The Study On The Migration And Transformation Of Arsenic In Soil

At present, with the rapid development of economic and urbanization speeding up, the soil pollution is very serious worldwide. As an important part of the heavy metal pollution, the arsenic pollution in soil is seriously harm to the ecological environment and human health which can not be ignored. The biological availability and the virulence of arsenic is close related with the existing forms in soil, so the study on the morphological changes and the migration and transformation characteristics of arsenic in the soil is more important than single consideration the total arsenic.The paper design the experiment to study the the migration and transformation characteristics of arsenic in soil, and the focused research has three aspects. Consider the relationship between the soil basic properties and arsenic speciation, research the influence of simulated acid rain soaking and added organic matter on the arsenic migration transformation in soil.Analysis the representative soil in the three regions of Jiading, Chongming and Minhang.The results showed that there exists correlation between the soil basic properties and arsenic speciation. The influence of soil cation exchange capacity on arsenic speciation is mainly reflected in the E-As, that its content increase caused the content increases of E-As. The content of soil carbonate will affect the C-As, presented the positive correlation. There is a high correlation with the content of Fe and Mn in soil, and with its content increased, the Fe,Mn-As is also increased. The organic matter in soil containing functional groups with arsenic binding, it will affect the content of O-As in soil.Simulated acid rain soaking the test soil samples, the influence on the soil is mainly through the pH value and ion. With the increase of soaking solution pH value, the content of A-As, E-As, C-As and Fe,Mn-As will increase, while the content of O-As and Res-As will reduce, showing the trend towards to more stable forms ofarsenic. The effect of acid type used in soaking solution on arsenic speciation, reflected that with the decrease of SO42- ions, the content of A-As, E-As, and Fe,Mn-As in soil is increase, while the content of C-As, O-As and Res-As is relatively reduced.The study of organic matter influenced the soil arsenic speciation migration transformation characteristics shows that, with the increase of the addition of fulvic acid concentration, A-As content increased, and the content of E-As and C-As is reduced. However the AE-As content with the strong bioavailability in soil is decreased. The content of Fe,Mn-As also presenting reduction trend and the content of O-As and Res-As is increased. Arsenic in soil will tend to the direction that the arsenic is stable, little biological toxicity and weak transformed.Arsenic in soil is mainly existed in the residue form, which is strong stability and poor activity, while the rest form content is a little less. The migration and transformation of arsenic is influenced by many factors. According to the conclusion of experimental study, put forward the application recommendations of the arsenic migration and transformation in soil remediation process, which can use the method that change the soil basic conditions, or add the external chemical reagent, to make the arsenic in soil change from the form that active, strong toxicity to the stability, low available and weak biological toxicity ation, which can reduce the hazards of arsenic to the environment and human body.