Fate and transport of forever chemicals in the aquatic environment: Partitioning and biotransformation of mixtures of Per- and Polyfluoroalkyl Substances (PFAS) from different point sources and resulting concentrations in biota
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- Institutt for biologi 
Fate and transport of forever chemicals in the aquatic environment Per- and polyfluorinated alkyl substances (PFAS) are anthropogenic organic pollutants, defined as aliphatic substances that contain at least one perfluoroalkyl moiety, i.e. "-CnF2n-". Thousands of PFAS exists, and they are often referred to as "forever chemicals" due to their persistence in the environment. PFAS have unique properties and have thus been used in a variety of industrial processes and products. However, a wide range of adverse health impacts have been identified as potential effects of elevated PFAS exposure. These include kidney and testicular cancer, liver damage, dyslipidemia, decreased fertility, thyroid problems, immunotoxicity, and adverse developmental effects. The widespread use of PFAS, including in a range of consumer products, leads to continual diffuse human and environmental exposure. PFAS emitted to the environment from point sources add to the total environmental burden. In addition, point sources (and resulting hot spot areas) may act as an additional source to local wildlife (including fish and invertebrates) and humans, and increased levels of PFAS have been detected in populations affected by a local PFAS source. The term PFAS mixture refers to the total number of substances that qualify as PFAS (according to the definition above). Many polyfluorinated PFAS can be transformed to other PFAS in the environment. The ultimate result of such transformation is the terminal PFAS. The PFAS undergoing transformation are termed precursors. Transformation of precursors can over time change the PFAS mixture in the environment. The overall objective of this work was to investigate how differences in PFAS mixtures released from different point sources (and hence products) can affect fate and transport in the aquatic environment, including uptake in biota. A thorough understanding of the fate and transport of the pollutants at a contaminated site is vital when carrying out risk assessments and selecting site remediation strategies. A subsequent objective was therefore to identify optimal ways in which PFAS contaminated site investigations can be carried out. In order to explore different PFAS sources and environmental conditions, three different case study sites in Norway were selected, each representing a (or several) specific PFAS source(s): 1) Lake Tyrifjorden, a freshwater lake polluted by PFAS, where a shutdown factory that produced paper products and a fire station were the two suspected PFAS sources; 2) Bodø airport where the local marine environment has been exposed to PFAS primarily from extensive use of aqueous film forming foam (AFFF) for firefighting; and 3) Svalbard airport where the local arctic marine environment was exposed to PFAS pollution from the use of AFFF, from runoff from local diffuse sources, and via long-range transport. Fieldwork and subsequent chemical analyses were conducted at the three case study sites. In order to investigate the spatial distribution of PFAS contamination, biota and abiotic media were sampled at different distances from the point source(s). PFAS profiles (i.e., the relative distribution of the different PFAS in a sample) and concentrations in samples from the recipients (the local marine environment or freshwater lake) were compared to concentrations and profiles in samples representing emissions from the sources. Concentrations of PFAS in animals at different trophic levels in the aquatic food chain were determined in order to investigate uptake and accumulation in the local biota. Investigations included zooplankton, benthic invertebrates, decapods, fish, and birds. In addition to the investigated case study sites, differences in PFAS profiles in fish depending on PFAS source were explored using available data from Norwegian freshwater systems as examples. Fish data from lakes subject to three different sources of PFAS were explored: 1) production of paper products, 2) the use AFFF, and 3) long-range atmospheric transport. A total of eight sites were included in the data analysis: four airports, three large lakes without major PFAS point sources, and lake Tyrifjorden. Data for the different sources were provided by Norwegian stakeholders (Avinor and the Norwegian Defence Estates Agency (Forsvarsbygg in Norwegian)) who own land that is contaminated by PFAS (the airports), monitoring data compiled through monitoring programs commissioned by the Norwegian Environment Agency (the three large lakes without major PFAS point sources), and data from the lake Tyrifjorden case study site. Both the abiotic and biotic compartments at all the case study sites (lake Tyrifjorden, Bodø airport, and Svalbard airport) showed elevated concentrations of PFAS in the environment close to the point sources compared to areas expected to receive PFAS mainly via long-range transport. Similarly, the comparison of fish data from Norwegian freshwater systems subject to different sources of PFAS showed higher concentrations in fish from lakes receiving PFAS directly from point sources compared to lakes considered to mainly receive PFAS via long-range atmospheric transport. Clear differences in environmental PFAS profiles were found, both in abiotic compartments and in biota, depending on the type of PFAS source. PFAS pollution arising from the production of paper products was dominated by precursor compounds to perfluorinated alkyl acids (PFAA) in sediments, and by long chained perfluoroalkyl carboxylic acids (PFCA) and perfluorooctanesulfonic acid (PFOS) in biota. The precursors to PFAA in sediments which were detected in the highest concentrations, i.e. the di-substituted phosphate ester of N-ethyl Perfluorooctane sulfonamido ethanol (SAmPAP diester) and the long chained fluorotelomer sulfonates (FTS; 10:2 FTS, 12:2 FTS, and 14:2 FTS) are not routinely targeted by chemical analyses. Significant concentrations