Post column infusion of an internal standard into LC-FT-ICR MS enables semi-quantitative comparison of dissolved organic matter in original samples.

Ultrahigh resolution mass spectrometry hyphenated with liquid chromatography (LC) is an emerging tool to explore the isomeric composition of dissolved organic matter (DOM). However, matrix effects limit the potential for semi-quantitative comparison of DOM molecule abundances across samples. We introduce a post-column infused internal standard (PCI-IS) for reversed-phase LC-FT-ICR MS measurements of DOM and systematically evaluate matrix effects, detector linearity and the precision of mass peak intensities. Matrix effects for model compounds spiked into freshwater DOM samples ranging from a headwater stream to a major river were reduced by 5-10% for PCI-IS corrected mass peak intensities as compared to raw (i.e., untransformed) intensities. A linear regression of PCI-IS corrected DOM mass peak intensities across a typical DOM concentration range (2-15 mg dissolved organic carbon L-1) in original, non-extracted freshwater samples demonstrates excellent linearity of the detector response (r2 > 0.9 for 98% of detected molecular formulas across retention times). Importantly, PCI-IS could compensate for 80% of matrix effects across an environmental gradient of DOM composition from groundwater to surface water. This enabled studying the ionization efficiency of DOM isomers and linking the observed differences to the biogeochemical sources. With PCI-IS original, non-extracted DOM samples can be analysed by LC-FT-ICR MS without carbon load adjustment, and mass peak intensities can be reliably used to semi-quantitatively compare isomer abundances between compositionally similar DOM samples.

The genes mgtE and spoVG are involved in zinc tolerance of Staphylococcus aureus.

Metals are essential for all living organisms, but the type of metal and its concentration determines its action. Even low concentrations of metals may have toxic effects on organisms and therefore exhibit antimicrobial activities. In this study, we investigate the evolutionary adaptation processes of Staphylococcus aureus to metals and common genes for metal tolerance. Laboratory and clinical isolates were treated with manganese, cobalt, zinc, or nickel metal salts to generate growth-adapted mutants. After growth in medium supplemented with zinc, whole-genome sequencing identified, among others, two genes, mgtE (SAUSA300_0910), a putative magnesium transporter and spoVG (SAUSA300_0475), a global transcriptional regulator, as hot spots for stress-induced single-nucleotide polymorphisms (SNPs). SNPs in mgtE were also detected in mutants treated with high levels of cobalt or nickel salts. To investigate the effect of these genes on metal tolerance, deletion mutants and complementation strains in an S. aureus USA300 LAC* laboratory strain were generated. Both, the mgtE and spoVG deletion strains were more tolerant to cobalt, manganese, and zinc. The mgtE mutant was also more tolerant to nickel exposure. Inductively coupled plasma mass spectrometry analysis demonstrated that the mgtE deletion mutant accumulated less intracellular zinc than the wild type, explaining increased tolerance. From these results, we conclude that mgtE gene inactivation increases zinc tolerance presumably due to reduced uptake of zinc. For the SpoVG mutant, no direct effect on the intracellular zinc concentration was detected, indicating toward different pathways to increase tolerance. Importantly, inactivation of these genes offers a growth advantage in environments containing certain metals, pointing toward a common tolerance mechanism. IMPORTANCE: Staphylococcus aureus is an opportunistic pathogen causing tremendous public health burden and high mortality in invasive infections. Treatment is becoming increasingly difficult due to antimicrobial resistances. The use of metals in animal husbandry and aquaculture to reduce bacterial growth and subsequent acquisition of metal resistances has been shown to co-select for antimicrobial resistance. Therefore, understanding adaptive mechanisms that help S. aureus to survive metal exposure is essential. Using a screening approach, we were able to identify two genes encoding the transporter MgtE and the transcriptional regulator SpoVG, which conferred increased tolerance to specific metals such as zinc when inactivated. Further testing showed that the deletion of mgtE leads to reduced intracellular zinc levels, suggesting a role in zinc uptake. The accumulation of mutations in these genes when exposed to other metals suggests that inactivation of these genes could be a common mechanism for intrinsic tolerance to certain metals.

