental impact of deep sea mining

Abstract

Submarine mineral resources such as manganese nodules and hydrothermal deposits (Cu, Zn rich sulfide minerals) in the deep sea contain a large amount of useful metals. Although deep sea mining technologies have been developed, there is a lack of information on significant environmental impacts. In this study, we aimed to assess the impact of metal elution in seawater from sulfide minerals. For elution experiments, two different sizes (20-63 um, <20 um) of sulfide minerals were prepared and seawater were sampled and filtered with 0.45 pore size capsule filter. The relative ratio of sulfide mineral and seawater were 0.01, 0.1, 1 g/L to estimate the amount of leaching of heavy metals such as Cr, Cu, Zn, As and Cd. The eluted seawater samples were collected at different sampling times and were measured by using the seaFAST SP3 system (ESI, Elemental Scientific) with Inductively Coupled Plasma Mass Spectrometry (NexION 2000, Perkin Elmer Inc.). The vertical distribution of these metals at the Indian Ocean were also investigated to evaluate the severity of metals released from sulfide minerals into seawater.