Study On The Influence Of Soil Enzyme Activity And Lettuce Enrichment Capacity To Compound Heavy Metal

This paper will analyze the law of change and mechanism of action absorption and accumulation of soil enzyme activity and lettuce to heavy metal by the influence of both single-factor and composite factor through the outdoor pot experiment of adding exogenous heavy metal in the soil, and show the variation tendency of them directly by intuitive charts. The degree of heavy metal pollution can be predicted and evaluated fast and accurately by the inhibition effect degree of the soil enzyme activities, which will be the scientific basis of the prevention and cure task on heavy metal pollution and the evaluation on effect of environment later , the conclusion of the study are as follows:1. In the environment of single-factor heavy-metal pollution, heavy metals Pb in the soil plays an significance role on the three enzymes including urease, phosphatase polyphenol oxidase activity with extremely significance level; Zn can better inhibit catalase, polyphenol oxidase activity with extremely significance level, inhibit urease activity with significance level; Cd can inhibit catalase, urease activity with extremely significance level, and inhibit phosphatase, polyphenol oxidase activity with significance level. We can select the appropriate soil enzymes inhibition as a single factor of heavy metal pollution indicators through the inhibition rate of these heave metal that are related above.2. In the environment of no heave metal multiple pollution, the relevance among Pb, Cd and catalase activity in the soil will reach a extremely significance level; the relevance among Pb, Zn, Cd concentration and urease activity will reach a extremely significance level; the relevance between Pb content and phosphatase activity in the soil will reach a extremely significance level; the relevance between Cd content and phosphatase activity will reach a extremely significance level; the relevance among Pb, Cd content and polyphenol oxidase activity will reach a extremely significance level. We can determine the soil enzymes related above as the evaluating norm of heavy metal.3. In general case, a separate soil enzymes can only be one summary evaluation of heave metal pollution in the soil, not the evaluating norm on the pollution degree of every heavy metal in multiple pollution. Therefore, through experiment, we can get the relevant relationship between several heavy metals and other soil enzyme activity and form a heavy metal multiple pollution evaluating system to soil enzyme activity. All these can not only reflect the complex effect of heavy metal in the soil, but also response the contents of heavy metal in the soil, which has a certain feasibility to evaluate heavy metal pollution in the soil.4. In the case of low quantity contents of heavy metal in the soil in growing period of vegetables, if we compare the fitting equation of heavy metal content of lettuce with soil heavy metal content of the slope, Pb, Zn, Cd are 0.495, 0.287, 0.502, which illustrates in the case of low quantity contents of heavy metal in the soil, the absorbing rates of these three heavy metals are Zn Zn> Pb in the scope of experience.6. In the complex pollution circumstance, only the relevant relationship of contents of Cd in the soil and the contents of Zn in the edible part of lettuce reaches the significance level with the p-value of 0.004, while the Cd influence index to the contents of Zn in the edible part of lettuce is negative. It illustrates that existing of Cd suppresses the increase of the contents of Zn in the edible part of lettuce.7. We find that the toxic action by the enrichment of different heavy metals have individual characteristics through the analysis of the heavy metal toxic token. Therefore, we can determine the types and contents of heavy metal in the polluted soil on time by using the toxic characteristics of lettuce as the indicating feature of the heavy metal disaster in the soil.