Assessment of ambient mercury deposition fluxes by numerical air quality modeling

Abstract

Since mercury monitoring activities are very limited in Japan and governmental monitoring data of mercury deposition fluxes are not available, it is necessary to choose some numerical models to protect and manage the local ambient air quality. Numerical models for mercury transportation and deposition should be developed to understand the scenario and pathway of atmospheric mercury concentration distributions and deposition fluxes in the local area of Japan. The ground-level mercury concentrations have to meet the environmental standards set by the Ministry of the Environment in Japan which is less than 40 mg m−3. The aim and scope of this research is to apply numerical models to forecast seasonal variation of ambient mercury concentrations and deposition fluxes in the local area of Japan. To estimate the ambient mercury concentrations in the local area, a dispersion model has been used, the National Institute of Advanced Science and Technology-Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER). The AIST-ADMER model calculated the yearly average concentration distributions of mercury in the Aichi Prefecture Japan, which serve as boundary and background concentrations of mercury for the mercury deposition model. Finally, the boundary and background concentrations of mercury calculated by the AIST-ADMER along with meteorological data were superposed in the mercury deposition model to calculate mercury deposition fluxes (dry and wet) in Isshiki Town of Aichi Prefecture. Maximum atmospheric concentrations of mercury were calculated as 2.89 ng m−3 by the AIST-ADMER model. In this study, total dry deposition fluxes and wet deposition fluxes were calculated to be 15.1 μg m−2 year−1 and 14.3 μg g m−2 year−1, respectively.