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Vertical Profiles, Sources and Transport of PFASs in the Arctic Ocean
Abstract
The relative importance of atmospheric versus oceanic transport for poly- and perfluorinated alkyl substances (PFASs) reaching the Arctic Ocean is not well understood. Vertical profiles from the Central Arctic Ocean and shelf water, snow and meltwater samples were collected in 2012; 13 PFASs (C6-C12 PFCAs; C6, 8, 10 PFSAs; MeFOSAA and EtFOSAA, and FOSA) were routinely detected (range: <5 - 343 pg/L). PFASs were only detectable above 150 m depth in the polar mixed layer (PML) and halocline. Enhanced concentrations were observed in snow and meltpond samples, implying atmospheric deposition as an important source of PFASs. Model results suggested atmospheric inputs to account for 34-59% (~11-19 pg/L) of measured PFOA concentrations in the PML (mean 32±15 pg/L). Modeled surface and halocline measurements for PFOS based on North Atlantic inflow (11-36 pg/L) agreed with measurements (mean, 17, range <5-41 pg/L). Modeled deep water concentrations below 200 m (5-15 pg/L) were slightly higher than measurements (<5 pg/L), suggesting the lower bound of PFAS emissions estimates from wastewater and rivers may provide the best estimate of inputs to the Arctic. Despite low concentrations in deep water, this reservoir is expected to contain most of the PFOS mass in the Arctic (63-180 Mg) and projected to continue increasing to 2038.
... Yeung et al. analyzed EtFOSAA, FOSA, MeFOSAA, C6-C12 PFCAs, and C4-C10 PFSAs in the Arctic Ocean, encompassing both deep ocean and shelf waters [38]. The study found that PFAS compounds were typically only detectable in the polar mixed layer at depths shallower than 150 m. ...
... The study found that PFAS compounds were typically only detectable in the polar mixed layer at depths shallower than 150 m. Vertical assessments conducted at four sites in the Amundsen and Nansen Basins revealed that PFOA (0.05 ng/L) and PFOS (0.047 ng/L) were the main types of PFAS found [38]. Other PFAS compounds, such as PFBS (0.04 ng/L), PFHpA (0.035 ng/L), PFHxA (0.037 ng/L), and PFNA (0.039 ng/L), were also commonly detected. ...
... A broader variety of PFAS compounds, including PFUnDA, FOSA, and EtFOSAA, were found in melt pond water gathered from various locations across the Nansen and Amundsen Basins. These concentrations were higher than those detected in seawater from the Arctic shelf and central basin, highlighting the significant role that atmospheric deposition plays in influencing surface waters [38]. Notably, PFAS levels in coastal waters off Greenland were generally greater than those measured in the open ocean within the northern North Atlantic [26]. ...
Per- and polyfluoroalkyl substances (PFAS) are increasingly detected in remote environments. This review aims to provide a comprehensive overview of the types and concentrations of PFAS found in the air, water, soil, sediments, ice, and precipitation across different remote environments globally. Most of the recent studies on PFAS remote occurrence have been conducted for the Arctic, the Antarctica, and the remote regions of China. Elevated perfluorooctane sulfonate (PFOS) in Meretta and Resolute Lakes reflects the impact of local sources like airports, while PFAS in lakes located in remote regions such as East Antarctica and the Canadian High Arctic suggest atmospheric deposition as a primary PFAS input. Long-chain PFAS (≥C7) accumulate in sediments, while short-chain PFAS remain in water, as shown in Hulun Lake. Oceanic PFAS are concentrated in surface waters, driven by atmospheric deposition, with PFOA and PFOS dominating across oceans due to current emissions and legacy contamination. Coastal areas display higher PFAS levels from local sources. Arctic sediment analysis highlights atmospheric deposition and ocean transport as significant PFAS contributors. PFAS in Antarctic coastal areas suggest local biological input, notably from penguins. The Tibetan Plateau and Arctic atmospheric data confirm long-range transport, with linear PFAS favoring gaseous states, while branched PFAS are more likely to associate with particulates. Climatic factors like the Indian monsoon and temperature fluctuations affect PFAS deposition. Short-chain PFAS are prevalent in snowpacks, serving as temporary reservoirs. Mountainous regions, such as the Tibetan Plateau, act as cold traps, accumulating PFAS from atmospheric precursors. Future studies should focus on identifying and quantifying primary sources of PFAS.
... The vertical profile of organic pollutants in water column is one of key information for understanding the potential biogeochemical processes of these pollutants, but less is known about PFASs to date (Yamazaki et al., 2019;Yeung et al., 2017). In general, the concentrations of PFASs in the deep-water column decreased with the increase of water depth ("conservative pattern") (Joerss et al., 2020a; J o u r n a l P r e -p r o o f Yamazaki et al., 2019;Yeung et al., 2017;Yamashita et al., 2008). ...
... The vertical profile of organic pollutants in water column is one of key information for understanding the potential biogeochemical processes of these pollutants, but less is known about PFASs to date (Yamazaki et al., 2019;Yeung et al., 2017). In general, the concentrations of PFASs in the deep-water column decreased with the increase of water depth ("conservative pattern") (Joerss et al., 2020a; J o u r n a l P r e -p r o o f Yamazaki et al., 2019;Yeung et al., 2017;Yamashita et al., 2008). The dispersive boundary of PFASs (the maximum depth where concentrations are above the method detection limit) often varies among oceanic areas. ...
... The dispersive boundary of PFASs (the maximum depth where concentrations are above the method detection limit) often varies among oceanic areas. Apart from PFAS concentrations in the surface water layer, the dispersive boundary is generally shaped by complicated and intense physical processes including eddy diffusion, subducting water masses and upwelling (Joerss et al., 2020a;Lohmann et al., 2006;Lohmann et al., 2013;Yeung et al., 2017;Zhang et al., 2017;Miranda et al., 2021). In the Northwest Pacific Ocean (NWPO), the dispersive boundaries are almost 1000-1500 m (Yamashita et al., 2008). ...
The contamination status and transport of per- and polyfluoroalkyl substances (PFASs) in the seawater of the Indian Ocean (IO) and an adjacent subregion of the Northwest Pacific Ocean (NWPO) were investigated. Eight legacy PFASs were widely distributed in the surface seawater, and perfluoroheptanoic acid (PFHpA) and perfluorooctanoic acid (PFOA) were the two predominant PFASs. ΣPFAS concentration decreased in the following order: NWPO>Joining area of Asia and Indian-Pacific Oceans (JAIPO)>Northeast Indian Ocean>Southwest Indian Ocean. Hexafluoropropylene oxide-dimer acid, a replacement surfactant for PFOA was extensively detected in the IO (~34.8 pg/L) for the first time, showing an early sign of emerging PFAS spread in global open oceans. Eight depth profiles across the JAIPO (down to 5433 m depth) revealed a “surface-enrichment” and “depth-depletion” pattern for PFASs in the water column, and two noticeable fluctuations were mainly located at depths of 150–200 and 200–500 m. Physical processes, including eddy diffusion, and the origin and trajectory of water mass were crucial factors for structuring PFAS vertical profiles. Mass transport estimates revealed a remarkable PFOA contribution through the JAIPO to IO carried by the Indonesian Throughflow, and a nonnegligible PFHpA contribution from Antarctic Immediate Water to deep water of the JAIPO driven by thermohaline circulation.
... The Arctic Ocean is predicted to become a significant PFOS reservoir, potentially storing between 63 and 180 t in the future (Yeung et al., 2017). Moreover, long-chain and emerging shortchain PFAS show significant temporal changes and are transported by ocean currents, resulting in consistent exposure over time within environmental matrices (Ahrens et al., 2023). ...
... Early models predicted that the decline of sea ice and subsequent increases in open water would enhance the exchange of chemicals between the atmosphere and ocean surface waters, raising exposure levels in marine environments (Stemmler and Lammel, 2010;Dunn et al., 2024). However, recent research revealed that PFAS behavior in sea ice involves complex interactions between contaminant retention, seasonal ice dynamics, and environmental release processes (Yeung et al., 2017;Hartz et al., 2023). ...
The cryosphere faces increasing threats from anthropogenic pollutants, including per- and polyfluoroalkyl substances (PFAS), a class of synthetic chemicals produced in significant quantities and released into the environment for over seven decades. PFAS are widely utilized for their water- and grease-resistant properties in numerous industrial, household, personal care, and medical products. Despite their widespread applications, all PFAS or their degradation and transformation products are environmentally persistent and pose health risks to humans. PFAS are detected ubiquitously, even in remote regions like the Arctic and Antarctica, and they bioaccumulate within polar trophic food chains. The primary transport and transmission mechanisms for PFAS involve atmospheric transport through volatile precursors, atmospheric oxidation, ocean currents, and the formation of sea spray aerosols. Additionally, contamination of surface snow, post-deposition processes in snow, and sediment interactions significantly contribute to PFAS transport. The physical and chemical properties, including density, melting points (Tm), boiling points (Tb), solubility, vapor pressure, electronegativity, low polarizability, chemical stability, and thermal stability, play key roles in determining their environmental fate and transformation. The toxicity of certain PFAS has raised concerns, prompting bans and efforts to develop safer alternatives. Despite increasing public awareness and regulations to limit the production of legacy PFAS, their long-term environmental impacts remain unclear. As global warming accelerates cryosphere shrinkage, which releases PFAS with meltwater, cold-adapted ecosystems and associated biota face unprecedented challenges and uncertainties, particularly regarding the accumulation of non-degradable materials. This situation underscores the urgent need to comprehensively understand the fate of PFAS and adopt effective management strategies for polar systems. This review summarizes current literature on the transport, distribution, and legacy of PFAS, along with their known ecological impacts, bioremediation potential, and other management options in the cryosphere.
... Because of their unique characteristics (thermal stability, high surface activity, and hydrophobicity) [1,2], PFASs were widely used in numerous consumer and industrial applications, such as fire-fighting foams, non-stick cookware, and convenience food packaging, leading to a widespread contamination [3,4]. PFASs were not only found ubiquitously in multiple environmental compartments [5,6], even the polar surface [7], but also observed in wildlife species and human tissues (serum, urine, liver and other tissues) [8,9]. Humans appear to have a long half-life of serum elimination of long-chain PFASs (perfluoroalkyl carboxylic acids (PFCAs) with ≥ 7 perfluorinated carbons, perfluoroalkyl sulfonic acids (PFSAs) with ≥ 6 perfluorinated carbons), which are assumed to have a higher bioaccumulation potential compared to short-chain PFASs [10]. ...
... A total of 21 target PFASs were analyzed, including PFASs (C [4][5][6][7][8][9][10][11][12][13][14] PFCAs and C 4-10 PFSAs), perfluoroalkyl phosphonic and phosphinic acids (PFPAs) (C 6 , C 8 , and C 10 ), sodium (1 H,1 H,2 H,2 H-perfluorooctyl) phosphate (6:2diPAP), and sodium (1 H,1 H,2 H,2 H-perfluorodecyl) phosphate (8:2diPAP). 13 C 2 -PFOA and 13 C 8 -PFOS were used as surrogate standards, and a mixture of eleven stable isotope-labeled PFASs (MPFAC-MXA, 13 C 2 -6:2diPAP, and 13 C 2 -8:2diPAP) were used as internal standards during analysis. ...
... One such mechanism is through long-range ocean currents, whereby ocean currents distribute PFAS from source regions to remote Arctic marine environments. 7,8 Marine aerosols have also been identified as PFAS carriers for long-range transport. 9 The long-range atmospheric transport of volatile precursor PFAS, followed by their atmospheric degradation to PFAAs and subsequent deposition has also been identified. ...
... This indicates that marine aerosols are not a significant source for PFAS in the Lomonosovfonna ice core. This is despite (i) the ability of PFAS to undergo long-range transport in the ocean, (ii) the variety of PFAS that have been measured in the Arctic basin, 8 and (iii) the proximity of Lomonosovfonna to several fjords (>20 km) and open sea (~120 km). ...
Per- and polyfluoroalkyl substances (PFAS) are a group of persistent organic contaminants of which some are toxic and bioaccumulative. Several PFAS can be formed from the atmospheric degradation of precursors such as fluorotelomer alcohols (FTOHs) as well as hydrochlorofluorocarbons (HFCs) and other ozone-depleting chlorofluorocarbon (CFC) replacement compounds. Svalbard ice cores have been shown to provide a valuable record of long-range atmospheric transport of contaminants to the Arctic. This study uses a 12.3 m ice core from the remote Lomonosovfonna ice cap on Svalbard to understand the atmospheric deposition of PFAS in the Arctic. A total of 45 PFAS were targeted, of which 26 were detected, using supercritical fluid chromatography (SFC) tandem mass spectrometry (MS/MS) and ultraperformance liquid chromatography (UPLC) MS/MS. C2 to C11 perfluoroalkyl carboxylic acids (PFCAs) were detected continuously in the ice core and their fluxes ranged from 2.5 – 8200 ng m-2 yr-1 (9.51 – 16,500 pg L-1). Trifluoroacetic acid (TFA) represented 71% of the total mass of C2 – C11 PFCAs in the ice core and had increasing temporal trends in deposition. The distribution profile of PFCAs suggested that FTOHs were likely the atmospheric precursor to C8 – C11 PFCAs, whereas C2 – C6 PFCAs had alternative sources, such as HFCs and other CFC replacement compounds. Perfluorooctanesulfonic acid (PFOS) was also widely detected in 82% of ice core subsections, and its isomer profile (81% linear) indicated an electrochemical fluorination manufacturing source. Comparisons of PFAS concentrations with a marine aerosol
proxy showed that marine aerosols were insignificant for the deposition of PFAS on Lomonosovfonna. Comparisons with a melt proxy showed that TFA and PFOS were mobile during meltwater percolation. This indicates that seasonal snowmelt and runoff from post-industrial accumulation on glaciers could be a significant seasonal source of PFAS to ecosystems in Arctic fjords.
