Relationships between PAHs and PCBs, and quantitative source apportionment of PAHs toxicity in sediments from Fenhe reservoir and watershed.

Sedimentary samples from 28 sites throughout the Fenhe reservoir and upstream watershed in China were measured, to study the relationships between PAHs and PCBs as well as perform quantitative source apportionment of toxicity. The distributions of ∑16PAHs and ∑123PCBs showed high correlation. The ∑7C-PAHs (total concentrations of seven carcinogenic PAHs) varied from 87.7 to 2005.0ngg(-1)dw, and the ∑6DL-PCBs (total concentrations of six dioxin-like PCB congeners) were n.d.-5.96ngg(-1)dw. Toxicity and biological risk were assessed using toxic equivalent quantity (TEQ) and sediment quality guideline quotient (SQGQ). The BaP played the dominant role for TEQPAH at most sites (37.17-89.40%), although the CHR showed the highest concentration level. PCB-81 contributed the highest TEQPCB. High correlations were observed between ∑16PAHs and ∑7C-PAHs, ∑123PCBs and ∑6DL-PCBs, ∑7C-PAHs and ∑6DL-PCBs as well as TEQPAH and TEQPCB. Furthermore, quantitative source apportionments for PAHs concentrations and TEQ were carried out, combining the positive matrix factorization (PMF) with the formula of TEQ. For most sites, the vehicular sources were the largest contributors to TEQPAH (46.58%), while coal combustion sources were the highest contributor for PAHs concentrations (43.31%). The relatively higher correlations between PCBs and contributions of coal combustion to PAHs might imply the similar distribution of industrial sources for PAHs and PCBs.