Study On The Relationship Between The Soil Enzyme Activity And The Content Of Heavy Metal And Its Forms

Soil heavy metal pollution problem increasingly prominent in our country in recent years,part of the farmland soil heavy metal pollution, cause loss of soil productivity, seriously affect the food safety, threatening human life and health. Studying the relation between soil enzyme activity and soil heavy metal and form, to find out under the condition of heavy metal pollution of heavy metals in the soil form distribution change law and the total amount of heavy metals, form relation with soil enzyme activity and provide reference basis for risk assessment of heavy metals, in a real environment plants affected by soil heavy metal biological effectiveness of heavy metals and have the further understanding of, the phytoremediation biological methods, such as management of soil heavy metal pollution has important theoretical and practical significance.This study selected xi ’an smaller typical contaminated farmland soil, at the current serious soil pollution of heavy metal cadmium(Cd),zinc(zinc), lead(Pb) of three kinds of heavy metal element as the research object, adopting indoor culture, pot experiment, the morphological classification of heavy metals and other research methods, discusses the heavy metals in the soil and the relationship between form and soil enzyme activity.The result shows:with the exogenous heavy metals(Cd, zinc, Pb), with the increase of adding amount of under the condition of low concentration(Cd 5 mg/kg soil, zinc, Pb 50mg/kg soil) can have inhibition effects on soil enzyme activity, under the condition of relatively high concentration, heavy metals on soil urease produce strong inhibition, produce certain inhibitory effect of H2O2 enzyme and soil urease activity increases with exogenous heavy metals added drops rapidly, after slowly into balance; Experiment under the condition of heavy metal inhibition strength Cd > zinc > Pb, three kinds of heavy metals on soil enzyme activity inhibition effect of urease > H2O2 enzyme.With exogenous heavy metals, with the increase of adding amount of redistribution formation distribution of heavy metals, to a more stable form of change; Heavy metalscompound pollution condition, the distribution changes with the increase of itself and other heavy metal concentration, increasing concentration of Cd are morphological distribution changes significantly, influenced by its recent, Pb is small, with the increase of Cd concentration, distribution of Cd patterns are interchangeable state and carbonate combined with state percentage increases in great quantities, can reach 38.09, the largest proportion of residual state decreased dramatically, minimum as low as 11.58%.Heavy metal zinc, Pb form is given priority to with residual state, can exchange state minimum, two kinds of formation distribution of heavy metals are greatly influenced by Cd concentration, three kinds of formation distribution of heavy metals is influenced by the interaction between each other.Effective state under the condition of compound pollution by heavy metals and the soil enzyme activity, multiple regression analysis results showed that the effective states of heavy metals is the main form, affecting the soil enzyme activity effective state of Cd and Pb on soil enzyme activities affect total affect an order of magnitude higher than that of the size, the effective influence degree and the total effect on heavy metal zinc roughly the same; Heavy metal Cd form and regression coefficients are much higher than the total amount of zinc, Pb,and shows the effects of Cd on soil enzyme activity is far higher than that of zinc, Pb,characterized by strong inhibition on soil enzymes, under the condition of compound pollution, low concentration of Pb effective state of soil enzyme activity showed slight activation, combination of three kinds of heavy metals on soil enzymes to produce synergistic inhibition effect.