The Study Of Biodegradability And Influencing Factors Of Phthalate Esters By Soil

Phthalates(PAEs)are common organic pollutants in the environment,and the pollution of PAEs in the environment is increasing due to widespread use,moreover,because of biological toxic,teratogenic and mutagenic of PAEs,it poses a great threat to human health.Under natural conditions,biodegradation is considered to be the main means of eliminating PAEs because the slow hydrolysis,photolysis and volatilization rate of PAEs.In this paper,soil samples were collected from typical farmland in four different regions of China(Changsha,Changchun,Cangzhou and Yinchuan).Two types of common PAEs,di-ethyl phthalate(DEP)and dibutyl phthalate(DBP)in the soil were taken as the target pollutants,combined with a series of kinetic experiments,the main factors affecting the degradation of PAEs in soil in different regions were explored.And the following conclusions are preliminarily drawn:(1)In the process of microbial degradation of PAEs,adsorption is the premise of degradation.The bacteria will first adsorb PAEs on the surface of the bacteria,and then the PAEs will be utilized by the microorganisms to be metabolized and transformed into self-nutrients under the action of degrading enzymes.The adsorption of PAEs on bacteria was primarily C-H stretching vibration.And Surfactants can further affect the degradation of PAEs by changing the adsorption of bacteria on PAEs.Therefore,selecting a suitable type and concentration of surfactants can repair PAEs pollution safely and efficiently in soil.(2)The adsorption of PAEs on soil in different regions is mainly controlled by soil organic matter,but there was no significant correlation between the degradation rate of PAEs in soil and the adsorption affinity of soil,which is more susceptible to the influence of other soil properties.Combined with the biodegradation experiments conducted in the homogeneous system showed that the content of soil organic matter and pH value were the main factors that changed the fate of PAEs in the soil.(3)DOM is a very important factor affecting PAEs biodegradation,which is mainly affected by two ways.On the one hand,DOM can promote the growth of microorganisms and improve the activity of enzymes.On the other hand,the combination of DOM and PAEs results in isolation from microorganisms.Based onthe experimental results in this paper,the enhanced mechanism of DOM for PAEs biodegradation is mainly due to the fact that DOM stimulating the growth of microorganisms and increasing the activity of degrading enzymes.