A study of atmosphere-forest exchange of reactive nitrogen via measurements of nitrate in canopy top leaves

Abstract

Nitric acid deposited on leaf surfaces may be an important player in the atmospheric nitrogen balance in the deciduous forest environment near UMBS. Levels of nitrate deposited on leaf surfaces at the top of the canopy were measured at different times of day to determine when the canopy was a source and when it was a sink of atmospheric nitrogen. Data was also analyzed in conjunction with precipitation and tree species recordings to determine whether these have an effect on deposited nitrogen and, in turn, on atmospheric nitrogen. A significant trend in nitrate concentrations throughout the day was found and involved decrease of leaf nitrate in the morning, changing to accumulation in the afternoon. This is suspected to be due to photolysis rates and the converion of nitric acid to nitrous acid and subsequent volatilization of nitrous acid.