Study On The Distribution Characteristics Of Organic And Elemental Carbon In Atmospheric Particles In Shijiazhuang City

This paper is engaged in a study of the pollution characteristic of organic carbon and elemental carbon in PM₁₀ and PM_2.5.5 in Shijiazhuang of Hebei.PM₁₀ and PM_2.5 samples had been collected by using TH150 series intelligent flow in the atmospheric sampler,which include samples by 6 sampling sites in Shijiazhuang urban from April to December in 2013 and by 7 sampling sites in television tower and six counties around Shijiazhuang from February 23 to March 9 of 2014.In addition,PM10 samples in the height of 20m and100m were also collected by using TH-16 four-channel atmospheric particulate matter sampling instrument in Shijiazhuang television tower from February 9 to March 9 of 2014.We investigated the mass concentration level of OC and EC,the ratio of OC to EC,SOC by DRI 2001 type hot light organic carbon or elemental carbon analyzer.Furthermore,studied on the main source of carbon in PM₁₀ and PM_2.5,the correlation of OC and EC,the variation characteristics with season and height,the abundance of 8 carbon components of OC and EC in PM₁₀ and PM_2.5 in Shijiazhuang.The main conclusions were as follows:1)The mass concentration of OC and EC in PM10 and PM2.5 changed with season and height.The mass concentration of OC and EC in PM₁₀ and PM_2.5 in 4 seasons presented the rule that in the winter>autumn>spring>summer,and the mass concentration of OC and EC in PM₁₀ and PM_2.5 increased with the increase of the height.The proportion of the total carbon?TC?in PM10 and PM2.5 samples in autumn and winter were in the range of 12.18%²1.81%.2)The OC/EC ratios in PM₁₀ and PM_2.5 samples by 6 sampling sites in Shijiazhuang urban and by 7 sampling sites in television tower and six counties around Shijiazhuang were greater than 2,which showed that there are secondary organic carbon in PM10 and PM_2.5.The seasonal change rule of OC/EC ratios in PM₁₀ is that the OC/EC ratios in winter>autumn>spring>summer.The seasonal change rule of OC/EC ratios in PM_2.5 is that the OC/EC ratios in the winter>autumn>summer>spring.3)In autumn and winter,the secondary organic carbon?SOC?pollution is more serious.The average concentration of SOC in PM10 and PM2.5 in autumn was respectively12.58?g/m³ and 8.99?g/m³,accounted for 45.28%and 38.21%of OC.The average concentration of SOC in PM₁₀0 and PM_2.5 in winter was respectively 20.92?g/m³ and23.50?g/m³,accounted for 48.82%and 57.04%of OC.4)The correlation coefficient between OC and EC in PM₁₀ is higher in the summer and winter,lower in the spring and autumn.On February 23 to March 9 of 2014,the correlation coefficient between OC and EC in PM₁₀ and PM_2.5 in Shijiazhuang city and around 6 counties is smaller.Meanwhile,On April to December of 2013,the correlation of OC and EC in PM₁₀ and PM_2.5 in the same height is lesser,which presented the trend that the correlation of OC and EC on different heights increased with the increase of sampling the height.5)In the sampling period,the main source of carbon in PM₁₀ and PM_2.5 in Shijiazhuang was by the automobile exhaust,followed by the road dust and coal.Carbon source in the autumn in PM₁₀ and PM_2.5 also included biomass combustion and atmospheric water soluble compounds.6)Research on carbon composition abundance has shown that the carbon component in PM_2.5 mainly comes from vehicle exhaust,combustion of biomass and coal.Moreover,the contribution rate from road dust in the carbon component main of PM10 is bigger than in PM_2.5;the contribution rate from water-soluble compounds in the carbon component of PM₁₀ was roughly same as PM_2.5.