Distribution and partitioning of perfluoroalkyl carboxylic acids in surface soil, plants, and earthworms at a contaminated site

Abstract

A field study was conducted to elucidate distribution and partitioning of perfluoroalkyl carboxylic acids (PFCAs; C7-12) in a terrestrial ecosystem that was contaminated with industrial sources of release. Surface soil (0-6 cm), plants, and earthworms were collected from a field located within a 1-mile radius of a fluoropolymer industry that had been manufacturing fluorochemicals for over five decades. The mean concentrations of ∑PFCAs were 150, 420, 61, 68, and 430 ng/g dry weight (dw) in surface soil, earthworms, grass roots, grass leaves, and tree leaves, respectively. The measured concentrations were higher than those reported for corresponding matrices in other locations worldwide, suggesting that fluorochemical manufacturing operations have contributed to the contamination of this nearby land. Soil and plant tissues consisted mainly of perfluorooctanoic acid (PFOA; C8) (77.3-97.1% of the total PFCAs), whereas longer-chain PFCAs, such as perfluoroundecanoic acid (PFUnDA; C11: 17.6%) and perfluorododecanoic acid (PFDoDA; C12: 31.9%), accounted for relatively higher proportions in earthworms. Spatial distribution of PFCAs at this site suggested that both atmospheric deposition and groundwater recharge have contributed to the sources of contamination. Both earthworm- and grass-accumulated PFCAs from soil with biota-soil accumulation factors and root concentration factors increased with perfluorocarbon chain length. The translocation factors of PFCAs in grass decreased as the number of carbons in the fluorocarbon moiety increased. This field study is appropriate to improve our understanding of partitioning of PFCAs among soil, plants, and earthworms.

Keywords: Bioaccumulation; Fluoropolymer manufacturing; Perfluorooctanoic acid (PFOA); Spatial distribution; Translocation.