Distribution Of Perfluoroalkyl Acids Research Articles

Mechanisms of propeller jet-induced migration, release, and distribution of perfluoroalkyl acids in sediment–water systems

Perfluoroalkyl acids (PFAAs) are continuously accumulated in surface sediments due to extensive and long-term application. However, the mechanisms through which disturbances induced by ship propeller jets at the riverbed cause secondary release of PFAAs from sediments remain unclear. In this study, the effects of different propeller rotational speeds on PFAA migration, release, and distribution in multiphase media were investigated by performing indoor flume experiments combined with particle tracking velocimetry. Moreover, key factors influencing PFAA migration and distribution were identified, and partial least squares regression (PLS) method was applied to develop quantitative prediction models of relationships among hydrodynamics, physicochemical parameters, and PFAA distribution coefficients. The total PFAA concentrations (ΣPFAAs) in overlying water under propeller jet action exhibited transient characteristics and hysteresis with time after the disturbance. In contrast, the ΣPFAAs in suspended particulate matter (SPM) exhibited an upward trend throughout the process with consistent characteristics. The spatial distribution trends of PFAAs in overlying water and SPM at different propeller rotational speeds featured vertical variability and axial consistency. Furthermore, PFAA release from sediments was driven by axial flow velocity (Vx) and Reynolds normal stress Ryy, while PFAA release from porewater was inextricably linked to Reynolds stresses Rxx, Rxy, and Rzz (p < 0.05). PLS regression models showed that variations in Vorticity, dissolved organic carbon, and pH influenced the decreases in PFAA distribution coefficients between SPM and overlying water (KD-SW) as propeller rotational speed increased, except for very long-chain PFAAs (C > 10). The increases in PFAA distribution coefficients between sediment and porewater (KD-SP) were mainly determined by physicochemical parameters of sediments, and the direct effect of hydrodynamics was relatively weak. Our study provides valuable information regarding the migration and distribution of PFAAs in multiphase media under propeller jet disturbance (both during and after disturbance).

Vermont-wide assessment of anthropogenic background concentrations of perfluoroalkyl substances in surface soils

Shallow surface soils from 66 suburban sampling locations across Vermont were analyzed for 17 different perfluoroalkyl acids (PFAA). PFAA were detected in all 66 surface soils, with a total concentration of PFAA ranging from 540 to 36,000 ng/kg dry soil weight (dw). Despite the complexity of site-specific factors, some general trends and correlations in PFAA concentrations were observed. For instance, perfluoro-1-octanesulfonate (PFOS) dominated in all soil samples while seven other PFAA, including perfluoro-n-nonanoic acid, perfluoro-n-octanoic acid, perfluoro-n-hexanoic acid, perfluoro-n-heptanoic acid, perfluoro-n-decanoic acid, perfluoro-n-undecanoic acid, perfluoro-1-butanesulfonate, and perfluoro-1-hexanesulfonate (PFNA, PFOA, PFHxA, PFHpA, PFDA, PFUnDA, and PFBS, respectively), were identified at more than 50 % of the locations. Perfluoroalkyl carboxylic acids (PFCA) showed a positive correlation with total organic carbon, whereas no clear correlation was observed for perfluoroalkyl sulfonate acids (PFSA). In addition, variations in geographical distributions of PFAA were observed, with relatively higher total PFAA in northern regions when compared to Southern Vermont. Moreover, PFHxA, PFNA, PFDA, PFUnDA, PFOS, and total PFAA were positively correlated to land-use types in Northern Vermont. These results are useful for understanding unique behaviors of PFCA vs. PFSA in geospatially distributed surface soils and for providing anthropogenic background data for setting PFAS cleanup standards for surface soils.

