Characteristics of chemical components in PM_(2.5) at a plateau city, South-west China

摘要

A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM_(2.5) at three sites of Kunming, a plateau city in South-west China. Nine kinds of water-soluble inorganic ions (WSI), organic and element carbon (OC and EC) in PM_(2.5) were analyzed by ion chromatography and thermal optical reflectance method, respectively. Results showed that the average concentrations of total WSI, OC and EC were 22.85±10.95 μg·m~(-3), 17.83±9.57 μg·m~(-3) and 5.11±4.29 μg·m~(-3), respectively. They totally accounted for 53.0% of PM_(2.5). Secondary organic and inorganic aerosols (SOA and SIA) were also assessed by the minimum ratio of OC/EC, nitrogen and sulfur oxidation ratios. The annual average concentrations of SOA and SIA totally accounted for 28.3% of the PM_(2.5) concentration. The low proportion suggested the primary emission was the main source of PM_(2.5) in Kunming. However, secondary pollution in the plateau city should also not be ignorable, due to the appropriate temperature and strong solar radiation, which can promote the atmospheric photochemical reactions.