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.

The Fenton reaction describes the reaction of Fe(II) with hydrogen peroxide. Several researchers proposed the formation of an intermediate iron-peroxo complex but experimental evidence for its existence is still missing. The present study investigates formation and lifetime of this intermediate at various conditions such as different Fe(II)-concentrations, absence vs presence of a hydroxyl radical scavenger (dimethyl sulfoxide, DMSO), and different pH values. Obtained results indicate that the iron-peroxo complex is formed under all experimental conditions. Based on these data, stability of the iron-peroxo complex could be examined. At pH 3 regardless of [Fe(II)] decay rates for the iron-peroxo complex of about 50 s were determined in absence and presence of DMSO. Without DMSO and [Fe(II)] = 300 μM variation of pH yielded decay rates of about 70 s for pH 1 and 2 and of about 50 s at pH 3 and 4. Hence, the iron-peroxo complex becomes more stable with increasing pH. Furthermore, pH-dependent hydroxyl radical yields were determined to investigate whether the increasing stability of the intermediate complex may indicate a different reaction of the iron-peroxo complex which might yield Fe(IV) instead of hydroxyl radical formation as suggested in literature. However, it was found that hydroxyl radicals were produced proportionally to the Fe(II)-concentration.

A new method for the growth-dependent headspace analysis of bacterial cultures by needle trap (NT)-gas chromatography-mass spectrometry (GC-MS) was established. NTs were used for the first time as enrichment technique for volatile organic compounds (VOCs) in the headspace of laboratory cultures. Reference strains of Escherichia coli and Pseudomonas aeruginosa were grown in different liquid culture media for 48 h at 36 °C. In the course of growth, bacterial culture headspace was analysed by NT-GC-MS. In parallel, the abiotic release of volatile organic compounds (VOC) from nutrient media was investigated by the same method. By examination of microbial headspace samples in comparison with those of uninoculated media, it could be clearly differentiated between products and compounds which serve as substrates. Specific microbial metabolites were detected and quantified during the stationary growth phase. P. aeruginosa produced dimethyl sulfide (max. 125 μg L(-1) < limits of quantification (LOQ)), 1-undecene (max. 164 μg L(-1)) and 2-nonanone (max. 200 μg L(-1)), whereas E. coli produced carbon disulfide, butanal and indole (max. 149 mg L(-1)). Both organisms produced isoprene.

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 1Hbenzotriazole, 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.

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