Analysis Of Ozone Pollution In Dalian City From 2015 To 2017

With the rapid development of China's economy and the increasing population,the problem of urban environmental air quality has become very prominent,and atmospheric pollution has become one of the most serious environmental problems in China.At present,ozone pollution in Dalian is becoming more and more serious,and O3 becomes a pollution factor that affects environmental quality after fine particulate matter(PM2.5).According to our analysis the temporal variation and spatial distribution characteristics of O3 concentration in Dalian urban area and 10 national control points by using the data of atmospheric automatic monitoring conventional stations and super stations from 2015~2017.The peak value of O3 concentration increased in 2015~2017.Heavy pollution day is from scratch,and the overall trend is on the rise,O3 concentration is high in summer and low in winter,O3 concentration hour value showed a unimodal distribution.The lowest value occurs at 6~8,and the high value occurs at 12~18.The peak of O3 may be delayed from May to July.When heavy pollution occurs,the change of O3 concentration is affected by local photochemical reaction and external pollution transmission.The pollution level of O3 in Dalian ranks moderate among 74 cities across the country,slightly lower than the average of 74 cities across the country.The effects of ultraviolet radiation,temperature,relative humidity,air pressure,wind speed and wind direction on O3 concentration were studied using meteorological data.The concentration of O3 was significantly positively correlated with UV radiation and temperature.The relationship between relative humidity and O3 was complicated.It was not a simple linear relationship.With the increase of relative humidity,the O3 exceeding rate basically increased first and then decreased.O3 and air pressure showed Significant negative correlation,when the O3 in Dalian exceeded the standard,the near-surface wind direction was south,southwest and southeast wind.With the increase of wind speed,the O3 exceeding standard rate increased first and then decreased,which was caused by the vertical convergence and horizontal diffusion.Through the analysis of weather conditions,pollutant analysis,meteorological elements analysis,and backward trajectory analysis,the two typical O3 pollution processes were analyzed in depth.The causes of O3 pollution were analyzed by means of polluted air mass trajectories.It was found that O3 pollution was caused by two reasons.First,the local temperature was high and the radiation was strong.The photochemical reaction produced a large amount of O3,and the unfavorable atmospheric diffusion conditions were superimposed.Lead to the accumulation of O3 concentration,the second is the impact of regional transmission,upstream O3 pollution is transmitted to Dalian,increasing local O3 pollution.Two typical pollution events show that the formation of atmospheric pollution is closely related to the atmosphericenvironment and regional transport.In order to control O3 pollution comprehensivelyand effectively,it should promote regional co-ordination and linkage to prevent and control of O3 and its precursors from the regional scale.