Characteristics of Atmospheric Pollutants Concentration and Clearance of Precipitation in Guiyang City

Based on the monitoring data of six major air pollutants (SO₂,NO₂,O₃,PM₁₀,CO,PM_2.5) from 9 environmental monitoring stations in Guiyang City from January 1,2013 to June 30,2015,the annual variation,diurnal variation characteristics of major air pollutants and the influence of precipitation on the concentration variation of primary air pollutants in Guiyang City were analyzed.It was found that the concentration of SO₂,NO₂,PM₁₀,CO and PM_2.5 varied annually in a single valley type,with the lowest concentration in summer and the highest concentration in winter,but the annual variation of O₃ concentration is bimodal,with two maximum values in April and October and two minimum values in November-February and July,respectively.Again the diurnal variations of SO₂,NO₂,PM₁₀,CO and PM_2.5 were bimodal,while the variation of O₃ were unimodal.Moreover,the average concentrations of SO₂,NO₂,PM₁₀,CO and PM_2.5 in suburban areas were lower than those in urban areas,which of O₃ in suburban areas were higher than those in urban areas.The wet removal effect of precipitation on O₃ is bad,but on other atmospheric pollutants is better.Especially,the removal effect of precipitation at night on particulate pollutants (PM_2.5,PM₁₀) is better than that of precipitation at daytime,yet the effect of precipitation at night on O₃ is negative.