Impact Of Non-agricultural Ammonia Emissions On Air Quality In The Yangtze River Delta Regio

Ammonia,as the main alkaline gas in the atmosphere,can react with sulfuric acid and nitric acid to produce large amounts of secondary inorganic aerosols.The main sources of ammonia can be divided into agricultural and non-agricultural sources,and non-agricultural sources include residential,motor vehicles,industry,and electricity.Although many observational studies have shown that it is the non-agricultural sources that are the main sources of ammonia in cities,there are few studies in China to quantitatively assess the specific impact of non-agricultural sources of ammonia on air quality.In this thesis,based on a comparative analysis of three atmospheric ammonia emission inventories,an air quality simulation study was conducted for July and December 2014 in the Yangtze River Delta region.Four scenario simulations were also set up to further explore the effects of non-agricultural sources of ammonia on ammonium,nitrate,sulfate,and PM_2.5.This thesis shows that:（1）Three ammonia emission inventories were compared and analyzed,namely the 2014Yangtze River Delta air pollutant emission inventory（YRD inventory）,the Chinese multi-scale emission inventory（MEIC inventory）,and the Chinese ammonia emission inventory（PKU inventory）.Ammonia from agricultural sources in the MEIC inventory and the PKU inventory accounted for a larger share in urban areas,and the spatial distribution of ammonia in the YRD inventory was more reasonable.Using the YRD inventory as the input data of the model,the simulation results showed that the statistical parameters of ammonia and PM_2.5 were within the benchmark range.（2）Agricultural and non-agricultural sources differed significantly in the proportion of contribution to NH_X（NH₃+NH₄⁺）at different stations.Non-agricultural sources of ammonia had a greater impact on the two urban sites,with non-agricultural sources contributing 70percent of ammonia and 63 percent of ammonium salts in summer and 85 percent of ammonia and 65 percent of ammonium salts in winter;the impact was smaller in the rural sites.Spatially agricultural sources of ammonia contributed more than ninety percent of NH_X.However,in urban areas,especially in mega-city urban areas like Shanghai,the contribution of ammonia from non-agricultural sources to NH_X was much higher than that from agricultural sources.When only non-agricultural sources of ammonia are used to calculate the ammonia-poor and ammonia-rich states,Shanghai city center showed an ammonia-rich state in both summer and winter.（4）Non-agricultural sources of ammonia had different effects on fine particulate matter(PM_2.5)generation at different stations.In the two urban sites,non-agricultural sources of ammonia contributed about 15%of PM_2.5 generation in summer and 30%in winter,while non-agricultural sources of ammonia had less impact in the rural sites.At the urban scale,the impact of non-agricultural sources of ammonia on PM_2.5 was higher than that of agricultural sources of ammonia,with the highest impact generating 18μg/m³ of PM_2.5 in the center of Shanghai in winter.Comparing the population-weighted concentrations of particulate matter in the Yangtze River Delta,Shanghai,Hangzhou and Nanjing in winter,it was found that the population-weighted concentrations of PM_2.5 generated by the influence of non-agricultural sources of ammonia in urban areas were much higher than the regional average of the Yangtze River Delta.This indicated the importance of implementing non-agricultural sources of ammonia emission reduction in urban areas.Overall,this thesis analyzed the impact of non-agricultural sources of ammonia on air quality in urban areas from the perspective of non-agricultural sources of ammonia,which contribute an average of 15%of PM_2.5 generation in summer and 30%in winter,providing a scientific basis for the development of ammonia reduction policies in urban areas.