Atmospheric nitrogen deposition to China: A model analysis on nitrogen budget and critical load exceedance. (March 2017)

• Record Type: Journal Article
• Authors: Zhao, Yuanhong; Zhang, Lin; Chen, Youfan; Liu, Xuejun; Xu, Wen; Pan, Yuepeng; Duan, Lei
• Is Part Of: Atmospheric environment. Volume 153(2017)
• Page Start: 32
• Page End: 40
• Publication Date: 2017-03
• Subjects: Nitrogen deposition -- Nitrogen budget -- Critical load -- Ammonia -- Nitrogen oxides; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2017.01.018
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: We present a national-scale model analysis on the sources and processes of inorganic nitrogen deposition over China using the GEOS-Chem model at 1/2° × 1/3° horizontal resolution. Model results for 2008–2012 are evaluated with an ensemble of surface measurements of wet deposition flux and gaseous ammonia (NH3 ) concentration, and satellite measurements of tropospheric NO2 columns. Annual total inorganic nitrogen deposition fluxes are simulated to be generally less than 10 kg N ha −1 a −1 in western China (less than 2 kg N ha −1 a −1 over Tibet), 15–50 kg N ha −1 a −1 in eastern China, and 16.4 kg N ha −1 a −1 averaged over China. Annual total deposition to China is 16.4 Tg N, with 10.2 Tg N (62%) from reduced nitrogen (NHx ) and 6.2 Tg N from oxidized nitrogen (NOy ). Domestic anthropogenic sources contribute 86% of the total deposition; foreign anthropogenic sources 7% and natural sources 7%. Annually 23% of domestically emitted NH3 and 36% for NOx are exported outside the terrestrial land of China. We find that atmospheric nitrogen deposition is about half of the nitrogen input from fertilizer application (29.6 Tg N a −1 ), and is much higher than that from natural biological fixation (7.3 Tg N a −1 ) over China. A comparison of nitrogen deposition with critical load estimates for eutrophication indicates that about 15% of the land over China experiences critical load exceedances, demonstrating the necessity of nitrogen emission controls to avoid potential negative ecological effects. Highlights: Sources and processes controlling nitrogen deposition over China are quantified. Reduced nitrogen (NH3 ) and dry deposition process are significant contributors. 15% of the China's land experiences critical load exceedances for eutrophication.