Heavy Metal Risk Assessment and Sources Distinguishing in Town Polluted River Sediment at the Three Gorges Reservoir

The Liangtan River is the typical river basin for urbanization pollution research in the Three Gorges Reservoir,and sediment samples in the basin were collected to analyse heavy metal concentrations for risk assessment and sources distinguishing. These results showed that As、Cd、Cr、Cu、Ni、Pb、Zn、Hg in sediment ranged in(2.31- 8.56) × 10^-6,(0.074- 0.574) × 10^-6,(92.85- 336.13) × 10^-6,(19.22-45.35) ×10^-6,(13.50- 48.37) × 10^-6,(11.77- 52.17) × 10^-6,(46.91- 1 035.30) × 10^-6and(0.012- 0.229) × 10^-6,respectively. Sediment risk index(SPI) suggested that the sediment kept in slight pollution and low ecologiclal risk with values ranged from 1.11 to 6.90. However,some heavy metals got polluted independently. Cr and Zn had reached serious pollution in sediment. Meanwhile,Cd and Hg aggavated in the population concentration areas which reached middle polluted state. The correlation and principal component analysis(PCA) suggested that the heavy metals of basin came from urban domestic pollution after river pollution control engineering processed.