Source-receptor relationships for fine particulate matter concentrations in the Eastern United States

摘要

The Particulate Matter Source Apportionment (PSAT) method is used to quantity the impacts of different source regions on fine particulate matter (PM) concentrations in the Eastern United States. Our analysis focuses both on how far pollutants are transported and the impacts they have in the corresponding receptor areas. Towards this goal, several quantitative measures of impact and transport distance are proposed and calculated for ten source regions for all seasons. The long range source impacts are extremely variable in space and time and are often in directions different than that of the average prevailing winds. Transport distances were usually lower during the summer than in other seasons for this region. The average transport distance (distance from the source area to the center of the pollution plume) for elemental carbon and other primary fine PM components was found to be 100-200 km for most source regions. On the other hand, the secondary PM species were found to be transported the furthest with sulfate and secondary organic aerosol (SOA) traveling on average over 350 km. Maximum transport distances are significant higher, with sulfate impacts reaching as far as 2000 km away from the SO_2 source region. The fractional contribution of a source region to fine PM ground level concentrations can be quite different (up to a factor of 3) than its emission contribution. This is mainly due to the height where the emissions are released. Regions with mainly ground level emissions contribute more while regions with elevated emissions less than the magnitude of their emissions suggests.