Monitoring Atmospheric Nitrogen Deposition in China

Abstract

Atmospheric nitrogen (N) deposition, one of the main pathways of loss for reactive N (Nr) species in the atmosphere, refers to the removal of Nr species as dry and wet deposition. It is an N input to terrestrial and water ecosystems and can have both substantially positive (as a nutrient source) and negative (e.g. biodiversity decline via N deposition-induced acidification and eutrophication) effects on ecosystems. Monitoring N deposition is crucial for a better understanding of its magnitude, optimizing deposition parameters in chemical transport models and evaluating the helpfulness of policies to reduce Nr emissions and deposition. This chapter reviews research progress in field and satellite monitoring of N depositions. Generally, dry and wet N deposition are of equal importance, and both vary greatly in space and time, with the former dominating mainly in northern China and the latter in southern China. Nitrogen deposition significantly increased during the period from 1980 to 2010 but has stabilized afterwards. We discuss the uncertainties in quantifying dry, wet and total N deposition. We also propose recommendations to address current challenges in developing a long-term, open-access deposition monitoring network with reasonable accuracy and representativeness in China.