Atmospheric particulate mercury: Concentrations and size distributions

In this study, the size distributions of atmospheric particulate mercury (PHg) were measured in both urban and rural areas during the summer, fall, and winter. Both PHg concentrations and the contribution of PHg to total PM aerosol were higher at the urban (PHg = 6.8 ± 6.5 pg m−3, PHg/total PM = 0.18 pg μg−1) than at the rural site (PHg = 4.6 ± 2.7 pg m−3, PHg/total PM = 0.06 pg μg−1). Based on size-distribution measurements, the fine mode was the dominant size at both sites in winter while the coarse mode became more important during summer. In winter PHg concentrations in the fine mode increased because of the effective adsorption of gaseous Hg onto the fine particles at the low temperature and increased Hg oxidation reactions in the presence of high particles concentrations. During winter elevated concentrations of total PHg were measured when the prevailing winds were northwesterly originating in China.