PM2.5 chemical source profiles for vehicle exhaust, vegetative burning, geological material, and coal burning in Northwestern Colorado during 1995

PM2.5 (particles with aerodynamic diameters less than 2.5 mum) chemical sou rce profiles applicable to speciated emissions inventories and receptor mod el source apportionment are reported for geological material, motor vehicle exhaust, residential coal (RCC) and wood combustion (RWC), forest fires, g eothermal hot springs; and coal-fired power generation units from northwest ern Colorado during 1995. Fuels and combustion conditions are similar to th ose of other communities of the inland western US. Coal-fired power station profiles differed substantially between different units using similar coal s, with the major difference being lack of selenium in emissions From the o nly unit that was equipped with a dry limestone sulfur dioxide (SO2) scrubb er. SO2 abundances relative to fine particle mass emissions in power plant emissions were seven to nine times higher than hydrogen sulfide (H2S) abund ances from geothermal springs, and one to two orders of magnitude higher th an SO2 abundances in RCC emissions, implying that the SO2 abundance is an i mportant marker for primary particle contributions of non-aged coal-fired p ower station contributions. The sum of organic and elemental carbon ranged from 1% to 10%;, of fine particle mass in coal-fired power plant emissions, from 5% to 10% in geological material, > 50% in forest fire emissions, > 6 0% in RWC emissions, and > 95% in RCC acid vehicle exhaust emissions. Water -soluble potassium (K+) was most abundant in vegetative burning profiles. K +/K ratios ranged from 0.1 in geological material profiles to 0.9 in vegeta tive burning emissions, confirming previous observations that soluble potas sium is a good marker for vegetative burning. (C) 2001 published by Elsevie r Science Ltd.