Study on allogynogenetic nuclear developed offspring of silver carp induced by Cyprinus carpio singuonensis.

Based on the investigative data of the year 2003 ～ 2010,the paper analyzed and evaluated the pollution of heavy metals and their ecological risk in the sediment of the Dongting Lake.The order of the average concentration of heavy metals was: Zn Cr Cu Pb As Cd Hg.The assessment results by using Muller's geo-accumulation index method were that: Zn was at little pollution level;As,Cr and Pb were all at light pollution level;Hg and Cu were all at middle pollution level;Cd was at heavy pollution level.The analysis results by using Hakanson's potential ecological risk index method were that: As,Cr,Pb,Cu and Zn were all at low potential ecological risk level;Hg was at high potential ecological risk level;Cd was at extremely high potential ecological risk level.