PM2.5 source profiles for black and organic carbon emission inventories

Abstract

Emission inventories for black or elemental (BC or EC) and organic (OC) carbon can be derived by multiplying PM2.5 emission estimates by mass fractions of these species in representative source profiles. This study examines the variability of source profiles and its effect on EC emission estimates. An examination of available profiles shows that EC and OC ranged from 6e13% and 35e40% for agricultural burning, 4e33% and 22e68% for residential wood combustion, 6e38% and 24e75% for on-road gasoline vehicles, and 33e74% and 20e47% for on-road heavy-duty diesel vehicles, respectively. Source profiles from the U.S. EPA SPECIATE data base were applied to PM2.5 emissions from the U.S. EPA National Emissions Inventory for 2005. The total estimated EC emissions of 432 Gg yr � 1 was apportioned as 42.5% from biomass burning, 35.4% from non-road mobile sources,15% from on-road mobile sources, 5.4% from fossil fuel (e.g., coal, oil, and natural gas) combustion in stationary sources, 1% from other stationary industrial sources, and 0.5% from fugitive dust. Considering the variability in available source profiles, BC emission estimates for major sources such as open fires and non-road diesels ranged from 42 to 133 (a factor of 3) and 25 to 100 (a factor of 4) Gg yr �1 , respectively. The choice of source profiles can be