Sources of persistent and mobile chemicals in municipal wastewater: a sewer perspective in Leipzig, Germany.

Persistent and mobile (PM) chemicals spread in the water cycle and have been widely detected, yet information about their sources is still scarce. In this study, 67 PM chemicals were analyzed in 19 wastewater samples taken in the sewer system of the city of Leipzig, Germany, covering different industrial, clinical, and domestic discharges. A total of 37 of these analytes could be detected, with highly variable median concentrations between substances (median: 0.5-800 µg L-1) and for single substances between samples (e.g., 1,4-diazabicyclo[2.2.2]octane) by up to three orders of magnitude, with the highest single concentration exceeding 10 mg L-1 (p-cumenesulfonic acid). The emission of PM chemicals into the sewer system was classified as stemming from diffuse (14 analytes) or point sources (23 analytes), while 9 analytes fulfill both criteria. Many so-called industrial chemicals were also discharged from households (e.g., tris(2-chloroethyl) phosphate or 1H-benzotriazole). Examples for analytes showing specific sources are tetrafluoroborate (traffic-related industry and metal production and finishing), ε-caprolactam (large-scale laundry), or cyanuric acid (likely swimming pool). Furthermore, a correlation between 1-cyanoguanidine and guanylurea was observed for the traffic-related industry. This study outlines that sewer sampling can provide valuable information on the sources of PM chemicals. This knowledge is a prerequisite for their future emission control at source or substitution as an alternative to end-of-pipe treatment in municipal wastewater treatment plants.

Should Transformation Products Change the Way We Manage Chemicals?

When chemical pollutants enter the environment, they can undergo diverse transformation processes, forming a wide range of transformation products (TPs), some of them benign and others more harmful than their precursors. To date, the majority of TPs remain largely unrecognized and unregulated, particularly as TPs are generally not part of routine chemical risk or hazard assessment. Since many TPs formed from oxidative processes are more polar than their precursors, they may be especially relevant in the context of persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances, which are two new hazard classes that have recently been established on a European level. We highlight herein that as a result, TPs deserve more attention in research, chemicals regulation, and chemicals management. This perspective summarizes the main challenges preventing a better integration of TPs in these areas: (1) the lack of reliable high-throughput TP identification methods, (2) uncertainties in TP prediction, (3) inadequately considered TP formation during (advanced) water treatment, and (4) insufficient integration and harmonization of TPs in most regulatory frameworks. A way forward to tackle these challenges and integrate TPs into chemical management is proposed.

Hotspots of Floating Plastic Particles across the North Pacific Ocean.

The pollution of the marine environment with plastic debris is expected to increase, where ocean currents and winds cause their accumulation in convergence zones like the North Pacific Subtropical Gyre (NPSG). Surface-floating plastic (>330 µm) was collected in the North Pacific Ocean between Vancouver (Canada) and Singapore using a neuston catamaran and identified by Fourier-transform infrared spectroscopy (FT-IR). Baseline concentrations of 41,600-102,700 items km-2 were found, dominated by polyethylene and polypropylene. Higher concentrations (factors 4-10) of plastic items occurred not only in the NPSG (452,800 items km-2) but also in a second area, the Papaha̅naumokua̅kea Marine National Monument (PMNM, 285,200 items km-2). This second maximum was neither reported previously nor predicted by the applied ocean current model. Visual observations of floating debris (>5 cm; 8-2565 items km-2 and 34-4941 items km-2 including smaller "white bits") yielded similar patterns of baseline pollution (34-3265 items km-2) and elevated concentrations of plastic debris in the NPSG (67-4941 items km-2) and the PMNM (295-3748 items km-2). These findings suggest that ocean currents are not the only factor provoking plastic debris accumulation in the ocean. Visual observations may be useful to increase our knowledge of large-scale (micro)plastic pollution in the global oceans.

Leaching of tire particles and simultaneous biodegradation of leachables.

