A spatially refined monitoring based study of atmospheric nitrogen deposition

Atmospheric concentrations of NO2, HNO3, NH3, aerosol NH4+ and NO3-, and the bulk deposition of NH4+ and NO3- were measured for two years at ten sites around the West Midlands, UK. Eight of these sites were spread across the 125 km(2) Lichfield nitrate vulnerable zone (NVZ). The measured data were interpolated across the area, and by applying land-use specific deposition velocities to the airborne concentrations, seasonal N deposition fluxes to the NVZ were estimated. There was a large spatial variation in deposition flux, driven mainly by land-use, but also by measured concentration gradients. Spatially averaged total flux exhibited a seasonal pattern; peaking in spring-summer. Each measured component contributed a substantial fraction of the total flux, but the importance of each varied seasonally. Oxidised-N and reduced-N fluxes were relatively equal. Annual average flux was approximately 20 kg N ha(-1) yr(-1). (C) 2004 Elsevier Ltd. All rights reserved.