Phytoremediation And Its Ca～(2+)-Enhanced Techniques For Metal Polluted Lands Contamination With Cadmium By Phragmites Australis

With the development of economic, the soil, air and water was seriously polluted by"Three-waste"poured, mine explored, irrigation by polluted water and the use of pesticide, herbicide, and fertilizer, which brings presses to the environment, society, economic and man. Heavy metal is one of the important pollutants in the earth. It is difficult to be removed from soil by setting on fire because of its high toxicity and hard-decomposing character. Heavy metal can lead to oxidized even death to plants through the effect of AOS. Simultaneity it can enrich in life form and bring hurt to human health. So studying the heavy metal injury mechanism has important meaning for us. Only learning the mechanism of heavy metal injury and resisting mechanism, we could think out corresponding control methods to improve the resistant ability and phytoremediation efficient. Calcium is one of the necessary nutrients to the plants, except which it has very important meaning to plant physiology. Calcium can reject the hurt of excess metal for plants. It also can restrain plant cell structure, resist the oxidative effect and improve photosynthesis and respiration.This experiment using Phragmites australis as materials discussed the mechanism of cadmium oxidize in different concentration (0.2 mmol/L, 0.4 mmol/L, 0.6 mmol/L). The increasing of cadmium concentration can bring with cadmium content increase, chlorophyll content decrease and MDA concentration elevation. All this showed the oxidative press increased. Meanwhile antioxidant activity, including SOD, POD, CAT, all changed with cadmium concentration. SOD is the enzyme which can change O2.- to O2, its activity slightly increased with cadmium concentration, except at 0.6 mmol/L. POD which can decompose oxidizes to protect plant appeared opposite trend to SOD. CAT is also necessary to plant, which can change H2O2 to H2O and O2. It showed that the increase of cadmium concentration also increased CAT activity. Otherwise, we studied if 10 mmol/L calcium can elevate the cadmium injury to plant. The result tell us that the high concentration of calcium not only resisted the entry of cadmium to plant and the change of chlorophyll, MDA, but also increased antioxidant activity. So we can conclude that calcium is useful to protect plant against environment presses.