... Basically, the soil composition, especially the proportion of the organic matters and mineral content, governs the conveyance of the PFASs from the sources such as firefighting, landfills, airports, and training fields to the groundwater (Mahinroosta and Senevirathna, 2020) can also be migrated from the WWTPs to the surface water bodies through the rivers and ultimately reached the oceans. Thereafter, the PFASs would be conveyed to the Polar Regions with the help of the water current, where the PFASs get iced-up and become iceberg-fragment (Yeung et al., 2017). Meanwhile, the concentration of the organic matters, water depth, and microbial activity has monumental impact on the distribution of the PFASs. ...
... At the top layers, the PFCA (up to 80%) dominates the PFSA, whereas at greater depth, the proportions of the PFCAs (55%) and PFSAs (42%) are comparable (Gonzalez-Gaya et al., 2019). Moreover, Yeung et al. (2017) found that the PFASs have been traced up to an enormous depth of 3.5 km in the Labrador Sea. However, the PFASs concentration varies inversely with the water depth (Zhi and Liu, 2019). ...
... 16,17 Hence, marine aerosols do not likely provide a long-range atmospheric pathway for the movement of PFAS to the Arctic or within the Arctic. This is an important observation since the Arctic Ocean contains a variety of PFAS, 8 and it is therefore likely that this is not able to be significantly redistributed to the terrestrial Arctic environment (e.g., ice caps) via marine aerosols. ...
Per-and polyfluoroalkyl substances (PFAS) are persistent anthropogenic contaminants, some of which are toxic and bioaccumulative. Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) can form during the atmospheric degradation of precursors such as fluorotelomer alcohols (FTOHs), N-alkylated perfluoroalkane sulfonamides (FASAs), and hydrofluorocarbons (HFCs). Since PFCAs and PFSAs will readily undergo wet deposition, snow and ice cores are useful for studying PFAS in the Arctic atmosphere. In this study, 36 PFAS were detected in surface snow around the Arctic island of Spitsbergen during January−August 2019 (i.e., 24 h darkness to 24 h daylight), indicating widespread and chemically diverse contamination, including at remote high elevation sites. Local sources meant some PFAS had concentrations in snow up to 54 times higher in Longyearbyen, compared to remote locations. At a remote high elevation ice cap, where PFAS input was from long-range atmospheric processes, the median deposition fluxes of C 2 − C 11 PFCAs, PFOS and HFPO−DA (GenX) were 7.6−71 times higher during 24 h daylight. These PFAS all positively correlated with solar flux. Together this suggests seasonal light is important to enable photochemistry for their atmospheric formation and subsequent deposition in the Arctic. This study provides the first evidence for the possible atmospheric formation of PFOS and GenX from precursors.
... The unique physiochemical properties of per-and polyfluoroalkyl substances (PFAS), with strong carbon-fluorine bonds (Smart, 1994) and relatively high water solubility (Post et al., 2017), make PFAS persistent, mobile (Wong et al., 2018;Yeung et al., 2017) and/or bioaccumulative in the environment (Boisvert et al., 2019;Houde et al., 2008). PFAS have become a serious global concern due to their widespread global distribution and toxicity to humans (Fenton et al., 2021) and other organisms (Chen et al., 2021). ...
... There are more investigations on PFAS in wet deposition compared with those in dry deposition. Multiple studies have monitored PFAS in rain and snow from around the globe, including North America, Europe, Asia, and the polar regions [163][164][165][166][167]. Rainfall processes can effectively remove PFAS with long carbon chains (≥C 6 ) in the atmosphere, and the removal efficiencies of PFOS and PFOA in APM can reach 68%-98% [129]. ...
With long-term production and widespread application, per- and polyfluoroalkyl substances (PFAS) have been detected in various media worldwide, including the atmosphere. Since the gradual restriction and phase-out of C8 perfluoroalkyl acids (PFAAs), environmental contamination by emerging PFAS substitutes such as short-chain PFAA homologues, perfluoroether carboxylic, and sulfonic acids has been reported. Although there has been extensive monitoring of emerging PFAS substitutes in the aquatic environment, few studies have conducted target analysis and nontarget screening (NTS) of emerging unknown PFAS in the atmosphere over the past decade. To fill the gap, this review focused on emerging PFAS in the atmosphere in addition to legacy PFAS. The reported sampling, pretreatment, and instrumental analysis methods for target analysis and NTS of both neutral and ionic PFAS in the atmosphere are summarized, along with the advantages and current limitations of different sampling and NTS methods for PFAS in the atmosphere. The global levels, composition, and spatiotemporal distribution characteristics of legacy and emerging PFAS in the atmosphere are summarized and their transport, transformation, and dry/wet deposition are elucidated. The review highlights the importance of developing and applying the all-in-one strategy integrating target, suspect screening, and NTS to gain insights into emerging PFAS in the atmosphere and provide a reference for future research.
... Perfluoroalkyl acid (PFAA) concentrations reported in the literature show decreasing patterns from coast to open waters which is referred as the "dilution effect" (Yamashita et al., 2008;Ahrens et al., 2009;Benskin et al., 2012;González-Gaya et al., 2014;Yeung et al., 2017;Shan et al., 2021;Savvidou et al., 2023). Physical processes (e.g., eddy diffusion, origin and trajectory of water mass) affect vertical change in concentration (González-Gaya et al., 2019;Han et al., 2022) and in general PFAC levels decrease with increasing depth. ...
... While in isolated regions, such as the Arctic, PFAS mainly derive from the oceanic currents and atmospheric transport of volatile precursors (Yeung et al., 2017), river discharges are the primary sources of PFAS in the Mediterranean basin (Brumovský et al., 2016). The Mediterranean Sea is also susceptible to significant environmental contamination due to its semi-enclosed geomorphology and high level of coastal human activity (Ahrens et al., 2010;Kurwadkar et al., 2022;Zhang et al., 2017). ...
Poly- and Perfluoroalkyl Substances (PFAS) are a well-known class of pollutants which can bioaccumulate and biomagnify with a vast majority being highly persistent. This study aims to determine the biomagnification rates of PFAS in sexually mature striped dolphins and to assess temporal trends on PFAS concentrations over the past three decades (1990–2021) in the North-Western Mediterranean Sea. Thirteen and 17 of the 19 targeted PFAS were detected in the samples of the dolphins’ digestive content and liver, respectively, at concentrations ranging between 43 and 1609 ng/g wet weight, and 254 and 7010 ng/g wet weight, respectively. The most abundant compounds in both types of samples were linear perfluorooctanesulfonic acid (n-PFOS) and perfluorooctanesulfonamide (FOSA), which were present in all samples, followed by perfluoroundecanoic acid (PFUnDA), perfluorotridecanoic acid (PFTrDA) and perfluorononanoic acid (PFNA). Long-chain PFAS (i.e., PFCAs C ≥ 7 and PFSAs C ≥ 6) biomagnified to a greater extent than short-chain PFAS, suggesting a potential effect on the health of striped dolphins. Environmental Quality Standards concentrations set in 2014 by the European Union were exceeded in half of the samples of digestive content, suggesting that polluted prey may pose potential health risks for striped dolphins. Concentrations of most long-chain PFAS increased from 1990 to 2004–2009, then stabilized during 2014–2021, possibly following country regulations and industrial initiatives. The current study highlights the persistent presence of banned PFAS and may contribute to future ecological risk assessments and the design of management strategies to mitigate PFAS pollution in marine ecosystems.
... The PFCAs contain a hydrophobic uoroalkyl tail which is tuned in length based on the desired application or local regulations. PFCAs have been reported in all types of environments, including freshwater, 11 arctic ecosystems 12 and atmospheric water 13 (fog, dew, rain) while also contaminating drinking water throughout the United States. 14 This is particularly alarming due to their potentially carcinogenic effects, 15 adverse impacts on brain function 16 and epidemiological association with various illnesses. ...
Microplastics and per- and polyfluoroalkyl substances (PFAS) are two of the most notable emerging contaminants reported in the environment. Micron and nanoscale plastics possess a high surface area-to-volume ratio, which could increase their potential to adsorb pollutants such as PFAS. One of the most concerning sub-classes of PFAS are the perfluoroalkyl carboxylic acids (PFCAs). PFCAs are often studied in the same context as other environmental contaminants, but their amphiphilic properties are often overlooked in determining their fate in the environment. This lack of consideration has resulted in a diminished understanding of the environmental mobility of PFCAs, as well as their interactions with environmental media. Here, we investigate the interaction of PFCAs with polyethylene microplastics, and identify the role of environmental weathering in modifying the nature of interactions. Through a series of adsorption-desorption experiments, we delineate the role of the fluoroalkyl tail in the binding of PFCAs to microplastics. As the number of carbon atoms in the fluoroalkyl chain increases, there is a corresponding increase in the adsorption of PFCAs onto microplastics. This relationship can become modified by environmental weathering, where the PFCAs are released from the macro and microplastic surface after exposure to simulated sunlight. This study identifies the fundamental relationship between PFCAs and plastic pollutants, where they can mutually impact their thermodynamic and transport properties.
... In contrast to the reported TFA concentration measurements, PFAS were not found at depths below 250 m in the Arctic Ocean and the study did not include TFA (Yeung et al., 2017). "The detection of PFASs in the four depth profiles was limited to the 150 m below the surface, except for the North Barents Sea where a PFAS was detected down to 250 m below surface." ...
... 6,7 As a consequence, high trophic level aquatic organisms including seabirds often have elevated tissue concentrations. 1,8 Oceanic and atmospheric transport can contribute to the long-range dispersal of PFAS, their precursors and breakdown products [9][10][11][12][13][14][15] which are found in wildlife tissues worldwide, including remote areas like the Arctic. 8,16 In birds, during egg formation, the female transfers various substances required to enable and sustain the development of the embryo. ...
The developmental period is a very sensitive phase since it sees the synthesis and maturation of all organs and functions of the future organism. Therefore, any disruption experienced early in life may have substantial subsequent consequences. In the context of the considerable impact of Human activities on wildlife, seabirds are particularly at risk since they are exposed to numerous threats, including fisheries interactions, habitat destruction, or environmental pollution. Among them, the later is maybe the most insidious, since it can also be transferred to the progeny via maternal transfer in eggs, and cause adverse effects as early as during the development. The 20th century saw the emergence of numerous synthetic substances. Among them, the per- and polyfluoroalkyl substances (PFAS) are found in seabird eggs, but little is known about their effects. In this thesis, I aimed at investigating the maternal transfer of PFAS in an Arctic seabird, the black-legged kittiwake (Rissa tridactyla). I also examined the eventual consequences of legacy and emerging PFAS exposure for the embryo in this species and in the yellow-legged gull (Larus michahellis). I found relatively high concentrations of legacy PFAS in eggs as well as some emerging compounds including 7:3 FTCA or PFEcHS. PFAS physicochemical characteristics influenced their transfer efficiency. My results also suggested that females PFAS might affect their transfer of maternal hormones in eggs, which may ultimately affect offspring at short and long term. Finally, I found no indications that PFAS deposited in eggs may affect the developing embryo on biomarkers of ageing (telomere length) or metabolism. I therefore suggested that both studied population should be relatively safe at least at the PFAS concentrations measured in their eggs. Nonetheless, additional studies would be needed to assess how PFAS may affect the endocrine maternal transfer and its consequences for the embryo.
... The extensive usage of PFASs has caused severe environmental contamination of water, air, soil and food, thereafter resulting in widespread public health threats (D'Ambro et al., 2021;Lim, 2019;Penland et al., 2020;Rahman et al., 2014). Among all the PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) draw the greatest concerns due to their known ubiquity, persistence, bioaccumulation and toxicity (Grandjean et al., 2012;Rich et al., 2015;Wang et al., 2021a;Yeung et al., 2017). Although the Stockholm Convention has phased out PFOA and PFOS, their exemption for usage, such as in aqueous fire-fighting foams (AFFF), still causes continuous water and soil contamination (Nickerson et al., 2021). ...
Per-/polyfluoroalkyl substances (PFASs) contamination has caused worldwide health concerns, and increased demand for effective elimination strategies. Herein, we developed a new indole derivative decorated with a hexadecane chain and a tertiary amine center (named di-indole hexadecyl ammonium, DIHA), which can form stable nanospheres (100-200 nm) in water via supramolecular assembly. As the DIHA nanospheres can induce electrostatic, hydrophobic and van der Waals interactions (all are long-ranged) that operative cooperatively, in addition to the nano-sized particles with large surface area, the DIHA nanocomposite exhibited extremely fast adsorption rates (in seconds), high adsorption capacities (0.764-0.857 g g⁻¹) and selective adsorption for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), outperformed the previous reported high-end PFASs adsorbents. Simultaneously, the DIHA nanospheres can produce hydrated electron (eaq⁻) when subjected to UV irradiation, with the virtue of constraining the photo-generated eaq⁻ and the adsorbed PFOA/PFOS molecules entirely inside the nanocomposite. As such, the UV/DIHA system exhibits extremely high degradation/defluorination efficiency for PFOA/PFOS, even under ambient conditions, especially with the advantages of low chemical dosage requirement (μM level) and robust performance against environmental variables. Therefore, it's a new attempt of using supramolecular approach to construct an indole-based nanocomposite, which can elegantly combine adsorption and degradation functions. The novel DIHA nanoemulsion system would shed light on the treatment of PFAS-contaminated wastewater.
... Per-and polyfluoroalkyl substances (PFAS) are a large class of synthetic chemicals that do not naturally degrade, thus they are continuously accumulating in our environment (Ghisi et al. 2019;Giesy and Kannan 2001;Kwiatkowski et al. 2020;Pan et al. 2017;Yeung et al. 2017). Some PFAS travel long distances from their source, contributing to global contamination, and some have been found to bioaccumulate in humans and animals. ...
