Study On Transfer And Transformation Rule Of Atrazine In Vadose Zone And Groundwater

Atrazine,also called atranex,is a kind of glebe herbicide already widely used in large areas of worldwide.Because of its stable chemical structure,it can accumulate in environment in a long time.During the 30 years when atrazine were using in business, the leftover amount of atrazine in groundwater of some areas had already been up to 3ppb.Validated by concerning experiments, atrazine of 3ppb could make rats'chromosome burst, kill arthropod in water bottom,destroy balance of ecology, and heavily threat human's health.Confronted with the severe challenge,scholars of every country made lots of studies on its pollution mechanism. These years the study of this field is becoming more and more popular,however,making a simulation of atrazine in vadose zone and groundwater, then doing a concere analysis on its regularity of transfer and transformation are comparatively not very common.This dissertation is based on atrazine.In the static state experiment, the adsorption and desorption of atrazine in three soil slurry samples are studied. The results show that it accords with Freundlich equation.The adsorption coefficient is 1.39, 2.03 and 1.22; Adsorption dynamical curves of three lithology soils indicate that the adsorption mainly finish in 24 hours,and the adsorption amount is the largest in previous two hours; The impact of pH,ionic strength,TOC on atrazine sorption is discussed.The result shows that organic content of the soil sample was the most important factor affecting the atrazine sorption capacity, and other factors also have some influence.The capacity was higher at a higher ionic strength and/or a lower pH of the slurry sample; The half life of atrazine in three lithology soils and groundwater arevery long:up to 116d,124d,151d and 521d,which can make a heavy pollution.In dynamic experiment aspect,I used filtering soil column and seeping trough to simulate atrazine transfer in vadose zone and groundwater repectively.The result indicates that in continuous rainfall,when the mass ratio between filtering water and soil reaches 0.34,atrazine leaked out,and when the mass ratio reaches 0.49,the biggest examined concentration is 0.69 mg/L,the gross of filtering atrazine is 1.2011mg,while in intermittent rainfall, when the mass ratio between filtering water and soil reaches 0.23, atrazine leaked out, and when the mass ratio reaches 0.37,the biggest examined concentration is 1.07 mg/L,the gross of filtering atrazine is 2.6801mg.After filtering,the remains of atrazine in column increase with the height of column.Large amount of atrazine is in topsoil(0-30cm).According to seeping trough experiment, atrazine moves quickly in groundwater, lowing its concentration through convection.Adsorption, hydrolyzation and degradation by aborigines microbe are not conspicuous.The concentration reduced rapidly after infusing predominant bacteria.The degradation rate in each sampling port reaches up to 90%;The degradation rate in each sampling port were still in a high level when increasing the flowing velocity of groundwater;The clogging problem, due to metabolism of bacteria,can be solved by increasing the flowing velocity of groundwater.In conclution, the half life of atrazine is very long;The sorption amount is not large in vadose zone,which results a easy penetrating to groundwater;The amount of degradation and transfer is also very small, which lead to a long rest in groundwater and make contamination. So,we must carry out some effective measures to deal with it.