Perfluoroalkyl acids (PFAAs) in urban surface water of Shijiazhuang, China: Occurrence, distribution, sources and ecological risks

It is extremely important to analyze the contaminative behaviors of Perfluoroalkyl acids (PFAAs) due to their serious threats to urban environments which are closely related to humans. Current study aimed to explore the distribution, source apportionment and ecological risk assessment of PFAAs in surface water from Shijiazhuang, China. The concentrations of ∑PFAAs ranged from 19.5 to 125.9 ng/L in the investigation area. Perfluorobutanesulfonic acid (PFBS) and perfluoropentanoic acid (PFPeA) were the predominant contaminants (mean value: 14.3 ng/L and 16.6 ng/L, respectively). The distribution of PFAAs according to geospatial analysis and hierarchical clustering analysis (HCA) showed that higher levels of ∑PFAAs were detected in the southern surface water of Shijiazhuang and there was a stepwise decrease from the wet season to the dry season. Furthermore, based on source apportionment, the dominant potential sources were found to be wastewater treatment plant (WWTP) effluents and industrial discharge. The risk quotients (RQs) revealed low ecological risks of all PFAAs for aquatic organisms in Shijiazhuang surface water. Collectively, this study provided basic data for regulatory strategies for controlling PFAA pollutions in urban surface water.

Shift in the distribution and fate of perfluoroalkyl acids by sluice gates in the multi-environment media of rivers

The impact of sluice operations on the distribution and fate of perfluoroalkyl acids (PFAAs) remains poorly understood. In this study, the distribution of PFAAs was investigated in water, suspended particles, sediment, and pore water from the upstream and downstream sections of six sluice gates along the Wangyu River, China. The target PFAAs were widely distributed in the dissolved phase (∑PFAAs: 447.61 ± 180.26 ng/L), particle phase (∑PFAAs: 2040.95 ± 1870.88 ng/g dw), sedimentary phase (∑PFAAs: 39.42 ± 35.38 ng/g dw), and pore water phase (∑PFAAs: 8172.54 ± 4278.60 ng/L). Our data suggest predominant detections of short-chain PFAAs such as perfluorobutanoic acid (PFBA) and perfluorohexanoic acid (PFHxA) in the four environmental media. Sediment pore water appeared as an essential repository and potential source for PFAA re-release to the river environment. The levels of PFAAs in the dissolved and suspended particle phase upstream of the sluices were significantly lower than those downstream, while the situation in the sediment and pore water phase was the opposite. Sluice operation caused PFAA redistribution among the multi-environment media but did not change the PFAA composition, which had the significant effect on the partition behavior of perfluoroalkyl carboxylic acids (PFCAs) between particles and water, as well as changed the migration pattern of PFOA, PFNA and PFOS from equilibrium to the migration state. Quantitative prediction models were developed for simulating fate of PFAAs in gate-controlled river, and the major factors affecting the distribution and fate of PFAAs were identified. Our findings provide insights into the redistribution mechanisms of PFAAs and an understanding of their environmental fate.

Spatial and temporal trends of perfluoroalkyl acids in water bodies: A case study in Taihu Lake, China (2009–2021)

Perfluoroalkyl acids (PFAAs) have been ubiquitously detected in water bodies and are a cause of great public concern due to their adverse effects. This study investigated the long-term temporal-spatial trends of PFAAs in the water bodies of the entire Taihu Lake, and predicted PFAA concentrations for 2024. A field investigation conducted in 2021 and previous data allowed to derive trends over a broad temporal-spatial scale, which is often not feasible in short-term studies. In the 2009–2021 period, the most quantifiable PFAAs increased, among which perfluorooctanoic acid and perfluorohexanoic acid were predominant. As of 2021, the mean total concentration of ten PFAAs (∑10PFAA) showed a distinct spatial decreasing trend, moving from north to south within the lake, and similar spatial distribution patterns were also noted in other years. The main PFAA input and most serious contamination were concentrated in the northern region, due to the riverine inputs and clustering of PFAA-related industries. The ∑10PFAA concentration in the wet season was greater and presented a more uniform distribution pattern than that in the dry season, possibly due to the combined effects of the degradation of PFAA precursors, water inflow, rainfall, shipping activities, and a shallow water column. From 2009 to 2021 the ∑10PFAA concentration of the entire lake showed an increasing trend, but the rate of increase was significantly reduced. In addition, a grey model predicted that the mean ∑10PFAA concentration in the entire Taihu Lake will reach 431 ng/L in 2024, and the northern region will be affected by a more serious PFAA pollution in the future because it exhibited a high mean ∑10PFAA concentration of 426 ng/L in 2021. These findings provide novel insights into the temporal-spatial distribution of PFAAs in Taihu Lake, and could help regulators to formulate policy decisions in response to PFAA pollution.

