The fate of nitrification and urease inhibitors in simulated bank filtration.

The application of nitrification and urease inhibitors (NUI) in conjunction with nitrogen (N) fertilizers improves the efficiency of N fertilizers. However, NUI are frequently found in surface waters through leaching or surface runoff. Bank filtration (BF) is considered as a low-cost water treatment system providing high quality water by efficiently removing large amounts of organic micropollutants from surface water. The fate of NUI in managed aquifer recharge systems such as BF is poorly known. The aim of this work was to investigate sorption and degradation of NUI in simulated BF under near-natural conditions. Besides, the effect of NUI on the microbial biomass of slowly growing microorganisms and the role of microbial biomass on NUI removal was investigated. Duplicate sand columns (length 1.7 m) fed with surface water were spiked with a pulse consisting of four nitrification (1,2,4-triazole, dicyanodiamide, 3,4-dimethylpyrazole and 3-methylpyrazole) and two urease inhibitors (n-butyl-thiophosphoric acid triamide and n-(2-nitrophenyl) phosphoric triamide). The average spiking concentration of each NUI was 5 µg/L. Experimental and modeled breakthrough curves of NUI indicated no retardation for any of the inhibitors. Therefore, biodegradation was identified as the main elimination pathway for all substances and was highest in zones of high microbial biomass. Removal of 1,2,4-triazole was 50% and n-butyl-thiophosphoric acid triamide proved to be highly degradable and was completely removed after a hydraulic retention time (HRT) of 24 h. 50% of the mass recovery for nitrification inhibitors except for 3,4-dimethylpyrazole was observed at the effluent (4 days HRT). In addition, a mild effect of NUI on microbial biomass was noted. This study highlights that the degradation of NUI in BF depends on HRT and microbial biomass.

Ultra-Short-Chain PFASs in the Sources of German Drinking Water: Prevalent, Overlooked, Difficult to Remove, and Unregulated.

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.

Occurrence, Distribution, and Environmental Behavior of Persistent, Mobile, and Toxic (PMT) and Very Persistent and Very Mobile (vPvM) Substances in the Sources of German Drinking Water.

Persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances have been recognized as a threat to both the aquatic environment and to drinking water resources. These substances are currently prioritized for regulatory action by the European Commission, whereby a proposal for the inclusion of hazard classes for PMT and vPvM substances has been put forward. Comprehensive monitoring data for many PMT/vPvM substances in drinking water sources are scarce. Herein, we analyze 34 PMT/vPvM substances in 46 surface water, groundwater, bank filtrate, and raw water samples taken throughout Germany. Results of the sampling campaign demonstrated that known PMT/vPvM substances such as 1H-benzotriazole, melamine, cyanuric acid, and 1,4-dioxane are responsible for substantial contamination in the sources of German drinking water. In addition, the results revealed the widespread presence of the emerging substances 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and diphenylguanidine (DPG). A correlation analysis showed a pronounced co-occurrence of PMT/vPvM substances associated predominantly with consumer or professional uses and also demonstrated an inhomogeneous co-occurrence for substances associated mainly with industrial use. These data were used to test the hypothesis that most PMT/vPvM substances pass bank filtration without significant concentration reduction, which is one of the main reasons for introducing PMT/vPvM as a hazard class within Europe.

Trifluoroacetate in Precipitation: Deriving a Benchmark Data Set.

Although precipitation is considered to be the most important diffuse source of trifluoroacetate (TFA) to the nonmarine environment, information regarding the wet deposition of TFA as well as general data on the spatial and temporal variations in TFA concentration in precipitation is scarce. This is the first study to provide a comprehensive overview of the occurrence of TFA in precipitation by a systematic and nation-wide field monitoring campaign. In total, 1187 precipitation samples, which were collected over the course of 12 consecutive months at eight locations across Germany, were analyzed. The median, the estimated average, and the precipitation-weighted average TFA concentration of all analyzed wet deposition samples were 0.210, 0.703, and 0.335 µg/L, respectively. For Germany, an annual wet deposition flux of 190 µg/m2 or approximately 68 t was calculated for the sampling period from February 2018 to January 2019. The campaign revealed a pronounced seasonality of the TFA concentration and wet deposition flux of collected samples. Correlation analysis suggested an enhanced transformation of TFA precursors in the troposphere in the summertime due to higher concentrations of photochemically generated oxidants such as hydroxyl radicals, ultimately leading to an enhanced atmospheric deposition of TFA during summer.

