Distribution and fate of perfluorinated compounds (PFCs) in wetland environment
Date Issued
2012
Date
2012
Author(s)
Chen, Ying-Chin
Abstract
Removals of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in pilot-scale field and sorption of PFOA and PFOS onto five types of soils were investigated in this study. Phytoextraction by four aquatic plants (Hygrophila pogonocalyx Hayata, Ipomoea aquatic Forssk, Ludwigia (x) taiwanensis and Eleocharis dulcis) and sorption onto soil were determined. Both PFOA and PFOS were fairly phytoextracted by four aquatic plants; the uptake capacity was found in the following order: Hygrophila pogonocalyx Hayata > Ipomoea aquatic Forssk ≈ Ludwigia (x) taiwanensis > Eleocharis dulcis. In the soil sorption experiment, equilibrium for PFOA and PFOS were achieved within 6 to 8 days; sorption capacity of 2–3 μg/g was observed at the end of the 15-d experiment. Experimental results and literature review suggest that phytoextraction and soil sorption were the most significant mechanisms for PFOA and PFOS disappearance in the pilot-scale constructed wetland, while contributions of biodegradation, photolysis, volatilization and hydrolysis were negligible.
Effects of inorganic salts (CaCl2, NaCl, and Na2SO4) and humic acid in solution on the extent of sorption of PFOA and PFOS were also evaluated. The results indicated that all types of soils had a higher affinity for PFOS than for PFOA. The extent of sorption for PFOA and PFOS increased with fraction of organic carbon (foc) of soils. The partition coefficient (Kd) values of PFOA and PFOS increased with foc and ionic strengths of inorganic salts. On the contrary, the Kd values decreased with an increase in the concentrations of humic acid in the solution. The existence of organic matters is the parameter dominating the sorption behaviors of both PFOA and PFOS onto all types of soils studies. In addition, the presence of inorganic salts also affects PFC’s sorption behaviors.
Subjects
Constructed wetland
Perfluorooctanoic acid
Perfluorooctane sulfonate
Phytoextraction
Soil Sorption
Inorganic salts
Organic matters
SDGs
Type
thesis
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