dc.description.abstract | Aerosol chemical properties are important in source apportionment, health effect, and radiative forcing. The goal of this study is to compare aerosol characteristics in terms of chemical properties on light-scattering coefficient and apportionment of source contributions from two different types of city in Taiwan. Atmospheric aerosols were collected using Honeycomb denuder and cyclone in Kao-hsiung City from December 20, 1999 to January 28, 2000 and in Taipei City from March 20 to May 18, 2000. Water-soluble ions, carbonaceous contents, metal elements, and water mass of aerosols are analyzed. A regression model for theoretical aerosol water mass is adopted for comparisons with the measurements (Lee and Hsu , 1998).
The daytime average of PM2.5 in Kao-hsiung City is 93.0μg/m3 with a standard deviation of 29.1μg/m3. Meanwhile, the average of aerosol mass scattering efficiency during this time period is at 2.37m2/g. Chemical analysis shows the mass fraction of water-soluble ions, carbonaceous contents, metal elements, water content, and unknown is 33.5%, 27.6%, 18%, 4.6%, and 16.3%, respectively.
Among the analyzed species, sulfate and nitrate ions are correlated well with aerosol light-scattering coefficient. The analysis of enhancement factor reveals sulfate and potassium ions are mostly originated from non-sea-salt aerosol, while chloride, magnesium, and calcium ions are mainly from sea-salt. As pointed out by chlorine loss algorithm, the water-soluble ions in Kao-hsiung city is mostly from the secondary photochemical reaction. The APCA analysis shows Kao-hsiung aerosols are contributed from the secondary reaction, sea-salt, and agricultural burning.
In contrast, the daytime average of PM2.5 in Taipei City is relatively lower at 50μg/m3 with a standard deviation of 22.3μg/m3. During this period, the average of aerosol mass scattering efficiency is higher at 3.1m2/g. Water-soluble ion is still the prominent species, the mass fraction of water-soluble ions, carbonaceous contents, metal elements, water content, and unknown is 35%, 31%, 12%, 2%, and 20%, respectively.
The regression analysis shows sulfate and nitrate ions are the two parameters adopted in the model to account for the variations of aerosol light-scattering coefficient. Similarly, the analysis of enhancement factor reveals sulfate, calcium and potassium ions are mostly originated from non-sea-salt aerosol, while chloride and magnesium ions are mainly from sea-salt. The chlorine loss algorithm infers the water-soluble ions in PM2.5 from Taipei City are mostly from the secondary photochemical reaction. The APCA analysis confirms Taipei City aerosols are contributed from the secondary reaction and agricultural burning. | en_US |