Effects of metoprolol on aquatic invertebrates in artificial indoor streams.

Aquatic organisms are impacted by various biotic and abiotic stressors such as current, inter- and intraspecific competition for food resources and habitat, neobiota as well as an increasing number of chemicals. The latter also include pharmaceuticals, which are increasingly being detected in surface waters due to their growing use. The aim of our study was to determine effect data for metoprolol as a model compound for beta-blockers under an environmentally realistic exposure scenario on aquatic invertebrates inhabiting lotic environments. To this end we performed a 40-day experiment in artificial indoor streams (AIS) located in a greenhouse. We focussed on three autochthonous invertebrate species with high relevance in stream ecology: the amphipod Gammarus fossarum, the gastropod Potamopyrgus antipodarum, and the oligochaete Lumbriculus variegatus. Effects on reproduction were found with EC10 (40 days) values of 0.092 mg L-1 (G. fossarum), 0.253 mg L-1 (P. antipodarum), and 0.596 mg L-1 (L. variegatus). Considering environmental data, metoprolol seems to pose no hazard for aquatic invertebrates at present exposure levels.

Health effects of metoprolol in epibenthic and endobenthic invertebrates-A basis to validate future in vitro biotests for effect-based biomonitoring.

The aim of this study was to determine the effect data for metoprolol as a model substance for beta-blockers in aquatic invertebrates. The results will be used as a basis for the validation of future mode of action-based in vitro test systems targeting this class of pharmaceuticals. Effects of metoprolol were investigated in two autochthonous species with high relevance in stream ecology: the amphipod Gammarus fossarum and the oligochaete Lumbriculus variegatus. Mortality in G. fossarum was not observed in acute toxicity testing (48 h), and a significant increase of mortality at 45 mg/L was found when amphipods were exposed chronically (40 days). The most sensitive population-relevant endpoints were the juvenile-adult ratio and number of egg-bearing females with NOEC/LOEC-values of 5/15 mg/L. No proteotoxic effects were identified in G. fossarum. The sediment toxicity test with L. variegatus according to the OECD Guideline 225 with an exposure time of 28 days resulted in EC10-values of 92.5 and 126.1 mg/kgdw for the endpoints reproduction and biomass, respectively. In L. variegatus the response kinetics of Hsp70 showed no significant difference between the treatments. A tendency for rising lipid peroxide concentrations was found between 0.03 and 10 mg/kgdw, which were significant between the treatments, but not to the control.

A sensitive multi-residue method for the determination of 35 micropollutants including pharmaceuticals, iodinated contrast media and pesticides in water.

A sensitive, multi-residue method using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to determine a representative group of 35 analytes, including corrosion inhibitors, pesticides and pharmaceuticals such as analgesic and anti-inflammatory drugs, five iodinated contrast media, ß-blockers and some of their metabolites and transformation products in water samples. Few other methods are capable of determining such a broad range of contrast media together with other analytes. We studied the parameters affecting the extraction of the target analytes, including sorbent selection and extraction conditions, their chromatographic separation (mobile phase composition and column) and detection conditions using two ionisation sources: electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI). In order to correct matrix effects, a total of 20 surrogate/internal standards were used. ESI was found to have better sensitivity than APCI. Recoveries ranging from 79 to 134 % for tap water and 66 to 144 % for surface water were obtained. Intra-day precision, calculated as relative standard deviation, was below 34 % for tap water and below 21 % for surface water, groundwater and effluent wastewater. Method quantification limits (MQL) were in the low ng L(-1) range, except for the contrast agents iomeprol, amidotrizoic acid and iohexol (22, 25.5 and 17.9 ng L(-1), respectively). Finally, the method was applied to the analysis of 56 real water samples as part of the validation procedure. All of the compounds were detected in at least some of the water samples analysed. Graphical Abstract Multi-residue method for the determination of micropollutants including pharmaceuticals, iodinated contrast media and pesticides in waters by LC-MS/MS.

Reduction of dioxin-like toxicity in effluents by additional wastewater treatment and related effects in fish.

