Abstract
Abstract. As a major alkaline gas in the atmosphere, NH3 significantly impacts atmospheric chemistry, ecological environment, and biodiversity. Gridded NH3 emission inventories can significantly affect the accuracy of model concentrations and play a crucial role in the refinement of mitigation strategies. However, several uncertainties are still associated with existing NH3 emission inventories in China. Therefore, in this study, we focused on improving fertilizer-application-related NH3 emission inventories. We comprehensively evaluated the dates and times of fertilizer application to the major crops that are cultivated in China, improved the spatial allocation methods for NH3 emissions from croplands with different rice types, and established a gridded NH3 emission inventory for mainland China with a resolution of 5 min × 5 min in 2016. The results showed that the atmospheric NH3 emissions in mainland China amounted to 12.11 Tg, with livestock waste (44.8 %) and fertilizer application (38.6 %) being the two main NH3 emission sources in China. Obvious spatial variability in NH3 emissions was also identified, and high emissions were predominantly concentrated in North China. Further, NH3 emissions tended to be high in summer and low in winter, and the ratio for the July–January period was 3.08. Furthermore, maize and rice fertilization in summer was primarily responsible for the increase in NH3 emissions in China, and the evaluation of the spatial and temporal accuracy of the NH3 emission inventory established in this study using the WRF-Chem and ground-station- and satellite-based observations showed that it was more accurate than other inventories.
Highlights
Ammonia, a major form of reactive nitrogen, plays an important role in atmospheric chemistry, the ecological environment, and biodiversity (Sheppard et al, 2011; Zhang et al, 2018)
As the major alkaline gas in the atmosphere, it can form (NH4)2SO4 and NH4NO3 with H2SO4 and HNO3 produced from the oxidation of SO2 and NOx, respectively, and contribute to the formation of secondary inorganic aerosols (SIAs), thereby increasing the concentration of PM2.5 (Fu et al, 2017)
To improve the accuracy of the emission inventory, we focused on improving the accuracy of NH3 emissions from fertilizer application, and the latest methods in the literature were used for quantifying emissions from other sources, such as livestock waste
Summary
A major form of reactive nitrogen, plays an important role in atmospheric chemistry, the ecological environment, and biodiversity (Sheppard et al, 2011; Zhang et al, 2018). As the major alkaline gas in the atmosphere, it can form (NH4)2SO4 and NH4NO3 with H2SO4 and HNO3 produced from the oxidation of SO2 and NOx, respectively, and contribute to the formation of secondary inorganic aerosols (SIAs), thereby increasing the concentration of PM2.5 (Fu et al, 2017). In China, the contribution of agriculture-related NH3 emissions to SIA and PM2.5 is 29 % and 16 %, respectively (Han et al, 2020) This fine-particle formation has led to substantial health and economic costs (Paulot and Jacob, 2014). Liu et al, 2019) Such increases in NH3 concentrations may reduce the effectiveness of particle pollution control achieved via SO2 and NOx emission reduction
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