Seasonal variations and chemical characteristics of PM(2.5) in Wuhan, central China.

PM2.5 samples were collected at an urban site (WD) and a suburban site (TH) in Wuhan from August 2012 to July 2013. The mass concentrations of water-soluble inorganic ions, carbonaceous species and elements of PM2.5 were measured. The annual mean concentrations of PM2.5 were 106.5 μg/m(3) and 114.9 μg/m(3) at WD and TH, respectively. The chemical compositions of PM2.5 at WD were similar to those at TH and the fractions of the major components of PM2.5 in Wuhan were in the following order of trace elements