of long chained FTS were also detected in biota. Environmental samples from areas receiving PFAS from AFFF point sources were dominated by perfluoroalkane sulfonic acids (PFSA), in addition to 6:2 FTS at areas where newer AFFF formulations have been used. PFAS profiles in fish receiving PFAS mainly via long-range atmospheric transport were dominated by PFCA. Ratios for specific PFCA pairs indicative of long-range atmospheric transport were identified. It was concluded that the different PFAS profiles can be used to identify the sources of pollution (i.e., by comparing PFAS profiles in samples in order to explore the origin of the pollution, termed fingerprinting). Variations in partitioning and environmental fractionation behaviour between different PFAS and isomers should be taken into consideration when comparing PFAS profiles and concentrations in different samples. Source tracking was conducted for lake Tyrifjorden using fingerprinting. PFAS profiles in samples representing the suspected sources and PFAS profiles in samples from the lake were compared. A sediment core was used to explore historic emissions of PFAS to the lake. It was concluded that the shutdown factory which produced paper products was the main source of the PFAS pollution in the lake. Further, it was concluded that emission volumes were high, and thus that production of paper products is likely a major, largely overlooked, global source of emissions of PFAS. (Bio)transformation of precursors was found to have a significant effect on the observed fate and transport. (Bio)transformation was found to change the physiochemical properties of a compound and thus its partitioning and thereby its transport and biota exposure route (i.e., via ambient water or diet). In lake Tyrifjorden, the relationships between PFAA concentrations in fish and concentrations in ambient water (i.e. bioaccumulation factors, BAF) were very high compared to relationships reported elsewhere. It was concluded that the reason for this is that hydrophobic precursors to PFAA in sediments are taken up into biota and are biotransformed into PFAA as they are transferred through the food chain. The main exposure route of PFAA to fish in lake Tyrifjorden was determined to be via diet. Therefore, it was concluded that PFAS burdens in biota cannot necessarily be estimated with sufficient accuracy based solely on water or sediment concentrations. Depending on the specific PFAS, species-specific accumulation was reported. Significant accumulation of 6:2 FTS was reported in invertebrates at Bodø airport and Svalbard airport. However, very low concentrations were reported for vertebrates (fish and birds). It was hypothesised that (some) invertebrates have a lower capacity for biotransformation of 6:2 FTS compared to vertebrates. It was further concluded that several species as well as abiotic media should be investigated to assess the environmental PFAS mixture, especially when the environmental behaviour of the relevant PFAS, or the PFAS mixture used at the source is unknown. The percentage of precursors (as a percentage of the total sum PFAS) decreased with distance from the PFAS sources. This was interpreted as an indication that precursor compounds in the environment are increasingly transformed to intermediate and terminal fluorinated degradation products with time, and hence distance. In lake Tyrifjorden, a strategy for characterising the total PFAS mixture was explored where a combination of targeted analyses and a method for estimating the total PFAS mixture were used for samples representing different degrees of (bio)transformation completeness. It was concluded that including a spatial dimension in a sampling campaign should be considered to evaluate the fate of the emitted PFAS mixture. Further, the combined approach of including a spatial dimension and applying both targeted analyses as well as approaches to quantify the total PFAS mixture, was considered to be a promising approach to more accurately understand PFAS environmental fate and transport.
Består avPaper 1: Langberg, Håkon A.; Hale, Sarah E.; Breedveld, Gijs D.; Jenssen, Bjørn M; Jartun, Morten. PFAS fingerprints in fish from Norwegian freshwater bodies subject to different source inputs.
Paper 2: Langberg, Håkon Austad; Arp, Hans Peter; Breedveld, Gijs D.; Slinde, Gøril Aasen; Høisæter, Åse; Grønning, Hege Mentzoni; Jartun, Morten; Rundberget, Thomas; Jenssen, Bjørn Munro; Hale, Sarah. Paper product production identified as the main source of per- and polyfluoroalkyl substances (PFAS) in a Norwegian lake: Source and historic emission tracking. Environmental Pollution (1987) 2020 ;Volum 273. https://doi.org/10.1016/j.envpol.2020.116259 This is an open access article under the CC BY license
Paper 3: Langberg, Håkon Austad; Breedveld, Gijs D.; Slinde, Gøril Aa; Grønning, Hege M; Høisæter, Åse; Jartun, Morten; Rundberget, Thomas; Jenssen, Bjørn M; Hale, Sarah E. Fluorinated Precursor Compounds in Sediments as a Source of Perfluorinated Alkyl Acids (PFAA) to Biota. Environmental Science and Technology 2020 ;Volum 54.(20) s. 13077-13089 https://dx.doi.org/10.1021/acs.est.0c04587 This is an open access article published under a Creative Commons Attribution (CC-BY)
Paper 4: Langberg, Håkon Austad; Breedveld, Gijs D.; Grønning, Hege Mentzoni; Kvennås, Marianne; Jenssen, Bjørn Munro; Hale, Sarah. Bioaccumulation of Fluorotelomer Sulfonates and Perfluoroalkyl Acids in Marine Organisms Living in Aqueous Film-Forming Foam Impacted Waters. Environmental Science and Technology 2019 ;Volum 53.(18) s. 10951-10960 https://doi.org/10.1021/acs.est.9b00927 This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
Paper 5: Ali, Aasim Musa Mohamed; Langberg, Håkon Austad; Hale, Sarah; Kallenborn, Roland; Mortensen, Åse-Karen; Hartz, William F; Ciesielski, Tomasz Maciej; McDonought, Carrie A.; Jenssen, Bjørn Munro; Breedveld, Gijs D.. The fate of poly- and perfluoroalkyl substances in a marine food web influenced by land-based sources in the Norwegian Arctic. Environmental Science: Processes & Impacts 2021 https://doi.org/10.1039/D0EM00510J his is an open access article published under Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0)