The fate of organic compounds released from tire wear particle (TWP) in the aquatic environment is still poorly understood. This is especially true near sources where biotic and abiotic transformation and leaching from TWP are simultaneous and competing processes. To address this knowledge-gap an experiment was performed, allowing for biodegradation (a) during the leaching from a suspension of cryo-milled tire tread (CMTT) and (b) subsequent to leaching. Besides measuring the Dissolved Organic Carbon (DOC) content, 19 tire-related chemicals were quantified, and non-target screening was performed by LC-HRMS. The non-inoculated control experiment exhibited a DOC of up to 4 mg g-1, with up to 700 µg g-1 of 1,3-diphenylguanidine (DPG) as the most prominent compound, followed by three benzothiazoles (2-mercaptobenzothiazole (2-MBT), 2-hydroxybenzothiazole (2-OHBT) and benzothiazole-2-sulfonic acid (BTSA); 50 µg g-1 each) and 4-hydroxydiphenylamine (4-HDPA) (50 µg g-1). Biodegradation reduced the DOC by 88 % and the concentration of most organic compounds by more than 85 %. At the end of the experiment hexamethoxymethylmelamine (HMMM) was the most prominent single compounds (18 µg g-1). Non-target screening showed a more complex picture. Another 25 transformation products (TPs) of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD) and 44 TPs and derivatives related to DPG were detected in solution, of which 11 and 28 were still present after or formed by biodegradation, respectively. Of these 39 TPs and derivatives, 31 could be detected in road runoff samples. This study provides a more comprehensive picture of the leachables of tire particles that are of environmental relevance. It also outlines that derivatives of tire additives formed during tire production and use may deserve more attention as leachables. The large extent of biodegradation of tire leachables suggests that settling ponds may be a useful treatment option for road runoff.

Influence of Silver Fiber Morphology on the Dose-Response Relationship and Enrichment in Daphnia magna Studied by Elemental Imaging with LA-ICP-TOF-MS.

This study aims to enhance the understanding of the environmental risks associated with nanomaterials, particularly nanofibers. Previous research suggested that silver fibers exhibit higher toxicity (EC50/48h 1.6-8.5 µg/L) compared to spherical silver particles (EC50/48h 43 µg/L). To investigate the hypothesis that toxicity is influenced by the morphology and size of nanomaterials, various silver nanofibers with different dimensions (length and diameter) were selected. The study assessed their toxicity toward Daphnia magna using the 48 h immobilization assay. The EC50 values for the different fibers ranged from 122 to 614 µg/L. Subsequently, the study quantified the uptake and distribution of two representative nanofibers in D. magna neonates by employing digestion and imaging mass spectrometry in the form of laser-ablation-ICP-MS. A novel sample preparation method was utilized, allowing the analysis of whole, intact daphnids, which facilitated the localization of silver material and prevented artifacts. The results revealed that, despite the similar ecotoxicity of the silver fibers, the amount of silver associated with the neonates differed by a factor of 2-3. However, both types of nanofibers were primarily found in the gut of the organisms. In conclusion, the findings of this study do not support the expectation that the morphology or size of silver materials affect their toxicity to D. magna.

Abundance and distribution of tire and road wear particles in the Seine River, France.

Tire and road wear particles (TRWP) are formed at the frictional interface between tires and the road surface. Tire tread and road pavement materials are denser than water but can be washed from the road surface into receiving water bodies, ultimately depositing into sediment, soil, or other media depending on the receiving environment. However, the paucity of mass-based measurements has limited the knowledge on the nature and extent of environmental concentrations necessary for environmental risk assessment of TRWP. Surface water and sediment samples were collected from the Seine River, France to characterize TRWP concentration. Sample locations were established upstream, within, and downstream of a major metropolitan area (Paris); downstream of smaller urban areas; adjacent to undeveloped land; and near the confluence of the estuary. Surface water and sediment were collected from the left and right banks at each of the eight locations, including two duplicates, for a total of 18 samples. Additionally, three sediment traps were deployed near the mouth of the river to quantify the flux of TRWP to sediment. Retained solids and sediment samples were analyzed using a modified pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) method that minimized the matrix interferences in the samples thus improving the current ISO Technical Specification ISO/TS 21396 : 2017 for TRWP mass concentration by Py-GC/MS. TRWP concentration was alternatively estimated by separating the sediment into the <1.9 g cm-3 fraction and analyzing for tread-derived zinc content. TRWP concentrations estimated by zinc method were significantly higher than results from the modified Py-GC/MS method. TRWP and total zinc concentrations show a decreasing trend from available historical data.

