Vertical profile, sources, and equivalent toxicity of polycyclic aromatic hydrocarbons in sediment cores from the river mouths of Kaohsiung Harbor, Taiwan

•The PAHs contamination and potential toxicity in core sediments from the river mouths were evaluated.•The vertical profile of various PAH species is relatively stable throughout the sediment cores.•Major sources of sediment PAHs come from those polluted urban rivers and industrial area.•Higher probability of toxicity pollution was found in the Salt River mouth. Six sediment cores collected at four contaminated river mouths and two harbor entrances in Kaohsiung Harbor (Taiwan) were analyzed to evaluate the sources and potential toxicity of polycyclic aromatic hydrocarbons (PAHs). PAHs presented the wide variations ranging from 369±656 to 33,772±14,378ngg−1 at the six sampling sites. The composition of PAHs presented a uniform profile reflecting the importance of atmospheric input from vehicle exhausts or coal combustion in the river mouths. PAHs diagnostic ratios indicated a stronger influence of coal combustion in the Salt River mouth and the prevalence of petroleum combustion and mixed sources in the other rivers and harbor entrances. PAHs toxicity assessment using the mean effect range-median quotient (m-ERM-q: 0.011–1.804), benzo[a]pyrene-toxicity equivalent (TEQcarc: 22–2819ngTEQg−1), and dioxin-toxicity equivalent (TEQfish: 37–5129pgTEQg−1) identified the Salt River mouth near the industrial area of the harbor as the most affected area.