Significant Increase in Ammonia Emissions in China: Considering Nonagricultural Sectors Based on Isotopic Source...

Isotopic source apportionment results revealed that nonagricultural sectors are significant sources of ammonia (NH₃) emissions, particularly in urban areas. Unfortunately, nonagricultural sources have been substantially underrepresented in the current anthropogenic NH₃ emission inventories (EIs). Here, we propose a novel approach to develop a gridded EI of nonagricultural NH₃ in China for 2016 using a combination of isotopic source apportionment results and the emission ratios of carbon monoxide (CO) and NH₃. We estimated that isotope-corrected nonagricultural NH₃ emissions were 4370 Gg in China in 2016, accounting for an increase in the total NH₃ emissions from 7 to 31%. As a result, compared to the original NH₃ EI, the annual emissions of total NH₃ increased by 35%. Thus, in comparison to the simulation driven by the original NH₃ EI, the WRF-Chem model driven by the isotope-corrected NH₃ EI has reduced the model biases in the surface concentrations and dry deposition flux of reduced nitrogen (NH = gaseous NH₃ + particulate NH₄⁺) by 23 and 31%, respectively. This study may have wide-ranging implications for formulating targeted strategies for nonagricultural NH₃ emissions controls, making it facilitate the achievement of simultaneously alleviating nitrogen deposition and atmospheric pollution in the future.