Uptake and Biotransformation of the Tire Rubber-derived Contaminants 6-PPD and 6-PPD Quinone in the Zebrafish Embryo (Danio rerio).

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD) is a widely used antioxidant in tire rubber known to enter the aquatic environment via road runoff. The associated transformation product (TP) 6-PPD quinone (6-PPDQ) causes extreme acute toxicity in some fish species (e.g., coho salmon). To interpret the species-specific toxicity, information about biotransformation products of 6-PPDQ would be relevant. This study investigated toxicokinetics of 6-PPD and 6-PPDQ in the zebrafish embryo (ZFE) model. Over 96 h of exposure, 6-PPD and 6-PPDQ accumulated in the ZFE with concentration factors ranging from 140 to 2500 for 6-PPD and 70 to 220 for 6-PPDQ. A total of 22 TPs of 6-PPD and 12 TPs of 6-PPDQ were tentatively identified using liquid chromatography coupled to high-resolution mass spectrometry. After 96 h of exposure to 6-PPD, the TPs of 6-PPD comprised 47% of the total peak area (TPA), with 4-hydroxydiphenylamine being the most prominent in the ZFE. Upon 6-PPDQ exposure, >95% of 6-PPDQ taken up in the ZFE was biotransformed, with 6-PPDQ + O + glucuronide dominating (>80% of the TPA). Among other TPs of 6-PPD, a reactive N-phenyl-p-benzoquinone imine was found. The knowledge of TPs of 6-PPD and 6-PPDQ from this study may support biotransformation studies in other organisms.

Accelerated aging of tire and road wear particles by elevated temperature, artificial sunlight and mechanical stress - A laboratory study on particle properties, extractables and leachables.

Tire and road wear particles (TRWP) are generated in large quantity by automobile traffic on roads but their way of degradation in the environment is largely unclear. Laboratory experiments were performed on the effect of elevated temperature (simulating 2-3 years), sunlight exposure (simulating 0.5 years) and mechanical stress on the physical properties and chemical composition of TRWP and of cryo-milled tire tread (CMTT). No significant effects were observed of the applied mechanical stress on mean properties of pristine particles. After sunlight exposure up to 40 % in mass were lost from the TRWP, likely due to the loss of mineral incrustations from their surface. The chemical composition of TRWP and CMTT was characterized by determining 27 compounds, antioxidants (phenylene diamines), vulcanization agents (benzothiazoles and guanidines) and their transformation products (TPs). Extractables of TRWP (580-850 µg/g) were dominated by TPs, namely benzothiazolesulfonic acid (BTSA). CMTT showed much higher amounts of extractables (4600 µg/g) which were dominated by parent chemicals such as N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (6-PPD), diphenylguanidine (DPG) and mercaptobenzothiazole (MBT). Sunlight exposure affected the amount of extractables more strongly than elevated temperature, for TRWP (-45 % vs -20 %) and CMTT (-80 % vs -25 %) and provoked a clear shift from parent compounds to their TPs. After sunlight exposure extractables of TRWP were dominated by BTSA and DPG. Sunlight exposure drastically reduced the 6-PPD amount extracted from both, TRWP and CMTT (-93 %, -98 %), while its quinone (6-PPDQ) increased by around 1 % of the 6-PPD decrease, only. For many TPs, concentration in leachates were higher than in extracts, indicating ongoing transformation of their parent compounds during leaching. These results highlight that abiotic aging of TRWP leads to strong changes in their chemical composition which affect their particle properties and are of relevance for the environmental exposure to tire-related chemicals.

Recently evolved combination of unique sulfatase and amidase genes enables bacterial degradation of the wastewater micropollutant acesulfame worldwide.

