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| Sorption-desorption and leaching characteristics of perfluoroalkyl acids in soils |
| Received:December 23, 2017 |
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| KeyWord:perfluoroalkyl acids;sorption;desorption;leaching;dissolved organic matter |
| Author Name | Affiliation | E-mail | | LAN Zhong-hui | College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300350, China | | | ZHOU Meng | Monitoring Center for Vehicle Emission, Tianjin 300391, China | | | YAO Yi-ming | College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300350, China | | | SUN Hong-wen | College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Nankai University, Tianjin 300350, China | sunhongwen@nankai.edu.cn |
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| Abstract: |
| To elucidate the sorption-desorption and leaching of typical perfluoroalkyl acids (PFAAs) with different chain lengths and head groups on soils, batch experiments and soil-column experiments were conducted to investigate the sorption-desorption and leaching behaviors of seven kinds of PFAAs on fluvo-aquic soil and black soil, respectively. The sorption and desorption of PFAAs on the two soils reached an equilibrium within 24 h and desorption hysteresis was observed during the desorption process. The sorption and desorption isotherms of PFAAs were fitted well with the Freundlich model (R2>0.900), with Kf ranging from 1.44 to 282. The sorption capacities of PFAAs increased with carbon chain lengths. Perfluoroalkyl sulfonates held a higher affinity to soils than perfluoroalkyl carboxylic acids of the same chain length. Soil organic matter, particle size distribution, and dissolved organic matter might co-influence the sorption capacity of PFAAs. The column experiments revealed that the recovery of short-chain PFAAs from leachate generally exceeded 97%, whereas long-chain PFAAs showed comparatively lower recoveries, longer leaching time and lower cumulative leaching rates, because of their higher affinity to soils. The PFAAs showed quite different leaching behavior in the two soils, and the leachate concentrations of PFAAs changed more drastically in fluvo-aquic soil than in black soil. The level of dissolved organic matter altered the shape of the relative leaching curve and promoted the leaching of short-chain PFAAs. In contrast, it inhibited the vertical transport of perfluorooctanoic acid and perfluorohexane sulfonic acid in the soil column. Our results indicated the strong mobility of the short-chain PFAAs in soils, which may cause potential risk to groundwater. |
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