Background
●PFAS (per-and polyfluoroalkyl substances) are a large class of synthetic chemicals widely used in consumer products and industrial processes. The scientific literature on PFAS has increased dramatically in the last decade. Many stakeholders, including regulators, scientists, non-governmental organizations, and concerned individuals could benefit from an efficient way to access the health and toxicological literature related to PFAS.
●Objective
●To create a systematic evidence map of the available peer-reviewed health or toxicological research for 29 PFAS.
●Methods
●A protocol for conducting this systematic evidence map was initially published on Zenodo (Pelch et al. 2019c), then peer reviewed and published in Environment International (Pelch et al. 2019d). PubMed database was searched through January 25, 2021. Studies were screened for inclusion and exclusion according to the Populations, Exposures, Comparators, and Outcomes (PECO) statement. Inclusion criteria were intentionally broad and included any human, animal, and/or in vitro study that investigated exposure to one of the 29 PFAS of interest and a human health or toxicological effect. Selected study details were extracted from included studies as described in the protocol. Study appraisal was not conducted. The included studies and extracted meta-data are freely available in the online, interactive systematic evidence map at https://pfastoxdatabase.org.
●Results
●Over 15,000 studies were retrieved from the PubMed literature searches. After manual screening, 1,067 studies were identified and included as investigating the health or toxicological effect of one or more PFAS of interest. There were 505 human, 385 animal, and 220 in vitro studies. Summary tables of the extracted data and overall observations are included in this report.
●Conclusions
●The PFAS-Tox Database is a useful tool for searching, filtering, and identifying peer reviewed research on the health and toxicological effects of the included PFAS. In this summary of the evidence map we provide examples of data gaps and clusters revealed by the database, with the goal of helping direct future research efforts, facilitate systematic reviews (e.g. on immune effects, mixtures of PFAS, or effects of short chain PFAS), inform regulatory risk assessments, and improve opportunities for cross-disciplinary coordination. We also discuss how this tool supports scientists, regulatory agencies, and other individuals by increasing awareness and access to current evidence regarding the health effects associated with PFAS exposure.
... PFASs concentrations varied considerably across different water columns, but varied little among layers at the same site (Fig. S3, Table S15), with average values of 820, 800, and 802 ng L -1 in the upper, middle, and bottom layers, respectively. When the sampling depth was less than 10 m, the fluctuation in PFASs concentration in different layers was less than 10%, consistent with the findings in reservoir water , coastal water (Zhou et al., 2018), and open seas (Yeung et al., 2017;Yamazaki et al., 2019). The average water depth of Baiyangdian Lake (~ 6.5 m) was shallow which resulted a good vertical mixing effect of PFASs, thereby supporting the state condition hypothesis for the QWASI model further. ...
Increased anthropogenic activities have caused contamination of perfluoroalkyl substances (PFASs) in lakes worldwide. However, how to remediate their contamination remains unclear. In this study, a heavily polluted lake, Baiyangdian Lake in China, was selected to investigate current PFASs levels in multimedia, stimulate their transport fate based upon an optimized fugacity model, and finally identify appropriate remediation pathways. From 2008 to 2019, the average concentrations of PFASs in the lake increased approximately 7-40 times in the environment and biota. Spatially, with continuous import of perfluorohexane sulfonate (PFHxS) and perfluorooctanoic acid (PFOA), barring fish, a noticeable north-south difference was distinguished in the PFASs composition in multimedia from the lake. Based on the optimized fugacity model simulation, the water phase was the primary transport path (~76.5%) for PFASs, with a total flux of 333 kg y⁻¹. Compared with bioaccumulation fluxes in submerged plants (6.2 kg y⁻¹), emerged plants (2.6 kg y⁻¹), and fish (1.1 kg y⁻¹), the exchange flux of PFASs between water and sediment remained high (~94 kg y⁻¹). Considering remediation cost, sediment cleaning is currently the most cost-effective pathway, while harvesting submerged plant could be a promising pathway in the future. This study provides a basis for remediating PFASs-polluted lakes on a global scale.
... RS significantly increased for PFCA ≥ PFUnA and PFSA ≥ PFNS (RS 384−1402, note: semiquantitative data). Above these chain lengths, atmospheric transport has been reported to be less relevant, 67,68 and such PFASs are considered to be less mobile with a log K OC > 3 (low RS PFASs are below a log K OC of 3, and high RS PFASs are above a log K OC of 3). This is an indicator that the presence of these longer chain PFASs in drinking water sources may be associated with local emissions, though subsequent studies would be needed to confirm this. ...
Per- and polyfluoroalkyl substances (PFASs) have been a focal point of environmental chemistry and chemical regulation in recent years, culminating in a shift from individual PFAS regulation toward a PFAS group regulatory approach in Europe. PFASs are a highly diverse group of substances, and knowledge about this group is still scarce beyond the well-studied, legacy long-chain, and short-chain perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs). Herein, quantitative and semiquantitative data for 43 legacy short-chain and ultra-short-chain PFASs (≤2 perfluorocarbon atoms for PFCAs, ≤3 for PFSAs and other PFASs) in 46 water samples collected from 13 different sources of German drinking water are presented. The PFASs considered include novel compounds like hexafluoroisopropanol, bis(trifluoromethylsulfonyl)imide, and tris(pentafluoroethyl)trifluorophosphate. The ultra-short-chain PFASs trifluoroacetate, perfluoropropanoate, and trifluoromethanesulfonate were ubiquitous and present at the highest concentrations (98% of sum target PFAS concentrations). “PFAS total” parameters like the adsorbable organic fluorine (AOF) and total oxidizable precursor (TOP) assay were found to provide only an incomplete picture of PFAS contamination in these water samples by not capturing these highly prevalent ultra-short-chain PFASs. These ultra-short-chain PFASs represent a major challenge for drinking water production and show that regulation in the form of preventive measures is required to manage them.
A novel adsorbent named corn stover-based lignin amine (CSLA) was prepared. Low-concentration perfluorooctanoic acid could be effectively removed by CSLA. The main adsorption mechanism is the synergy of electrostatic and hydrophobic interactions.
Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants with known toxicity and bioaccumulation issues. Their widespread industrial use and resistance to degradation have led to global environmental contamination and significant health concerns. While a minority of PFAS have been extensively studied, the toxicity of many PFAS remains poorly understood due to limited direct toxicological data. This study advances the predictive modeling of PFAS toxicity by combining semi-supervised graph convolutional networks (GCNs) with molecular descriptors and fingerprints. We propose a novel approach to enhance the prediction of PFAS binding affinities by isolating molecular fingerprints to construct graphs where then descriptors are set as the node features. This approach specifically captures the structural, physicochemical, and topological features of PFAS without overfitting due to an abundance of features. Unsupervised clustering then identifies representative compounds for detailed binding studies. Our results provide a more accurate ability to estimate PFAS hepatotoxicity to provide guidance in chemical discovery of new PFAS and the development of new safety regulations.
Per- and polyfluoroalkyl substances (PFASs) are a class of synthetic organic chemicals of global concern. A group of 36 scientists and regulators from 18 countries held a hybrid workshop in 2022 in Zürich, Switzerland. The workshop, a sequel to a previous Zürich workshop held in 2017, deliberated on progress in the last five years and discussed further needs for cooperative scientific research and regulatory action on PFASs. This review reflects discussion and insights gained during and after this workshop and summarizes key signs of progress in science and policy, ongoing critical issues to be addressed, and possible ways forward. Some key take home messages include: 1) understanding of human health effects continues to develop dramatically, 2) regulatory guidelines continue to drop, 3) better understanding of emissions and contamination levels is needed in more parts of the world, 4) analytical methods, while improving, still only cover around 50 PFASs, and 5) discussions of how to group PFASs for regulation (including subgroupings) have gathered momentum with several jurisdictions proposing restricting a large proportion of PFAS uses. It was concluded that more multi-group exchanges are needed in the future and that there should be a greater diversity of participants at future workshops.
Perfluoroalkyl acids (PFAAs) are highly persistent anthropogenic pollutants that have been detected in the global oceans. Our previous laboratory studies demonstrated that PFAAs in seawater are remobilized to the air in sea spray aerosols (SSAs). Here, we conducted field experiments along a north-south transect of the Atlantic Ocean to study the enrichment of PFAAs in SSA. We show that in some cases PFAAs were enriched >100,000 times in the SSA relative to seawater concentrations. On the basis of the results of the field experiments, we estimate that the secondary emission of certain PFAAs from the global oceans via SSA emission is comparable to or greater than estimates for the other known global sources of PFAAs to the atmosphere from manufacturing emissions and precursor degradation.
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic
compounds manufactured for their heat, water, and stain-resistant properties. PFAS can be found ubiquitously in the environment because they are widely used in everyday consumer products such as fast-food wrappers, non-stick cookware, stain-resistant products, cosmetics, aqueous film-forming foams, etc. As a result, PFAS are commonly detected in surface water, wastewater, and biosolids from wastewater treatment plants (WWTPs). These are the direct sources of PFAS
contamination in drinking water supplies, which are substantial sources of human exposure.
Among these PFAS chemicals, two major groups are perfluoroalkyl carboxylic acids (PFCAs) and their precursors, fluorotelomer alcohols (FTOHs). Even though studies have been conducted nationwide to evaluate the degree of these PFAS in the environment, research is lacking in our region. To fill the knowledge gap, we aimed to investigate the occurrence and transport of PFCAs and FTOHs in wastewater and biosolids. Furthermore, it is crucial to have a simple, fast, green, and reliable detection technique that can monitor the trace amount of PFCAs and FTOHs in water and biosolid matrices. In this study, we developed and validated a simple, low-cost, no clean-up, and sensitive method for the determination of PFCAs and FTOHs in water by applying 'green chemistry' based extraction named stir bar sorptive extraction (SBSE) coupled with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Three commonly detected FTOHs (6:2 FTOH, 8:2 FTOH, and 10:2 FTOH) were selected as the model compounds to develop an enhanced SBSE-TD-GC-MS for the analysis of FTOHs in water. Factors such as extraction time, stirring speed, solvent composition, salt addition, and pH
were investigated to achieve optimal extraction efficiency. This "green chemistry" based extraction provided good sensitivity and precision with low method limits of detection ranging from 2.16 ng/L to 16.7 ng/L and with an extraction recovery ranging 55% to 111%. The developed methods were tested on tap water, brackish water, and wastewater influent and effluent. In two wastewater samples, 6:2 FTOH and 8:2 FTOH were detected at 78.0 and 34.8 ng/L, respectively.
This optimized SBSE-TD-GC-MS method stands as a valuable alternative to investigate FTOHs in water matrices. In addition, we developed an enhanced SBSE-TD-GC-MS for the analysis of PFCAs in water. Our study provides a comprehensive evaluation of the method's linearity, recovery, sensitivity, repeatability, and spiked recovery across diverse water matrices. The method demonstrates linearity with coefficients of determination (R²) spanning from 0.9892 to 0.9988. Sensitivity metrics showed low limits of detection (LOD) in the low ng/L (ppt) range for all
analytes, achieving LODs between 21.2 ng/L to 74.0 ng/L. The recoveries for the method varied from 47-97%, suggesting an efficient extraction process. Additionally, the method’s robustness across various water matrices (tap water, wastewater influent, and effluent) reflected by the spiked recovery experiment underscored the method’s efficiency in real-world applications. In comparison with traditional PFCAs analysis methods, our optimized SBSE technique requires only
a minimum sample volume of 1 mL and minimal solvent usage, enhancing eco-friendliness and reducing potential contamination and handling errors. Repeatability assessments at two concentration levels produced %RSD (Relative Standard Deviation) values at 14% or less for any target PFCA compounds, indicating good precision. These attributes showcase the developed method's capability to serve as a precise, eco-friendly, and reliable tool for the analysis of PFCAs
across diverse water matrices.
This study also presents a comprehensive exploration into the presence and transport behavior of FTOHs and PFCAs in biosolid samples collected from wastewater treatment plants (WWTPs) in El Paso, Texas. We optimized an ultrasonic extraction method for efficient recovery of FTOHs and PFCAs compounds from biosolids followed by SBSE-TD-GC-MS analysis. The results showed specific concentrations of FTOHs compounds in biosolid samples from the different WWTPs. 6:2 FTOH was not detected in any of the samples, while 8:2 FTOH was found
in three WWTPs at varying concentrations: 100.30 ng/g in WWTP-1, 62.87 ng/g in WWTP-2, and 56.41 ng/g in WWTP-4. Additionally, 10:2 FTOH was detected in WWTP-1 at a concentration of 68.07 ng/g. Interestingly, despite the sensitive analytical approach employed, none of the targeted PFCAs were detected in any of the biosolid samples. These findings provide important insights
into the distribution and prevalence of specific FTOHs in biosolids from WWTPs, that highlight the inherent variability in their occurrence.
Through the development and validation of a cost-effective, environmentally friendly, and sensitive analytical method, this dissertation represents a reliable alternative analytical technique for monitoring PFCAs and FTOHs in aquatic matrices and contributes valuable data to the ongoing efforts to monitor and manage emerging contaminants in wastewater treatment systems.
