Significant Increase in Ammonia Emissions in China: Considering Nonagricultural Sectors Based on Isotopic Source Apportionment
Fenghua Yan, Weihua Chen, Xuemei Wang, Shiguo Jia, Jingying Mao, Jiachen Cao, Ming Chang
Abstract
Isotopic source apportionment results revealed that nonagricultural sectors are significant sources of ammonia (NH 3 ) emissions, particularly in urban areas. Unfortunately, nonagricultural sources have been substantially underrepresented in the current anthropogenic NH 3 emission inventories (EIs). Here, we propose a novel approach to develop a gridded EI of nonagricultural NH 3 in China for 2016 using a combination of isotopic source apportionment results and the emission ratios of carbon monoxide (CO) and NH 3 . We estimated that isotope-corrected nonagricultural NH 3 emissions were 4370 Gg in China in 2016, accounting for an increase in the total NH 3 emissions from 7 to 31%. As a result, compared to the original NH 3 EI, the annual emissions of total NH 3 increased by 35%. Thus, in comparison to the simulation driven by the original NH 3 EI, the WRF-Chem model driven by the isotope-corrected NH 3 EI has reduced the model biases in the surface concentrations and dry deposition flux of reduced nitrogen (NH x = gaseous NH 3 + particulate NH 4 + ) by 23 and 31%, respectively. This study may have wide-ranging implications for formulating targeted strategies for nonagricultural NH 3 emissions controls, making it facilitate the achievement of simultaneously alleviating nitrogen deposition and atmospheric pollution in the future.