Correlating the spatial distribution of atmospheric ammonia with delta super(15)n values at an ammonia release site

A field ammonia (NH sub(3)) release experiment and open top chambers containing moorland monoliths continuously fumigated with NH sub(3) or sprayed with NH sub(4)Cl were used to assess the potential for using delta super(15)N values in determining the area of influence around a point NH sub(3) emission source. delta super(15)N values are being increasingly used as environmental tracers and we tested the hypothesis that the delta super(15)N signal from an NH sub(3) emission source is observable in nearby vegetation. Using modified monitoring devices, atmospheric NH sub(3) concentrations were found to decrease with distance from source, with delta super(15)N values also reflecting this trend, producing a signal shift with changing concentration. Open top chamber studies of delta super(15)N values of Calluna vulgaris (L.) Hull indicated a correlation with deposition treatments in current year shoots. Analysis of Calluna shoots from the NH sub(3) release showed a similar trend of delta super(15)N enrichment. Significant linear correlations between delta super(15)N and percent N in plant material were found, both in the controlled conditions of the open top chambers and at the NH sub(3) release site, illustrating the possible use of this technique in N deposition biomonitoring.