Research On The Pollution Status And Trend Of Polychlorinated Dibenzo-p-Dioxin And Polychlorinated Dibenzofuran(PCDD/Fs)in Atmosphere Of Hangzhou

In this research,the monitoring activities were carried out at different seasons,different time and different monitoring points from 2009 to 2012.In this paper the concentrations of total suspended particulate matter（TSP）and polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran（PCDD/Fs）in atmosphere of Hangzhou were detected to analyze the annual variation trend of TSP and PCDD/Fs concentrations and summarize their regional distribution characteristics,the solid/gas distribution characteristics of PCDD/Fs and the circadian rhythm of its concentration.Results of the analysis on pollutants in ambient air of Hangzhou in three years（2009.07～2012.02）demonstrated that the concentrations of particulate matter in atmosphere were in the range of 0.08 to 0.58 mg·m^-3 and the average value was 0.24mg·m^-3;the PCDD/Fs concentration range in atmosphere was 1.48～12.0 pg·m^-3 and the average value was 5.38 pg·m^-3;the toxic equivalent quantity of PCDD/Fs were in the range of 0.12 to 0.55 I-TEQ pg·m^-3 and the average value was 0.34 I-TEQ pg·m^-3.According to Ambient Air Quality Standard（GB3095-1996）,the average concentration of TSP was lower than daily average concentration limitation of level 2(0.30 mg·m^-3)while higher than the annual average concentration limitation(0.20mg·m^-3).Moreover,both the average and maximum concentrations of toxic equivalent quantity of PCDD/Fs were lower than 0.6 I-TEQ pg·m^-3,which was the evaluation criteria recommended by the Ministry of Environmental Protection.The concentration of TSP and the annual average concentration of PCDD/Fs in ambient air of Hangzhou did not have a significant variation trend,meanwhile the environmental air quality was also relatively stable during these three years of monitoring.The concentration of PCDD/Fs in atmosphere had a relatively uniform distribution with unconspicuous regional differences while the concentrations of TSP and PCDD/Fs showed seasonality that the average concentrations in winter were relatively higher than in summer.The sources of PCDD/Fs in some areas which were affected less by seasonal emissions were relatively stable,and the TEQ concentration of PCDD/Fs did not change obviously in winter and summer;the sources of some areas which were affected larger by seasonal emissions were relatively unstable,and the TEQ concentration of PCDD/Fs in winter was significantly different from it in summer.