Distribution of perfluoroalkyl acids in fish species from the Baltic Sea and freshwaters in Finland

Occurrence and distribution of perfluoroalkyl acids (PFAAs), a sub-category of per- and polyfluoroalkyl substances (PFASs), is widespread in the environment. Food, especially fish meat, is a major pathway via which humans are exposed to PFAAs. As fish is an integral part of Nordic diet, therefore, in this study, several fish species, caught in selected Baltic Sea basins and freshwater bodies of Finland, were analysed for PFAAs. Perfluorooctane sulfonate (PFOS) was detected in all Baltic Sea fish samples and in >80% fish samples from freshwaters. PFOS contributed between 46 and 100% to the total PFAA concentration in Baltic Sea fish samples and between 19 and 28% in fish samples from freshwaters. Geographically, concentration ratios of PFOS to other PFAAs differed between fish from the Baltic Sea and Finnish lakes suggesting that distribution of PFAAs differ in these environments. Results were compared with current safety thresholds – environmental quality standard for biota (EQSbiota) set by the European Commission and a group tolerable weekly intake (TWI) for the sum of four PFASs (∑PFAS-4) i.e. perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS) and PFOS, recommended by the European Food Authority (EFSA). EQSbiota compliance was observed for PFOS in all species except smelt caught in the Baltic Sea and also in the River Aurajoki, where smelt had migrated from the Baltic Sea for spawning. Moderate consumption of most Baltic fishes (200 g week−1) results in an exceedance of the new TWI (4.4 ng kg−1 body weight week−1) for ∑PFAS-4.

Estimating the Equilibrium Distribution of Perfluoroalkyl Acids and 4 of Their Alternatives in Mammals.

Perfluoroalkyl acids (PFAAs) mostly exist as ionic compounds that are of major concern because of their accumulative behavior. The discussion about their risk is ongoing considering the increasing production of structurally similar alternatives. We conducted model calculations based on equilibrium distribution coefficients that allow studying the distribution of PFAAs and their alternatives in various mammalian organs through comparison to empirical measurements in humans and rats. The calculations rely on experimentally determined distribution coefficients of a series of PFAAs and 4 of their alternatives to physiological matrices such as structural proteins, storage lipids, membrane lipids, albumin, and fatty acid binding protein (FABP). The relative sorption capacities in each organ were calculated from the combination of distribution coefficients and physiological data. The calculated distribution of PFAAs and alternatives within the organs showed that albumin and membrane lipids and, to a lesser extent, structural proteins have the highest relative sorption capacities for the compounds. Sorption to FABP is only relevant in the distribution of short-chain PFAAs. Storage lipids play a minor role in the distribution of all studied compounds. Our calculated distribution of PFAAs was evaluated by comparison to reported PFAA concentrations in various organs. Environ Toxicol Chem 2021;40:910-920. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Elevated bioaccumulation of PFAAs in Oryzias melastigma following the increase of salinity is associated with the up-regulated expression of PFAA-binding proteins

