『Abstract
Dry and wet deposition of atmospheric nitrogen species (NO2 and HNO3) coming from nitrogen
oxides emissions in Buenos Aires city to surface waters of de
la Plata River were estimated. Atmospheric dispersion models DAUMOD-RD
(v.2) and CALPUFF were applied to area and point sources, respectively.
These models were run considering 1 year of hourly meteorological
data. Emission information included a typical diurnal variation
of area source emissions. Annual atmospheric nitrogen (N -NO2 + N-HNO3) deposition to
1,763 km2 of the river was 35,600 kg-N year-1.
dry deposition processes accounted for 89％ of this value. The
small contribution of wet deposition was a consequence of the
very few cases (5％) of rain events during offshore wind conditions.
Monthly dry deposition to 1,763 km2 of the river varied
from 1,628 kg-N month-1 in February to 3,799 kg-N month-1
in December, following the monthly occurrence of offshore winds.
Monthly wet deposition varied from 1 kg-N month-1 in
June to 1,162 kg-N month-1 in February. These results
came from the combination of favorable conditions for formation
of HNO3 and the occurrence of precipitation
during offshore wind situation. Spatial distribution of annual
atmospheric N deposition showed a strong coastal gradient. Deposition
values reached a maximum of 137.1 kg-N km-2 year-1
near the shoreline, which was reduced to the half at 4 km from
the coast.
Keywords: Atmospheric dispersion modeling; Buenos Aires; Dry deposition;
Nitric acid; Nitrogen dioxide; Wet deposition』
1. Introduction
2. Nitrogen oxides emitted in the city of Buenos Aires
3. Atmospheric dispersion-deposition models used in calculations
3.1. DAUMOD-RD (v.2) Model
3.1.1. Wet deposition parameterization
3.1.2. Dry deposition parameterization
3.2. CALPUFF model
4. Atmospheric N deposition to de la Plata River
5. Conclusions
Acknowledgements
References