Fluxes, variability and sources of cadmium, lead, arsenic and mercury in dry atmospheric depositions in urban, suburban and rural areas

In China's largest city, Shanghai, dry deposition fluxes of Cd, Pb, As and Hg were 137, 19 354, 2897 and 9.4 μg m−2 a−1, respectively in an urban area, intermediate in a suburban area, and 51.7, 5311, 1703 and 7.3 μg m−2 a−1, respectively in a rural area. Enrichment factors were Cd>Pb>As>Hg. Seasonal variations of metals differed: Pb and As were dominated by fossil fuel combustion, Cd was related to industrial pollution, and natural source controlled Hg levels.