The Relation Between NO sub(x) Emissions and Precipitation NO sub(3) super(-) in the Eastern USA

Nitrogen oxides emission data categorized by major sectors were used with precipitation chemistry data derived from the NADP/NTN and NADP/AIRMoN networks to quantify the relations between NO sub(x) emissions and precipitation nitrate for the eastern US. The northeastern and mid-Atlantic regions were divided into four areas, and NO sub(x) emissions were converted to NO sub(x) emissions per unit of source area. The NOAA Air Resources Laboratory's Hysplit-4 model was used to define back trajectories, and based on cluster analysis, three source areas were established for each region. A random coefficient model was applied to quantify the relations between NO sub(x) emissions and precipitation NO sub(3) super(-). Model results are presented for emissions based on 12-, 24-, and 36-h back trajectories. For the period 1991 2000, the changes in total NO sub(x) emissions were relatively small for all four regions, while vehicle NO sub(x) emissions were nearly unchanged or increased. However, significant declines in non-vehicle emissions occurred in New England, New York State, Pennsylvania, and the mid-Atlantic region. The model results indicated that reducing total NO sub(x) emissions would significantly reduce precipitation NO sub(3) super(-) concentrations.