| As a result of the accelerated process of industrialization, and the popular use of agricultural chemicals, fertilizers and pesticides, more and more arsenic enter to the soils, arsenic pollution has become increasingly prominent. Compared with other heavy-metal, research of arsenic contamination was relatively weak, especially the characteristics of arsenic adsorption on brown soil was still remained elusive. This paper chooses the arsenic(V) for typical representative pollutant, used brown soil which was a typical soil in Liaoning province, to study As adsorption behavior and its influencing factors. With the help of methods such as balanced adsorption, indoor culture and mathematical analysis, batch system dynamics as well as X-ray diffraction (XRD). Simultaneously, we determined the As form of different As burden soils with the methods of continuous extraction. The purpose of the study was to understand the behavior of As adsorption in the soils, and the impact factors and its mechanisms. The main results of this study were presented:1.Characteristic of As(V) sorption-desorption was studied on farm and natural forest soils and its soil profile with the method of one way balancing towards the brown soil,fluvo-aquic brown soil,brown earth soil and bajing brown soil. The result indicated: Isothermal adsorption of As(V) can be fitted by Langmuir and Freundlich equation, the correlation coefficient achieves remarkable or the extremely remarkable level. The maximum adsorption from the Langmuir equation indicated that the fluvo-aquic brown soil has the biggest amount of As sorption; Capacity of As(V) sorption on illuvial horizon and parent material horizon were far beyond eluvial horizon; As(V) adsorption capacity of high fertility level should be less than the level of low fertility. Desorption experiments show that desorption of adsorbed As(V) was not easy, and the amount of desorption increases with the adsorption, the amount of sorbed and desorbed As(V) could be described by twice power function equation.2. Relationship between maximum As(V) sorption and physical and chemical properties was conducted by establish model with the help of multiple linear stepwise regression. Regression equation was derived. Regression results showed that capacity of arsenic (V) adsorption in the brown soil was related to organic matter content, Fe and Mn content, pH value, phosphorus content ect.3. On the pH range 2-10, As(V) sorption mostly increase with pH fluctuate, as the further increase of pH (pH=11.59), As(V) sorption increase suddenly. The reason was that under the low pH values, electrostatic adsorption play a major role on adsorption; but under the high pH value, the increase in adsorption due to generated insoluble precipitation of arsenate.4. After remove of organic matter, amount of As(V) adsorption on high fertility and low fertility levels were 3.23 and 2.3 times than origin soil, variable charge decrease 27.9% and 20.3%, its may conclude that organic matter compete adsorption sites with arsenic to inhibit As(V) Adsorption in the brown soil.5. Adsorption and desorption process was affected by the order and the concentration of phosphorus. Adsorption of As(V) decline with the increased of P, while desorption rate of As(V) was step up .About the order of P added (â… :As>P;â…¡:As = P;â…¢:As |
PDF Full Text Request