Impact of meteorological parameters and gaseous pollutants on PM_2.5 and PM₁₀ mass concentrations during 2010 in Xi’an, China

Mass concentrations of PM_2.5 and PM₁₀ from the six urban/rural sampling sites of Xi’an were obtained during two weeks of every month corresponding to January, April, July and October during 2010, together with the six meteorological parameters and the data of two precursors. The result showed that the average annual mass concentrations of PM_2.5 and PM₁₀ were 140.9 ± 108.9 µg m^–3 and 257.8 ± 194.7 µg m^–3, respectively. Basin terrain constrains the diffusion of PM_2.5 and PM₁₀ concentration spatially. High concentrations in wintertime and low concentrations in summertime are due to seasonal variations of meteorological parameters and cyclic changes of precursors (SO₂ and NO₂). Stepwise Multiple Linear Regression (MLR) analysis indicates that relative humidity is the main factor influencing on meteorological parameter. Entry MLR analysis suggests that SO₂ from local coal-burning power plants is still the primary pollutant. Trajectory cluster results of PM_2.5 at BRR indicate that the entrained urban pollutants carried by the westerly or winter monsoon forms the dominant regional pollution sources in winter and spring. Ultraviolet (UV) aerosol index verified the source and pathway of dust storm in spring.