海洋における水銀の濃度分布と動態

抄録

This review summarizes recent advances in studies of the distribution of total and speciated mercury (Hg) in the ocean including the Pacific, Atlantic and polar regions. In addition, clean sampling technologies and the analytical methods for trace Hg-species are also presented. The distribution of the Total Hg in the Pacific and Atlantic Oceans represents at “Scavenge-type” in subsurface layers and “Nutrient-type” in mesopelagic zone, whereas the distributions of Total Hg in the polar oceans are unique with higher concentrations near the surface due to the inclusion of melting sea-ice and brine. Mono-Methyl Hg (MMHg) and Methylated Hg (MeHg) represent at “Nutrient-type” distribution. They are correlated with the apparent oxygen utilization in the Pacific and the Southern Oceans, suggesting the Hg methylation is related to organic carbon remineralization by microbial respiration. However, this correlation is not significantly observed in the North Atlantic Ocean and the Arctic. In addition, mechanisms of MMHg and Di-Methyl Hg (DMHg) production in water column are still under discussion. A further understanding of the distribution of speciated Hg and their interactions in oceanic environments are required for establishing a global model which are able to predict the future Hg biogeochemical cycle including the influences by climate change.