Composition and distribution of the fluoride compounds in topsoil samples of Shenzhen

In order to explore the composition of fluoride compounds and their relationship with soil parameters, 23topsoil samples were collected from Shenzhen. The total contant of fluorine (TF) and extractable organic fluorine (EOF) were measured using fluoride ion selective electrode, and the residue level of 13perfluorinated compounds (PFCs) were analyzed using high performance liquid chromatography-tandem mass spectrometry combined with solid phase extraction enrichment. The results indicated that the fluoride mainly existed in the form of inorganic fluoride, and its distribution followed the order of TFEOF IF (Identified Fluorine) in topsoil samples. EOF only accounted for 0.04% of TF, and IF accounted for 0.32% of EOF, indicating that nearly 99.7% of the EOF was unknown. Perfluorooctanoic acid and perfluorooctane sulfonate were the major PFCs residue species, accounting for 43%(18%~100%) and 20% (n.d.~44%) of ∑PFCs, which were higher in the west than in the east of Shenzhen. Soil parameters could affect the levels of EOF and ∑PFCs, which negatively correlated with pH, and positively correlated with topsoil organic carbon. ©, 2015, Chinese Society for Environmental Sciences. All right reserved.