In the Arctic, environment and health are linked in myriad ways. A key emphasis has been on numerous long-lived contaminants in traditional foods, particularly marine mammals, and their well-documented impacts on human, animal and environmental health (“One health approach”). More recent concerns for Indigenous communities focus on the (side) effects of the switch to a modern, processed diet, which is accompanied by a loss of tradition and emerging health impacts. Furthermore, the availability of traditional foods is increasingly threatened by the impacts of climate change, which also causes the emergence and spread of new and old diseases, such as anthrax. Climate change, including thawing permafrost and new forest fire regimes, threatens the built environment and infrastructure. In particular, well-built, planned, and healthy housing is urgently needed, given that much time is spent indoors. Health care, particularly for remote and Indigenous communities, is sparse, and often ignores traditional knowledge and local languages. Indigenous communities in the Arctic continue to suffer from marginalization, resource colonization/extraction, and the impacts of racism. Recent examples of the green energy transition, such as in Norway, continue a pattern of ignoring Indigenous rights and lifestyles. Overall, the connection between environment and health in the Arctic is multifaceted and complex, and investigations and solutions ought to embrace an interdisciplinary and holistic approach toward improving Environmental and Human Health in the region.
In this study, an integrated QuEChERS method was developed for the rapid determination of 22 per- and polyfluoroalkyl substances (PFASs) in milk by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The extraction and purification processes were combined into one step with this method. Meanwhile, the solid–liquid separation was carried out by magnetic suction (Fe3O4-SiO2) instead of the centrifugal process. The primary experimental parameters were optimized, including the type of extraction solvent, the amounts of magnetic nanomaterials (Fe3O4-SiO2), and the purification materials (ZrO2 and C18). The developed method exhibits high precision (RSDs < 9.9%), low limits of detection (0.004–0.079 μg/kg) and limits of quantitation (0.01–0.26 μg/kg), and acceptable recovery (71.7–116%) under optimized conditions. The developed integrated QuEChERS method had clear superiority in terms of sample pretreatment time, operating procedures, reagent amount, and recovery. This makes it an excellent alternative analytical technique for PFAS residue measurement at low micrograms-per-kilogram ranges with desirable sensitivity.
Perfluoroalkyl acids (PFAAs) are widely distributed in the oceans which are their largest global reservoir, but knowledge is limited about their vertical distribution and fate. This study measured the concentrations of PFAAs (perfluoroalkyl carboxylic acids (PFCAs) with 6 to 11 carbons and perfluoroalkanesulfonic acids (PFSAs) with 6 and 8 carbons) in the surface and deep ocean. Seawater depth profiles from the surface to a 5000 m depth at 28 sampling stations were collected in the Atlantic Ocean from ∼50° N to ∼50° S. The results demonstrated PFAA input from the Mediterranean Sea and the English Channel. Elevated PFAA concentrations were observed at the eastern edge of the Northern Atlantic Subtropical Gyre, suggesting that persistent contaminants may accumulate in ocean gyres. The median ΣPFAA surface concentration in the Northern Hemisphere (n = 17) was 105 pg L-1, while for the Southern Hemisphere (n = 11) it was 28 pg L-1. Generally, PFAA concentrations decreased with increasing distance to the coast and increasing depth. The C6-C9 PFCAs and C6 and C8 PFSAs dominated in surface waters, while longer-chain PFAAs (C10-C11 PFCAs) peaked at intermediate depths (500-1500 m). This profile may be explained by stronger sedimentation of longer-chain PFAAs, as they sorb more strongly to particulate organic matter.
Per- and polyfluoroalkyl substances (PFASs) are anthropogenic contaminants of emerging concern that are ubiquitous in the marine environment. This chapter provides recent insights into the main aspects of research on this class of compounds in the oceans. It describes their main uses and predominant sources in the marine environment and provides an update on the analytical procedures fit for marine matrices. Occurrence and processes affecting these compounds in abiotic compartments are addressed, followed by a focus on bioaccumulation and biomagnification in biota. The biological effects in marine organisms are then reviewed per taxa. In agreement with recent literature, recommendations for future research are proposed, which should guide future efforts toward the key environmental questions on PFASs.
Perfluorooctanoic acid (PFOA) is a typical C8 representative compound of perfluoroalkyl and polyfluoroalkyl substances (PFAS) widely used in industrial and domestic products. It is a persistent organic pollutant found in the environment as well as in the tissues of humans and wildlife. Despite emerging scientific and public interest, the precise mechanisms of PFOA toxicity remain unclear. In this study, male rats were exposed to 1.25, 5, and 20 mg PFOA/kg body weight/day for 14 days. Urine samples were also collected and monitored by raising rats in metabolic cages. In vivo results demonstrate that PFOA exposure induces significant hepatocellular hypertrophy and reduced urea metabolism. iTRAQ-based quantitative proteomics analysis of Sprague-Dawley (SD) rats livers identified 3,327 non-redundant proteins of which 112 proteins were significantly upregulated and 80 proteins were downregulated. Gene ontology analysis revealed proteins are primarily involved in cellular, metabolic and single − organism processes. Among them, eight proteins (ACOX1, ACOX2, ACOX3, ACSL1, EHHADH, GOT2, MTOR and ACAA1) were related to oxidation of fatty acids and two proteins (ASS1 and CPS1) were found to be associated with urea cycle disorder. The downregulation of urea synthesis proteins ASS1 and CPS1 after exposure to PFOA was then confirmed through qPCR and western blot analysis. Together, these data demonstrate that PFOA exposure directly influences urea metabolism and identify CPS1 as a potential regulatory target.
Per-and polyfluoroalkyl substances (PFASs) are omnipresent globally and received increasing attention recently. However, there are limited data on PFASs in the Tibetan Plateau (TP), a remote high-altitude mountain region, which is regard as an important indicator region to study long-range transport behaviors of contaminants. This study investigates the occurrence, distribution, partitioning behavior, and sources of 26 PFASs in water and sediments from the four lakes of TP. The ΣPFAS concentrations ranged from 338 to 9766 pg L-1 in water, and 12.2-414 pg g-1 dry weight in sediments. Perfluorobutanonic acid (PFBA) and perfluorooctane sulfonate (PFOS) were detected in all samples. Qinghai Lake had the highest ΣPFAS concentrations in both water and sediments, while the Ranwu Lake had the lowest. The functional groups and CF2 moiety units were investigated as essential factors influencing the partition behavior. Principal component analysis (PCA) combined back-trajectory was used to infer possible sources of PFASs. The results suggested that the main source of PFASs in Yamdrok Lake, Namco Lake, and Ranwu Lake on southern TP were mainly originated from South Asia via long-range atmospheric transport (LRAT); while for the Qinghai Lake of northern TP, LRAT, local emissions, and tourism activities were the primary sources of PFASs.
Persistent Organic Pollutants (POPs) are chemicals that are persistent, bio-accumulative, and toxic to humans and/or the environment. Consequently, their releases to the environment must be minimised and, where feasible eliminated as soon as possible. The main goal of this study is to support DG Environment in preparing an impact assessment accompanying a legislative proposal to amend Annexes IV and V of the POPs Regulation (Regulation (EU) No 2019/1021) which set concentration limits for POP substances in waste. The study provides an impact assessment of Annex IV Low POP Content Limit (LPCL) options for the following substances: polybrominated diphenyl ethers (PBDEs); short-chain chlorinated paraffins) (SCCPs); perfluorooctanoic acid (PFOA), its salts and PFOA-related compounds; perfluorohexane sulfonic acid (PFHxS), its salts and PFHxS-related compounds; polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs); polychlorinated biphenyls (PCBs) (differentiating between dioxin-like (dl) PCBs and non-dioxin like (ndl) PCBs); pentachlorophenol (PCP), its salts and esters; and hexabromocyclododecane (HBCDD).
Boron nitride (BN) has the newly-found property of degrading recalcitrant polyfluoroalkyl substances (PFAS) under ultraviolet C (UV-C, 254 nm) irradiation. It is ineffective at longer wavelengths, though. In this study, we report the simple calcination of BN and UV-A active titanium oxide (TiO2) creates a BN/TiO2 composite that is more photocatalytically active than BN or TiO2 under UV-A for perfluorooctanoic acid (PFOA). Under UV-A, BN/TiO2 degraded PFOA ∼15× faster than TiO2, while BN was inactive. Band diagram analysis and photocurrent response measurements indicated that BN/TiO2 is a type-II heterojunction semiconductor, facilitating charge carrier separation. Additional experiments confirmed the importance of photogenerated holes for degrading PFOA. Outdoor experimentation under natural sunlight found BN/TiO2 to degrade PFOA in deionized water and salt-containing water with a half-life of 1.7 h and 4.5 h, respectively. These identified photocatalytic properties of BN/TiO2 highlight the potential for the light-driven destruction of other PFAS.
A meta-analysis was conducted of published literature reporting concentrations of per- and polyfluoroalkyl substances (PFAS) in groundwater for sites distributed in 21 countries across the globe. Data for >35 PFAS were aggregated from 96 reports published from 1999 to 2021. The final data set comprised approximately 21,000 data points after removal of time-series and duplicate samples as well as non-detects. The reported concentrations ranged over many orders of magnitude, from ng/L to mg/L levels. Distinct differences in concentration ranges were observed between sites located within or near sources versus those that are not. Perfluorooctanoic acid (PFOA), ranging from <0.03 ng/L to ~7 mg/L, and perfluorooctanesulfonic acid (PFOS), ranging from 0.01 ng/L to ~5 mg/L, were the two most reported PFAS. The highest PFAS concentration in groundwater was ~15 mg/L reported for the replacement-PFAS 6:2 fluorotelomer sulfonate (6:2 FTS). Maximum reported groundwater concentrations for PFOA and PFOS were compared to concentrations reported for soils, surface waters, marine waters, and precipitation. Soil concentrations are generally significantly higher than those reported for the other media. This accrues to soil being the primary entry point for PFAS release into the environment for many sites, as well as the generally significantly greater retention capacity of soil compared to the other media. The presence of PFAS has been reported for all media in all regions tested including areas that are far removed from specific PFAS sources. This gives rise to the existence of a “background” concentration of PFAS that must be accounted for in both regional and site-specific risk assessments. The presence of this background is a reflection of the large-scale use of PFAS, their general recalcitrance, and the action of long-range transport processes that distribute PFAS across regional and global scales. This ubiquitous distribution has the potential to significantly impact the quality and availability of water resources in many regions. In addition, the pervasive presence of PFAS in the environment engenders concerns for impacts to ecosystem and human health.
Heat and freshwater transports through Fram Strait are understood to have a significant influence on the hydrographic conditions in the Arctic Ocean and on water mass modifications in the Nordic seas. To determine these transports and their variability reliable estimates of the volume transport through the strait are required. Current meter moorings were deployed in Fram Strait from September 1997 to September 1999 in the framework of the EU MAST III Variability of Exchanges in the Northern Seas programme. The monthly mean velocity fields reveal marked velocity variations over seasonal and annual time scales, and the spatial structure of the northward flowing West Spitsbergen Current and the southward East Greenland Current with a maximum in spring and a minimum in summer. The volume transport obtained by averaging the monthly means over two years amounts to 9.5 ± 1.4 Sv to the north and 11.1 ± 1.7 Sv to the south (1 Sv = 106 m3s?1). The West Spitsbergen Current has a strong barotropic and a weaker baroclinic component; in the East Greenland Current barotropic and baroclinic components are of similar magnitude. The net transport through the strait is 4.2 ± 2.3 Sv to the south. The obtained northward and southward transports are significantly larger than earlier estimates in the literature; however, within its range of uncertainty the balance obtained from a two year average is consistent with earlier estimates.
The distribution of 32 per/polyfluoroalkyl substances (PFASs) in surface soils was determined at 62 locations representing all continents (North America n = 33, Europe n = 10, Asia n = 6, Africa n = 5, Australia n = 4, South America n = 3 and Antarctica n = 1) using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) systems. Quantifiable levels of perfluoroalkyl carboxylates (PFCAs: PFHxA-PFTeDA) were observed in all samples with total concentrations ranging from 29 to 14,300 pg/g (dry weight), while perfluoroalkane sulfonates (PFSAs: PFHxS, PFOS and PFDS) were detected in all samples but one, ranging from <LOQ-3270 pg/g, confirming the global distribution of PFASs in terrestrial settings. The geometric mean PFCA and PFSA concentrations were observed to be higher in the northern hemisphere (930 and 170 pg/g) compared to the southern hemisphere (190 and 33 pg/g). Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were the most commonly detected analytes at concentrations up to 2670 and 3100 pg/g, respectively. The sum of PFCA homologues of PFOA commonly were roughly twice the concentration of PFOA. The PFCA and PFSA congener profiles were similar amongst most locations, with a few principal-component statistical anomalies suggesting impact from nearby urban and point sources. The ratio of even to odd PFCAs was consistent with the atmospheric oxidation of fluorotelomer-based precursors previously observed in laboratory and environmental studies. Given the soils were collected from locations absent of direct human activity, these results suggest that the atmospheric long-range transport (LRT) of neutral PFASs followed by oxidation and deposition are a significant source of PFCAs and PFSAs to soils.
Elevated biological concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, are observed throughout the Arctic Ocean but major sources and degradation pathways in seawater are not well understood. We develop a mass budget for mercury species in the Arctic Ocean based on available data since 2004 and discuss implications and uncertainties. Our calculations show that high total Hg in Arctic seawater relative to other basins reflect large freshwater inputs and sea ice cover that inhibits losses through evasion. We find that most net MeHg production (20 Mg a-1) occurs in the subsurface ocean (20-200 m). There, it is converted to dimethylmercury (Me2Hg: 17 Mg a-1), which diffuses to the polar mixed layer and evades to the atmosphere (14 Mg a-1). Me2Hg has a short atmospheric lifetime and rapidly degrades back to MeHg. We postulate that most evaded Me2Hg is re-deposited as MeHg and that atmospheric deposition is the largest net MeHg source (8 Mg a-1) to the biologically productive surface ocean. MeHg concentrations in Arctic Ocean seawater are elevated compared to lower latitudes. Riverine MeHg inputs accounts for an approximately 15% of inputs to the surface ocean (2.5 Mg a-1) but greater importance in the future is likely given increasing freshwater discharges and permafrost melt. This may offset potential declines driven by increasing evasion from ice-free surface waters. Geochemical model simulations illustrate that for the most biologically relevant regions of the ocean, regulatory actions that decrease Hg inputs have the capacity to rapidly affect aquatic Hg concentrations.
