The purposes of this project include to evaluate the PM2.5 forecasting system, to analyze the water soluble chemical species in PM2.5, to evaluate the contributions of various sectors to PM2.5 and ozone based on TEDS9 and to evaluate the various control strategies based on cost/benefit analyses. The results show that the correct ratios of DAQI forecasting system for PM2.5 are the greatest, up to 99%, at northern and eastern Taiwan and are the least, about 97%, at Yuchinan air basin. The results of air quality index (AQI) shows that the major air pollutants are fine particles and ozone 8-hour average for AQI greater than 100. Note that the dominant pollutant for AQI greater than 200 is ozone 8-hour average.
The concentrations of water soluble chemical species in PM2.5 are analyzed by ion chromatography. The results show that the major species are sulfate, ammonium, and nitrate. The fractions of sulfate are the greatest among all analyzed species and are greater than 20% at all sites; those of ammonium and nitrate are 9%～14% and 3%～12%, respectively. Among the analyzed water soluble organic species, the fractions of oxalate, 0.7%～0.9%, are the greatest except for the Yangmin site, followed by formate of 0.2%～0.7%. The concentrations of oxalate in southern Taiwan are greater than those in northern Taiwan and are greater in winter season. The contributions of biomass sources to oxalate are 7.5%～12.5% in Taiwan based on the ratios of oxalate and potassium and the greater contributions periods are in June and October to December, which are the major rice straw open burning periods in Taiwan. The concentrations of levoglucosan、mannosan、galactosan and threitol are greater in winter season, especially in November and December. Levoglucosan is also used as tracer to estimate the contributions of biomass sources to the ambient fine particle concentrations. The results show that the contributions of biomass sources to ambient fine particle concentrations are about 5～19% and 7～18% at central and Yuchinan air basins, respectively.
The contributions of various sectors to the ambient fine particle and ozone concentrations are evaluated by Models-3/CMAQ. For every ten thousand tons of fine particles emitted, the contribution of cooking, 6.85%, is the greatest, followed by dust from paved road, 5.88%, and passenger car, 5.62%. For NOx, the contribution of printed circuit board,5.32%, is the greatest, followed by cooking, 3.83%, and two-stroke motorcylse, 1.03%. The annual average contribution of Taichung power plant to the ambient fine particle concentration is 2.3% in Taiwan based on the simulation by CMAQ. Note that the contribution to each site may be up to 6.3% at PM2.5 daily concentration greater than 50 μg/m3. The sensitivity analysis for ozone control has been conducted by observation based method using the ratio of H2O2 to HNO3. The results shows that VOC-control for northern Taiwan and NOx-control for central and southern Taiwan in ozone season.
The cost/benefit analysis for fine particle control shows that the order of pollutant control is primary particle, SO2 and NOx. The amounts of primary fine particle, SO2 and NOx need to be reduced are 27300 tons, 89400 tons, and 178400 tons, respectively and these are 70.9%, 85.0%, and 51.9% of the emission of year 2013. However, these end-of-pipe control measures can only reduce the ambient fine particle concentration by 25%.