Perfluoroalkyl acids (PFAAs) are widely detected in the environment, especially in estuarine and coastal areas where fluctuation of salinity occurs. Salinity alteration affected the distribution of PFAAs and even the bioaccumulation in organisms. However, the inner mechanism is still unclear. In this study, the marine medaka (Oryzias melastigma), a euryhaline fish model, was exposed to four PFAAs congeners under three different salinities (0, 15 and 35 psu). Results showed that the bioaccumulation of PFAAs increased in fish as the water salinity increased. PFAAs with longer lengths of carbon‑fluorine bond showed higher bioaccumulation in the fish. Salinity did not alter the levels of PFAAs in water media, however, the uptake rate of PFAAs from gills did increase with the salinity. Further analysis of the mechanism showed that PFAA bound to branchial proteins as confirmed by fluorescence spectroscopy. Higher expressions of proteins binding to PFAAs including organic anion transporter 1 (OAT1) and fatty acid-binding protein (FABP) facilitated the uptake of PFAAs through gills in fish culturing under higher salinity. In all, our study showed that elevation of salinity can induce the expression of proteins binding to PFAAs in gills, thus facilitate the uptake of water PFAAs. Salinity fluctuation should be taken into consideration when assessing the chemical risk in the estuarine and coastal areas.

Membrane/Water Partitioning and Permeabilities of Perfluoroalkyl Acids and Four of their Alternatives and the Effects on Toxicokinetic Behavior.

The search for alternatives to bioaccumulative perfluoroalkyl acids (PFAAs) is ongoing. New, still highly fluorinated alternatives are produced in hopes of reducing bioaccumulation. To better estimate this bioaccumulative behavior, we performed dialysis experiments and determined membrane/water partition coefficients, Kmem/w, of six perfluoroalkyl carboxylic acids (PFCAs), three perfluoroalkanesulfonic acids, and four alternatives. We also investigated how passive permeation might influence the uptake kinetics into cells, measuring the passive anionic membrane permeability Pion through planar lipid bilayers for six PFAAs and three alternatives. Experimental Kmem/w and Pion were both predicted well by the COSMO-RS theory (log RMSE 0.61 and 0.46, respectively). Kmem/w values were consistent with the literature data, and alternatives showed similar sorption behavior as PFAAs. Experimental Pion values were high enough to explain observed cellular uptake by passive diffusion with no need to postulate the existence of active uptake processes. However, predicted pKa and neutral permeabilities suggest that also the permeation of the neutral species should be significant in case of PFCAs. This can have direct consequences on the steady-state distribution of PFAAs across cell membranes and thus toxicity. Consequently, we propose a model to predict pH-dependent baseline toxicity based on Kmem/w, which considers the permeation of both neutral and anionic species.

Spatial distribution of perfluoroalkyl acids (PFAAs) and their precursors and conversion of precursors in seawater deeply affected by a city in China.

Conversion of perfluoroalkyl acid (PFAA) precursors in the environment has been a hotspot research in recent years. This study firstly determined the spatial distribution of PFAAs and their precursors including 8:2 fluorotelomer unsaturated acid (8:2 FTUCA), perfluorooctane sulfoneamide (FOSA), and diperfluorooctane sulfonamido ethanol-based phosphate (di-SAmPAP), then investigated the conversion of the potential precursors in the seawater and sewage treatment plants (STPs) effluents. The results indicated that the target pollutants showed a typical concentration gradient from nearshore to offshore. And the obviously increased concentration of perfluorinated carboxylic acids (△[PFCAs]) after oxidation treatment can verify the existence of PFAA precursors in the seawater and STP effluents. The concentrations of PFCAs with carbon atom numbers 4-9 (PFCAC4-C9) revealed the most increase. Moreover, the levels of △[PFCAs] and the ratios of △[PFCAs] to their concentration before oxidation (△[PFCA]/[PFCA]before oxidation) indicated obvious spatial variations in the seawater and STP effluents. The higher levels of △[PFCAC4-C12] and the lower ratios of ∑△[PFCAC4-C12]/∑[PFAA]before oxidation were observed in the STP effluents, which implied that precursors might be decomposed during the sewage treatment process. These results suggested the STP effluents might have an important effect on the PFAAs levels of seawater.