Xenobiotics often challenge the principle of microbial infallibility. One example is acesulfame introduced in the 1980s as zero-calorie sweetener, which was recalcitrant in wastewater treatment plants until the early 2010s. Then, efficient removal has been reported with increasing frequency. By studying acesulfame metabolism in alphaproteobacterial degraders of the genera Bosea and Chelatococcus, we experimentally confirmed the previously postulated route of two subsequent hydrolysis steps via acetoacetamide-N-sulfonate (ANSA) to acetoacetate and sulfamate. Genome comparison of wildtype Bosea sp. 100-5 and an acesulfame degradation-defective mutant revealed the involvement of two plasmid-borne gene clusters. The acesulfame-hydrolyzing sulfatase is strictly manganese-dependent and belongs to the metallo beta-lactamase family. In all degraders analyzed, it is encoded on a highly conserved gene cluster embedded in a composite transposon. The ANSA amidase, on the other hand, is an amidase signature domain enzyme encoded in another gene cluster showing variable length among degrading strains. Transposition of the sulfatase gene cluster between chromosome and plasmid explains how the two catabolic gene clusters recently combined for the degradation of acesulfame. Searching available genomes and metagenomes for the two hydrolases and associated genes indicates that the acesulfame plasmid evolved and spread worldwide in short time. While the sulfatase is unprecedented and unique for acesulfame degraders, the amidase occurs in different genetic environments and likely evolved for the degradation of other substrates. Evolution of the acesulfame degradation pathway might have been supported by the presence of structurally related natural and anthropogenic compounds, such as aminoacyl sulfamate ribonucleotide or sulfonamide antibiotics.

Efficacy of activated carbon filtration and ozonation to remove persistent and mobile substances - A case study in two wastewater treatment plants.

Persistent and mobile (PM) substances are able to spread quickly in the water cycle and were thus identified as potentially problematic for the environment and water quality. If also toxic (PMT) or very persistent and very mobile (vPvM) their regulation under REACH as substances of very high concern is foreseen. Yet, knowledge on the effectiveness of advanced wastewater treatment in removing PM-substances from WWTP effluents is limited to few rather well-known chemicals. The occurrence and behavior of 111 suspected and known PM-substances was investigated in two wastewater treatment plants employing either powdered activated carbon (PAC, full-scale) or ozonation with subsequent sand/anthracite filtration (pilot-scale) and an additional granular activated carbon (GAC) filtration was investigated. 72 of the 111 PM-substances analyzed were detected at least once in the secondary effluent of either wastewater treatment plant, resulting in total concentrations of 104 µg/L and 40 µg/L, respectively. While PAC removed 32 % of PM-substances well, the total PM burden in the effluent was only reduced from 103 µg/L to 87 µg/L. Ozonation and the subsequent sand/anthracite filtration was able to reduce the PM burden in wastewater from 40 µg/L to 19 µg/L, showing a higher removal efficacy than PAC in this study. The additional GAC filtration further reduced the total PM-concentration to 13 µg/L. Among the investigated PM-chemicals detected were constituents of ionic liquids: The anion hexafluorophosphate was one of few chemicals that was detected in effluent concentrations >1 µg/L and could not be removed by the processes studied, showing that for some chemicals preventive actions may be required.

Pilot-scale removal of persistent and mobile organic substances in granular activated carbon filters and experimental predictability at lab-scale.

Present knowledge about the fate of persistent and mobile (PM) substances in drinking water treatment is limited. Hence, this study assesses the potential of fixed-bed granular activated carbon (GAC) filters to fill the treatment gap for PM substances and the elimination predictability from lab-scale experiments. Two parallel pilot filters (GAC bed height 2 m, diameter 15 cm) with different GAC were operated for 1.5 years (ca. 47,000 BV throughput) alongside rapid small-scale column tests (RSSCT) designed based on the proportional diffusivity (PD) and the constant diffusivity (CD) approaches. Background dissolved organic matter (DOM) and a set of 17 target substances were investigated, among them 2-acrylamido-2-methylpropane sulfonate (AAMPS), adamantan-1-amine (ATA), melamine (MEL) and trifluoromethanesulfonic acid (TFMSA). Nine substances were predominantly present in the drinking water used as pilot filter influent (frequencies of detection above 80 %, median concentrations 0.003-1.868 µg/L) and their breakthrough behaviors could be observed: TFMSA was not retained at all, four substances including AAMPS and ATA reached complete breakthrough below 20,000 BV, three compounds were partially retained until the end of operation and oxypurinol was retained completely. The comparable PM candidate and DOM removal performances of both GAC aligns with their very similar surface characteristics and elemental compositions. The agreement of results between RSSCT with the pilot-scale filters were substance specific and no superior RSSCT design could be identified. However, CD-RSSCT provide a conservative removal prediction for most studied compounds. MEL adsorption was significantly underestimated by both RSSCT designs. Using the criterion of a carbon usage rate (with respect to 50 % breakthrough) below 25 mgGAC/Lwater for an economic retention by fixed-bed GAC filters, five (out of nine) substances met the requirement.