Efficiency of advanced wastewater treatment technologies to reduce micropollutants which mediate dioxin-like toxicity was investigated. Technologies compared included ozonation, powdered activated carbon and granular activated carbon. In addition to chemical analyses in samples of effluents, surface waters, sediments, and fish, (1) dioxin-like potentials were measured in paired samples of effluents, surface waters, and sediments by use of an in vitro biotest (reporter gene assay) and (2) dioxin-like effects were investigated in exposed fish by use of in vivo activity of the mixed-function, monooxygenase enzyme, ethoxyresorufin O-deethylase (EROD) in liver. All advanced technologies studied, based on degradation or adsorption, significantly reduced dioxin-like potentials in samples and resulted in lesser EROD activity in livers of fish. Results of in vitro and in vivo biological responses were not clearly related to quantification of targeted analytes by use of instrumental analyses.

Metabolites are overlooked in environmental risk assessments and monitoring of pharmaceuticals: The case study of pantoprazole.

The proton-pump inhibitor pantoprazole (PPZ) is one of the most consumed pharmaceuticals worldwide. Despite its high usage, reported PPZ concentrations in environmental water samples are comparatively low, which can be explained by the extensive metabolism of PPZ in the human body. Since most previous studies did not consider human PPZ metabolites it can be assumed that the current environmental exposure associated with the application of PPZ is substantially underestimated. In our study, 4'-O-demethyl-PPZ sulfide (M1) was identified as the predominant PPZ metabolite by analyzing urine of a PPZ consumer as well as the influent and effluent of a wastewater treatment plant (WWTP) using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS). M1 was found to be ubiquitously present in WWTP effluents (max. concentration: 3 000 ng/L) and surface waters in Germany. On average, the surface water concentrations of M1 were approximately 30 times higher than those of the parent compound PPZ. Laboratory scale experiments demonstrated that activated carbon can considerably adsorb M1 und thus improve its removal during wastewater and drinking water treatment. Laboratory ozonation experiments showed a fast oxidation of M1, accompanied by the formation of several ozonation products. Certain ozonation products (identities confirmed via synthesized reference standards) were also detected in water samples collected after ozonation in a full-scale WWTP. Overall lower signal intensities were observed in the effluents of a sand filter and biologically active granular activated carbon filter, suggesting that the compounds were significantly removed during these post-ozonation treatment stages.

Artificial sweeteners--a recently recognized class of emerging environmental contaminants: a review.

An overview is given of existing trace analytical methods for the determination of seven popular artificial sweeteners [acesulfame (ACE), aspartame, cyclamate (CYC), neotame, neohesperidine dihydrochalcone, saccharin (SAC), and sucralose (SUC)] from aqueous environmental samples. Liquid chromatography-electrospray ionization tandem mass spectrometry and liquid chromatography-electrospray ionization high-resolution mass spectrometry are the methods most widely applied, either directly or after solid-phase extraction. Limits of detection and limits of quantification down to the low nanogram per liter range can be achieved. ACE, CYC, SAC, and SUC were detected in wastewater treatment plants in high microgram per liter concentrations. Per capita loads of individual sweeteners can vary within a wide range depending on their use in different countries. Whereas CYC and SAC are usually degraded by more than 90% during wastewater treatment, ACE and SUC pass through wastewater treatment plants mainly unchanged. This suggests their use as virtually perfect markers for the study of the impact of wastewater on source waters and drinking waters. In finished water of drinking water treatment plants using surface-water-influenced source water, ACE and SUC were detected in concentrations up to 7 and 2.4 µg/L, respectively. ACE was identified as a precursor of oxidation byproducts during ozonation, resulting in an aldehyde intermediate and acetic acid. Although the concentrations of ACE and SUC are among the highest measured for anthropogenic trace pollutants found in surface water, groundwater, and drinking water, the levels are at least three orders of magnitude lower than organoleptic threshold values. However, ecotoxicology studies are scarce and have focused on SUC. Thus, further research is needed both on identification of transformation products and on the ecotoxicological impact of artificial sweeteners and their transformation products.

Evidence for Specific Receptor-Mediated Toxicity of Pharmaceuticals in Aquatic Organisms Derived from Acute and Chronic Standard Endpoints.

