Research On The Temporal And Spatial Distribution Of Ozone And Its Influencing Factors In The Yangtze River Delta Urban Agglomeration

Near-surface ozone pollution poses great harm to human body,animals and plants.As one of the urban agglomerations with the largest population and the most developed economy in China,the air pollution situation in urban agglomerations of Yangtze River Delta is increasingly aggravated,and ozone has replaced PM_2.5as the primary air pollutant in urban agglomerations.Complex causes,ozone and its precursor to the nonlinear relationship between,different action in the troposphere and the stratosphere,the integrated use of OMI total atmospheric ozone column data and high resolution on the near side of ozone concentration simulation data of Yangtze river delta urban agglomerations overall distribution characteristics were analyzed,and the combination of population data for the surface ozone exposure risks and health damage assessment,Finally,the geographic detector model was used to explore the causes of pollution,in order to provide basic data and scientific theoretical basis for improving public awareness of environmental protection and air pollution prevention,and formulating accurate and effective pollution prevention and control policies for specific regions.The main conclusions of the study are as follows:(1)Total atmospheric ozone in the Yangtze River Delta urban agglomerations showed an upward trend from 2005 to 2020,and concentrations peaked in 2010,2015and 2018,respectively.Under the influence of photochemical equilibrium and stratospheric atmospheric circulation,the seasonal variation of ozone column concentration is spring>summer>winter>autumn.The spatial distribution of atmospheric ozone in urban agglomeration is low in the south and high in the north,and the concentration decreases from high latitude to low latitude.In spring,the concentration of atmospheric ozone decreased gradually,and reached the lowest value in autumn.In winter,the concentration of ozone column in the northern part of the urban agglomeration increased.(2)The concentration of near-surface ozone generally increased with the change of years from 2013 to 2020,and significantly increased in 2017.27 cities can be divided into four types according to the change of annual evaluation value of urban ozone concentration.The high incidence of ozone pollution mainly occurs in spring and summer,and there are two concentration peaks in a year.The first peak occurs in May and June in late spring and early summer,which is also the most serious period of ozone pollution in urban agglomeration.The second peak usually occurs in September in autumn.The ozone pollution in the urban agglomeration spread to the north and west of Shanghai and Jiaxing year by year,and finally formed the high ozone concentration area in the northern part of the stable urban agglomeration,and the area of the polluted area expanded most obviously in summer.(3)The risk assessment of ozone population exposure in the Yangtze River Delta urban agglomeration showed that the distribution of high-risk and extremely high risk areas was basically consistent with the distribution of high ozone concentration near the surface of the urban agglomeration,and also the distribution of hot spots in the exposed areas.For specific cities,the high-risk areas of ozone population exposure are mainly concentrated in the central urban areas with large population density and relatively developed economy.Taking COPD as the endpoint of disease,the health loss caused by ozone exposure in urban agglomerations in the Yangtze River Delta was evaluated.The results showed that the number of excess COPD deaths attributed to ozone exposure increased year by year in urban agglomerations,and Shanghai and Suzhou showed stable high-value loss areas.However,due to the large increase of ozone concentration in Cities of Anhui province,the number of excess COPD deaths has doubled,so it is urgent to formulate pollution prevention and control measures.(4)The causes of near-surface ozone pollution in urban agglomerations in the Yangtze River Delta were investigated by using a geographic detector model combined with multiple meteorological factors,anthropogenic precursor emission data,tropospheric NO₂ concentration and atmospheric ozone column concentration.The results show that meteorological factors are the main factors affecting the distribution of near-surface ozone,and the vertical and horizontal components of wind are the main factors,and the strong surface solar radiation and temperature are very important for the formation of high-concentration near-surface ozone.For man-made emissions of precursors,the eastern part of the urban agglomeration is greatly affected by VOC_s,while the western part is mainly in the NO_xcontrol area.Tropospheric NO₂ and atmospheric ozone concentration also contribute to the formation of near-surface ozone,which is reflected in influencing the concentration of ozone precursors and as the source of vertical transport.The variation of near-surface ozone concentration in urban agglomerations is the result of the interaction of many factors.