Little is known about the distribution of polybrominated diphenyl ethers (PBDE) -also known as flame retardants- in major ocean compartments, with no reports yet for the large deep-water masses of the Arctic Ocean. Here, PBDE concentrations, congener patterns and inventories are presented for the different water masses of the pan-Arctic shelf seas and the interior basin. Seawater samples were collected onboard three cross-basin oceanographic campaigns in 2001, 2005 and 2008 following strict trace-clean protocols. ∑14PBDE concentrations in the Polar Mixed Layer (PML; a surface water mass) range from 0.3 to 11.2 pg·L(-1), with higher concentrations in the pan-Arctic shelf seas and lower levels in the interior basin. BDE-209 is the dominant congener in most of the pan-Arctic areas except for the ones close to North America, where penta-BDE and tetra-BDE congeners predominate. In deep-water masses, ∑14PBDE concentrations are up to one order of magnitude higher than in the PML. Whereas BDE-209 decreases with depth, the less-brominated congeners, particularly BDE-47 and BDE-99, increase down through the water column. Likewise, concentrations of BDE-71 -a congener not present in any PBDE commercial mixture- increase with depth, which potentially is the result of debromination of BDE-209. The inventories in the three water masses of the Central Arctic Basin (PML, intermediate Atlantic Water Layer, and the Arctic Deep Water Layer) are 158±77 kg, 6320±235 kg and 30800±3100 kg, respectively. The total load of PBDEs in the entire Arctic Ocean shows that only a minor fraction of PBDEs emissions are transported to the Arctic Ocean. These findings represent the first PBDE data in the deep-water compartments of an ocean.
In the Arctic, under-ice primary production is limited to summer months and is restricted not only by ice thickness and snow
cover but also by the stratification of the water column, which constrains nutrient supply for algal growth. Research Vessel
Polarstern visited the ice-covered eastern-central basins between 82° to 89°N and 30° to 130°E in summer 2012, when Arctic
sea ice declined to a record minimum. During this cruise, we observed a widespread deposition of ice algal biomass of on average
9 grams of carbon per square meter to the deep-sea floor of the central Arctic basins. Data from this cruise will contribute
to assessing the effect of current climate change on Arctic productivity, biodiversity, and ecological function.
The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers.
The widespread distribution of perfluorinated chemicals (PFCs) in different environmental matrices has prompted concern about the sources, fate, and transport of these classes of chemicals. PFCs are present in the atmosphere, but only a few studies have investigated their occurrence in precipitation. In this study, concentrations of 20 PFCs, including C3-C5 short-chain PFCs, were quantified using HPLC-MS/MS in precipitation samples from Japan (n = 31), the United States (n = 12), China (n = 5), India (n = 2), and France (n = 2). Among the PFCs measured, perfluoropropanoic acid (PFPrA) was detected in all of the precipitation samples. Average total PFC concentrations ranged from 1.40 to 18.1 ng/L for the seven cities studied. The greatest total PFC concentrations were detected in Tsukuba, Japan, whereas the lowest concentrations were detected in Patna, India. PFPrA, perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were found to be the dominant PFCs in Japanese and U.S. precipitation samples. No observable seasonal trend was found in precipitation samples from two locations in Japan. Annual fluxes of PFCs were estimated for Japan and the U.S. and the evidence for precipitation as an effective scavenger of PFCs in the atmosphere is reported.
Polyfluoroalkyl substances (PFSs) are used in industrial and commercial products and can degrade to persistent perfluorocarboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs). Temporal trend studies using human, fish, bird, and marine mammal samples indicate that exposure to PFSs has increased significantly over the past 15-25 years. This review summarizes the biological monitoring of PFCAs, PFSAs, and related PFSs in wildlife and humans, compares concentrations and contamination profiles among species and locations, evaluatesthe bioaccumulation/biomagnification in the environment, discusses possible sources, and identifies knowledge gaps. PFSs can reach elevated concentrations in humans and wildlife inhabiting industrialized areas of North America, Europe, and Asia (2-30,000 ng/ mL or ng/g of wet weight (ww)). PFSs have also been detected in organisms from the Arctic and mid-ocean islands (< or = 3000 ng/g ww). In humans, PFSAs and PFCAs have been shown to vary among ethnic groups and PFCA/PFSA profiles differ from those in wildlife with high proportions of perfluorooctanoic acid and perfluorooctane sulfonate. The pattern of contamination in wildlife varied among species and locations suggesting multiple emission sources. Food web analyses have shown that PFCAs and PFSAs can bioaccumulate and biomagnify in marine and freshwater ecosystems. Knowledge gaps with respect to the transport, accumulation, biodegradation, temporal/spatial trends and PFS precursors have been identified. Continuous monitoring with key sentinel species and standardization of analytical methods are recommended.
Following a decision by the Arctic Ocean Sciences Board (AOSB) in July 1996 the then chainnan, Geoffrey Holland, wrote a letter of invitation to a meeting to plan a "Symposium on the Freshwater Balance of the Arctic". The meeting was held in Ottawa on November 12-13 1996 and was attended by representatives of various organisations, including the U.S. National Science Foundation (NSF), as well as individual scientists. Results of this meeting included: • Co-sponsorship with AOSB by the Scientific Committee on Ocean Research (SCOR), the Arctic Climate System Study (ACSYS) and the Global Energy and Water Cycle Experiment (GEWEX). • A decision to apply for funding as a Advanced Research Workshop (ARW) of the North Atlantic Treaty Organisation (NATO) Scientific Affairs Division. • That expenses would be covered in part by funds available through an existing NSF grant to the SCOR Executive offices in Baltimore, MD. • The appointment of myself to be Chairman/Manager for the Symposium. • Provision of a recommended list of Scientific Advisors to assist the Chainnan in selecting key speakers.
The bioaccumulation of perfluoroalkylated substances (PFASs) in plankton has previously been evaluated only in freshwater and regional seas, but not for the large oligotrophic global oceans. Plankton samples from the tropical and subtropical Pacific, Atlantic and Indian Oceans were collected during the Malaspina 2010 circumnavigation expedition, and analyzed for 14 ionizable PFASs, including perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS) and their respective linear and branched isomers. PFOA and PFOS concentrations in plankton ranged from 0.1 to 43 ng gdw-1 and from 0.5 to 6.7 ng gdw-1, respectively. The relative abundance of branched PFOA in the northern hemisphere was correlated with distance to North America, consistent with the historical production and coherent with previously reported patterns in seawater. The plankton samples showing the highest PFOS concentrations also presented the largest relative abundances of branched PFOS, suggesting a selective cycling/fractionation of branched PFOS in the surface ocean mediated by plankton. Bioaccumulation factors (BAFs) for plankton were calculated for 6 PFASs, including short chain PFASs. PFASs Log BAFs (wet weight) ranged from 2.6 ± 0.8 for perfluorohexane sulfonic acid (PFHxS), to 4.4 ± 0.6 for perfluoroheptanoic acid (PFHpA). The vertical transport of PFASs due to the settling of organic matter bound PFAS (biological pump) was estimated from an organic matter settling fluxes climatology and the PFAS concentrations in plankton. The global average sinking fluxes were 0.8 ± 1.3 ng m-2d-1 for PFOA, and 1.1 ± 2.1 ng m-2d-1 for PFOS. The residence times of PFAS in the surface ocean, assuming the biological pump as the unique sink, showed a wide range of variability, from few years to millennia, depending on the sampling site and individual compound. Further process-based studies are needed to constrain the oceanic sink of PFAS.
The legacy and reach of anthropogenic influence is most clearly evidenced by its impact on the most remote and inaccessible habitats on Earth. Here we identify extraordinary levels of persistent organic pollutants in the endemic amphipod fauna from two of the deepest ocean trenches (>10,000 metres). Contaminant levels were considerably higher than documented for nearby regions of heavy industrialization, indicating bioaccumulation of anthropogenic contamination and inferring that these pollutants are pervasive across the world’s oceans and to full ocean depth.
To improve understanding of long-range transport of perfluoroalkyl substances to the High Arctic, samples were collected from a snow pit on the Devon Ice Cap in spring 2008. Snow was analyzed for perfluoroalkyl acids (PFAAs), including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), as well as perfluorooctane sulfonamide (FOSA). PFAAs were detected in all samples dated from 1993 to 2007. PFAA fluxes ranged from <1 to hundreds of ng per m(2) per year. Flux ratios of even-odd PFCA homologues were mostly between 0.5 and 2, corresponding to molar ratios expected from atmospheric oxidation of fluorotelomer compounds. Concentrations of perfluorobutanoic acid (PFBA) were much higher than other PFCAs, suggesting PFBA loading on the Devon Ice Cap is influenced by additional sources, such as the oxidation of heat transfer fluids. All PFCA fluxes increased with time, while PFSA fluxes generally decreased with time. No correlations were observed between PFAAs and the marine aerosol tracer, sodium. Perfluoro-4-ethylcyclohexanesulfonate (PFECHS) was detected for the first time in an atmospherically - derived sample, and its presence may be attributed to aircraft hydraulic system leakage. Observations of PFAAs from these samples provide further evidence that atmospheric oxidation of volatile precursors is an important source of PFAAs to the Arctic environment.
Little is known of the distribution of persistent organic pollutants (POPs) in the deep ocean. Polyethylene passive samplers were used to detect the vertical distribution of truly dissolved POPs at two sites in the Atlantic Ocean. Samplers were deployed at five depths covering 26-2535 m in the northern Atlantic and Tropical Atlantic, in approximately one year deployments. Samplers of different thickness were used to determine the state of equilibrium POPs reached in the passive samplers. Concentrations of POPs detected in the North Atlantic near the surface (e.g. sum of 14 polychlorinated biphenyls, PCBs: 0.84 pg L-1) were similar to previous measurements. At both sites, PCB concentrations showed sub-surface maxima (tropical Atlantic Ocean – 800 m, North Atlantic – 500 m). Currents seemed more important in moving POPs to deeper water masses than the biological pump. The ratio of PCB concentrations in near surface waters (excluding PCB-28) between the two sites was inversely correlated with congeners’ sub-cooled liquid vapor pressure, in support of the latitudinal fractionation. The results presented here implied a significant amount of HCB is stored in the Atlantic Ocean (4.8-26 % of the global HCB environmental burdens), contrasting traditional beliefs that POPs do not reach the deep ocean.
Observations have revealed persistent flows of relatively low salinity from the Pacific to the Arctic and from the Arctic to the Atlantic (Melling 2000). It is customary to associate fluxes of fresh-water with these flows of brine, as follows: the fresh-water flux is the volume of fresh water that must be combined with a volume of reference-salinity water to yield the volume of seawater of the salinity observed. As with sensible heat flux, the choice of reference is arbitrary, but the value 34.8 is often used in discussions of the Arctic. This value is an estimate of the mean salinity of the Arctic Ocean by Aagaard and Carmack (1989) for a time period and averaging domain that were not specified. Because the salinity of seawater flowing across the shallow Bering, Chukchi and Canadian Polar shelves is typically lower than 34.8, these flows transport fresh-water from the Pacific to the Atlantic Ocean.
In this study, perfluoroalkylated substances (PFASs) were analyzed in 92 surface seawater samples taken during the Malaspina 2010 expedition which covered all the tropical and subtropical Atlantic, Pacific and Indian oceans. Nine ionic PFASs including C6-C10 perfluoroalkyl carboxylic acids (PFCAs), C4 and C6-C8 perfluoroalkyl sulfonic acids (PFSAs) and two neutral precursors perfluoroalkyl sulfonamides (PFASAs), were identified and quantified. The Atlantic Ocean presented the broader range in concentrations of total PFASs (131-10900 pg/L, median 645 pg/L, n=45) compared to the other oceanic basins, probably due to a better spatial coverage. Total concentrations in the Pacific ranged from 344 to 2500 pg/L (median=527 pg/L, n=27) and in the Indian Ocean from 176 to 1976 pg/L (median=329, n=18). Perfluorooctane sulfonic acid (PFOS) was the most abundant compound, accounting for 33% of the total PFASs globally, followed by perfluorodecanoic acid (PFDA, 22%) and perfluorohexanoic acid (PFHxA, 12%), being the rest of the individual congeners under 10% of total PFASs, even for perfluorooctane carboxylic acid (PFOA, 6%). PFASAs accounted for less than 1% of the total PFASs concentration. This study reports the ubiquitous occurrence of PFCAs, PFSAs and PFASAs in the global ocean, being the first attempt, to our knowledge, to show a comprehensive assessment in surface water samples collected in a single oceanic expedition covering tropical and subtropical oceans for the first time. The potential factors affecting their distribution patterns were assessed including the distance to coastal regions, oceanic subtropical gyres, currents and biogeochemical processes. Field evidence of biogeochemical controls on the occurrence of PFASs was tentatively assessed considering environmental variables (solar radiation, temperature, chlorophyll a concentrations among others), and these showed significant correlations with some PFASs, but explaining small to moderate percentages of variability. This suggests that a number of physical and biogeochemical processes collectively drive the oceanic occurrence and fate of PFASs in a complex manner.