Uptake and translocation of perfluoroalkyl acids (PFAA) in red chicory (Cichorium intybus L.) under various treatments with pre-contaminated soil and irrigation water

Perfluoroalkyl acids (PFAAs), particularly short-chained ones, have high potential for crop uptake, posing a threat to human health in contaminated areas. There is a scarcity of studies using contaminated water as the medium for PFAAs delivery to crops, and a lack of data on the partitioning of PFAA mixtures in growing media. In this context, a controlled experimental study was carried out in a greenhouse to investigate the uptake of a PFAA mixture into red chicory, a typical crop from a major PFAA contamination hot-spot in northern Italy, under treatments with environmentally relevant concentrations in spiked irrigation water and soil, separately and simultaneously. To our knowledge, this is the first study involving multiple exposure media and laboratory adsorption/desorption batch tests as a way of assessing the decrease in the bioavailability of PFAAs from soil. Exposure concentrations for each of the 9 utilized PFAAs were 0, 1, 10 and 80 µg/L in irrigation water and 0, 100 and 200 ng/gdw in soil, combined into 12 treatments. The highest bioaccumulation was measured for PFBA in roots (maximum of 43 µg/gdw), followed by leaves and heads of the chicory plants in all treatments, with the concentrations exponentially decreasing with an increasing PFAA chain length in all plant compartments. The use of irrigation water as the delivery medium increased the transport of PFAAs to the aerial chicory parts, long-chain substances in particular. Additionally, the distribution of PFAAs in the soil was assessed by depth and compared with laboratory measured soil-water equilibrium partition coefficients, revealing only partial dependency of PFAAs bioavailability on the adsorption in soil.

Comparisons of tissue distributions and health risks of perfluoroalkyl acids (PFAAs) in two fish species with different trophic levels from Lake Chaohu, China

Perfluoroalkyl acids (PFAAs) are a type of persistent organic pollutants that are widely distributed in multiple environmental media and organisms and have a teratogenic effect on and toxicity to animals and humans. The residual levels of seventeen PFAAs in the tissues of two regular consumption fish species, Culter erythropterus and Aristichthys nobilis in Lake Chaohu were measured by a high-performance liquid chromatograph – mass spectrometer (HPLC-MS). The distributions of PFAAs and the effect of the lipid contents were analyzed, and the health risks of typical PFAAs were evaluated. The results showed that perfluorohexanoic acid (PFHxA) was the predominant contaminant (80.50 ± 58.31 ng/g and 19.17 ± 12.57 ng/g wet weight, ww), followed by perfluorooctanesulfonic acid (PFOS) (55.02 ± 34.82 and 14.79 ± 6.24 ng/g, ww) in both fish. The level of total PFAAs was the highest in the liver tissues of Culter erythropterus (359.87 ng/g, ww) and the lowest in the kidney tissues in A. nobilis (10.06 ng/g, ww). Due to the higher trophic level of C. erythropteru, the total PFAA concentrations were significantly higher in all tissues than those in A. nobilis. Liver muscle ratio of C. erythropteru was the highest, indicating the most accumulation in the liver. The concentrations of PFAAs in fish tissues were influenced by the lipid content, resulting in a difference between the lipid-normalized concentrations and the wet weight concentrations of the PFAAs. The non-carcinogenic risks of PFOS were higher than those of PFOA through the ingestion of C. erythropterus and A. nobilis. Both the carcinogenic and non-carcinogenic risks of C. erythropterus were greater than those of A. nobilis, and fish tissue intake could cause an increasing of risks up to 60%, indicating that long-term and large amount ingestion of carnivorous fish and related tissues with higher trophic level, such as C. erythropterus should be avoided.

