| Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants and widely exist in environment, known for their teratogenic, carcinogenetic and mutagenic effects. Research results have demonstrated that most waters in the world are polluted by PAHs to different extent. In this study, water samples collected from 12 sections in Chongqing along the Yangtze River and Jialing River, China from June to November. Concentration levels of 5 PAHs, including Nap, Ace, Fle, Flu and B[a]p were analyzed in these samples by liquid-liquid extraction and Gas Chromatogram-FID determination. The pollution level, distribution and health risk of PAHs in this area were analyzed.Except for the low detection rate for B[a]p in this area, Nap,Ace,Fle and Flu were proved universally exist in the water samples. The concentration of Nap, Ace, Fle, Flu and B[a]p ranged from 0.010 to 10.983μg/L, 0.007 to 2.138μg/L, 0.009 to 7.83μg/L, 0.003 to 4.582μg/L and 0.006 to 1.566μg/L, respectively. And the concentrations of these five PAHs changed greatly from upstream to downstream of the Yangtze River and Jialing River. The average concentrations of∑5PAHs (sum of 5 PAHs) in all samples during the six months were between 1.220 to 5.669μg/L. Ace,Fle and Flu concentrations were lower than the chronic for aquatic life criteria, but Nap and B[a]p higher than this criteria. Fle and Flu concentrations lower than EPA water quality standard. But B[a]p concentrations exceeded the water quality standard of China and US EPA.Distribution characteristics of the sum of 5 PAHs fluctuated greatly in the Yangtze River and Jialing River. Generally,∑5PAHs concentrations of Yangtze River were higher than that of Jialing River. Nap concentrations were changed greatly in this area and comparatively high in the confluent section of these two rivers. However, the concentrations of the other four PAHs had small confluction among different sites. The spatial distribution of these five PAHs was related to the industrial distribution of Chongqing city. Five PAHs varied greatly in different months, the concentration of which was relatively high in July, low in Augest and November. Two rings and three rings PAHs were the main components in the area.1. A water environmental health risk assessment model was established to evaluate the health risk caused by these five PAHs. The results indicated that the health risk caused by the Nap, Ace, Fle and Flu in the 12 sections ranged between 1.12×10-11a-1 and 9.89×10-11a-1, 6.98×10-13a-1 and 5.92×10-11a-1, 5.50×10-13a-1 and 3.15×10-11a-1, 1.89×10-12a-1 and 7.48×10-12a-1, respectively, lower than the neglectable risk level recommended by relevant management departments.The health risk coused by B[a]p was from 1.16×10-8a-1 to 1.20×10-6 a-1 in this area, and the value were lightly lower than the maximum tolerable value (5.0×10-5a-1) recommended by International Commission on Radiological Protection. |
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