Land atmosphere exchange of reactive nitrogen

The fixed nitrogen entering the global atmosphere has increased by a factor of three since 1850 as a consequence of human activity, resulting in a faster global cycling of reactive nitrogen compounds between the biosphere and atmosphere and much larger deposition fluxes into ecosystems. As the number of compounds involved in the exchange is large it is necessary to take a holistic approach in the study of exchange between reactive N compounds and provide accurate estimates and predictions of all reactive N species together. This paper outlines the approach the EU project 'NitroEurope IP' is taking to improve our understanding of reactive N in Europe. The three-tier network of measurement sites across Europe, the type of measurements made, and examples of early results are provided.