Cost-effectiveness Analysis Of Short-term Air Pollution Control And Evaluation System Construction Of Emission Reduction Measures In Wuhan City Circle

With the implementation of a series of atmospheric environmental protection policies,the air quality in China has been significantly improved.But there are still some short-term air pollution incidents.For this,national or local governments often adopt certain emission reduction measures to achieve air quality improvement goals,and give some economic investment to follow the implementation of emission reduction measures.Therefore,on the basis of constructing a reduction cost calculation model based on the linear programming method,combining with the WRF-CMAQ model,this paper carries out the cost-effectiveness analysis of short-term emission reduction measures.At the same time,the comprehensive evaluation system for short-term emission reduction measures is builded with analytic hierarchy process,entropy method and TOPSIS method.The main research conclusions are as follows:1.The statistical analysis results show that the air quality and primary pollutants in Wuhan have obvious seasonal variation characteristics.In summer and autumn,the air quality is relatively optimal and the primary pollutant is mainly O₃.Around winter,the air quality is relatively worst and the primary pollutant is mainly PM_2.5.Moreover,the daily average O₃concentration compliance rate shows a downward trend in recent years,and it is necessary to strengthen the coordinated control of O₃ and PM_2.5 pollution.Statistics also show that Wuhan is dominated by light air pollution,so strengthening pollution control for lightly polluted days is important to further improvement of air quality.2.The classified statistical results of the pollution source emission inventory show that the total emissions of point source and surface source pollutants in Wuhan are highest in Wuhan city circle.Among them,the proportion of each pollutant of SO₂,NO_x,PM₁₀,PM_2.5and VOCs emitted by the point sources in Wuhan are between 26%-48%,and the proportion of each pollutant of these five pollutants emitted by the surface sources in Wuhan are between33%-53%.Moreover,the emission of various pollutants has different characteristics in the distribution of point sources or surface sources.3.The emission reduction cost model was constructed through the linear programming method and minimum emission reduction cost was calculated under different emission reduction targets.According to the results,when the reduction of different individual pollutants is the purpose,the pollutants with relatively high minimum emission reduction cost in the key point sources of Wuhan city circle are SO₂ and PM,while PM in the surface sources;the minimum emission reduction cost increase substantially when the emission reduction ratio is 90%-100%,so priority of emission reduction can be given to key sources in practice.When PM_2.5 control or O₃ control is the purpose,the economic benefits of the coordinated reduction of five pollutants are greater than when each pollutant is reduced individually by key point sources;the difference of the minimum emission reduction cost between these two purposes can reach 2.6×10⁴ million yuan/day by surface sources,so it is necessary to selectively reduce emissions for different primary pollutants to improve economic benefits.4.Based on the difference between the meteorological conditions and the primary pollutants,two typical short-term air pollution scenarios were selected,whose primary pollutant were PM_2.5 and O₃ respectively.The short-term emission reduction measures were formulated respectively for the two scenarios,and the implementation effects of each measure were simulated through the WRF-CMAQ model.The results show that among the 6 types of emission reduction measures in scenario 1,the strongest emission reduction measure VI can make AQI average decline from 146 to 114.Among the 4 types of emission reduction measures in scenario 2,the strongest emission reduction measure X₄ can make AQI average decline from 110 to 103,and after the VOCs/NO_x reduction ratio was optimized,it is found that the O₃ control effect is better when VOCs/NO_x=3:1.5.The weight of each evaluation indicator was determined through the analytic hierarchy process and entropy method.The indicator weight of operability,implementation cost and air quality simulation results is 23.85%,13.65%,62.50%respectively.Moreover,the TOPSIS method was combined to calculate the pros and cons of various short-term emission reduction measures.The results show that the measure VI in scenario 1 is the best with comprehensive superiority of 58.78%,which requires the key point sources of Wuhan city circle and surface sources of Wuhan to reduce their all emissions.The measure X₃ in scenario 2 is the best with comprehensive superiority of 59.65%,which requires the local pollution sources in Wuhan reduce 50%of emissions.