PCDD/Fs and dl-PCBs concentrations in water samples of Taiwan

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (dioxin-like PCBs) have received much public concern worldwide due to their persistence and toxicity. The presence of these compounds in environmental matrices, especially in water bodies, enhances the risk of human exposure to these toxic pollutants. In this study, seventeen 2,3,7,8 chlorinated PCDD/Fs and twelve dl-PCBs were measured in 11 groundwater samples collected throughout Taiwan and 2 surface water samples collected in northern Taiwan. PCDD/F and PCB concentrations in two surface water samples are relatively low, with the average concentrations of 0.038 and 0.001 pg WHO-TEQ/L (7.474 and 1.862 pg L^-1), respectively. As for groundwater samples, PCDD/F concentrations measured range from 0.005 to 3.963 pg WHO-TEQ/L, while dl-PCB concentrations range from 2.5 × 10^-5 to 0.189 pg WHO-TEQ/L. Total WHO-TEQ concentrations range from 0.005 to 3.963 pg WHO-TEQ/L, reflecting serious contamination of PCDD/Fs and PCBs in groundwater at some sampling sites. In term of total PCDD/Fs, PCDDs constitute a significant fraction (77.3%), and OCDD is most abundant, followed by HpCDD/Fs and HxCDD/Fs. PCB 118 is dominant among 12 dl-PCBs measured, followed by PCB 105 and PCB 77. Solid-phase PCDD/Fs generally predominate in water samples and PCDFs are of slightly lower distribution in solid phase in comparison with PCDDs, while PCBs are mainly distributed in dissolved phase. Results of principal component analysis (PCA) indicate that use of PCP and Na-PCP, thermal processes and PCBs-containing products might be the major sources of PCDD/Fs and PCBs in water samples measured.