Distribution and Bioaccumulation of Perfluoroalkyl Acids in Xiamen Coastal Waters

Since perfluoroalkyl acids (PFAs) are widely used and harmless to organisms, they have attracted great attention in recent years. The distribution of PFAs in the oceans all around the world is well documented. However, the study of PFAs in Xiamen could be a beneficial complement, for its unique geologies of no rivers that originate from other cities to influence the concentration of PFAs in this area. In this paper, six PFAs were analyzed in water, sediments, and organisms from both freshwater and seawater and the bioaccumulation factors (BAFs) were calculated with the quantity of PFAs in different trophic levels of aquatic organisms. The results showed that the ΣPFA concentrations ranged from 7.66 to 11.98 ng·L−1 for seawater samples and from 2.12 to 8.61 ng·L−1 for freshwater. The concentration of ΣPFAs in sediments was 7.43–12.89 ng·g−1 and 4.53–5.80 ng·g−1 in seawater and freshwater, respectively. The PFA concentration in water is highly positive correlated with the PFA concentration in sediments (R2 = 0.85). The calculated bioaccumulation factors (BCFs) were 6412–14254 L·kg−1 and 2927–7959 L·kg−1 for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonates (PFOS), respectively. PFOA seems more bioaccumulative than PFOS in seawater. The results illustrated the PFA pollution in the Xiamen sea area, and it is useful for the protection and control of the organic pollutants in this area.

Effects of fluorescent dissolved organic matters (FDOMs) on perfluoroalkyl acids (PFAAs) in lake and river water

This study presents the effects of fluorescent dissolved organic matters (FDOM) on perfluoroalkyl acids (PFAAs) in western Lake Chaohu and its inflow rivers. The surface water samples from the 27 sites in western Lake Chaohu and its inflow rivers were collected in March and September 2013. The contents of PFAAs and the FDOM in the water samples were measured by a high-performance liquid chromatograph - mass spectrometer (HPLC-MS) and by a fluorescence spectrophotometer, respectively. The temporal-spatial distributions of PFAAs and FDOM, as well as their interrelationships, were investigated. Eleven PFAA components were detected, and the mean concentration of total PFAAs (TPFAAs) in western Lake Chaohu and its inflow rivers were 12.93 ± 5.19 ng/L and 11.84 ± 9.50 ng/L, respectively. PFOA was the predominant contaminant in two regions (7.13 ± 3.07 ng/L and 4.30 ± 2.14 ng/L) followed by PFHxA (1.72 ± 0.80 ng/L and 1.42 ± 1.41 ng/L) and PFBA (1.44 ± 0.78 ng/L and 1.37 ± 0.78 ng/L). The mean concentration of total FDOM in western Lake Chaohu and its inflow rivers were 220.0 ± 40.30 μg quinine sulfate units (Q.S.)/L and 406.3 ± 213.1 μg Q.S./L, respectively. The significant, positive correlations were observed between the PFAAs and FDOMs in both the lake area and the inflow rivers. However, no significant correlation was observed between PFAAs and the dissolved organic carbon (DOC) in the lake area. This finding indicated that the residues and distributions of PFAAs were significantly dependent on the compositions of dissolved organic matters (DOM) and not on the total content of DOM.

Occurrence and health risk of perfluoroalkyl acids (PFAAs) in seafood from Yellow Sea, China

PFAAs have emerged as persistent organic pollutants (POPs) in a variety of environmental matrixes and biota, posing potential hazards for wildlife and humans. Diet has been considered as an important source for human exposure to PFAAs and seafood accounts for a relatively large proportion in human diets, especially for coastal residents. In an effort to clarify the impact of PFAAs in seafood on human health, 17 PFAAs were determined in 42 pooled seafood samples (14 species) from the Yellow Sea areas, China. The concentrations of total PFAAs (sum of 17 PFAAs, ∑PFAAs) were in the range of 1.10–1067 ng/g dry weight (dw), with the highest concentration found in swimming crab (Portunus trituberculatus) and the lowest in silvery pomfret (Pampus argenteus). Concentrations and composition profiles of PFAAs varied significantly among different species, suggesting that bioaccumulation potential of PFAAs differed from species to species. The distinct spatial distribution of PFAAs in four categories of seafood could be mainly attributed to the contamination patterns of PFAAs in three nearby cities. PFBA was presented as the most abundant PFAA in this study, which was different from the findings in many other studies where PFOS was the predominant compound. Furthermore, the human health risk assessment suggested that a comprehensive action plan is needed to protect people from high exposure to PFAAs through seafood consumption.