There is a wealth of studies of polychlorinated biphenyls (PCB) in surface water and biota of the Arctic Ocean. Still, there are no observation-based assessments of PCB distribution and inventories in and between the major Arctic Ocean compartments. Here, the first water column distribution of PCBs in the central Arctic Ocean basins (Nansen, Amundsen, and Makarov) is presented, demonstrating nutrient-like vertical profiles with 5–10 times higher concentrations in the intermediate and deep water masses than in surface waters. The consistent vertical profiles in all three Arctic Ocean basins likely reflect buildup of PCBs transported from the shelf seas and from dissolution and/or mineralization of settling particles. Combined with measurement data on PCBs in other Arctic Ocean compartments collected over the past decade, the total Arctic Ocean inventory of ∑7PCB was estimated to 182 ± 40 t (±1 standard error of the mean), with sediments (144 ± 40 t), intermediate (5 ± 1 t) and deep water masses (30 ± 2 t) storing 98% of the PCBs in the Arctic Ocean. Further, we used hydrographic and carbon cycle parametrizations to assess the main pathways of PCBs into and out of the Arctic Ocean during the 20th century. River discharge appeared to be the major pathway for PCBs into the Arctic Ocean with 115 ± 11 t, followed by ocean currents (52 ± 17 t) and net atmospheric deposition (30 ± 28 t). Ocean currents provided the only important pathway out of the Arctic Ocean, with an estimated cumulative flux of 22 ± 10 t. The observation-based inventory of ∑7PCB of 182 ± 40 t is consistent with the contemporary inventory based on cumulative fluxes for ∑7PCB of 173 ± 36 t. Information on the concentration and distribution of PCBs in the deeper compartments of the Arctic Ocean improves our understanding of the large-scale fate of POPs in the Arctic and may also provide a means to test and improve models used to assess the fate of organic pollutants in the Arctic.
The horizontal and vertical flux of particulate material in the
nearshore of southern Lake Michigan (0-40 m) was estimated with the
naturally occurring radionuclide 234Th. Horizontal fluxes of
234Th supplemented apparent vertical fluxes of
234Th in the water column (based on local
234Th/238U disequilibria) by a factor of 7-14,
reinforcing the importance of lateral transport in coastal environments.
Calculated onshore transport of particulate material across the 40 m
isobath was as high as 1.1 × 106 kg km-1
d-1, and exceeds estimates of terrigenous (riverine and bluff
erosion) loading. Estimates of onshore flux of organic carbon exceeded
areal primary productivity by as much as ˜300%, and should be
considered in nearshore carbon budgets. Bottom-tethered sediment traps
(placed 5 m above the bottom) measured sedimentation rates that were
˜1 order of magnitude lower than 234Th derived mass
fluxes from the water column and ˜2 orders of magnitude lower than
234Th derived mass fluxes to the lakebed. We ascribe this
difference to under collecting by the sediment trap either because of
trap hydrodynamics or flux occurring below the trap capture plane.
Cross-shore fluxes showed a periodicity of ˜4 days and correlated
strongly with a topographic vorticity wave that is present throughout
the year in southern Lake Michigan. The impact of this wave (as a driver
of bidirectional cross-shore flux) on biogeochemical cycling and both
nearshore and offshore food webs has not yet been explicitly considered.
The Bering Strait throughflow is important for the Chukchi Sea and the Arctic and Atlantic oceans. A realistic assessment of throughflow properties is also necessary for validation and boundary conditions of high resolution ocean models. From 14 years of moored measurements, we construct a monthly climatology of temperature, salinity and transport. The strong seasonality in all properties (~ 31.9 to 33 psu, ~ -1.8 to 2.3°C and ~ 0.4 to 1.2 Sv) dominates the Chukchi Sea hydrography and implies significant seasonal variability in the equilibrium depth and ventilation properties of Pacific waters in the Arctic Ocean. Interannual variability is large in temperature and salinity. Although missing some significant events, an empirical linear fit to a local (model) wind yields a reasonable reconstruction of the water velocity, and we use the coefficients of this fit to estimate the magnitude of the Pacific-Arctic pressure-head forcing of the Bering Strait throughflow. INDEX TERMS: 4207 General Oceanography: Arctic and Antarctic oceanography (9310, 9315); 4215 General Oceanography: Climate and interannual variability (1616, 1635, 3305, 3309, 4513); 4223 General Oceanography: Descriptive and regional oceanography; 4227 General Oceanography: Diurnal, seasonal, and annual cycles (0438).
The global-scale fate and transport processes of perfluorooctanoic acid (PFOA) and perfluorooctanoate (PFO) emitted from direct sources were simulated using a multispecies mass balance model over the period 1950 to 2010. The main goal of this study was to assess the atmospheric and oceanic long-range transport potential of direct source emissions and the implications for the contamination of terrestrial and marine systems worldwide. Consistent with previous modeling studies, ocean transport was found to be the dominant pathway for delivering PFO(A) associated with direct sources to the Arctic marine environment regardless of model assumptions. The modeled concentrations for surface ocean waters were insensitive to assumptions regarding physical-chemical properties and emission mode of entry and were in reasonable agreement with available monitoring data from the Northern Hemisphere. In contrast, model outputs characterizing atmospheric transport potential were highly sensitive to model assumptions, especiallythe assumed value of the acid dissociation constant (pKa). However, the complete range of model results for scenarios with different assumptions about partitioning and emissions provide evidence that the atmospheric transport of directly emitted PFO(A) can deliver this substance to terrestrial environments distant from sources. Additional studies in remote or isolated terrestrial systems may provide further insight into the scale of contamination actually attributable to direct sources.
Little is known of the atmospheric fate(s) of fluorotelomer alcohols (FTOHs), a class of high-production-volume chemicals used in the production of water- and oil-repelling surface coatings and which have been detected in a wide variety of urban and remote environmental matrices. In the present study, we investigated the uptake and photochemistry of FTOHs at the surface of TiO2, Fe2O3, Mauritanian sand, and Icelandic volcanic ash. Gas-phase 3,3,3-trifluoropropanol, 4:2 FTOH, and 6:2 FTOH exhibited significant uptake to each of the surfaces under study. The sand- and ash-catalyzed heterogeneous photooxidation of 6:2 FTOH resulted in the rapid production and subsequent slow degradation of surface-sorbed perfluorinated carboxylic acids (PFCAs). We suggest that this transformation, which proceeds via fluorotelomer carboxylic acid intermediates (6:2 FTCA/FTUCA), is catalyzed by Fe and Ti contained within the samples. These results provide the first evidence that the heterogeneous oxidation of FTOHs at metal-rich atmospheric surfaces may provide a significant loss mechanism for these chemicals and also act as a source of aerosol-phase PFCAs close to source regions. Subsequent long-range transport of these aerosol-sorbed PFCAs has the potential to join oceanic transport and local gas-phase FTOH oxidation as a source of PFCAs to Arctic regions.
A total of 420 human plasma samples from two cities (Halle and Münster, Germany), collected between 1982 and 2009, were analyzed for a suite of PFCAs (C6-C12) and selected PFCA precursors (4:2-, 4:2/6:2-, 6:2-, 6:2/8:2-, 8:2-, 8:2/10:2- and 10:2 diPAPs). PFCAs (C7 - C11, 13) were detected in over 80% of the samples (<0.005 - 39.4 ng/mL) while C12 PFCA was detected in fewer than 10% of the samples. In a range of 10-46% of the samples, 4:2-, 4:2/6:2-, 6:2, and 8:2- diPAPs were identified at concentrations of <0.0002 ng/mL to 0.687 ng/mL; fewer than 10% of the samples had detectable 10:2 diPAP. Temporal trends (2000-2009) showed increasing concentrations of PFNA, PFDA, and PFUnDA, whereas PFOA concentrations were decreasing. Calculated population halving time for PFOA varied between 8.2 - 14.5 years which contrasts to the generally accepted value of 3.8 years. This suggests an ongoing or additional exposure to PFOA or one of its precursor compounds. DiPAPs, known to metabolize rapidly to PFCAs, were detected in a significant number of samples and at concentrations that have not declined significantly over the past half-decade. The evidence suggests they have contributed to the continued presence of the longer chain PFCAs and perhaps contribute to the slow decline of PFOA.
Perfluoroalkyl substances (PFAS) have been globally detected in various environmental matrices, yet their fate and transport to the Arctic is still unclear, especially for the European Arctic. In this study, concentrations of 17 PFAS were quantified in two ice cores (n=26), surface snow (n=9) and surface water samples (n=14) collected along a spatial gradient in Svalbard, Norway. Concentrations of selected ions (Na(+), SO(4)(2-), etc.) were also determined for tracing the origins and sources of PFAS. Perfluorobutanoate (PFBA), perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) were the dominant compounds found in ice core samples. Taking PFOA, PFNA and perfluorooctane-sulfonate (PFOS) as examples, higher concentrations were detected in the middle layers of the ice cores representing the period of 1997-2000. Lower concentrations of C8-C12 perfluorocarboxylates (PFCAs) were detected in comparison with concentrations measured previously in an ice core from the Canadian Arctic, indicating that contamination levels in the European Arctic are lower. Average PFAS concentrations were found to be lower in surface snow and melted glacier water samples, while increased concentrations were observed in river water downstream near the coastal area. Perfluorohexanesulfonate (PFHxS) was detected in the downstream locations, but not in the glacier, suggesting existence of local sources of this compound. Long-range atmospheric transport of PFAS was the major deposition pathway for the glaciers, while local sources (e.g., skiing activities) were identified in the downstream locations.
Atmospheric concentrations of hexachlorocyclohexanes (HCHs) have declined over the last two decades, and the Arctic Ocean is now eliminating HCHs through degradation, volatilization, and advective outflow. Air and water samples were collected on a cruise of the eastern Arctic Ocean in July−September 1996 for HCHs and enantiomers of α-HCH. Mean concentrations of α- and γ-HCH in air were 37 and 17 pg m-3. Back trajectories indicated that the concentration and proportion of γ-HCH increased when air parcels passed over Eurasia where lindane (γ-HCH) is currently used. Mean concentrations in surface water (910 pg L-1 α-HCH; 270 pg L-1 γ-HCH) were lower than those in the western Arctic. The enantiomer ratio, ER = (+)-α-HCH /(−)-α-HCH, averaged 0.87 ± 0.06 (n = 21) in surface water and decreased with depth. Microbial degradation rates of HCHs were estimated using vertical profiles of ER and concentration, surface water data from 1979 (21), and the “ventilation” age of water at a particular depth (22). Microbial rate constants were 3−10 times greater than those for hydrolysis. Half-lives for (+)-α-HCH, (−)-α-HCH, and γ-HCH were 5.9, 23.1, and 18.8 years, respectively. Water−air fugacity ratios (fw/fa) indicated that α-HCH was near steady state, while γ-HCH was undergoing deposition to the ocean. ERs of α-HCH in air (0.95 ± 0.03, n = 16) were slightly less than racemic, showing the contribution of volatilization to the boundary layer.
The Arctic Ocean constitutes a large body of water that is still relatively poorly surveyed because of logistical difficulties, although the importance of the Arctic Ocean for global circulation and climate is widely recognized. For instance, the concentration and inventory of anthropogenic CO2 (C ant) in the Arctic Ocean are not properly known despite its relatively large volume of well-ventilated waters. In this work, we have synthesized available transient tracer measurements (e.g., CFCs and SF6) made during more than two decades by the authors. The tracer data are used to estimate the ventilation of the Arctic Ocean, to infer deep-water pathways, and to estimate the Arctic Ocean inventory of C ant. For these calculations, we used the transit time distribution (TTD) concept that makes tracer measurements collected over several decades comparable with each other. The bottom water in the Arctic Ocean has CFC values close to the detection limit, with somewhat higher values in the Eurasian Basin. The ventilation time for the intermediate water column is shorter in the Eurasian Basin (∼200 years) than in the Canadian Basin (∼300 years). We calculate the Arctic Ocean C ant inventory range to be 2.5 to 3.3 Pg-C, normalized to 2005, i.e., ∼2% of the global ocean C ant inventory despite being composed of only ∼1% of the global ocean volume. In a similar fashion, we use the TTD field to calculate the Arctic Ocean inventory of CFC-11 to be 26.2 ± 2.6 × 106 moles for year 1994, which is ∼5% of the global ocean CFC-11 inventory.
During the past decades, a variety of transient tracers have been used to derive information on pathways and mean residence times of oceanic water masses. Here, we discuss how information obtained in such studies can be applied to studying the spreading of dissolved pollutants in the ocean. The discussion focuses on the transient tracers tritium/3He and the H218O/H216O ratio of water. These tracers are used in combination with CFCs and 14C in a case study of Arctic Ocean contaminant transport to: (1) separate the freshwater components contained in the near-surface waters; (2) infer mean pathways of freshwater and associated contaminants from the H218O/H216O distribution in the surface waters; and (3) determine mean residence times of the surface, intermediate, deep and bottom waters.
The global distribution and long-range transport of polyfluoroalkyl substances (PFASs) were investigated using seawater samples collected from the Greenland Sea, East Atlantic Ocean and the Southern Ocean in 2009-2010. Elevated levels of ΣPFASs were detected in the North Atlantic Ocean with the concentrations ranging from 130 to 650 pg/L. In the Greenland Sea, the ΣPFASs concentrations ranged from 45 to 280 pg/L, and five most frequently detected compounds were perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS). PFOA (15 pg/L) and PFOS (25-45 pg/L) were occasionally found in the Southern Ocean. In the Atlantic Ocean, the ΣPFASs concentration decreased from 2007 to 2010. The elevated PFOA level that resulted from melting snow and ice in Greenland Sea implies that the Arctic may have been driven by climate change and turned to be a source of PFASs for the marine ecosystem.
We report here on the spatial distribution of C(4), C(6), and C(8) perfluoroalkyl sulfonates, C(6)-C(14) perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (∑PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). ∑PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L ∑PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, ∑PFAAs were <210 pg/L. PFOA/PFOS ratios were typically ≥1 in the northern hemisphere, ∼1 near the equator, and ≤1 in the southern hemisphere. In the Canadian Arctic, ∑PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically ≫1) decreased from Baffin Bay to the Amundsen Gulf, possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.
