Modelling and analysis of the atmospheric nitrogen deposition in North Carolina

The United States Environmental Protection Agency's Community Multiscale Air Quality (CMAQ) regional-scale model is used to study concentrations and dry deposition of nitrogen species in North Carolina (NC) during the summer season. Each modelled and measured species featured a similar diurnal trend. A process budget analysis (production and removal evaluation) of NO, NO<SUB align="right"><SMALL>2</SMALL></SUB>, and NO<SUB align="right"><SMALL>Y</SMALL></SUB> depicted the model's capability to evaluate various process contributions. Dry deposition of NH<SUB align="right"><SMALL>3</SMALL></SUB> contributed 34.2 ± 57.9 µg N m<SUP align="right"><SMALL>-2</SMALL></SUP> hr<SUP align="right"><SMALL>-1</SMALL></SUP>; whereas HNO<SUB align="right"><SMALL>3</SMALL></SUB> contributed slightly larger dry deposition of nitrogen, 35.2 ± 16.0 µg N m<SUP align="right"><SMALL>-2</SMALL></SUP> hr<SUP align="right"><SMALL>-1</SMALL></SUP>, in NC. NH<SUB align="right"><SMALL>4</SMALL></SUB><SUP align="right"><SMALL>+</SMALL></SUP> and NO<SUB align="right"><SMALL>3</SMALL></SUB><SUP align="right"><SMALL>-</SMALL></SUP> hourly-averaged wet deposition fluxes were calculated as 37.3 ± 19.7 µg N <SUP align="right"><SMALL>-2</SMALL></SUP> hr<SUP align="right"><SMALL>-1</SMALL></SUP> and 40.6 ± 11.8 µg N m<SUP align="right"><SMALL>-2</SMALL></SUP> hr<SUP align="right"><SMALL>-1</SMALL></SUP>, respectively. Examination of total nitrogen deposition during the summer season in NC found that NH<SUB align="right"><SMALL>3</SMALL></SUB> contributes approximately 50% of the dry deposition and NO<SUB align="right"><SMALL>3</SMALL></SUB><SUP align="right"><SMALL>-</SMALL></SUP> contributes approximately 50% of the wet deposition.