Monitoring and identification of polychlorinated dibenzo-p-dioxins and dibenzofurans in the ambient central Taiwan

Polychlorinated Dibenzo-p-dioxins and Dibenzofurans (PCDD/Fs) in the ambient air of five sampling sites around central Taiwan were investigated. Principal components analysis (PCA), cluster analysis (CA) and the chemical massbalance (CMB) model were adopted to assess possible PCDD/F sources and their effects on the air quality levels. Field experimental results showed that the mean PCDD/F concentrations in the ambient air were 0.0526, 0.0591, 0.0339 and0.0727 pg I-TEQ/Nm³ in winter, spring, summer and autumn, respectively. Analysis of atmospheric isopleths for fivesampling sites displayed that high PCDD/F concentrations were mostly close to electric arc furnace plants (EAF). ThroughPCA and CA, the congener profiles of ambient air sampling sites were close to medical waste incinerators (MWI),secondary aluminum smelters (ALS), EAF, waste open burning (OB) and crematories (CM). By using the CMB model,the dominant sources of PCDD/Fs in ambient air were EAF, medical waste incinerator/municipal solid waste incinerators (MWI/MSWI) and unleaded gasoline fuel vehicle/diesel fuel vehicle (UGFV/DFV), which contributed 22-23%, 17-31%and 9-22%, respectively. The above results revealed that ambient air was affected by surrounding PCDD/F sources (MWI,ALS, EAF, CM and OB). However, due to high stack height and low emission concentration, the impact of coal-firedpower plant on the PCDD/F levels of ambient air was insignificant.