Protein-specific distribution patterns of perfluoroalkyl acids in egg yolk and albumen samples around a fluorochemical facility

In this study, eggs from free-range and barn chickens in farms around a fluorochemical facility were collected to assess the distribution profiles of perfluoroalkyl acids (PFAAs), including isomers of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonate (PFHxS), in egg yolk and albumen. The results revealed that the concentrations of PFAAs in yolks were significantly higher than those in albumen. All 17 PFAAs examined could be detected in yolks, showing decreasing concentrations with increasing distance from the fluorochemical facility. The three predominant compounds in yolks were perfluorobutanoic acid (PFBA, mean concentration 81.4 ng/g ww), PFOS (28.0 ng/g ww), and PFOA (4.83 ng/g ww), and this result is consistent with the product structure of the facility. Moreover, n-PFOA, n-PFOS, and n-PFHxS were the dominant contaminants in yolk, with mean concentrations of 4.75, 25.7, and 4.29 ng/g ww, respectively. In albumen, PFBA was still the predominant PFAA congener (mean concentration = 3.93 ng/g ww), followed by PFOA. Docking analysis indicated that the PFAAs presented higher binding abilities with the low density lipoprotein, high density lipoprotein, and vitellin proteins in yolk than that with ovalbumin albumen proteins, which might be the main factor influencing the possible difference in distributions of PFAAs in yolk and albumen.

Perfluoroalkyl acids in surface seawater from the North Pacific to the Arctic Ocean: Contamination, distribution and transportation

The bioaccumulative, persistent and toxic properties of long-chain perfluoroalkyl acids (PFAAs) resulted in strict regulations on PFAAs, especially in developed countries. Consequently, the industry manufacturing of PFAAs shifts from long-chain to short-chain. In order to better understand the pollution situation of PFAAs in marine environment under this new circumstance, the occurrence of 17 linear PFAAs was investigated in 30 surface seawater samples from the North Pacific to Arctic Ocean (123°E to 24°W, 32 to 82°N) during the sixth Chinese Arctic Expedition in 2014. Total concentrations of PFAAs (∑PFAAs) were between 346.9 pg per liter (pg/L) to 3045.3 pg/L. The average concentrations of ∑PFAAs decreased in the order of East China Sea (2791.4 pg/L, n = 2), Sea of Japan (East Sea) (832.8 pg/L, n = 6), Arctic Ocean (516.9 pg/L, n = 7), Chukchi Sea (505.2 pg/L, n = 4), Bering Sea (501.2 pg/L, n = 8) and Sea of Okhotsk (417.7 pg/L, n = 3). C4 to C9 perfluoroalkyl carboxylic acids (PFCAs) were detected in more than 80% of the surface water samples. Perfluorobutanoic acid (PFBA) was the most prevalent compound and perfluorooctanoic acid (PFOA) was the second abundant homolog. The concentration of individual PFAAs in the surface seawater of East China Sea was much higher than other sampling seas. As the spatial distribution of PFAAs in the marine environment was mainly influenced by the river inflow from the basin countries, which proved the large input from China. Furthermore, the marginal seas of China were found with the greatest burden of PFOA comparing the pollution level in surface seawater worldwide. PFBA concentration in the surrounding seas of China was also high, but distributed more evenly with an obvious increase in recent years. This large-scale monitoring survey will help the improvement and development of PFAAs regulations and management, where production shift should be taken into consideration.

