| The Ziya River is one of the major branches of the Haihe River, showing a typical conventional water supply characteristics. With the rapid development of industry and agriculture and the increase of population of the Hebei Plain, the water consumption and wastewater discharged from industries increased year by year. The emission of pollutant brought about deposit accumulation and more pollution. However, when the hydrodynamic condition changed, the pollutant in sediment released into water body, that leaded to secondary pollution of the water quality directly. Therefore, after taking effectual control of external contamination, it seems more important to study the internal contamination of Ziya River. In our research, collecting 39 samples were studied, we ananlyze the heavy metal (Cd, Cr, Cu, Mo, Ni, Ta, Tl, V, W, Zn, Pb) and PAHs. Furthermore, the pollution characteristics of Persistent Toxic Substances in sediment were analyzed in order to assess their ecological risk. The developed risk-based screening approach was applied to screen the priority contaminants in multi-medium, such as sediment in Ziya River. The following conclusions have been made:(1) There was a certain degree of enrichment of heavy metals at north Ziya River and mid lake region, indicting serious ecological risk. The average concentrations of Cd、Cr、Cu、 Mo、Ni、Ta、Tl、V、W、Zn and Pb were 124.73、0.81、53.45、 2.94、31.4、0.67、0.76、63.48、1.44、276.61、53.09 mg·kg-1. Compared with the background values, Cd was indicting serious ecological risk. From the spatial distribution, the average concentrations of heavy metals in surface sediment had the following characteristic:Beili River was polluted mostly. Associated with the principal component analysis (PCA), Cd、Cr、Cu、Mo、Tl、Zn and Pb were probably derived from the discharge of industrial wastewater and domestic sewage. The ecological risk degree of 6 heavy metals was:Cd> Pb>Cu>Tl>Ni>Mo>Cr>Zn>V>W>Ta.(2) A screening approach for identification and ranking of potential risky contaminants was proposed to overcome the drawbacks of traditional analytical methods designed for a specific class of contaminants. The developed risk-based screening approach was applied to screen the priority contaminants in multi-medium, such as sediment in Ziya River. We found 2508 kinds of compounds, including to industrial chemicals, PPCPs, pesticides and PAHs and so on. The phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), benzothiophene, caprolactam and BHT were detected in all sample.(3) The polycyclic aromatic hydrocarbon (PAHs) in sediments of Ziya River were at a high pollution level, so that there was a seriouss ecological risk. The total concentration of 16 PAHs in surface sediment of Ziya River ranged from 3372 to 92949 μg·kg-1, with an average concentration of 16626 μg·kg-1, indicting a high pollution level. Among the 16 PAHs, middle and high ring PAHs dominated. From the spatial distribution, the average concentrations of PAHs in surface sediment had the following characteristic:Niuwei River was polluted mostly. The PAHs in surface sediment of Ziya River were maily derived from wood and coal burning, gasoline and diesel combustion and coke incineration. PAHs in surface sediment of Ziya River that suggesting a certain potential toxicity were at high ecological risk。... |
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