Advanced oxidation processes for removal of monocyclic aromatic hydrocarbon from water: Effects of O3/H2O2 and UV/H2O2 treatment on product formation and biological post-treatment.

Several oxidative treatment technologies, such as ozonation or Fenton reaction, have been studied and applied to remove monocyclic hydroaromatic carbon from water. Despite decades of application, little seems to be known about formation of transformation products while employing different ozone- or ∙OH-based treatment methods and their fate in biodegradation. In this study, we demonstrate that O3/H2O2 treatment of benzene, toluene, ethylbenzene (BTE), and benzoic acid (BA) leads to less hydroxylated aromatic transformation products compared to UV/H2O2 as reference system - this at a similar ∙OH exposure and parent compound removal efficiency. Aerobic biodegradation tests after oxidation of 0.15 mM BA (12.6 mg C L-1 theoretical DOC) revealed that a less biodegradable DOC fraction > 4 mg C L-1 was formed in both oxidative treatments compared to the BA control. No advantage of ozonation over UV/H2O2 treatment was observed in terms of mineralization capabilities, however, we detected less transformation products after oxidation and biodegradation using high-resolution mass spectrometry. Biodegradation of BA that was not oxidized was more complete with minimal organic residual. Overall, the study provides new insights into the oxidation of monocyclic aromatics and raises questions regarding the biodegradability of oxidation products, which is relevant for several treatment applications.

Is adsorption onto activated carbon a feasible drinking water treatment option for persistent and mobile substances?

Persistent and mobile (PM) substances among the organic micropollutants have gained increasing interest since their inherent properties enable them to enrich in water cycles. This study set out to investigate the potential of adsorption onto activated carbon as a drinking water treatment option for 19 PM candidates in batch experiments in a drinking water matrix using a microporous and a mesoporous activated carbon. Overall, adsorption of PM candidates proved to be very variable and the extent of removal could not be directly related to molecular properties. At an activated carbon dose of 10 mg/L and 48 h contact time, five (out of 19) substances were readily removed (≥ 80%), among them N-(3-(dimethylamino)-propyl)methacrylamide, which was investigated for the first time. For five other substances, no or negligible removal (< 20%) was observed, including 2-methyl-2-propene-1-sulfonic acid and 4­hydroxy-1-(2-hydroxyethyl)-2,2,6,6,-tetramethylpiperidine. For the former, current state of the art adsorption processes may pose a sufficient barrier. Additionally, substance specific surrogate correlations between removals and UVA254 abatements were established to provide a cheap and fast estimate for PM candidate elimination. Adsorption onto activated carbon could contribute significantly to PM substance elimination as part of multi barrier approaches, but assessments for individual substances still require clarification, as demonstrated for the investigated PM candidates.

Revisiting Disinfection Byproducts with Supercritical Fluid Chromatography-High Resolution-Mass Spectrometry: Identification of Novel Halogenated Sulfonic Acids in Disinfected Drinking Water.

