Study On Phytoremediation Of Cd-Polluted Water And Toxicity

Plants can accumulate heavy metals fprm the environment. Phytoremediation of Cd polluted environment is an available method, gichhornia crassipes and ttosta ventricosa were the accumulating plants of Cd. Throughout the experiment, plants' amount of cadmium concentration showed law changes. Cadmium concentration in the same strength, plants' cadmium concentration with time increased, But when the amount reaches a certain concentration values, the values with the time of small changes. In such case, the plants in Cd solution accumulate cadmium element from the surrounding environment through absorption process. In this biological accumulation process, the element cadmium has been entering and exiting the plant. This material exchange need some time to achieve dynamic equilibrium. Since then, such a state of equilibrium is within fluctuations only in a certain range. Then the ratio of plant's concentration of cadmium and solution concentration of cadmium is called balance enrichment coefficient. Comparing two Cd-accumulating plants the Eichhornia crassipes accumulating ability is 5-7 times of Hosta ventricosa. Eichhornia crassipes can be used on Cd pollution Phytoremediation.Cd is a plant of non-essential element. If the environment Cd content is too high it will affect plant growth and development. Eichhornia crassipes and Hosta ventricosa is used as experimental material to study Cd stress on the two plants growth, chlorophyll content, MDA and root peroxidase activity and other physiological indicators to investigate the effect of Cd on the toxic effect of higher plants,with a view to Cd pollution Phytoremediation providing a theoretical basis.Eichhornia crassipes was water cultured in 0, 0.01, 0.t and 0.3mgCd/L. Throughout the experiment, plants in control group grew ordinarily. Root-shaped stalk is short and strong with slender majority of fibrous roots black, Leaves were dark green and smooth. Gourd-shaped balloon is inflated and round. 80% of the plants opened bright purple flowers for 3-5 days and yielded egg-shaped fruit after 15 culturing days. Eichhornia crassipes from the third day showed varying degrees of poisoning symptoms under 3 Cd treatments, the more obvious symptoms of poisoning came under higher Cadmium concentration and longer time. Eichhornia crassipes cultured in 0.01mgCd/L is slightly shorter with only 30% of the plants flowering. In Cd O. 1 and 0.3mg/L treatments the plants were significantly inhibited. The plants grew slowly and were short. Gourd-shaped balloons became smaller or even disappeared. The leaves had big or small yellow-patch and had thinned. Only a handful of plants Flowered. The main roots lignified. Fibrous roots became less. Its color became lighter. In Cd 0.3mg/L treatment the lignification of the main roots was particularly serious. Hosta ventricosa in control group grew ordinarily. The diameter of can reach 2 cm. The plants were vertical and straight. The main roots have a lot of fibrous roots. They were white. The leaves were green. 80% of the plants flowered in July. In Cd treatments the plants showed varying degrees of poisoning symptoms from the third day. The more obvious symptoms of poisoning came under higher Cadmium concentration and longer time. The plants cultured in 0.01 mgCd/L were slightly shorter with leaf color lighter. In Cd 0.1 and 0.3mg/L treatments the plants were significantly inhibited. The plants grew slowly and were short. The leaves had big or small yellow-patch. The big yellow-patch rotted. The main roots lignified. Fibrous roots became less. Its color became lighter. In Cd 0.3mg/L treatment the lignification of the main roots was particularly serious. Overally. Along with Cd concentration increasing, plant leaf chlorophyll content come downward. Cd affects the chlorophyll a content and its content and Cd concentration was negatively correlated. Cd affects chlorophyll b slightly. MDA is a membrane lipid peroxidation product, its contents were used as indicators of membrane damage. In the experiment, leaf MDA gradually increased over time but amplitude is small. With Cd concentrations increasing and time passing, the MDA content increased. The results showed that membrane lipid peroxidation strenghen resulting in the membrane damage. The activity of POD in plant roots strengthens with Cd concentrations increasing and time passing.