Toxicological Effects On Four Aquatic Plants By Cd,Cu,Zn

In this dissertation,the single toxic effects and joint toxic effect of Cadmium,Copper and zinc were detected in Eichhornia Crassipes,Lemna minor,Hydrilla verticillata Roy,Trapa taiwanensis L.The effects of Cadmium,single pollution and compined pollution on the concent of Chloorplyll,the content of MDA in leaves of Eichhornia Crassipes,Lemna minor,Hydrilla verticillata Roy,Trapa taiwanensis L were studied.The thesis also discussed the absorption of heavy metal(Cd,Cu,Zn)by Eichhornia Crassipes,Lemna minor,Hydrilla verticillata Roy,Trapa taiwanensis L in water and the analysis of the relationship between time and toxicity.The mainly results were summarized as follow:In early period of exposure to the same metal, it is vital difference bewteen growth status of high dose group and growth status of low dose group:there was no obvious poisoning symtom in low dose group and obvious poisoning symtom in high dose group.But in last period of exposure to the same metal,all of groups show poisoning symptom.Under the conditon of single pullution,the physiological and biochemical indexes,such as content of chlorophyll and content of MDA, had changed to different degree compared with control: the content of chlorophyll had the tendency to reduce and content of MDA had the tendency to increase.In four aquatic plants, change of hephysiological and biochemical indexes on Lemna minor is significant.In three heavy metal,Cd had the most obvious effect on physiological and biochemical indexes of aquatic plants.Three aquatic plants when exposed to combined pollution ,suffers much more harmful hurt than the case of single pollution.Under low-concetradtion Cd/Zn condition,resistant plants(such as Eichhornia Crassipes,Hydrilla verticillata Roy) show antagonistic action;but under high-concertradion conditions,all of aquatic plants show synergistic action.Root absorbed the most proportion of metal for all these four kinds of aquatic plants at every treatment. Resistant strains absorbe metal of Cu most,Zn least; susceptible strains absorbe metal of Zn most,Cd least.