High resolution mass spectrometry (HRMS) coupled to either gas chromatography or reversed-phase liquid chromatography is the generic method to identify unknown disinfection byproducts (DBPs) but can easily overlook their highly polar fractions. In this study, we applied an alternative chromatographic separation method, supercritical fluid chromatography-HRMS, to characterize DBPs in disinfected water. In total, 15 DBPs were tentatively identified for the first time as haloacetonitrilesulfonic acids, haloacetamidesulfonic acids, and haloacetaldehydesulfonic acids. Cysteine, glutathione, and p-phenolsulfonic acid were found as precursors during lab-scale chlorination, with cysteine providing the highest yield. A mixture of the labeled analogues of these DBPs was prepared by chlorination of 13C3-15N-cysteine and analyzed using nuclear magnetic resonance spectroscopy for structural confirmation and quantification. A total of 6 drinking water treatment plants utilizing various source waters and treatment trains produced sulfonated DBPs upon disinfection. Those were widespread in the tap water of 8 cities across Europe, with estimated concentrations up to 50 and 800 ng/L for total haloacetonitrilesulfonic acids and haloacetaldehydesulfonic acids, respectively. Up to 850 ng/L haloacetonitrilesulfonic acids were found in 3 public swimming pools. Considering the stronger toxicity of haloacetonitriles, haloacetamides, and haloacetaldehydes than the regulated DBPs, these newly found sulfonic acid derivatives may also pose a health risk.

Comprehensive target analysis and TOP assay of per- and polyfluoroalkyl substances (PFAS) in wild boar livers indicate contamination hot-spots in the environment.

The suitability of wild boar liver as a bioindicator of per- and polyfluoroalkyl substances (PFAS) in the terrestrial environment was investigated. Samples from 50 animals in three different areas associated with (1) contaminated paper sludges distributed on arable land (PS), (2) industrial emissions of PFAS (IE) and (3) background contamination (BC) were analyzed for 66 PFAS, including legacy PFAS, novel substitutes and precursors of perfluoroalkyl acids (PFAAs). Additionally, the Total Oxidizable Precursor (TOP) assay was performed to determine the formation potential of PFAAs from precursors. In total, 31 PFAS were detected with site-specific contamination profiles. PFAS concentrations in livers from area PS and IE (567 and 944 µg kg-1 wet weight, respectively) were multiple times higher than from area BC (120 µg kg-1). The dominating PFAS were the legacy compounds perfluorooctane sulfonic acid (PFOS) in areas PS and BC (426 and 82 µg kg-1, respectively) and perfluorooctanoic acid (PFOA) in area IE (650 µg kg-1). In area IE, the compounds 4,8-dioxa-3H-perfluorononanoic acid (DONA) and hexafluoropropylene oxide dimer acid (HFPO-DA) - which are used as substitutes for PFOA - were determined at 15 and 0.29 µg kg-1, respectively. The formation potential of PFAAs was highest in area PS, but generally lower than the contamination with PFAAs. The pattern of perfluoroalkyl carboxylic acids (PFCAs) in wild boar liver reflects the contamination of the local soil at the two hot-spot areas IE and PS. This first comparison of PFAS contamination between wild boars and soil suggests that wild boar livers are suitable bioindicators for PFAS contamination in the terrestrial environment. Moreover, in terrestrial samples from area IE, legacy PFAS were found to be retained for a longer period as compared to riverine samples (suspended particulate matter and chub filet).

Differences in the internal PFAS patterns of herbivores, omnivores and carnivores - lessons learned from target screening and the total oxidizable precursor assay.

