Trophic Magnification and Isomer Fractionation of Perfluoroalkyl Substances in the Food Web of Taihu Lake, China

Abstract

Biomagnification of perfluoroalkyl substances (PFASs) are well studied in marine food webs, but related information in fresh water ecosystem and knowledge on fractionation of their isomers along the food web are limited. The distribution, bioaccumulation, magnification, and isomer fractionation of PFASs were investigated in a food web of Taihu Lake, China. Perfluorooctanesulfonate (PFOS) and perfluorocarboxylates (PFCAs) with longer carbon chain lengths, such as perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnA), were predominant in organisms, while perfluorohexanoate (PFHxA) and perfluorooctanoate (∑PFOA) contributed more in the water phase. The consistent profile signature of PFOA isomers in water phase with 3M electrochemical fluorination (ECF) products suggests that ECF production of PFOA still exists in China. Linear proportions of PFOA, PFOS and perfluorooctane sulfonamide (PFOSA) in the biota were in the range of 91.9-100%, 78.6-95.5%, and 72.2-95.5%, respectively, indicating preferential bioaccumulation of linear isomers in biota. Trophic magnification factors (TMFs) were estimated for PFDA (2.43), perfluorododecanoate (PFDoA) (2.68) and PFOS (3.46) when all biota were included, suggesting that PFOS and long-chained PFCAs are biomagnified in the fresh water food web. The TMF of PFOS isomers descended in the order: n-PFOS (3.86) > 3+5m-PFOS (3.35) > 4m-PFOS (3.32) > 1m-PFOS (2.92) > m2-PFOS (2.67) > iso-PFOS (2.59), which is roughly identical to their elution order on a FluoroSep-RP Octyl column, suggesting that hydrophobicity may be an important contributor for isomer discrimination in biota.

What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review

“…Although properties vary with chain-length, the environmental fate and bioaccumulation behavior of PFSAs is broadly similar to that of PFCAs. PFSAs are fully dissociated anions in environmental media [53] and tend to accumulate in surface waters [31], they are persistent, bind weakly to organic phases [54] compared to other persistent organic substances, bioaccumulate in laboratory studies [55,56] and biomagnify in food webs [57,58]. In 2000 the major manufacturer of PFOS in the US (3M) announced they would cease the production of C6, C8 and C10 perfluoroalkane sulfonyl fluoride (PASF)-based products and completed the phase out in 2002 [59].…”

Characterizing direct emissions of perfluoroalkyl substances from ongoing fluoropolymer production sources: A spatial trend study of Xiaoqing River, China

“…The principal idea behind this source apportionment tool is that the two major synthesis routes to produce PFOA result in distinct profiles of branched and linear isomers. Provided that ocean water is the final reservoir of PFOA, isomer profiles in water samples from industrialized or remote regions can be used for tracking production sources (Benskin et al, 2010b(Benskin et al, , 2012aYu et al, 2013;Fang et al, 2014aFang et al, , 2014b. Electrochemical fluorination (ECF), which results in a mixture of branched and linear isomers, was used to produce the majority of APFO in Europe and North America between 1951 and 2000 .…”

Simultaneous qualitative and quantitative analysis of fluoroalkyl sulfonates in riverine water by liquid chromatography coupled with Orbitrap high resolution mass spectrometry

“…The wide usages of the chemicals in industry and daily necessities, such as surfactants, textile, aqueous fire-forming foam, mist suppressant and coatings, have resulted in their inevitable release into the environment since 1950s [2]. Particularly, linear and branched perfluorooctane sulfonate (PFOS) isomers as well as other perfluoroalkyl sulfonate analogs (PFSAs) have become world-wide contaminants due to the persistent and long-range transport characteristics as well as their ubiquitous presence in aqueous environmental com-partments [3][4][5][6][7]. For example, perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS) and PFOS were present with a concentration ranged of 0.94-13.7 ng/L in Taihu Lake [3].…”

“…Particularly, linear and branched perfluorooctane sulfonate (PFOS) isomers as well as other perfluoroalkyl sulfonate analogs (PFSAs) have become world-wide contaminants due to the persistent and long-range transport characteristics as well as their ubiquitous presence in aqueous environmental com-partments [3][4][5][6][7]. For example, perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS) and PFOS were present with a concentration ranged of 0.94-13.7 ng/L in Taihu Lake [3]. A range of 0.03-89 ng/L PFOS was detected in river water of eastern China [4].…”