The pathway and transformation of water from the Norwegian Sea across the Barents Sea and through the St. Anna Trough are documented from hydrographic and current measurements of the 1990s. The transport through an array of moorings in the north-eastern Barents Sea was between in summer and in winter towards the Kara Sea and between zero and towards the Barents Sea with a record mean net flow of . The westward flow originates in the Fram Strait branch of Atlantic Water at the Eurasian continental slope, while the eastward flow constitutes the Barents Sea branch, continuing from the western Barents Sea opening.
Multi-tracer data sets collected in the Greenland/Norwegian seas and the Eurasian Basin of the Arctic Ocean in the 1970s and 1980s are used, together with temperature and salinity, to (1) constrain box model calculations of the deep water formation rates in the Greenland Sea and the Eurasian Basin of the Arctic Ocean, and (2) estimate the exchange rates of deep waters (depth ≥1,500m) between the Greenland/Norwegian Seas and the Eurasian Basin. We obtain deep water formation rates of 0.1Sv (since 1980) to 0.47Sv (from at least 1965 to 1980) for the Greenland Sea, and 0.3Sv for the Eurasian Basin of the Arctic Ocean. The southward flux of Eurasian Basin Deep Water through Fram Strait is estimated to be about 1Sv. About 0.12Sv of this flux are transported into the Greenland Sea, about 0.37Sv reach the deep Norwegian Sea through the Jan Mayen Fracture Zone, and about 0.39Sv leave the Arctic Ocean through a shallower core which more or less directly feeds into the Iceland Sea, and, after modification, eventually ends up in the overflow waters. The outflow of Eurasian Basin Deep Water is balanced by deep water formation in the Arctic Ocean and by inflow of Norwegian Sea Deep water. About 0.77Sv of deep water formed in the Greenland Sea and the Eurasian Basin contribute to the formation of North Atlantic Deep Water. Uncertainties of the fluxes are estimated to be roughly ±20 to 30%.
The biodegradation pathways and metabolite yields of [3-14C] 8-2 fluorotelomer alcohol [8-2 FTOH, F(CF2)714CF2CH2CH2OH) in aerobic soils were investigated. Studies were conducted under closed (static) and continuous headspace air flow to assess differences in degradation rate and metabolite concentrations in soil and headspace. Aerobic degradation pathways in soils were in general similar to those in aerobic sludge and bacterial culture. 14C mass balance was achieved in soils incubated for up to 7 months. Up to 35% 14C dosed was irreversibly bound to soils and was only recoverable by soil combustion. The average PFOA yield was approximately 25%. Perfluorohexanoic acid (PFHxA) yield reached approximately 4%. 14CO2 yield was 6.8% under continuous air flow for 33 days. Three metabolites not previously identified in environmental samples were detected: 3-OH-7-3 acid [F(CF2)7CHOHCH2COOH], 7-2 FT ketone [F(CF2)7COCH3] and 2H-PFOA [F(CF2)6CFHCOOH]. No perfluorononanoic acid (PFNA) was observed. The formation of 2H-PFOA, PFHxA, and 14CO2 shows that multiple –CF2– groups were removed from 8-2 FTOH. 7-3 Acid [F(CF2)7CH2CH2COOH] reached a yield of 11% at day 7 and did not change thereafter. 7-3 Acid was incubated in aerobic soil and did not degrade to PFOA. 7-2 sFTOH [F(CF2)7CH(OH)CH3], a transient metabolite, was incubated and degraded principally to PFOA. 7-3 Acid may be a unique metabolite from 8-2 FTOH biodegradation. The terminal ratio of PFOA to 7-3 acid ranged between 1.8–2.5 in soils and 0.6–3.2 in activated sludge, sediment, and mixed bacterial culture. This ratio may be useful in evaluating environmental samples to distinguish the potential contribution of 8-2 FTOH biodegradation to PFOA observed versus PFOA originating from other sources.
The global distribution of perfluoroalkyl compounds (PFCs) were investigated in surface water samples collected onboard the Polarstern in Northern Europe, Atlantic and Southern Ocean (52°N–69°S) in 2008. The water samples were solid-phase extracted with Oasis WAX cartridges and analysed using the high-performance liquid chromatography interfaced to tandem mass spectrometry. Concentrations of various PFCs, including C4, C6, C8 perfluoroalkyl sulfonates (PFSAs), perfluorooctane sulfinate (PFOSi), C5–C12 perfluoroalkyl carboxylic acids (PFCA) and perfluorooctane sulfonamide (FOSA) were quantified. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the predominant compounds with a maximum concentration of 232 and 223 pg L−1, respectively. Results indicate that industrial areas like the European Continent act as source of PFCs, while ocean water is an important as a sink as well as the transport medium of these compounds. Interestingly, in the equator area the ∑PFC concentration increased, which indicates that there exists an atmospheric or other unknown input source of PFCs. In the Southern Ocean only PFOS was detected which could be caused by atmospheric transport of its precursors.
Perfluoroalkyl compounds (PFCs) were determined in 22 surface water samples (39-76°N) and three sea ice core and snow samples (77-87°N) collected from North Pacific to the Arctic Ocean during the fourth Chinese Arctic Expedition in 2010. Geographically, the average concentration of ∑PFC in surface water samples were 560 ± 170 pg L(-1) for the Northwest Pacific Ocean, 500 ± 170 pg L(-1) for the Arctic Ocean, and 340 ± 130 pg L(-1) for the Bering Sea, respectively. The perfluoroalkyl carboxylates (PFCAs) were the dominant PFC class in the water samples, however, the spatial pattern of PFCs varied. The C(5), C(7) and C(8) PFCAs (i.e., perfluoropentanoate (PFPA), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA)) were the dominant PFCs in the Northwest Pacific Ocean while in the Bering Sea the PFPA dominated. The changing in the pattern and concentrations in Pacific Ocean indicate that the PFCs in surface water were influenced by sources from the East-Asian (such as Japan and China) and North American coast, and dilution effect during their transport to the Arctic. The presence of PFCs in the snow and ice core samples indicates an atmospheric deposition of PFCs in the Arctic. The elevated PFC concentration in the Arctic Ocean shows that the ice melting had an impact on the PFC levels and distribution. In addition, the C(4) and C(5) PFCAs (i.e., perfluorobutanoate (PFBA), PFPA) became the dominant PFCs in the Arctic Ocean indicating that PFBA is a marker for sea ice melting as the source of exposure.
Poly- and perfluorinated organic compounds (PFCs) are ubiquitous in the Arctic environment. Several modeling studies have been conducted in attempt to resolve the dominant transport pathway of PFCs to the arctic-atmospheric transport of precursors versus direct transport via ocean currents. These studies are generally limited by their focus on perfluorooctanoate (PFOA) fluxes to arctic seawater and thus far have only used fluorotelomer alcohols (FTOHs) and sulfonamide alcohols as inputs for volatile precursors. There have been many monitoring studies from the North American and European Arctic, however, almost nothing is known about PFC levels from the Russian Arctic. In general, there are very few measurements of PFCs from the abiotic environment. Atmospheric measurements show the widespread occurrence of PFC precursors, FTOHs and perfluorinated sulfonamide alcohols. Further, PFCAs and PFSAs have been detected on atmospheric particles. The detection of PFCAs and PFSAs in snow deposition is consistent with the volatile precursor transport hypothesis. There are very limited measurements of PFCs in seawater. PFOA is generally detected in the greatest concentrations. Additional seawater measurements are needed to validate existing model predications. The bulk of the monitoring efforts in biological samples have focused on the perfluorinated carboxylates (PFCAs) and sulfonates (PFSAs), although there are very few measurements of PFC precursors. The marine food web has been well studied, particularly the top predators. In contrast, freshwater and terrestrial ecosystems have been poorly studied. Studies show that in wildlife perfluorooctane sulfonate (PFOS) is generally measured in the highest concentration, followed by either perfluorononanoate (PFNA) or perfluoroundecanoate (PFUnA). However, some whale species show relatively high levels of perfluorooctane sulfonamide (PFOSA) and seabirds are typically characterized by high proportions of the C(11)-C(15) PFCAs. PFOA is generally infrequently detected and is present in low concentrations in arctic biota. Food web studies show high bioaccumulation in the upper trophic-level animals, although the mechanism of PFC biomagnification is not understood. Spatial trend studies show some differences between populations, although there are inconsistencies between PFC trends. The majority of temporal trend studies are from the Northern American Arctic and Greenland. Studies show generally increasing levels of PFCs from the 1970s, although some studies from the Canadian Arctic show recent declines in PFOS levels. In contrast, ringed seals and polar bears from Greenland continue to show increasing PFOS concentrations. The inconsistent temporal trends between regions may be representative of differences in emissions from source regions.
Polyfluoroalkyl compounds (PFCs) can be found ubiquitously in the marine environment. The transport of PFCs to remote locations is assumed to be by direct transport via oceanic water currents or indirectly via atmospheric transport of volatile precursor compounds. This study investigates the influence of ocean currents and atmospheric transport to the East Greenland Arctic Ocean (67.5-80.4 degrees N). In this study, 38 water samples were collected in the Arctic summer in 2009 and analyzed by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Concentrations of three PFC classes could be quantified (i.e., perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkyl sulfonates (PFSAs) and perfluoroalkyl sulfonamides) predominantly in a low pg L(-1) range. Dominating compounds were PFOSA and PFOA with mean concentrations of 61 pg L(-1) and 51 pg L(-1), respectively. Statistically significant higher concentrations for PFOSA and PFHxA in the samples taken north of 75 degrees N indicate an atmospheric influence on the concentrations found in the water samples. Significant differences in concentrations of PFHxS, PFHxA, PFHpA and PFOA for samples taken in coastal areas indicate an influence from the Greenlandic mainland.
A global-scale fate and transport model was applied to investigate the historic and future trends in ambient concentrations of perfluorooctane sulfonate (PFOS) and volatile perfluorooctane sulfonyl fluoride (POSF)-based precursor compounds in the environment. First, a global emission inventory for PFOS and its precursor compounds was estimated for the period 1957-2010. We used this inventory as input to a global-scale contaminant fate model and compared modeled concentrations with field data. The main focus of the simulations was to examine how modeled concentrations of PFOS and volatile precursor compounds respond to the major production phase-out that occurred in 2000-2002. Modeled concentrations of PFOS in surface ocean waters are generally within a factor of 5 of field data and are dominated by direct emissions of this substance. In contrast, modeled concentrations of the precursor compounds considered in this study are lower than measured concentrations both before and after the production phase-out. Modeled surface ocean water concentrations of PFOS in source regions decline slowly in response to the production phase-out while concentrations in remote regions continue to increase until 2030. In contrast, modeled concentrations of precursor compounds in both the atmosphere and surface ocean water compartment in all regions respond rapidly to the production phase-out (i.e., decline quickly to much lower levels). With respect to wildlife biomonitoring data, since precursor compounds are bioavailable and degrade to PFOS in vivo, it is at least plausible that declining trends in PFOS body burdens observed in some marine organisms are attributable to this exposure pathway. The continued increases in PFOS body burdens observed in marine organisms inhabiting other regions may reflect exposure primarily to PFOS itself, present in the environment due to production and use of this compound as well as degradation of precursor compounds.
Perfluoroalkyl compounds (PFCs) were determined in 2 L surface water samples collected in the Atlantic Ocean onboard the research vessels Maria S. Merian along the longitudinal gradient from Las Palmas (Spain) to St. Johns (Canada) (15 degrees W to 52 degrees W) and Polarstern along the latitudinal gradient from the Bay of Biscay to the South Atlantic Ocean (46 degrees N to 26 degrees S) in spring and fall 2007, respectively. After filtration the dissolved and particulate phases were extracted separately, and PFC concentrationswere determined using high-performance liquid chromatography interfaced to tandem mass spectrometry. No PFCs were detected in the particulate phase. This study provides the first concentration data of perfluorooctanesulfonamide (FOSA), perfluorohexanoic acid, and perfluoroheptanoic acid from the Atlantic Ocean. Results indicate that trans-Atlantic Ocean currents caused the decreasing concentration gradient from the Bay of Biscay to the South Atlantic Ocean and the concentration drop-off close to the Labrador Sea. Maximum concentrations were found for FOSA, perfluorooctanesulfonate, and perfluorooctanoic acid at 302, 291, and 229 pg L(-1), respectively. However, the concentration of each single compound was usually in the tens of picograms per liter range. South of the equator only FOSA and below 4 degrees S no PFCs could be detected.
Here we report, for the first time, on the global distribution of perfluorooctanesulfonate (PFOS), a fluorinated organic contaminant. PFOS was measured in the tissues of wildlife, including, fish, birds, and marine mammals. Some of the species studied include bald eagles, polar bears, albatrosses, and various species of seals. Samples were collected from urbanized areas in North America, especially the Great Lakes region and coastal marine areas and rivers, and Europe. Samples were also collected from a number of more remote, less urbanized locations such as the Arctic and the North Pacific Oceans. The results demonstrated that PFOS is widespread in the environment. Concentrations of PFOS in animals from relatively more populated and industrialized regions, such as the North American Great Lakes, Baltic Sea, and Mediterranean Sea,were greaterthan those in animals from remote marine locations. Fish-eating, predatory animals such as mink and bald eagles contained concentrations of PFOS that were greater than the concentrations in their diets. This suggests that PFOS can bioaccumulate to higher trophic levels of the food chain. Currently available data indicate that the concentrations of PFOS in wildlife are less than those required to cause adverse effects in laboratory animals.
