A Study On The Quality And Change Trend Of Ambient Air Quality In Dalian

With the rapid development of industrialization and urbanization in Dalian,the ambient air has been greatly affected.The monthly average,season average and annual mean of PM₁₀,PM_2.5,O₃,CO,SO₂,NO₂ in the ambient air from 2014 to 2020 in Dalian are statistically analyzed in this paper.Results show that the annual concentrations of PM₁₀ and PM_2.5 in the air in Dalian Exceed the ambient air quality standards on different levels.O₃ has the highest average monthly concentration in May and June,while higher concentrations of other basic pollutants are shown in January,February,March,November and December.And the concentrations of the basic pollutants in spring and winter are higher than that in summer and autumn,in addition to O₃,which shows the opposite seasonal distribution.Combined with the statistical analysis above,it can be seen that the main emission sources of local basic pollutants are the emissions from coal-fired boilers in the heating season,oil-fired vehicles,and power combustion and process production in industrial production.The average daily concentrations of pollutants PM₁₀,PM_2.5and SO₂ are indeed affected by fireworks and crackers during the Spring Festival from 2015 to 2019.At the same time,influence factor and phases effected are both different.Influenced by the COVID-19 epidemic in 2020,Dalian implemented control measures to restrict non-essential activities of population,such as traffic blockade,large-scale production and so on,which indeed resulted in the decrease of the six basic pollutants in the ambient air to varying degrees.Spearman rank correlation coefficient is used to quantitatively verify the trend of the historical data of ambient air in Dalian,and it shows that the trend of ambient air quality in Dalian is improving as a whole.At the same time,the actual changing trends of sources of pollution,climate and meteorological factors,geomorphology,population density,industrial structure and local environmental protection policies are good for the air environment in the short term.Combined with environmental air related factors and prevention and control measures that have been implemented in Dalian,suggestions are put forward for local people’s government as optimizing the energy consumption structure further,controlling the exhaust gas emissions of the secondary industry further,accelerating the improvement of the green transportation framework and improving the coordination control of fine particulate matter and ozone.