The toxicity of 17 active pharmaceutical ingredients (APIs) was investigated using standardized acute and chronic tests with Daphnia magna and 2 algae species. Chronic toxicity was generally greater for Daphnia than for algae. Compilation of additional data resulted in 100 APIs for which the acute-to-chronic ratio (ACR) was determined for Daphnia. The frequency of high ACRs (~20% with ACRs > 100) indicates that specific receptor-mediated toxicity toward D. magna is rather common among APIs. The 11 APIs with ACRs > 1000 included lipid-modifying agents, immunosuppressants, antibiotics, antineoplastics, antiobesics, antivirals, and antihistamines. There was no consistent association between ACR and chronic toxicity, ionization status, or lipophilicity. High ACRs were not exclusively associated with the presence of orthologs of the pharmacological target in Daphnia. Statins, acetylcholinesterase inhibitors, and antihistamines are discussed in more detail regarding the link between targets and toxic mode of action. For acetylcholinesterase inhibitors, receptor-mediated toxicity was already apparent after acute exposure, whereas the high ACR and chronic toxicity of some antihistamines probably related to interaction with a secondary rather than the primary pharmacological target. Acute or modeled chronic toxicity estimates have often been used for prioritizing pharmaceuticals. This may be seriously misleading because chronic effects are currently not predictable for APIs with specific receptor-mediated toxicity. However, it is exactly these APIs that are the most relevant in terms of environmental risks. Environ Toxicol Chem 2022;41:601-613. © 2021 SETAC.

Combining target analysis with sum parameters-a comprehensive approach to determine sediment contamination with PFAS and further fluorinated substances.

Recent studies aiming at a fluorine mass balance analysis in sediments combined the determination of extractable organic fluorine (EOF) with target analysis. They reported high fractions of unidentified organic fluorine (UOF) compounds, as the target analysis covers only a limited number of per- and polyfluoroalkyl substances (PFAS). For this reason, in this study, a comprehensive approach was used combining target analysis with an extended PFAS spectrum, the EOF and a modified total oxidisable precursor (TOP) assay, which includes trifluoroacetic acid, to determine the PFAS contamination in sediments (n=41) and suspended solids (n=1) from water bodies in Northern Germany (Lower Saxony). PFAS are ubiquitous in the sediments (detected in 83% of the samples). Perfluorinated carboxylic acids (PFCAs) were found in 64% of the samples; perfluorinated sulfonic acids (PFSAs) were detected less frequently (21%), with the highest concentration observed for perfluorooctanesulfonic acid (PFOS). Levels of precursors and substitutes were lower. Applying the TOP assay resulted in an increase in PFCAs in 43% of the samples analysed. In most cases, target analysis and the TOP assay could not account for the EOF concentrations measured. However, as the fraction of UOF decreased significantly, the application of the TOP assay in fluorine mass balance analysis proved to be an important tool in characterising the PFAS contamination of riverine sediments.

Biological effect and chemical monitoring of Watch List substances in European surface waters: Steroidal estrogens and diclofenac - Effect-based methods for monitoring frameworks.

Three steroidal estrogens, 17α-ethinylestradiol (EE2), 17ß-estradiol (E2), estrone (E1), and the non-steroidal anti-inflammatory drug (NSAID), diclofenac have been included in the first Watch List of the Water Framework Directive (WFD, EU Directive 2000/60/EC, EU Implementing Decision 2015/495). This triggered the need for more EU-wide surface water monitoring data on these micropollutants, before they can be considered for inclusion in the list of priority substances regularly monitored in aquatic ecosystems. The revision of the priority substance list of the WFD offers the opportunity to incorporate more holistic bioanalytical approaches, such as effect-based monitoring, alongside single substance chemical monitoring. Effect-based methods (EBMs) are able to measure total biological activities (e.g., estrogenic activity or cyxlooxygenase [COX]-inhibition) of specific group of substances (such as estrogens and NSAIDs) in the aquatic environment at low concentrations (pg/L). This makes them potential tools for a cost-effective and ecotoxicologically comprehensive water quality assessment. In parallel, the use of such methods could build a bridge from chemical status assessments towards ecological status assessments by adressing mixture effects for relevant modes of action. Our study aimed to assess the suitability of implementing EBMs in the WFD, by conducting a large-scale sampling and analysis campaign of more than 70 surface waters across Europe. This resulted in the generation of high-quality chemical and effect-based monitoring data for the selected Watch List substances. Overall, water samples contained low estrogenicity (0.01-1.3 ng E2-Equivalent/L) and a range of COX-inhibition activity similar to previously reported levels (12-1600 ng Diclofenac-Equivalent/L). Comparison between effect-based and conventional analytical chemical methods showed that the chemical analytical approach for steroidal estrogens resulted in more (76%) non-quantifiable data, i.e., concentrations were below detection limits, compared to the EBMs (28%). These results demonstrate the excellent and sensitive screening capability of EBMs.

Correlation of six anthropogenic markers in wastewater, surface water, bank filtrate, and soil aquifer treatment.

