Source-receptor relationships for atmospheric mercury deposition in the context of global change

Abstract

There have been growing concerns about mercury pollution in the global environment and better understanding of the source-receptor relationships for mercury deposition in the context of global change is greatly needed. We use a global 3-D chemical transport model (GEOS-Chem) to examine the source-receptor relationships between various regions as well as the impacts from changes in anthropogenic emissions, climate, land use and land cover. Through an extensive set of sensitivity simulations, we quantify the relative contributions from various sources (such as domestic vs. foreign anthropogenic sources; anthropogenic vs. natural sources) to total mercury deposition in specific receptor regions (East Asia, South Asia, Europe, North America, and the Laurentian Great Lakes). Under the 2050 A1B emission scenario (the higher emission scenario with fast economic growth and balanced emphasis on all energy sources), the relative contributions from anthropogenic emissions to total mercury deposition for each receptor region are calculated to increase in general, while the relative contributions from ocean and terrestrial sources are found to decrease. On the other hand, with the 2050 B1 emission scenario (the lower emission scenario with rapid introduction of clean energy and resource-efficient technologies), we find the changes in the relative contributions from anthropogenic emissions show different signs over different regions, reflecting the divergent trends in future anthropogenic emissions (notably, emissions increase in South Asia and decrease in East Asia). Compared to the impacts of anthropogenic emissions on the source-receptor relationships of mercury deposition, the impacts from changes in climate and land use/land cover are generally smaller in magnitudes but show stronger spatial variations.