| With people’s increasing attention to the quality of life,the problem of air pollution has been widely concerned.The air pollution in Baoji City is serious because this city has a specific valley terrain,the geographical location of mountains on three sides,and the climate conditions that are not conducive to the diffusion and transfer of pollutants.In addition,Baoji City is an old industrial base of national key development.In the process of industrial development,it consumes a lot of energy,and the pollutants discharged have a great impact on the environment,especially the emission of harmful gases.After the implementation of"haze control with an iron hand"and a series of pollution control measures by the government,the air quality of Baoji City has improved to a certain extent,but on the whole,it is still not optimistic,and there are still many pollution problems.Therefore,through the analysis of the characteristics of the changes of atmospheric environmental quality in Baoji City,we can provide a scientific basis for the formulation of reasonable air pollution control strategies.Based on the analysis of the spatial and temporal variation characteristics of 8 air automatic monitoring points in Baoji City from 2016 to2019,this paper discusses the sources of air pollution in Baoji City,and puts forward the air pollution prevention measures and suggestions,and draws the following conclusions.（1）The average annual concentration of five pollutants is decreasing year by year.Among them,the average annual concentration of NO2 in 2017 and 2018 exceeded the secondary concentration limit of Ambient Air Quality Standard（40μg/m3）.The annual average concentrations of PM10 and PM2.5 in four years（2016-2019）exceeded the standard,and in 2019,the annual average concentrations of PM10 and PM2.5 exceeded the secondary standard by 1.17 times and 1.46 times respectively.The primary pollutants in the air vary from season to season,with PM2.5 pollution in winter,PM10 pollution in spring and autumn,and O3pollution in summer.（2）By analyzing the time characteristics of the five pollutants,it is found that the monthly average emission concentrations of SO2,NO2,PM2.5 and PM10 in a year from 2016to 2019 show an inverted"several"trend,all of which run at a low peak in summer,and the concentrations gradually increase from October every year to February next year and then gradually decrease.This is closely related to the heating in winter and the meteorological conditions in Baoji City in Xia Dong.In 2016-2019,the monthly average change trend of O3concentration in a year is in the shape of"several",and the monthly average emission trend shows obvious seasonal characteristics,namely,summer>spring>autumn>winter,which is just opposite to the change trend of NO2 concentration.Summer is the most serious season of ozone pollution in a year.The weather with high temperature,high ultraviolet radiation intensity and high visibility is conducive to photochemical reaction and O3 production.（3）By analyzing the spatial characteristics of five pollutants,it is found that the monitoring values of SO2,PM10 and PM2.5 are at a high level at the monitoring points of environmental protection family buildings in chencang district,which are located in industrial areas,under the conditions that are unfavorable to the diffusion of pollutants in winter;The NO2 concentration at Sandi Primary School,which is located in dense traffic area,is higher than that at other monitoring points.In summer,the O3 concentration of liberal arts colleges located in the mixed area of business and housing and traffic congestion is higher than that of other monitoring points.However,in Zhuyuangou and Miaogou villages,which are located at clean points,the concentration of O3 is higher than or equal to other monitoring points under the condition of high sunshine intensity in summer.（4）Correlation analysis showed that the concentration changes of five pollutants were significantly correlated.Among them,the correlation between SO2 and PM10 is the highest,and the R value is as high as 0.976.However,NO2 and O3 were negatively correlated（P<0.05）.Therefore,it can be concluded that the five pollutants have similar pollution sources.From the analysis of the causes of the five pollutants,the exhaust emissions from industrial coal combustion and traffic exhaust pollution are the main sources of the five pollutants.In addition,the sandstorm is high in Baoji City from March to May,so the pollution sources of PM10 also include peripheral imported pollution.According to the spatial and temporal variation characteristics and correlation analysis results of five pollutants,the strategies and suggestions for air pollution prevention and control in Baoji City are put forward as follows:1)adjust industrial structure and deepen industrial emission reduction.Shut down industrial enterprises with high energy consumption and heavy pollution;Urge all enterprises to launch mature desulfurization and denitrification facilities;Vigorously promote central heating;Promote the use of clean energy;All sewage companies are required to install online monitoring equipment.2)The local environmental protection department shall establish an emergency plan for seriously polluted weather,and start the emergency plan in the high-incidence season of smog and haze in cities every year to reduce the harmfulness of seriously polluted weather.3)Take public transport fare subsidies for urban residents to travel,and encourage residents to travel by public transport;Promote the bike-sharing project;The purchase of new cars and the transformation of old cars should be based on environmental protection;The government has comprehensively strengthened the supervision and inspection of the quality of gasoline products,intensified the investigation of non-road mobile construction machinery,improved the supervision,focused on controlling the emission of some harmful gases,and controlled the emission of mechanical pollutants within the requirements set by the state.4)Afforestation,establishment of natural barriers to prevent the surrounding dust invasion,and reduction of smog,particulate matter and other pollutants concentration in Baoji City. |
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