Seasonal variation of atmospheric particulate mercury over the East China Sea, an outflow region of anthropogenic pollutants to the open Pacific Ocean

Özet

In this study, PM2.5 and total suspended particulate (TSP) aerosol samples were collected to investigateatmospheric mercury pollution on a pristine island in the East China Sea (ECS) from October 2011 toAugust 2012. The sampling site is located in the downwind path of the outflow of anthropogenic pollutantsfrom East Asia to the Pacific Ocean, driven by the East Asian monsoon. Average concentrations ofparticulate mercury (PHg, in pg/m3) were 16.6 for PM2.5 and 24.2 for TSP. Particulate mercury wasmainly present in the fine mode, with 68.5% of the total PHg being present in PM2.5. Obvious seasonalvariations were observed for both PM2.5 and TSP. The dry deposition flux of PHg over the ECS wasestimated to be 1.69 mg m2 yr1. Three episodes of high PHg concentrations were observed during thesampling period. An episode in fall (84.1 pg/m3 in TSP) was induced by biomass burning in East China,and PHg was more concentrated in the fine mode (PM2.5/TSP ¼ 0.91). An episode in winter was triggeredby serious anthropogenic emissions in northern China, with PHg levels reaching 132.7 pg/m3 in TSP. Anepisode in spring was attributed to the long-range transport of Asian dust mixed with anthropogenicaerosols, with increased levels of PHg in the coarse mode (PM2.5/TSP ¼ 0.61). Principal componentanalysis (PCA) indicated that fossil fuel combustion and biomass burning from the Asian mainland werethe two major sources of atmospheric PHg over the ECS.