Integrating total oxidizable precursor assay data to evaluate fate and transport of PFASs

AbstractFate and transport of per‐ and polyfluoroalkyl substances (PFASs) are complex and are not well understood. Among this class of emerging contaminants, perfluoroalkyl acids (PFAAs) comprising perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs) are being studied more frequently than polyfluorinated compounds. PFAAs are persistent in the environment, recalcitrant to biological degradation, and, therefore, widespread. Previous studies have indicated that some PFASs bioaccumulate. The fate and transport of PFAAs can be complicated by the presence of PFAA precursors. The PFAA precursors are defined in this article as those fluorinated chemicals that can be potentially transformed abiotically or biotically into terminal PFCA or PFSA products. Due to potential biotransformation in the environment, PFAA precursors can influence the temporal and lateral distribution of PFAAs in the environment. Presently, only a very small number of PFAA precursors can be quantitatively analyzed by commercial laboratories. For instance, N‐ethyl perfluorooctanesulfonamidoacetic acid and N‐methyl perfluorooctanesulfonamidoacetic acid are the only two precursors included in the most commonly applied PFAS analytical method, U.S. Environmental Protection Agency Method 537. The current commercial laboratory methodologies primarily quantify between 14 and 31 PFASs. As an alternative, a total oxidizable precursor assay (TOPA) was developed to quantify the measurable PFSA and PFCA concentrations after aggressive oxidation converting PFAA precursors abiotically into PFCAs. The difference between PFAA concentrations before and after oxidation can be used to estimate the amount of oxidizable PFAA precursors in the sample. This is one of the first articles that utilized TOPA data to help interpret PFAS fate and transport in the environment.

Spatiotemporal distribution and potential sources of perfluoroalkyl acids in Huangpu River, Shanghai, China

Perfluoroalkyl acids (PFAAs) have been found to be ubiquitously disseminated in the environment due to their widespread use in recent decades. In this study, the occurrence and spatiotemporal distribution of PFAAs in the surface water of Huangpu River, Shanghai, China were investigated from 2012 to 2014. The total concentration of 14 PFAAs (ΣPFAAs) ranged from 39.8 to 596.2 ng L−1, with a mean value of 226.3 ng L−1. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were dominant, with their mean concentrations of 139.6 and 46.5 ng L−1, respectively. The concentration of ΣPFAAs increased greatly downstream especially in the lower reach of an industrial and urbanized area. Samples collected in different seasons were used to analyze the seasonal variation. The results showed that higher concentration of ΣPFAAs occurred in the wet season, especially downstream. Therefore, industrial discharges, municipal wastewater and surface runoff were identified as major potential sources. The annual discharge load of ΣPFAAs from Huangpu River to Yangtze River was estimated to be 2263.4 kg yr−1. The hazard assessment suggested that the contamination of PFAAs in Huangpu River could pose risks to the aquatic environment and drinking water safety, which should draw more attention.

Perfluoroalkyl acids in the water cycle from a freshwater river basin to coastal waters in eastern China

The distribution of perfluoroalkyl acids (PFAAs), one class of persistent organic pollutants, in groundwater, especially in confined aquifers remains poorly understood. In this study, we investigated the occurrence of 12 PFAAs through a water cycle from the Huai River Basin to the Yellow Sea, including confined aquifers, unconfined aquifers, rivers, and coastal waters. We found the ubiquity of PFAAs in all types of samples, including those from confined aquifers (2.7–6.8 ng/L). Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were the major PFAAs in all samples, accounting for an average of 49.1% (0.8–84.8%) and 33.3% (6.3–92.2%) of total PFAAs, respectively. Comparing the concentration of PFOA with that of PFOS, we found a higher concentration of PFOA in rivers and a higher concentration of PFOS in confined aquifers. Short-chain perfluoropentanoic acid accounted for an average of 10.3% (1.9–24.6%) of total PFAAs in rivers and coastal waters. Branched isomers of both PFOA and PFOS were detected in most samples (36/42 and 39/42, respectively). One-way analysis of variance indicated a significant difference in the profiles of PFAAs among the different types of water samples. Principal component analysis suggested that rainwater and recent uses of PFAAs could be the major sources of PFAAs in confined aquifers, while recent and current uses of PFAAs could be the major source of PFAAs in unconfined aquifers, rivers and coastal waters. The risk quotients of PFOA and PFOS in groundwater and rivers were 2–3 orders of magnitude lower than unity, indicating no immediate risks via drinking water consumption.