Study On The Characteristics And Effects Of Ammonium Salt Pollution In The Atmosphere And Atmospheric Particles In The Shihezi Region

Atmospheric ammonia（NH₃）,on the one hand,participates in the nitrogen cycle as an active nitrogen compound,and on the other hand,as the only basic gas in the atmosphere reacts with acidic gas to form the main component of atmospheric particulate matter,the secondary inorganic water-soluble ammonium ion（SNA）.Due to the serious pollution of atmospheric particulate matter in Shihezi area in recent years,the pollution characteristics and influencing factors of local atmospheric ammonia and atmospheric particulate matter carrying ammonium salt ion concentration were explored,and then the correlation and transformation relationship between atmospheric ammonia and ammonium salt were revealed to provide accurate and scientific data support for the prevention and control of local atmospheric particulate matter pollution,especially source control.In this thesis,through the online monitoring of atmospheric ammonia in Shihezi area,combined with meteorological factors and conventional pollutants to explore the factors affecting the change of atmospheric ammonia concentration and correlation.At the same time,the time trend and pollution characteristics of PM₁₀,PM_2.5,PM₁and SNA components as well as their components were obtained through manual collection of atmospheric particulate matter with three particle sizes.The influence of NH₃on the generation of ammonium ion was analyzed by combining local meteorological data and conventional pollutants,and the correlation and transformation relationship between atmospheric ammonia and ammonium salt was explored.Specific research contents are as follows:In this thesis,the pollution characteristics of atmospheric ammonia,PM₁₀,PM_2.5,PM₁and 9 ionic components,including SNA,were obtained by collecting atmospheric particulate matter with three particle sizes and carrying out online monitoring of atmospheric ammonia in Shihezi area.Meanwhile,correlation analysis of atmospheric ammonia was conducted based on local meteorological data,conventional pollutants and other influencing factors.Finally,the influence of NH₃on secondary inorganic ions was analyzed,and the conversion relationship between atmospheric ammonia and ammonium salt was explored.The research contents are as follows:（1）Firstly,the pollution characteristics of the precursor atmospheric ammonia（NH₃）were analyzed,and the order of four seasons was obtained as winter<autumn<spring<summer.The annual atmospheric ammonia monthly average concentration was 30.66μg/m³,and the annual peripheral variation average daily concentration was 30.70μg/m³.The average concentration on Friday was the lowest,because a large number of motor vehicle flows not only aggravated the NH₃production,but also emitted a certain amount of nitrogen oxides,and then weakened the NH₃content in the atmosphere.The annual peak concentration of NH₃at 5 o’clock was 34.15μg/m³,which may be related to dew evaporation.The correlation analysis of meteorological factors and conventional pollutants in NH₃concentration was carried out,and the results showed that temperature and visibility had promoting effects on NH₃concentration.However,The opposite trend of NH₃with atmospheric pressure and relative humidity indicates that the increase in atmospheric pressure and relative humidity has an inhibitory effect on the concentration of NH_3。（2）The analysis of the pollution characteristics of atmospheric particulate matter and its ammonium salt ion shows that the average annual concentration level of atmospheric particulate matter of three particle sizes is PM₁<PM_2.5<PM₁₀,showing a trend of summer<spring<autumn<winter,and the annual average ratio of PM₁/PM_2.5is higher than that of PM_2.5/PM₁₀.It can be seen that PM₁contributes more to PM_2.5,and the closer the particle size is,the greater the concentration contribution is.The order of the average annual concentration of SNA in the three particle sizes is SO₄^2->NO₃^->NH₄⁺.The contribution of SO₄^2-is the largest in large particle size,and the contribution of NH₄⁺in small particle size is larger than that in large particle size.（3）By exploring the influence of meteorological factors and precursors in the process of air-particle transformation between NH₃and NH₄⁺,it is concluded that low temperature and high humidity are conducive to the transformation of atmospheric particles NH₄⁺with different particle sizes throughout the year,and the formation of ammonium salt in the atmosphere will be facilitated when NO₂concentration is higher.Finally,the transformation mechanism of different particle sizes was revealed,and it was found that ammonia was more conducive to the formation of ammonium salts in fine particles,while the anions in large particle sizes were more likely to combine with other cations to form salts.