Effects Of Different Types Of Organic Materials On Contents And Speciation Distribution Of Pb In Black Soil

Culture experiments and field experiments were combined to study the effects of different types of organic materials on contents and speciation distribution of Pb. This research was focus on the effects on the total Pb contents, fraction contents of Pb, fraction changing trends of Pb, analysis on relative factors affection fraction changes of Pb, adsorption characteristics of Pb and vertical distribution characteristics of Pb. The main conclusions are as follows: 1. Livestock manure, natural organic materials and semi decomposed organic material all reduced the total content of Pb with the order of semi decomposed organic material > natural organic materials > livestock and poultry manure in soil, except for fertilizers only. The total content of Pb in black soil decreased year by year, but the reduce quantity was small, which was the results of one time fertilization and no plants growth. In the view of total Pb contents. 2.The morphology proportion of Pb showed the same rules no matter what kinds of organic materials was, residual state of Pb> the reduced state of Pb>oxidation state of Pb> acid extractable Pb. Three types of organic materials all increased the content of acid extractable Pb and the reduced state of Pb,decreased the content of oxidation state of Pb and residual state of Pbin black soil. The rule of increasing of livestock and poultry manure > natural organic materials > semi decomposed organic material. chiken manure increased most among livestock and poultry manure, leaf increased most among natural organic materials. The biological activity of large of acid extractable Pb and oxidation state of Pb increased, but the proportion of this two forms is not large, so the addition of biological toxicity of Pb in soil is not serious.3.No matter what organic materials it was, acid extractable Pb and the reduced state of Pb increased year by year, and the growth of acid extractable Pb in soil were higher than reduced state of Pb, moreover, oxidation state of Pb and residual state of Pb reduced year by year, and and the decreasing of oxidation state of Pb in soil were higher than residual state of Pb. Three types of organic materials combined with chemical fertilizer make Pb transformed from low bioavailability fraction(oxidation states of Pb and the residual state of Pb) to high bioavailability fraction(acid extractable of Pb and reducible Pb).Over all,the transformation of chiken manure was the biggest among livestock and poultry manure, and leaf was the biggest among natural organic materials, and peat was the biggest among natural semi decomposed organic material. Three types of organic materials combined with chemical fertilizer increased biological activity of Pb in soil, but the increase of the load is not big. 4. Besides chemical fertilizer treatment, different types of organic manure with chemical fertilizer into soil, the overall of trend the correlation between various forms of Pb in soil and the total content of Pb in soil,organic matter,p H was consistent. In all treatment, acid extractable Pb, reducible Pb and organic matter, the total content of Pb, p H showed a negative correlation, oxidation states of Pb、the residual state of Pb and organic matter, the total content of Pb, p H showed a positive correlation.Analysis of what the correlation between various forms of Pb and organic matter, the total content of Pb, p H under different types of organic manure with chemical fertilizer into soil, the maximum amount of influence on the the total content of Pb, organic matter influence greatly, and little correlation between its p H. 5. Livestock and poultry manure applied to soil for three years,the adsorption of Pb in soil of different treatments have been rules: when adsorption equilibrium concentration is very low,adsorption capacity is very small, but the adsorption curve slope is larger. With the increase of adsorption equilibrium concentration, adsorption quantity increases rapidly,but the adsorption curve slope becomes small, and the adsorption equilibrium concentration continues to increase,the adsorption capacity gradually small. When the equilibrium concentration was low, there was no obvious difference among different treatments on adsorption capacity and the order of adsorption quantity is the blank> chemical fertilizer> chicken manure> pig manure> cow dung. The changes of all the treatments of three years are the adsorption capacity of the first year is the strongest, adsorption capacity decreased in second years, third years is the weakest on adsorption capacity, adsorption capacity decreased gradually with time. Langmuir equation and the Freundlich equation used in this study, Langmuir in fitting equation is Better.The order of using the K value of Langmuir equation and the n value of Freundlich equation evaluate the strength of the adsorption is the blank> chemical fertilizer> chicken manure> pig manure> cow dung. The adsorption strength of three years among different treatments is the first year > second years > third years. The desorption rules of three years have little consistent among different treatments.With the increasing of adsorption capacity, desorption gradually also increases,and the difference of desorption capacity is very small among different treatments, only in the adsorption capacity increases when more show great differences.The order of desorption capacity among different treatments is the blank> chemical fertilizer> chicken manure> pig manure> cow dung. The desorption capacity of Pb of each processing of three years only little difference, there are differences in the adsorption capacity increases, the ranking of each processing of desorption quantity of Pb for the first year > second years > third years. 6. All the processing in the total content of Pb from 0-20 cm to 20-40 cm increased slightly, but the increased amount is not large, while in the following 40 cm bottom, the total content of Pb decreased with increasing depth, but decreasing of the total content of Pb is not large, the total content of Pb of organic materials treatment in every layer relative to chemical fertilizer also a little lower. The contents of various forms of Pb in each layer showed the same rules: acid extractable Pb, reducible Pb, oxidation states of Pb are gradually decreasing with depth and residual forms of Pb increased slightly with increasing depth; The proportion of all processing accounted for the morphology in various forms of Pb also showed the same rules: the proportion of acid extractable Pb, reducible Pb, oxidation state of Pb of all treatments are gradually decreasing with depth in each layer. high bioavailability fraction(acid extractable of Pb,oxidation states of Pb and reducible Pb) to low bioavailability fraction(the residual state of Pb), which shows that biological activity decreased with the increase of depth of soil Pb. The 0-20 cm and 20-40 cm in the surface soil of biological activity of Pb is higher, And it leads to biological toxicity of Pb in tow layers is higher. The proportion of various forms of Pb in each layer and in the surface is consistent, all is the residual state of Pb> reducible Pb >oxidation states of Pb> acid extractable of Pb.