Research On The Characteristics Of Ozone Pollution In Beijing And Its Sensitivity To Precursors

In recent years,along with treatment of fine particulate matter pollution to improved ozone pollution problems have become increasingly prominent.Beijing as the capital of our country,good sense of environmental protection work extra significance.This article features from ozone pollution,ozone pollution and meteorological conditions three aspects of ozone precursors,such as susceptibility to explore the issue generate ozone pollution in Beijing.This study comprehensively analyzes the trend of near-surface tropospheric ozone pollution in Beijing in recent years(2013-2017),studies the relationship between ozone concentration and meteorological elements,and analyzes meteorological elements and precursors that are prone to pollution can provide important meteorological background information for the prediction and warning of ozone pollution in Beijing.This is to develop scientific and reasonable pollution reduction measures for effective prevention and control of air pollution and local conditions.Improving the air quality in Beijing has important practical significance.This paper uses the 2013-2017 Beijing ground conventional meteorological observation data,solar radiation data and the O3 data of 22 monitoring stations of the Beijing Municipal Environmental Protection Bureau,and simulated screening for two typical composite pollution processes from October 1st,2015 to 12:00 October 8th,00:00 and May 13th,2017 to 20:00-May 23rd,20:00,respectively.Simulation studies were performed using the WRF-Chem model.The main findings of this paper are summarized as follows:Data analysis shows that in recent years(2013-2017),the concentration of O3 in Beijing has increased year by year.The long-distance transportation was carried out,the pollution process became more,the duration was longer,and the photochemical pollution was strengthened.The concentration of suburbs was higher than that in urban areas.The O3 concentration was the highest in summer,the second in spring,and the lowest in winter.Ozone pollution was the most serious from 13:00 to 18:00 in May-August;the daily change and monthly variation of O3 concentration were unimodal,the daily variation of NO2 was bimodal,the weekend effect was significant,and the concentration of O3 was negatively correlated with NO2 concentration.The ozone concentration is positively correlated with solar radiation,temperature and sunshine time.The relative humidity range which is most favorable for the increase of ozone concentration in spring is 45-50%,and the relative humidity range which is most favorable for ozone generation in summer and autumn is 60-65%.The relative humidity is significantly negatively correlated with the ozone concentration;high humidity and high wind speed are not conducive to the increase of ozone concentration;the average wind speed is 2.0-2.5m/s,which is most beneficial to the increase of ozone concentration.A typical case was screened and the simulation study using the WRF-Chem model showed that the model can well simulate the photochemical and smog complex enthalpy pollution process of this composite continuous pollution on May 13-23,2017.When VOCs and NOx are cut at the same ratio at different times,the peak concentration O3 concentration reduction effect is more obvious,and the daytime effect is more significant than nighttime;obvious degree of ozone concentration change:peak time>daytime average>nighttime average;When reducing and increasing the proportion of precursors(NOx and VOCs)by 25%at the same time,the reduction of 25%VOCs has the most significant effect on the average ozone concentration reduction,and the change of ozone concentration decreases with the increase of height,and the position of the maximum and minimum ozone concentration changes to the west and the range decreases,the VOCs control area decreases,the VOCs sensitivity is weaker,the NOx sensitivity is strengthened,and the VOCs control area changes to the NOx control area.Combining WRF-Chem mode and empirical dynamics modeling method(EKMA curve)to study the sensitivity of ozone precursors in complex pollution processes under two different weather conditions.It was found that the pollution process in two suburbs(Changping)and the urban area(Wan Shou Xigong)were VOCs-sensitive.In this paper,the following emission reduction schemes are formulated for two pollution processes:in the case of the pollution process suburb(Changping)on October 5,2015,when the 25%VOCs are cut,the O3-1h concentration can reach the standard,and the urban area(Wan Shou Xigong)is reduced by 10%VOCs,the O3-1h concentration can reach the standard.On October 5,2015,the effect of reducing the VOCs in the pollution process is better than the reduction of NOx and VOCs.On May 18,2017,the pollution process,when the suburb(Changping)cuts 60%of VOCs,the concentration of O3-1h can reach the standard.When the urban area(Wan Shou Xigong)cuts about 50%of VOCs,the concentration of O3-1h can reach the standard.