Preliminary Study On Photochemical Characteristics Of Atmospheric Ozone In Chengdu

Ozone is an unstable,very stench and poisonous light blue gas.Ozone is not only one of the strong oxidants.Its change in the troposphere can affect the concentration and life span of chemical substances such as free radicals.It is a key component in the process of atmospheric dynamics,heat,radiation and chemistry.As our country continues to intensify efforts to control haze,PM_2.5.5 and other atmospheric particulate pollution levels have been effectively controlled at the same time,the issue of ozone pollution more significant.With the increase of car ownership in China,the pollution of nitrogen oxides in big cities is worsening day by day,and the possibility of photochemical smog is also more and more serious.In this study,the research area is Chengdu,and applied the"correlation method"of mathematical statistics to the pollution of NOx,NO₂,THC,OX,NO₂/NO.The relationship and sensitivity of different precursor concentrations to O₃ pollution levels were compared.The reasons for the differences and the mechanism of photochemical pollution were discussed.The correlation between precursor pollution and O₃ was initially established.Atmospheric photochemistry Oxidative monthly distribution and seasonal distribution,and analyzed the atmospheric oxidation level in Chengdu.The relationship between OX and ozone pollution was analyzed.The relationship between atmospheric photochemical oxidation and O₃generation was analyzed.And the NO₂ photodegradation rate,the photochemical reaction environment of Chengdu was quantitatively studied.At last,the photochemical smog production（SP）of Chengdu was calculated and the relationship between NOx,THC,O₃ was calculated by using the photochemical smog production model（SPM）.The factor E（t）,quantitative analysis the relationship in NOx,THC and O₃.Through these researches,some meaningful results are obtained.The conclusions are as follows:（1）The trend of NOx and ozone in Chengdu showed a negative correlation.The negative correlation between NOx and O₃ in spring was particularly significant,followed by summer,autumn and winter,and the negative correlation decreased in turn;O₃ pollution and atmospheric photochemical production in Chengdu The consumption of NOx in the O₃ process is closely related.During the O₃ pollution process in Chengdu,the spring,summer,autumn and winter representative days are sensitive to NOx,and the spring representative day is most sensitive to NOx;in the spring,summer,autumn and winter seasons.Both THC and O₃ are negatively correlated,indicating that THC is sensitive to O₃ pollution in Chengdu.In the spring,summer and winter,Chengdu has the main effect of NOx,and the influence of precursors such as CO and VOCs is second.In the autumn,the sensitivity of NOx to O₃ pollution is reduced.Compared with cities such as Lin’an and Beijing,the NO₂/NO ratio is basically below 20,indicating that the formation mechanism of Chengdu O₃ is relatively simple.（2）The monthly average range of atmospheric oxidative O_X in Chengdu is small,the difference is less than 5%,the atmospheric oxidation is very stable and less than that in Beijing.The possibility of photochemical smog pollution in Chengdu is much smaller than that in Beijing;the photolysis of NO₂ in Chengdu The season seasons are:summer>spring=autumn>winter;summer conditions are more suitable for photochemical reactions than other seasons.The average photolysis rate of NO₂ in Chengdu is0.0085 min-1,which is lower than that in Beijing.In contrast,the environmental conditions in Chengdu are not conducive to the photolysis of NO₂,which may be better than the sunshine in Chengdu.Correlation is related;with the increase of O₃ pollution level,atmospheric oxidative O_X is negatively correlated with O₃;the contribution of local pollution in different seasons in Chengdu is that the contribution of local pollutants to atmospheric oxidization at night is higher than that during the day.Chengdu OX local contribution（O_X slope）ranged from-0.131 to 0.547,showing that Chengdu’s spring atmospheric oxidation capacity is higher than other seasons.（3）Through the calculation of the photochemical smog production model in Chengdu,it is found that Chengdu is in the alternate control zone of NOx and VOCs.The NOx control ratio of spring,summer,autumn and winter in Chengdu ranges from 37.5%to 58.33%.The results show that during the NOx control period.A higher proportion of spring control NOx emissions can more effectively reduce O₃pollution levels,and control VOCs emissions in the remaining seasons will achieve better O₃ pollution reduction.It shows that the photochemical smog yield in Chengdu is closely related to the concentration of O₃,which determines the O₃ concentration level in Chengdu.It is suggested that Chengdu should focus on controlling VOCs emissions,supplemented by NOx emission control,and reduce emissions in both directions to jointly reduce ozone pollution levels.