Chemical Compositions And Source Apportionment Of Inhalable Particulate Matter At Suburban Area Of Changsha

Inhalable particulate matters (including PM₁₀ and PM_2.5) are very harmful to human health, and also can cause some environmental effects such as visibility deterioration, acid rain and climate change. The annual concentrations of PM₁₀ in Changsha had constantly exceeded the annual National Gradeâ…¡Standard for four years from 2004 to 2007, which was extreme serious. Recently, as rapid urbanization occurred in China, great changes have taken place at the suburban area. Therefore, it is meaningful to investigate the chemical conpositions and source apportionment of inhalable particulate matters at suburban of Changsha, which will be helpful for making economic and effective control strategies and improving city air quality.Twenty-four hours average atmospheric PM₁₀ and PM_2.5 samples were collected with TEOM 1400a and ACCU system from July to December in 2008 at suburban area of Changsha, China. Daily concentrations of PM₁₀ and PM_2.5 were caculated respectively through weighing method. A total of 16 chemical species (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Ni, Cu, Zn, Pb and Fe) in both PM₁₀ and PM_2.5 were detected by Wave Dispersive X-ray fluorescence (WD-XRF). Chemical compositions were analyzed and compared with results in other cities. Finally, chemical mass concentrations were used for receptor modeling. Principal component analysis (PCA)/absolute principal component analysis (APCA) were applied to identify and determine the possible pollution sources and their contributions to PM₁₀ and PM_2.5 respectively.Inhalable particulate matters and their chemical compositions analysis indicates that the mean concentration of PM₁₀ is 101.1μg/m³ at suburban area of Changsha in July and October 2008, which is close to the annual National Gradeâ…¡Standard 100μg/m₃. Significant concentration differences of elements Mg, S, Ca, Ti, Mn, Zn and Pb in PM₁₀ are observed between July and October. Concentrations of most elements (except Na, Ca, Mg, Mn, Zn and Pb) in PM₁₀ increase from clear days, moderate polluted days to high polluted days, but the concentration percentages of almost every species (except Cl) in PM₁₀ decrease with the increasing PM₁₀ pollution. Average concentration of PM_2.5 reaches 91.5μg/m³ at suburban area of Changsha from November to December 2008, which is very high. Concentrations of elements S and Si are the most abundant in PM_2.5. Besides, Concentrations of Ni and Cu in PM₁₀ and PM_2.5 at suburban of Changsha are higher than those of most other cities.Source apportionment finds that six pollution sources are obtained for PM₁₀: soil dust (contributes 57.7%), secondary aerosols (contributes 24.0%), domestic oil combustion (contributes 9.8%), waste incineration (contributes 5.0%), traffic emission (contributes 2.0%) and industrial emission (contributes 1.5%). Six pollution sources for PM2.5 are also concluded, including secondary aerosols (contributes 27.8%), soil dust (contributes 24.1%), industrial emission (contributes 16.4%), domestic oil combustion (contributes 16.1%), waste incineration (contributes 11.0%) and traffic emission (contributes 5.8%). Source types are almost the same for PM₁₀ and PM_2.5 at suburban area of Changsha, but the absolute mass contributions of the same source to PM₁₀ and PM_2.5 are different.