Spatial distribution and source apportionment of atmospheric dust fall at Beijing during spring of 2008-2009.

Beijing is a megacity, where atmospheric dust fall amount is great, and its resultant air pollution is serious. So, analyzing the chemical elements in atmospheric dust fall and revealing its various sources can provide a scientific basis for taking effective measures to improve atmospheric environmental quality. In this paper, we investigated the spatial and temporal distribution of dust fall in Beijing, based on the dust samples collected in the spring of 2008 and 2009 at 18 observation sites laid out in Beijing and then analyzed the sources of atmospheric dust fall based on the test of samples, adopting enrichment factor and factor analysis methods. Our results found that the dust fall quantity in the observation periods was respectively 33.6230 t km(-2) and 28.7130 t km(-2); the dust fall quantity varied significantly in different months in the spring, but the variation trend was similar at the sites. There were two centers of large quantity in Beijing; one was in the southwest of downtown, and the other was in the northeast of downtown. The spatial distribution of dust fall generally showed a structural feature of three loops; the northwestern mountainous area was a small quantity belt; the plain area around the downtown was a large quantity belt, and the central downtown was a center of small quantity. Soil dust, construction dust, coal dust, and vehicle exhaust were the four major sources of dust fall in spring of Beijing, respectively, accounting for 38.50, 22.25, 14.06, and 20.82 % of the total dust fall quantity.