Seasonal variations and sources of mass and chemical composition for PM10 aerosol in Hangzhou,China

Aerosol observation was conducted for four seasons from September 2001 to August 2002 at five sampling sites in Hangzhou, South China, on PM₁₀ mass, 22 elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Cd, Ba, and Pb), 5 major ions (F^?, Cl^?, NO₃^?, SO₄^2?, and NH₄⁺), and organic and elemental carbon (OC and EC), showing that PM₁₀ mass ranged from 46.7 to 270.8 μg/m³, with an annual average of 119.2 μg/m³. Na, Al, Si, S, K, Ca, and Fe were the most abundant elements in PM₁₀, most of S being in the form of SO₄^2?. SO₄^2?, NO₃^?, and NH₄⁺ were the major ions, which contributed to about 20% of the PM₁₀ mass. The mean seasonal concentrations for SO₄^2?, averaged over all sites, were found to be 18.0, 18.5, 24.7, and 21.4 μg/m³, for spring, summer, autumn, and winter, respectively, while the corresponding loadings for NO₃^? were 7.2, 4.7, 7.1, and 11.2 μg/m³, and for NH₄⁺ were 6.0, 5.9, 8.2, and 9.3 μg/m³, in the form mostly of NH₄NO₃ in spring, autumn, and winter, and mostly of (NH₄)₂SO₄ in summer. The low NO₃^?/SO₄^2? ratio found indicates coal combustion as the major source throughout the year. The mean annual concentrations of OC and EC in PM₁₀ were found to be 21.4, and 4.1 μg/m³, respectively. Material balance calculation indicated that fugitive dust, the secondary aerosol, and carbonaceous matter were the most abundant species in PM₁₀ for the four seasons, as is characteristic for cities in South China.