Influence Of Soil Properties On The Adsorption Of PFAs

In recent years, as PFAs generally detected in the soil and groundwater,particularly food crops can bioconcentrate PFAs on soil, and the potential contamination risk of PFAs is exist when groundwater used as drinking water. So that people are increasingly concerned about PFAs pollution in the soil and groundwater systems, and the environmental behavior and degradation fate of them. Therefore, this paper mainly study the experiment of adsorption PFAs by soil, and analysis and discussion of the major factors of soil physical and chemical properties which influencing PFAs adsorption onto soil.According to the literature, the adsorption equilibrium time selected 48 h.When the adsorption experiments were completed, liquid chromatography-tandem mass spectrometry(LC-MS/MS) were used for qualitative and quantitative analysis of target analytes concentration in the aqueous phase C_w, and then calculate the concentration in the soil phase C_s by aqueous loss method. Finally, the Freundlich adsorption isotherm equation was chosen for linear fitting. And analyzing the relationship between soil physical and chemical properties and log KF. The concentrations of PFAs in the part of soil experiments should be detected to calculate the recovery of the experiments. The mass balance of the target analytes before and after the experiment is good. Exception of some soil samples, the recovery rate is generally between 71%±4%~128%±17%, and the average value is 101%±15%. The method of adsorption experiment has good precision and reliability, the MDL and MQL range from 0.1ug/L to 1.0ug/L and 0.75ug/L to 25 ug /L, respectively.Through analysis and discussion, the experimental results are as follows:(1) The correlation coefficient R2 between log KF of PFAs and soil free iron oxide contents are range from 0.5013 to 0.6633, and R2 between log KF of PFAs and the protein contents in soil are range from 0.5288 to 0.6792. The R2 are all higher than 0.5, which means that there are certain positive correlations between log KF and free iron oxide contents and protein contents in soil. The results ofadsorption experiments indicate that soil iron contents and soil protein contents was the dominant soil-parameter affecting adsorption.(2) Secondary factors influencing the adsorption of PFAs onto soil are p H, TOC contents, AEC and fulvic acid contents in the soil, which only have obvious impacts on certain PFAs. The p H of soils have obvious impacts on PFCAs which carbon chain length is ≤5. TOC contents and AEC have obvious impacts on PFCAs which carbon chain length is ≤5,and PFSAs which carbon chain length is >5. And fulvic acid contents of the soil have obvious impacts on PFCAs which carbon chain length is≥8,and PFSAs which carbon chain length is ≥6.(3)The mechanical composition of soils, polysaccharide contents, CEC and humus contents of the soil can not significantly affect the ability of soil to adsorb PFAs, so these factors are not key factors. The CEC, humic acid contents and mechanical composition of soils have little effect on the adsorption of all PFAs onto soil.