A spatially refined monitoring based study of atmospheric nitrogen deposition

Abstract

Atmospheric concentrations of NO 2, HNO 3, NH 3, aerosol NH 4+ and NO 3-, and the bulk deposition of NH 4+ and NO 3- were measured for two years at ten sites around the West Midlands, UK. Eight of these sites were spread across the 125km 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 20kgNha -1yr -1. © 2004 Elsevier Ltd. All rights reserved.