[Concentrations of PCDD/Fs in the atmosphere of Chongqing City and its seasonal variation].

As a comprehensive monitoring survey on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in Chongqing, 20 ambient air samples taken from 5 locations in four seasons were studied. The PCDD/F TEQ concentrations varied from 0.017 pg x m(-3) to 0.21 pg x m(-3). The average value was (0.094 +/- 0.054) pg x m(-3). The PCDD/F concentrations varied by locations and seasons, and the orders were: urban area > suburban area > background area, and Winter > Spring > Autumn > Summer. The concentrations of PCDD/Fs were 2.2-4.6 times higher in the winter than during the summer. The PCA results indicated that PCDD/F homologue pattern varied by seasons. The PCDD/F homologue pattern in particle dominated in winter and spring, and the pattern in gas dominated in summer and autumn. The mass concentration of PCDD/F congener was significantly positively correlated with that of SO2, NO2, PM10 and TSP, and insignificantly negatively correlated with that of O3, respectively. The results showed that spatial distribution and seasonal variation of atmospheric PCDD/Fs in Chongqing was consistent with that of these conventional indicators, and the PCDD/Fs pollution was closely related with the emission sources of SO2, NO2, PM10 and TSP.