Chemical Characteristics of Fine Particles (PM1) from Xi'an, China

ISSN： 1521-7388

Source： Aerosol Science and Technology, Vol.44, Iss.6, 2010-06, pp. : 461-472

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Abstract

Daily mass concentrations of water-soluble inorganic (WS-i) ions, organic carbon (OC), and elemental carbon (EC) were determined for fine particulate matter (PM1, particles < 1.0="" m="" in="" diameter)="" collected="" at="" xi'an,="" china.="" the="" annual="" mean="" pm1="" mass="" concentration="" was="" 127.3="" ±="" 62.1="" g="" m-3:="" ws-i="" ions="" accounted="" for="" ∼38%="" of="" the="" pm1="" mass;="" carbonaceous="" aerosol="" was="" ∼30%;="" and="" an="" unidentified="" fraction,="" probably="" mostly="" mineral="" dust,="" was="" ∼32%.="" ws-i="" ions="" and="" carbonaceous="" aerosol="" were="" the="" dominant="" species="" in="" winter="" and="" autumn,="" whereas="" the="" unidentified="" fraction="" had="" stronger="" influences="" in="" spring="" and="" summer.="" ion="" balance="" calculations="" indicate="" that="" pm1="" was="" more="" acidic="" than="" pm2.5="" from="" the="" same="" site.="" pm1="" mass,="" sulfate="" and="" nitrate="" concentrations="" followed="" the="" order="" winter=""> spring > autumn > summer, but OC and EC levels were higher in autumn than spring. Annual mean OC and EC concentrations were 21.0 ± 12.0 g m-3 and 5.1 ± 2.7 g m-3 with high OC/EC ratios, presumably reflecting emissions from coal combustion and biomass burning. Secondary organic carbon, estimated from the minimum OC/EC ratios, comprised 28.9% of the OC. Positive matrix factorization (PMF) analysis indicates that secondary aerosol and combustion emissions were the major sources for PM1.