Occurrence and ecological risks of PAHs in the dissolved and particulate phases of coastal surface water of Taiwan

Abstract

Surface seawater were collected from seven sites along the coast of Taiwan. A total of 100 L seawater was pre-concentrated from each site and the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the dissolved and particulate phases were analyzed. The characteristics, potential sources, and ecological risks of PAHs in seawater were assessed. The concentration of total PAHs (TPAHs) in the dissolved phases ranged between 3.3–25.8 ng/L, with an average of 14.7 ± 8.9 ng/L, classified as slightly contaminated, while the particulate phase ranged between 3.3–22.4 ng/L (8.5 ± 6.8 ng/L). The TPAHs concentrations in seawater are mainly dominated in the dissolved phase (60.4 ± 22.0%). The partition coefficients of PAHs in the particulate and dissolved phases were linearly correlated significantly with octanol–water partition coefficient (r = 0.744; p<0.01), indicating that hydrophobicity plays a key role in the partitioning behavior of PAHs. The dissolved phase PAHs in seawater were dominated by 3-ring PAHs (84.8 ± 3.9%), while the particulate phase was dominated by 5-ring PAHs (88.4 ± 9.1%). According to the diagnostic ratio, coal and biomass combustion are the main sources of PAHs, while petroleum and petroleum combustion sources also contributed to the northeast coast. The results of toxic equivalence quotients and mean risk quotient showed that the toxicity and risks of PAHs in the particulate phases were higher than those in the dissolved phases. Furthermore, the proportion of 5-ring PAHs in the dissolved phase was low (5.9 ± 4.3%), but relatively contributed high potential toxicity.