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AGRICULTURAL AMMONIA EMISSIONS AND AMMONIUM DEPOSITION IN THE SOUTHEAST UNITED STATES
Citation:
Nelson, D. R., V. P. Aneja, AND J T. Walker*. AGRICULTURAL AMMONIA EMISSIONS AND AMMONIUM DEPOSITION IN THE SOUTHEAST UNITED STATES. Presented at Int. Symposium on Measurement of Toxic and Related Air Pollutants, RTP, NC, 9/12-14/2000.
Description:
The paper gives an estimate of county-scale annual ammonia (NH3) emissions in eight Southeastern States for the year 1997, using emission factors and activity data for all domestic livestock and fertilizer sources. A geographical distribution of the data yields local areas (1000-4000 sq mi) of elevated NH3 emissions (>2000 kg NH3/sq km). Temporal and spatial variation in ambient ammonium (NH4+) concentrations and volume-weighted NH4+ ion concentration in precipitation are investigated between 1990 and 1998 in and around these source regions. Regression analysis for the year 1997 shows that annual average ambient NH4+ increases logarithmically (R2=0.86) with the total annual NH3 emission within the corresponding county. It is also shown that annual volume-weighted average NH4+ concentration in precipitation increases linearly with annual NH3 emission within the corresponding county when precipitation effects are accounted for. Analysis of ambient NH4+ concentration at the various Clean Air Status and Trends Network(CASTNet) sites revealed that temperature, precipitation amount, and relative humidity are the most statistically significant (p<0.05) parameters in predicting the weekly concentrations of NH4+ between 1990 and 1998. Wind speed and direction were also statistically significant at several sites, but the results were less consistent.