海洋における鉄，ニッケル，銅，亜鉛，カドミウムの安定同位体比分布とその分析法

抄録

Isotope ratios of trace metals in the ocean have been used as tracers to understand the sources of trace metals and their biogeochemical processes. This paper focuses on iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd), which are essential or toxic to marine organisms, and reviews the isotopic distribution of these metals in the ocean and the factors controlling their distribution. The distribution of Fe isotope ratios (δ^56/54Fe) varies greatly among ocean regions. This is explained by the supply of Fe from different sources (atmospheric aerosols, sediments, and hydrothermal vent). The isotope ratios of Ni and Cd in the ocean (δ^60/58Ni and δ^114/110Cd) are globally constant in the deep water below 1000 m, and increase with decreasing their concentrations in the surface water above 1000 m, suggesting preferential uptake of lighter isotopes by phytoplankton. The Cu isotope ratios (δ^65/63Cu) in the ocean show large variations in both the surface and deep waters, which are accounted for phytoplankton uptake and atmospheric aerosol deposition in the surface water and adsorption on particles in the deep water. The isotope ratios of Zn (δ^66/64Zn) in the ocean are almost constant in the deep water, and shift positively and negatively in the surface water. This variation is explained by phytoplankton uptake, adsorption on biogenic particles, and input of anthropogenic substances.