Six trace contaminants (acesulfame (ACE), sucralose (SUC), carbamazepine (CBZ), diatrizoic acid (DTA), 1H-benzotriazole (BTZ) and its 4-methyl analogue (4-TTri)) were traced from wastewater treatment plants (WWTPs) to receiving waters and further to riverbank filtration (RBF) wells to evaluate their prediction power as potential wastewater markers. Furthermore, the persistence of some compounds was investigated in advanced wastewater treatment by soil aquifer treatment (SAT). During wastewater treatment in four conventional activated sludge WWTPs ACE, SUC, and CBZ showed a pronounced stability expressed by stable concentration ratios in influent (in) and effluent (out) (ACE/CBZ: in45, out40; SUC/CBZ: in1.8, out1.7; and ACE/SUC: in24, out24). In a fifth WWTP, additional treatment with powdered activated carbon led to a strong elimination of CBZ, BTZ, and 4-TTri of about 80% and consequently to a distinctive shift of their ratios with unaffected compounds. Data from a seven month monitoring program at seven sampling locations at the rivers Rhine and Main in Germany revealed the best concentration correlation for ACE and CBZ (r(2) = 0.94) and also a good correlation of ACE and CBZ concentrations to BTZ and 4-TTri levels (r(2) = 0.66 to 0.82). The comparison of ratios at different sampling sites allowed for the identification of a CBZ point source. Furthermore, in Switzerland a higher consumption of SUC compared to Germany can be assumed, as a steadily increasing ACE/SUC ratio along the river Rhine was observed. In RBF wells a good correlation (r(2) = 0.85) was again observed for ACE and CBZ. Both also showed the highest stability at a prolonged residence time in the subsurface of a SAT field. In the most peripheral wells ACE and CBZ were still detected with mean values higher than 36 µg L(-1) and 1.3 µg L(-1), respectively. Although SUC concentrations in wastewater used for SAT decreased by more than 80% from about 18 µg L(-1) to 2.1 µg L(-1) and 3.5 µg L(-1) in these outlying wells, the compound was still adequate to indicate a wastewater impact in a qualitative way.

Ultrashort-chain perfluoroalkyl substance trifluoroacetate (TFA) in beer and tea - An unintended aqueous extraction.

Trifluoroacetate (TFA) is an ultrashort-chain perfluoroalkyl substance, which is ubiquitously present in the aqueous environment. Due to its high mobility, it accumulates in plant material. The study presented here shows for the first time that TFA is a widely spread contaminant in beer and tea / herbal infusions. In 104beer samples from 23countries, TFA was detected up to 51 µg/L with a median concentration of 6.1 µg/L. An indicative brewing test and a correlation approach with potassium (K) indicate that the main source of TFA in beer is most likely the applied malt. It could be proven that the impact of the applied water is negligible in terms of TFA, which was supported by the analysis of numerous tap water samples from different countries. The unintended extraction of TFA was also demonstrated for tea / herbal infusions with a median concentration of 2.4 µg/L.

Extending the knowledge about PFAS bioaccumulation factors for agricultural plants - A review.

A main source of perfluoroalkyl and polyfluoroalkyl substances (PFASs) residues in agricultural plants is their uptake from contaminated soil. Bioaccumulation factors (BAFs) can be an important tool to derive recommendations for cultivation or handling of crops prior consumption. This review compiles >4500 soil-to-plant BAFs for 45 PFASs from 24 studies involving 27 genera of agricultural crops. Grasses (Poaceae) provided most BAFs with the highest number of values for perfluorooctanoic acid and perfluorooctane sulfonic acid. Influencing factors on PFAS transfer like compound-specific properties (hydrophobicity, chain length, functional group, etc.), plant species, compartments, and other boundary conditions are critically discussed. Throughout the literature, BAFs were higher for vegetative plant compartments than for reproductive and storage organs. Decreasing BAFs per additional perfluorinated carbon were clearly apparent for aboveground parts (up to 1.16 in grains) but not always for roots (partly down to zero). Combining all BAFs per single perfluoroalkyl carboxylic acid (C4-C14) and sulfonic acid (C4-C10), median log BAFs decreased by -0.25(±0.029) and -0.24(±0.013) per fluorinated carbon, respectively. For the first time, the plant uptake of ultra-short-chain (≤ C3) perfluoroalkyl acids (PFAAs) was reviewed and showed a ubiquitous occurrence of trifluoroacetic acid in plants independent from the presence of other PFAAs. Based on identified knowledge gaps, it is suggested to focus on the uptake of precursors to PFAAs, PFAAs ≤C3, and additional emerging PFASs such as GenX or fluorinated ethers in future research. Studies regarding the uptake of PFASs by sugar cane, which accounts for about one fifth of the global crop production, are completely lacking and are also recommended. Furthermore, aqueous soil leachates should be tested as an alternative to the solvent extraction of soils as a base for BAF calculations.

