Research On Zinc Adsorption And Desorption Characteristics Of Chernozem In Songnen Plain

Zinc is a heavy metal elements, Zinc is one of the trace elements in the growth and development of plants and animals are indispensable. Ease of zinc in alkaline soils OH- generated Zn(OH)2 precipitate and lose effectiveness, so in alkaline soils, the effective zinc content was low. Songnen Plain is an important part of Northeast China Plain, the distribution of a large area of chernozem, whose common feature is the soil texture is light, the ability to retain water and nutrients is not strong, fertility is not high, mostly low-yielding soils. Soils commonly contain higher amounts of carbonates, weakly alkaline soil reaction, soil available zinc content is generally low. In order to prevent the occurrence of zinc deficiency disease, from eight years of the late start, popularized corn rice zinc fertilizer(zinc sulfate) application technology. Adsorption desorption largely determines the amount of zinc in the presence of soil, restricting the accumulation of zinc in the soil or migration, can reflect the cushioning effect of zinc in the soil. Therefore, this study chernozem on zinc adsorption and desorption characteristics, evaluation of the environmental impact of heavy metals instructive, but also provides a theoretical basis for the rational application of zinc fertilizer on agriculture and agricultural production and environmental safety prevention.Based on the Songnen plain soil as the research object, discusses the characteristics of adsorption and desorption of zinc in soil profile distribution and chernozem of zinc, the main research results are as follows:(1) The average value of the total Zn content of the 11 tested chernozem 33 layers in the sample is 84.84 mg/kg, lower than the average domestic soil total amount of zinc(100.0 mg/kg), the whole plow layer soil samples of zinc the average amount of 103.29 mg/kg. From the figure can also be seen 11 kinds of chernozem full content of zinc are the plow layer> plow> heart soil, all the zinc content of the table there is a certain degree of polymerization characteristics.(2) The average value of available zinc content in the tested 11 samples of 33 layered soil is only 0.3 mg/kg, and the average content(0.84 mg/kg) domestic soil Zn vary widely, but less than the critical soil Zn point(1.5 mg/kg), the mean effective plow layer soil sample of zinc is only 0.6mg/kg. So it can be seen in the Songnen Plain chernozem are in zinc status. From the figure Can also be seen 11 kinds of chernozem in the plow layer are available Zn> plow> heart soil, showing effective form of zinc poly phenomenon.(3) Adsorption test of 11 kinds of chernozem zinc all have in common, that is proportional to the concentration and amount of adsorption equilibrium solution, the greater the concentration of fluid balance, the greater the amount adsorbed. At lower concentrations the equilibrium solution, adsorption curve showing a rapid rate of increase, when the concentration of the equilibration solution rises to a certain extent, the adsorption curve starts to decrease at an increased rate, but still in an upward trend. The experimental results show that the Songnen Plain chernozem on zinc adsorption characteristics of the main factors affecting soil pH and organic matter.(4) For the test of 11 kinds of chernozem on Zn adsorption isotherms have adopted the Langmuir, Freundlich and Temkin equation to fit the correlation coefficient(R) are above 0.94, showing a 1% of all highly significant correlation. Freundlich equation relative effect of which is optimal, R values are all above 0.97, Langmuir equation fitting results followed, R values are all above 0.94 is relatively less effective Temkin equation.(5) 11 typical of the zinc in the soil desorption and adsorption is proportional to the amount of zinc adsorption desorption amount is larger, the greater the correlation coefficient between the two, and in more than 0.9. 11 arable layer soil, in addition to 10 soil profiles, the adsorption amount and desorption curve is roughly the same. The desorption behavior of zinc in the soil have shown a certain degree of hysteresis phenomenon. When the concentration of the equilibrium solution is very small, the curve rises slowly; when the adsorption capacity increased to relatively high, the amount of desorption started its rapid rise, the shape is close to a straight line.