The southern part of the Haihe River system, the largest river system in the Haihe River Basin, is important to maintain a healthy ecosystem and safe drinking water as well as for the economic development of China. To assess the effect of rapid industrialization and urbanization on the pattern of polycyclic aromatic hydrocarbon (PAH) contamination, the PAH pollution characteristics of the southern part of the Haihe River system was investigated. Sixteen PAHs in surface sediments samples collected from 24 sites covering the southern part of the Haihe River system from the upstream to the estuaries were detected and analyzed. The total PAH concentration ranged from 258.77 to 11296.66 ng/g dry weight. On average, 2-, 3-, 4-, 5and 6-ring PAHs comprised 25.32%, 27.22%, 22.62%, 14.89% and 9.96% of the total PAHs, respectively. Sites with high concentrations were concentrated in the Fuhe River, Fuyang River and Wei River, which are located near cities. A risk quotient (RQ) was used to assess the ecological risk of PAHs. The mean values of the RQ(MPCs) of individual PAHs were lower than 1.00, except for those of naphthalene (2.00) and pyrene (1.67). The RQPAHs calculated for the samples indicated that the Xidayang reservoir and the estuary of the Ziya River were determined to be at a low risk level, while Baoding City, Handan City and Aixinzhuang were determined to be at a high risk level.
LIU FengLIU JingLingCHEN QiuYingWANG BinBinCAO ZhiGuo
The distribution and characteristics of seven heavy metals in sediments located in the typical ecological units （eco-units） （e.g., rivers, lakes, and estuaries） of Haihe River Basin were analyzed. The Hakanson potential ecological risk index was used for ecological risk assessment. The results indicated that the concentration scales of As, Hg, Cr, Cd, Pb, Cu, and Zn in the eco-units were 2.08 to 24.80 mg·g-1, 0.01 to 1135.50 mg·g-1, 28.70 to 152.73mg·g-1, 0.03 to 195765.83mg·g-1, 8.65 to 157.82mg·g-1, 6.47 to 178.61mg·g-1, and 21.09 to 1076.25 mg·g-1, respectively. The maximum concentra- tions of Hg, Cd, and Zn showed higher levels than other water bodies around the world. Hg and Cd have high concentrations in Zhangweinanhe River （1135.50 and 195765.83mg·g-1, respectively） and Haihe Estuary （790.50 and 548.47 mg·g-1, respectively）. According to the ecological factor, Cd and Hg showed very strong ecological risks. The seven heavy metals, namely, Cd, Hg, As, Cr, Pb, Cu, and Zn, exhibited ecological risk levels in descending order. Based on the potential ecological risk index, Luanhe River and Baiyangdian Lake had moderate ecological risks, whereas every site in Zhangweinanhe River and Haihe Estuary had substantial risk levels. The risk order of the typical eco-units are as follows： Zhangweinan River （2278345.68） 〉 Estuary （161914.74） 〉 Luanhe River （191.54）〉Baiyangdian Lake （120.95）. These results provided a scientific basis for water environment improve- ment and risk management of the Haihe River Basin.
Jingling LIUTao YANGQiuying CHENFeng LIUBinbin WANG