Per- and polyfluorinated alkyl substances (PFAS) are a group of anthropogenic chemicals, which are not (fully) biodegradable and accumulate in different environmental compartments worldwide. A comprehensive, quantitative analysis - consisting of target analysis (66 different analytes, including e. g. ultrashort-chain perfluorinated carboxylic acids (PFCAs), precursor compounds and novel substitutes) and the Total Oxidisable Precursor (TOP) assay (including trifluoroacetic acid (TFA)) - were conducted to analyse the PFAS concentrations and patterns in 12 mammalian and two bird species from different areas of Germany and Denmark. The PFAS contamination was investigated in dependance of the trophic class (herbivores, omnivores, carnivores), ecological habitat (terrestrial, (semi-) aquatic) and body tissue (liver, musculature). PFAS concentrations were highest in carnivores, followed by omnivores and herbivores, with ∑PFAS concentration ranging from 1274 µg/kg (Eurasian otter liver) to 22 µg/kg (roe deer liver). TFA dominated in the herbivorous species, whereas perfluorooctanesulfonic acid (PFOS) and the long-chain PFCAs covered the majority of the PFAS contamination in carnivorous species. Besides trophic class, ecological habitat also affected the PFAS levels in the different species, with terrestrial herbivores and omnivores showing higher PFAS concentration than their aquatic counterparts, whereas for carnivores this relationship was reversed. The TOP assay analysis indicated similar trends, with the PFCA formation pattern differing significantly between the trophic classes. TFA was formed predominantly in herbivorous and omnivorous species, whereas in carnivorous species a broad spectrum of PFCAs (chain-length C2-C14) was formed. Musculature tissue of six species exhibited significantly lower PFAS concentrations than the respective liver tissue, but with similar PFAS patterns. The comprehensive approach applied in the present study showed, that primarily the trophic class is decisive for the PFAS concentration, as herbivores, omnivores and carnivores clearly differed in their PFAS concentrations and patterns. Additionally, the TOP assay gave novel insights in the PFCA formation potential in biota samples.

Isotopically labeled ozone: A new approach to elucidate the formation of ozonation products.

As ozonation becomes a widespread treatment for removal of chemicals of emerging concern from wastewater treatment plant effluents, there are increasing concerns regarding the formation of ozonation products (OPs), and their possible impacts on the aquatic environment and eventually human health. In this study, a novel method was developed that utilizes heavy oxygen (18O2) for the production of heavy ozone ([18O1]O2, [18O2]O1, [18O3]) to actively label OPs from oxygen transfer reactions. To establish and validate this new approach, venlafaxine with a well-described oxygen transfer reaction (tertiary amine -> N-oxide) was chosen as a model compound. Observed 18O/16O ratios in the major OP venlafaxine N-oxide (NOV) correlated with expected 18O purities based on tracer experiments. These results confirmed the successful labeling with heavy oxygen and furthermore demonstrate the potential to monitor NOV as an indicator of 18O/16O ratios during ozonation. As a next step, 18O/16O ratios were used to elucidate the formation mechanism of previously described OPs from sulfamethoxazole (SMX). Seven OPs were detected including the frequently described nitro-SMX, which was formed with a maximum yield of 3.2% (of initial SMX). With the successful labeling of six of the seven OPs from sulfamethoxazole, it was possible to confirm their previously proposed formation pathways, and to distinguish oxygen transfer from electron transfer reactions. 18O/16O ratios in OPs indicate that hydroxylation of the aromatic ring and formation of nitro-groups mostly follows oxygen transfer reactions, while electron transfer reactions initiate the formation of hydroxylamine and the abstraction of NH2 leading to catechol.

Stable isotope labeling for detection of ozonation byproducts in effluent organic matter with FT-ICR-MS.

Despite effluent organic matter (EfOM) being a major consumer of ozone during wastewater treatment, little is known about ozonation byproducts (OBPs) produced from EfOM. To unambiguously identify OBPs, heavy ozone was used to ozonate EfOM, resulting in 18O labeled and unlabeled OBPs. Labeled OBPs mostly represent a single 18O transfer and were classified as either direct or indirect OBPs based on the 18O/16O intensity ratios of the isotopologues. Of the 929 labeled OBPs, 84 were unequivocally classified as direct OBPs. The remainder suggest a major contribution by indirect, hydroxyl radical induced formation of OBPs in EfOM. Overall, labelled OBPs possess a low degree of unsaturation and contributed most to OBP peak intensity - marking them as potential end products. A few direct and indirect OBPs with high peak intensity containing 18O and heteroatoms (N, S) were fragmented with CID FT-ICR-MS/MS and screened for indicative neutral losses carrying heavy oxygen. The neutral loss screening was used to detect the 18O location on the OBP and indicate the original functional group in EfOM based on known reaction mechanisms. We identified sulfoxide and sulfonic acid functional groups in selected OBPs - implying the presence of reduced sulfur in EfOM molecules - while no evidence for nitrogen containing functional groups reacting with ozone was found.