Microplastic analysis in drinking water based on fractionated filtration sampling and Raman microspectroscopy.

Microplastics (MP) as emerging persistent pollutants were found in raw and drinking water worldwide. Since different methods were used, there is an urgent need for harmonized protocols for sampling, sample preparation, and analysis. In this study, a holistic and validated analytical workflow for MP analysis in aqueous matrices down to 5 µm is presented. For sampling of several cubic meters of water, an easily portable filter cascade unit with different pore sizes (100-20-5 µm) was developed and successfully applied for the sampling of three processed drinking waters, two tap waters and one groundwater. The size distribution and polymer types of MP were determined using a two-step semi-automated Raman microspectroscopy analysis. For quality control, comprehensive process blanks were considered at all times and a recovery test yielded an overall recovery of 81%. The average concentration of identified MP was 66 ± 76 MP/m3 ranging from 1 MP/m3 to 197 MP/m3. All found concentrations were below the limit of quantitation (LOQ) of 1880 MP/m3. The majority consisted of PE (86% ± 111%) while comparatively low numbers of PET (10% ± 25%), PP (3% ± 6%), and PA (1% ± 4%) were found. 79% of all particles were smaller than 20 µm. In summary, this study presents the application of a workflow for sampling and analysis of MP down to 5 µm with first results of no significant contamination in drinking water and groundwater.

Air-drying of soil samples - A crucial step in the determination of leachable concentrations of per- and polyfluoroalkyl substances.

Batch leaching tests at a liquid to solid ratio of 2 L/kg are a valuable tool for the assessment of low PFAS levels in soils. Data from different monitoring programs comprising samples without known local source of PFAS contamination showed that soil-sample drying at ambient temperature or at 40 °C prior to the leaching process leads to higher PFAS leachate levels compared to non-dried samples. The effect was greater for perfluoroalkyl carboxylic acids (PFCAs) than for perfluoroalkyl sulfonic acids (PFSAs). In a controlled field study comparing field-fresh (frozen to -18 °C and thawed) samples with air-dried (room temperature) samples median levels after drying increased to 140%-470% for C4 to C10 PFCAs and to 130%-200% for C4, C6, and C8 PFSAs, respectively. Thus, using field-fresh samples for batch leaching tests might underestimate the leachable fraction of PFAA in the field, where drying and leaching periods alternate.

Can determination of extractable organofluorine (EOF) be standardized? First interlaboratory comparisons of EOF and fluorine mass balance in sludge and water matrices.

The high proportion of unidentified extractable organofluorine (EOF) observed globally in humans and the environment indicates widespread occurrence of unknown per- and polyfluoroalkyl substances (PFAS). However, efforts to standardize or assess the reproducibility of EOF methods are currently lacking. Here we present the first EOF interlaboratory comparison in water and sludge. Three participants (four organizations) analyzed unfortified and PFAS-fortified ultrapure water, two unfortified groundwater samples, unfortified wastewater treatment plant effluent and sludge, and an unfortified groundwater extract. Participants adopted common sample handling strategies and target lists for EOF mass balance but used in-house combustion ion-chromatography (CIC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. EOF accuracy ranged from 85-101% and 76-109% for the 60 and 334 ng L-1 fluorine (F) - fortified water samples, respectively, with between-laboratory variation of 9-19%, and within-laboratory variation of 3-27%. In unfortified sludge and aqueous samples, between-laboratory variation ranged from 21-37%. The contribution from sum concentrations of 16 individual PFAS (∑PFAS-16) to EOF ranged from 2.2-60% but extended analysis showed that other targets were prevalent, in particular ultra-short-chain perfluoroalkyl acids (e.g. trifluoroacetic acid) in aqueous samples and perfluoroalkyl acid-precursors (e.g. polyfluoroalkyl phosphate diesters) in sludge. The EOF-CIC method demonstrated promising accuracy, robustness and reporting limits but poor extraction efficiency was observed for some targets (e.g. trifluoroacetic acid).