Rainbow trout (Oncorhynchus mykiss) were exposed simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates in a flow-through system to determine compound-specific tissue distribution and bioconcentration parameters for perfluorinated acids (PFAs). In general, PFAs accumulated to the greatest extent in blood > kidney > liver > gall bladder. Carboxylates and sulfonates with perfluoroalkyl chain lengths shorter than seven and six carbons, respectively, could not be detected in most tissues and were considered to have insignificant bioconcentration factors (BCFs). For detectable PFAs, carcass BCFs increased with increasing length of the perfluoroalkyl chain, ranging from 4.0 to 23,000, based on wet weight concentrations. Carboxylate carcass BCFs increased by a factor of eight for each additional carbon in the perfluoroalkyl chain between 8 and 12 carbons, but this relationship deviated from linearity for the longest PFA tested, possibly because of decreased gill permeability. In general, half-lives (3.9-28 d) and uptake rates (0.053-1.700 L/kg/d) also increased with increasing length of the perfluoroalkyl chain in all tissues. Sulfonates had greater BCFs, half-lives, and rates of uptake than the corresponding carboxylate of equal perfluoroalkyl chain length, indicating that hydrophobicity, as predicted by the critical micelle concentration, is not the only determinant of PFA bioaccumulation potential and that the acid function must be considered.
Perfluorinated acids (PFAs) recently have emerged as persistent global contaminants after their detection in wildlife and humans from various geographic locations. The highest concentrations of perfluorooctane sulfonate are characteristically observed in high trophic level organisms, indicating that PFAs may have a significant bioaccumulation potential. To examine this phenomenon quantitatively, we exposed juvenile rainbow trout (Oncorhynchus mykiss) simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates for 34 d in the diet, followed by a 41-d depuration period. Carcass and liver concentrations were determined by using liquid chromatography-tandem mass spectrometry, and kinetic rates were calculated to determine compound-specific bioaccumulation parameters. Depuration rate constants ranged from 0.02 to 0.23/d, and decreased as the length of the fluorinated chain increased. Assimilation efficiency was greater than 50% for all test compounds, indicating efficient absorption from food. Bioaccumulation factors (BAFs) ranged from 0.038 to 1.0 and increased with length of the perfluorinated chain; however, BAFs were not statistically greater than 1 for any PFA. Sulfonates bioaccumulated to a greater extent than carboxylates of equivalent perfluoroalkyl chain length, indicating that hydrophobicity is not the sole determinant of PFA accumulation potential and that the acid function must be considered. Dietary exposure will not result in biomagnification of PFAs in juvenile trout, but extrapolation of these bioaccumulation parameters to larger fish and homeothermic organisms should not be performed.
Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with a series of fluorotelomer alcohols, F(CF2CF2)nCH2CH2OH (n = 2, 3, 4), in 700 Torr of N2 or air, diluent at 296 +/- 2K. The length of the F(CF2CF2)n- group had no discernible impact on the reactivity of the molecule. For n = 2, 3, or 4, k(Cl + F(CF2CF2)nCH2CH2OH) = (1.61 +/- 0.49) x 10(-11) and k(OH + F(CF2CF2)nCH2CH2OH) = (1.07 +/- 0.22) x 10(-12) cm3 molecule(-1) s(-1). Consideration of the likely rates of other possible atmospheric loss mechanisms leads to the conclusion that the atmospheric lifetime of F(CF2CF2)nCH2CH2OH (n > or = 2) is determined by reaction with OH radicals and is approximately 20 d.
Perfluorooctanesulfonyl fluoride (POSF, C8F17SO2F) related-materials have been used as surfactants, paper and packaging treatments, and surface (e.g., carpet, textile, upholstery) protectants. A metabolite, perfluorooctanesulfonate (PFOS, C8F17SO3-), has been identified in the serum and liver of non-occupationally exposed humans and wildlife. Because of its persistence, an important question was whether elderly humans might have higher PFOS concentrations. From a prospective study designed to examine cognitive function in the Seattle (WA) metropolitan area, blood samples were collected from 238 dementia-free subjects (ages 65-96). High-pressure liquid chromatography-electrospray tandem mass spectrometry determined seven fluorochemicals: PFOS; N-ethyl perfluorooctanesulfonamidoacetate; N-methyl perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamide; perfluorooctanoate; and perfluorohexanesulfonate. Serum PFOS concentrations ranged from less than the lower limit of quantitation (3.4 ppb) to 175.0 ppb (geometric mean 31.0 ppb; 95% CI 28.8-33.4). An estimate of the 95% tolerance limit was 84.1 ppb (upper 95% confidence limit 104.0 ppb). Serum PFOS concentrations were slightly lower among the most elderly. There were no significant differences by sex or years residence in Seattle. The distributions of the other fluorochemicals were approximately an order of magnitude lower. Similar to other reported findings of younger adults, the geometric mean serum PFOS concentration in non-occupational adult populations likely approximates 30-40 ppb with 95% of the population's serum PFOS concentrations below 100 ppb.
Human and animal tissues collected in urban and remote global locations contain persistent and bioaccumulative perfluorinated carboxylic acids (PFCAs). The source of PFCAs was previously unknown. Here we present smog chamber studies that indicate fluorotelomer alcohols (FTOHs) can degrade in the atmosphere to yield a homologous series of PFCAs. Atmospheric degradation of FTOHs is likely to contribute to the widespread dissemination of PFCAs. After their bioaccumulation potential is accounted for, the pattern of PFCAs yielded from FTOHs could account for the distinct contamination profile of PFCAs observed in arctic animals. Furthermore, polar bear liver was shown to contain predominately linear isomers (>99%) of perfluorononanoic acid (PFNA), while both branched and linear isomers were observed for perfluorooctanoic acid, strongly suggesting a sole input of PFNA from "telomer"-based products. The significance of the gas-phase peroxy radical cross reactions that produce PFCAs has not been recognized previously. Such reactions are expected to occur during the atmospheric degradation of all polyfluorinated materials, necessitating a reexamination of the environmental fate and impact of this important class of industrial chemicals.
Perfluorinated acids and their salts have emerged as an important class of global environmental contaminants. Biological monitoring surveys conducted using tissues of marine organisms reported the occurrence of perfluorooctanesulfonate (PFOS) and related perfluorinated compounds in biota from various seas and oceans, including the Arctic and the Antarctic Oceans. Occurrence of perfluorinated compounds in remote marine locations is of concern and indicates the need for studies to trace sources and pathways of these compounds to the oceans. Determination of sub-parts-per-trillion (ng/L) or parts-per-quadrillion (pg/L) concentrations of aqueous media has been impeded by relatively high background levels arising from procedural or instrumental blanks. Our research group has developed a reliable and highly sensitive analytical method by which to monitor perfluorinated compounds in oceanic waters. The method developed is capable of detecting PFOS, perfluorohexanesulfonate (PFHS), perfluorobutanesulfonate (PFBS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), and perfluorooctanesulfonamide (PFOSA) at a few pg/L in oceanic waters. The method was applied to seawater samples collected during several international research cruises undertaken during 2002-2004 in the central to eastern Pacific Ocean (19 locations), South China Sea and Sulu Seas (five), north and mid Atlantic Ocean (12), and the Labrador Sea (20). An additional 50 samples of coastal seawater from several Asian countries (Japan, China, Korea) were analyzed. PFOA was found at levels ranging from several thousands of pg/L in water samples collected from coastal areas in Japan to a few tens of pg/L in the central Pacific Ocean. PFOA was the major contaminant detected in oceanic waters, followed by PFOS. Further studies are being conducted to elucidate the distribution and fate of perfluorinated acids in oceans.
This review describes the sources, fate, and transport of perfluorocarboxylates (PFCAs) in the environment, with a specific focus on perfluorooctanoate (PFO). The global historical industry-wide emissions of total PFCAs from direct (manufacture, use, consumer products) and indirect (PFCA impurities and/or precursors) sources were estimated to be 3200-7300 tonnes. It was estimated that the majority (approximately 80%) of PFCAs have been released to the environment from fluoropolymer manufacture and use. Although indirect sources were estimated to be much less importantthan direct sources, there were larger uncertainties associated with the calculations for indirect sources. The physical-chemical properties of PFO (negligible vapor pressure, high solubility in water, and moderate sorption to solids) suggested that PFO would accumulate in surface waters. Estimated mass inventories of PFO in various environmental compartments confirmed that surface waters, especially oceans, contain the majority of PFO. The only environmental sinks for PFO were identified to be sediment burial and transport to the deep oceans, implying a long environmental residence time. Transport pathways for PFCAs in the environment were reviewed, and it was concluded that, in addition to atmospheric transport/degradation of precursors, atmospheric and ocean water transport of the PFCAs themselves could significantly contribute to their long-range transport. It was estimated that 2-12 tonnes/ year of PFO are transported to the Artic by oceanic transport, which is greater than the amount estimated to result from atmospheric transport/degradation of precursors.
Perfluorooctanesulfonamides [C8F17SO2N(R1)(R2)] are present in the atmosphere and may, via atmospheric transport and oxidation, contribute to perfluorocarboxylates (PFCA) and perfluorooctanesulfonate (PFOS) pollution in remote locations. Smog chamber experiments with the perfluorobutanesulfonyl analogue N-ethyl perfluorobutanesulfonamide [NEtFBSA; C4F9SO2N(H)CH2CH3] were performed to assess this possibility. By use of relative rate methods, rate constants for reactions of NEtFBSA with chlorine atoms (296 K) and OH radicals (301 K) were determined to be kCL) = (8.37 +/- 1.44) x 10(-12) and kOH = (3.74 +/- 0.77) x 10(-13) cm3 molecule(-1) s(-1), indicating OH reactions will be dominant in the troposphere. Simple modeling exercises suggestthat reaction with OH radicals will dominate removal of perfluoroalkanesulfonamides from the gas phase (wet and dry deposition will not be important) and that the atmospheric lifetime of NEtFBSA in the gas phase will be 20-50 days, thus allowing substantial long-range atmospheric transport. Liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis showed that the primary products of chlorine atom initiated oxidation were the ketone C4F9SO2N(H)COCH3; aldehyde 1, C4F9SO2N(H)CH2CHO; and a product identified as C4F9SO2N(C2H5O)- by high-resolution MS but whose structure remains tentative. Another reaction product, aldehyde 2, C4F9SO2N(H)CHO, was also observed and was presumed to be a secondary oxidation product of aldehyde 1. Perfluorobutanesulfonate was not detected above the level of the blank in any sample; however, three perfluoroalkanecarboxylates (C3F7CO2-, C2F5CO2-, and CF3CO2-) were detected in all samples. Taken together, results suggest a plausible route by which perfluorooctanesulfonamides may serve as atmospheric sources of PFCAs, including perfluorooctanoic acid.
Relative rate methods were used to measure the gas-phase reaction of N-methyl perfluorobutane sulfonamidoethanol (NMeFBSE) with OH radicals, giving k(OH + NMeFBSE) = (5.8 +/- 0.8) x 10(-12) cm3 molecule(-1) s(-1) in 750 Torr of air diluent at 296 K. The atmospheric lifetime of NMeFBSE is determined by reaction with OH radicals and is approximately 2 days. Degradation products were identified by in situ FTIR spectroscopy and offline GC-MS and LC-MS/MS analysis. The primary carbonyl product C4F9SO2N(CH3)CH2CHO, N-methyl perfluorobutane sulfonamide (C4F9SO2NH(CH3)), perfluorobutanoic acid (C3F7C(O)OH), perfluoropropanoic acid (C2F5C(O)OH), trifluoroacetic acid (CF3C(O)OH), carbonyl fluoride (COF2), and perfluorobutane sulfonic acid (C4F9SO3H) were identified as products. A mechanism involving the addition of OH to the sulfone double bond was proposed to explain the production of perfluorobutane sulfonic acid and perfluorinated carboxylic acids in yields of 1 and 10%, respectively. The gas-phase N-dealkylation product, N-methyl perfluorobutane sulfonamide (NMeFBSA), has an atmospheric lifetime (>20 days) which is much longer than that of the parent compound, NMeFBSE. Accordingly,the production of NMeFBSA exposes a mechanism by which NMeFBSE may contribute to the burden of perfluorinated contamination in remote locations despite its relatively short atmospheric lifetime. Using the atmospheric fate of NMeFBSE as a guide, it appears that anthropogenic production of N-methyl perfluorooctane sulfonamidoethanol (NMeFOSE) contributes to the ubiquity of perfluoroalkyl sulfonate and carboxylate compounds in the environment.
Relative rate techniques were used to study the kinetics of the reactions of Cl atoms and OH radicals with CF(3)CH(2)C(O)H and CF(3)CH(2)CH(2)OH in 700 Torr of N(2) or air diluent at 296 +/- 2 K. The rate constants determined were k(Cl+CF(3)CH(2)C(O)H) = (1.81 +/- 0.27) x 10(-11), k(OH+CF(3)CH(2)C(O)H) = (2.57 +/- 0.44) x 10(-12), k(Cl+CF(3)CH(2)CH(2)OH) = (1.59 +/- 0.20) x 10(-11), and k(OH+CF(3)CH(2)CH(2)OH) = (6.91 +/- 0.91) x 10(-13) cm(3) molecule(-1) s(-1). Product studies of the chlorine initiated oxidation of CF(3)CH(2)CH(2)OH in the absence of NO show the sole primary product to be CF(3)CH(2)C(O)H. Product studies of the chlorine initiated oxidation of CF(3)CH(2)CH(2)OH in the presence of NO show the primary products to be CF(3)CH(2)C(O)H (81%), HC(O)OH (10%), and CF(3)C(O)H. Product studies of the chlorine initiated oxidation of CF(3)CH(2)C(O)H in the absence of NO show the primary products to be CF(3)C(O)H (76%), CF(3)CH(2)C(O)OH (14%), and CF(3)CH(2)C(O)OOH (< or =10%). As part of this work, an upper limit of k(O(3)+CF(3)CH(2)CH(2)OH) < 2 x 10(-21) cm(3) molecule(-1) s(-1) was established. Results are discussed with respect to the atmospheric chemistry of fluorinated alcohols.