Concentration, Distribution, Source, and Risk Assessment of PAHs and Heavy Metals in Surface Water from the Three Gorges Reservoir, China

ABSTRACT

Fifteen polycyclic aromatic hydrocarbons (PAHs) and heavy metals (Cr, Ni, As, Cd, Pb, and Hg) were quantified in 19 surface water sites of the Three Gorges Reservoir, China. The total concentrations of 15 PAHs and six heavy metals in the 19 sample sites ranged from 130.8 ng L⁻¹ to 227.5 ng L⁻¹ and 3.2 μg L⁻¹ to 6.0 μg L⁻¹, respectively. The mean concentration of As was the highest among the six heavy metals (2.1 ± 0.3 μg L⁻¹), followed by Cr (0.5 ± 0.3 μg L⁻¹), Ni (1.3 ± 0.1 μg L⁻¹), Cd (0.2 ± 0.01 μg L⁻¹), Pb (0.07 ± 0.08 μ g L⁻¹) and Hg (0.05 ± 0.08 μg L⁻¹). The isomer ratio results suggest that PAHs at most sites were mainly from petroleum combustion, while coal and biomass combustion was the main source at sites 1, 2, 6, 7, 9, 14, and 17. Based on principal component analysis, the main source of heavy metals was anthropogenic activities and weathering of bedrocks. Depending on characteristic of RQ_(NCs) ≥ 1 and RQ_(MPCs) < 1, BaA showed higher potential ecological risk than other PAHs, therefore, all sampling site needed to be paid much more attention, included some remedial actions. Meanwhile, after assessing human health risk of heavy metal, it was unlikely to experience adverse health effects, even exposing through more pathways and six kinds of heavy metals simultaneously.

Key Words:

• PAHs
• heavy metals
• source
• risk assessment
• Three Gorges Reservoir (TGR).