The Influence Of Key Industrial Pollution Sources On Air Quality In Jiayuguan City Based On CMAQ

Atmospheric environmental quality is affected by meteorological fields,pollution sources and physical and chemical processes.Jiayuguan City is located in the middle of the Hexi Corridor.It is a typical modern industrial tourism city.The key industrial pollution sources are concentrated and various pollution sources intersect.It can not only pollute the local area,but also form the pollutant regional transport.It has an impact of the environment air quality on East Town of Yumen city and Suzhou District of Jiuquan city.The numerical simulation of air quality in Jiayuguan City and its surrounding areas is of great significance for understanding the formation process and regional transport effects of local pollutants.This study collects information on the key industrial pollution sources in Jiayuguan City,couples them with the MEIC list,sets up two simulation schemes for the baseline scenario and the control scenario,and uses the CMAQ model to simulate the air quality in Jiayuguan City and surrounding areas.The typical time period is screened by analyzing the pollution level during the simulation,and the spatial distribution characteristics of the main conventional pollutants SO₂,NO₂,PM_2.5 and PM₁₀ are analyzed according to the simulation results of the baseline scenario.The CMAQ model IPR process analysis tool is used to analyze the process of pollution formation in the urban area of Jiayuguan City,and quantify the contribution of different types of atmospheric physicochemical processes to the concentration of major pollutants.According to the simulation results of the control scenario,combined with the flow field analysis during the typical period of the simulation period,the impact of the air pollutant discharge of key industrial pollution sources in Jiayuguan City on the regional transmission of Suzhou District of Jiuquan city and East Town of Yumen city is quantitatively analyzed.The main conclusions of the paper are as follows:（1）Evaluating the model simulation results.The root mean square error of the WRF model analog value and the monitored value is between 1.0³.3,and the correlation coefficient is between 0.78⁰.95.The simulation result can be used as the meteorological field input of the air quality model.The normalized deviation of the simulated and monitored values of CMAQ model is between-39.58%¹6.34%,and the correlation coefficient is between 0.41⁰.65.The model well simulates the pollutant concentration level.（2）Analyzing the spatial distribution characteristics of the main atmospheric pollutant concentrations.The results show that the high concentration of atmospheric pollutants is mainly concentrated in the urban area of Jiayuguan City and the urban area of Suzhou District of Jiuquan city.The pollutant concentration during heating period is higher than that in non-heating period.（3）Analyzing of the process of formation of atmospheric pollution in Jiayuguan City.The results show that the physical and chemical processes have different effects on different atmospheric pollutants and different sites.At the weather bureau site,the positive contribution rate of source emissions to SO₂,PM_2.5,and PM₁₀ concentrations is between 36.55%⁸9.96%,the positive contribution rate of horizontal transport is between 9.64%⁶3.45%,and the negative contribution rate of vertical transport is between 52.43%⁹7.40%.At the Jiugang Hotel site,the positive contribution rate of source emissions to SO₂,PM_2.5,and PM₁₀ concentrations is 100%,the horizontal contribution negative contribution rate is between 32.80%⁶4.40%,and the vertical transport negative contribution rate is between 27.99%⁶2.97%.The positive contribution process to the NO₂ concentration is the gas phase chemical reaction.The positive contribution rate is between 74.75%⁹2.12%,followed by the source emission process,and the horizontal and vertical transport are negative contributions.From the perspective of the whole atmosphere,horizontal transport and vertical transport basically have negative correlation effects and have obvious effects.In the urban area of Jiayuguan City,the emission of atmospheric pollutants is relatively large.The concentration of pollutants is mainly determined by source emission,horizontal transport and vertical transport.The discharge of atmospheric pollutants in the suburbs is relatively low.The concentration of pollutants is mainly determined by horizontal transport and vertical transport.（4）Analyzing the impact of the emission of atmospheric pollutants from key industrial sources in Jiayuguan City on the regional transport of Suzhou District of Jiuquan city and East Town of Yumen city during the simulation period and typical period.According to the simulation results of the control scenario and the baseline scenario,the average contribution rate and maximum value of SO₂,NO₂,PM_2.5 and PM₁₀ emitted by key industrial sources in Jiayuguan City to the urban area of Suzhou District of Jiuquan city are 19.79%,14.81%,12.76%and 12.66%,respectively.The average contribution rate and maximum value to East Town of Yumen city are 17.49%,15.91%,13.29%and 13.18%,respectively.According to the analysis of the local flow field in a typical time period,the near-surface hourly concentration distribution is basically consistent with the horizontal flow field.The contribution rates of SO₂,NO₂,PM_2.5.5 and PM₁₀ emitted by key industrial sources in Jiayuguan City to the hourly concentration of the urban area of Suzhou District of Jiuquan city at 02:00 are 46.34%,34.26%,28.29%and 24.13%,respectively.At 14:00 on May 19,the contribution rate to the hourly concentration of East Town of Yumen city are 38.85%,31.96%,24.00%and 20.52%,respectively.At 02 o’clock on November 18,the contribution rate to the hourly concentration of East Town of Yumen city are 22.99%,15.31%,10.84%and8.81%,respectively.At 11:00 on November 18,the contribution rate to the hourly concentration of the urban area of Suzhou District of Jiuquan city are 13.10%,13.88%,7.07%and4.89%,respectively.The results show that the transmission of key industrial source pollutants in Jiayuguan City is closely related to the meteorological field during the typical period.Under different meteorological conditions,the transmission effects of the urban area of Suzhou District of Jiuquan city and East Town of Yumen city are different.Therefore,it is important to analyze the regional transmission effects of pollutants in combination with the meteorological flow field during a typical time period.