Research On Heavy Metal And HCB Pollution In The Sediment Of Haihe River, Tianjin Urban Area

The surface sediment was sampled at five important sites in the mainstream of Haihe River, Tianjin urban area. The main pollutants in the sediment were analyzed and we choose the heavy metals (Cu,Pb,Zn,Cr,Cd) and hexachlorobenzene as the investigating objects. The distribution characteristics of heavy metals are increased first, decreased then. We add organic solvent to distill the pollutants using ultrasonic method and analyzed with gas chromatography. The result shows that the hexachlorobenzene concentration in dried sediment is 6.8～16.7μg/kg. In this paper, the influence factors of temperature,pH,granularity,disturbing effect were studied. The results showed that if the temperature and degree of disturbing increases, pH and granularity decreases, the heavy metals in the sediment would have more release capability. The desorption rule of heavy metals in sediment accords with the equation of Elovich and the Freundlich kinetics equation. The hexachlorobenzene will have larger desorption quantity if the temperature,degree of disturbing increases and the granularity and TOC decreases. The desorption rule of hexachlorobenzene accords with one order kinetics equation. Misgurnus anguillicaudatus lives in the bottom of the river water, which can eat the food in the sediment and assimilate the heavy metals. Through analysis the concentration of the heavy metal pollutants in Misgurnus anguillicaudatus caught in Haihe River. The heavy metals of Cu,Pb,Zn,Cd and Cr in the gill, viscera and muscle were examined. It was found that there are different contents in its three tissues; the contents of Cu,Cd are: viscera>gill>muscle; the contents of Zn,Pb,Cr are: gill> viscera>muscle. It can be seen that the contents of Pb,Cd,Cr in the muscle overruns the heavy metal limitation set to aquatic products. Using the index number techniques of single factor and Hakanson ecological risk evaluative method, the ecological status of the sediment was calculated. The result shows that the sediment of Haihe River was contaminated or highly contaminated. The potential ecological risk index number RI arranged from 38.67 to 179.9. Most sections of Haihe River have low potential ecological risk and some have middle potential ecological risk...