Study Of Phthalic Acid Esters Transport In Unsaturated Zone And Microbial Degradation

Phthalates (PAEs) is a kind of important compound among environment hormones. It is mainly used as plasticizer in the manufacture of plastics. It may affect human and animals on their endocrine systems, leading to abnormalities of reproduction, development and behavior. As a sort of synthetic persistent organic pollutant, PAEs is mass-produce and widely used all over the world. Environment problems caused by this have drawn global attention.This article gives an introduction on physical and chemical properties, damage, migration state in vadose zone and microorganism degradation of Phthalates and also discuss its environment behaviors and destinations in various environmental media. In this paper we choose six PAEs substances, DMP, DEP, DBP, DOP, BBP and DEHP as research subjects which are taken by National Environmental Protection Agency(EPA) as priority control toxin pollutants. Analytical method is employed by high-performance liquid chromatography and we study their migration state in vadose zone, microorganism degradation and impact of salinity on migration and transformation.The studies of six PAEs adsorption kinetics shows that 48 hours is needed for their adsorption equilibrium. Research on microorganism degradation of Phthalates proved that degradation rates of DMP, DEP, BBP, DBP are 100%, 100%, 98.66%, 99.69%, respectively. It is not easy to be degradated for DEHP and DOP. This is a dynamic process, degradation to desorption, desorption to degradation, continuously. The difficult degree of degradation are dependent on molecular weight and side chain, i.e., DMP>DEP >BBP>DBP >DEHP>DOP, and this is helpful for microorganism degradation in a certain range with increase of initial concentration of PAEs. Beyond permissible point microorganism degradation is retrained.We also study the effect of seven different seawater salinities, 0‰, 5‰, 10‰, 20‰, 30‰, 35‰,40‰, on PAEs. Research shows that the concentrations in aqueous phase of different concentration gradient DMP, DEP are slightly influenced by salinity and as initial concentration is 50ug/ml, the effect of salinity on DEP is stronger than that on DMP. However, aqueous media are still main settlement sites for DEP and DMP. Adsorptions of different concentration gradient BBP,DEHP,DOP decrease with increase of water salinity and tend to migrate from liquid phase to solid phase.In the range of the experiment concentration, the type of DEP and DBP's adsorption isotherm is linear. On the basis of regression analysis of their adsorption isotherm in different salinity, concentrations of them decrease in water and increase in sand and they tend to migrate from liquid phase to solid phase with increase of salinity.