Mathematical modeling and control of the dry deposition flux of nitrogen-containing air pollutants

Abstract

An Eulerian grid-based air quality model has been modified to include a resistance-based dry deposition code. The magnitude and spatial distribution of the dry deposition flux of nitrogen-containing pollutants to the surface of the Los Angeles area was calculated as a function of land use. For August 1982 base case conditions, the dry deposition flux was 247 t of N per day (5 from NO, 49 from NO_2, 7 from PAN, 101 from HNO_3, 59 from NH_3, and 26 from NH4_NO_3), which corresponds to more than half of the daily NO_x emissions to the local atmosphere. The effects of emission controls on NO_x and hydrocarbon sources in Southern California as they existed in 1982 were examined. At the highest level of control studied (37% reactive hydrocarbon reduction, 61 % NO_x reduction), the nitrogen dry flux would be 174 t of N per day after control (2 from NO, 20 from NO_2, 7 from PAN, 58 from HNO_3, 75 from NH_3, and 12 from NH_4NO_3.

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