Study On Ozone Generation Sensitivity And Source Analysis In Typical Coastal Cities In Summer

The problem of ozone pollution in Weihai City has become increasingly prominent.Ozone has strong oxidation,which can react with many pollutants in the atmosphere.High concentration of ozone can cause serious harm to human life,animal and plant growth and ecological environment.Compared with primary pollutants,the mechanism of ozone generation is more complicated,which makes it more difficult to accurately and quantitatively assess the impact of pollutant transboundary transport.Therefore,clarifying the source of ozone precursors and the response of ozone pollution to the emission reduction of precursors has become a very important and complex issue in environmental management and scientific decision-making.It is of great practical significance for the research and analysis of ozone pollution control in Weihai City,and also provides theoretical and technical support for the prevention and control of ozone pollution.In this paper,the characteristics of ozone pollution,the sensitivity of ozone generation and the source of precursors in Weihai City were studied by means of statistical analysis,sampling analysis and calculation simulation,and suggestions for local ozone control were put forward.The main conclusions are as follows:?1?The present situation of ozone pollution in Weihai City from 2015 to 2018was analyzed.The results showed that ozone pollution showed an increasing trend year by year;ozone concentration was highest in spring,decreased in summer,autumn and winter,and lowest in winter;the monthly variation of ozone concentration showed a"double peak"trend,reaching two peaks in April-June and September;and the diurnal variation of ozone showed a"single peak"trend.At2:00-4:00 pm,when the temperature was the highest and the solar radiation was the strongest,there was an obvious peak.?2?The spatial distribution characteristics of ozone in Weihai City were as follows:there were some spatial differences in the annual average ozone concentration of each station,the concentration of Lantian Hotel and Shanda Campus was higher;the spatial distribution of daily variation of ozone was lower in Rushan Environmental Protection Bureau,Wendeng Development Zone and Rushan Meteorological Bureau.?3?The research on the relationship between ozone and NO_X,VOCs showed that ozone concentration was highly correlated with VOCs concentration.RIR method of ozone sensitivity analysis showed that Lingang station belonged to VOCs control area,while Shanda Campus Station belonged to VOCs and NOX co-control area.The photochemistry sensitivity of ozone formation rate to different VOC sources was compared.It was found that ozone had the highest incremental activity for olefin VOCs,followed by aromatic hydrocarbons and high carbon alkanes.?4?Based on the basic activity level of"top-down,bottom-up"pull-net pollution sources,referring to the Guidelines for the Compilation of Urban Air Pollutant Emission Inventory,combing systematically the study of emission factors,and referring to the literature of other cities,the emission inventory of Weihai air pollution sources in 2017 was established.CMAQ model was used to simulate the contribution of ozone in different regions and industries of typical pollution process in Weihai in May 2018.The results showed that the contribution rate of ozone concentration in the daytime near the surface of this process was greater than that of external transport,which contributed more than 80%.Especially in coastal areas,the contribution rate can reach more than 90%.The total contribution of land pollution emissions to O₃ in seven administrative divisions of Weihai City was less than20%.The contribution of mobile sources to ozone was relatively large among local sources,with a contribution rate of 20%.The simulation of regional contribution to NO_X showed that the internal areas of Weihai City were greatly affected by local emissions.The main reason was that NO_X has strong chemical activity and short life.The contribution of mobile sources was larger,especially the ship pollution emission,which contributed more than 60%of NO_X in coastal areas.NO_X contribution was related to the dominant wind direction.?5?In conclusion,the ozone pollution control suggestions in Weihai City were put forward from four aspects:pollution source control,strengthening monitoring and supervision of environmental pollutants,promoting pollution source emission reduction technology and regional joint prevention and control.Priority was given to the control of VOCs and the reduction of VOCs and NOx was in a reasonable proportion.For VOCs,priority should be given to olefins,aromatic hydrocarbons and high-carbon alkanes.For pollution sources,we should focus on controlling mobile sources,solvent sources,volatile sources of oil and gas,LPG/NG emissions.Industry should focus on controlling sources of rubber tyres and chemical industries and manufacturing industries involving spraying.The monitoring of VOCs,the precursor of ozone,should be strengthened.Based on the analysis of the chemical reactivity of VOCs,the monitoring of VOCs should be included in the conventional monitoring factors,and the control degree and proportion of precursors should be studied.Mobile sources in Weihai are the common sources of VOCs and NOx,especially ship emissions.It is necessary to carry out research on ship pollutant emission reduction technology,including improving the quality of ship oil,setting up coastal deceleration belts,and switching to low-sulfur fuel oil when driving into offshore waters.Develop the research and popularization of VOC control technology in tire and shipbuilding industries with local characteristics.According to the results of CMAQ simulation,the proportion of external transportation of O₃ in Weihai City is relatively high,and joint defense and control mechanism should be established with other cities.