Abteilung Umweltchemie

Pharmaceuticals and their human metabolites are significant sources of micropollutants in the aquatic environments due to incomplete removal during wastewater treatment. While parent compounds have been widely studied, the fate of their metabolites across treatment stages remains poorly understood, despite the fact that most pharmaceuticals are excreted in metabolized forms. Using a combination of full-scale wastewater treatment plant (WWTP) observations, laboratory experiments, and modeling, this study aimed to assess and compare the removal of 290 parent pharmaceuticals and 154 human metabolites across biological and advanced wastewater treatment stages, to evaluate the influence of human metabolic modifications on removal rates. The findings from the field data confirmed that phase II metabolites are often efficiently degraded during biological treatment, and cleaved into corresponding parent compounds or phase I metabolites, with median removals of 84% to 97% in the three WWTPs. In contrast, phase I metabolites show a similar behavior to their parent compounds and are often not more efficiently abated, with median removals ranging between 38% to 53% for parents and phase I metabolites. Advanced treatments, including ozonation with and without granular activated carbon filtration, showed significant median reductions of 79% to 92% for parent pharmaceuticals and 54% to 82% for metabolites, with removal efficiencies correlating with ozone doses. Laboratory biotransformation experiments identified reaction-specific pseudo-first-order rate constants, with carboxylic acids showing increased persistence, potentially as a result of their high oxidation state, which limits further degradation under aerobic conditions. Moreover, the laboratory experiments confirmed that acetylated and glucuronidated phase II metabolites are more efficiently abated during biological treatment, while sulfates are more stable compared to their parent compounds. A mechanistic model using the experimentally determined biotransformation rate constants was established, showing strong agreement with measured data for compounds with high or low biotransformation rates. Predictions for partially degraded compounds showed higher uncertainty, reflecting the complex interactions between biotransformation, sorption and operational parameters. This work provides a detailed assessment of the behavior and fate of pharmaceuticals and especially their metabolites during wastewater treatment, emphasizes the importance of understanding transformation pathways, and offers valuable insights for optimizing removal strategies and minimizing environmental impacts.

Tintenstrich communities are specialized lithic biofilms dominated by free-living cyanobacteria, also occurring in lichen associations, forming a unique ecological interface between rock environments and aquatic habitats in mountainous areas. To better understand their composition and genetic and metabolic potential, we analyzed 207 samples from the Swiss Alps and Jura Mountains. We determined how key environmental factors shaped cyanobacterial abundance, assessed whether these communities harbor genes for toxin biosynthesis, characterized their taxonomic composition at the family and genus level, and evaluated the actual occurrence of cyanotoxins and other bioactive metabolites. Cyanobacterial abundance proved to be influenced by factors such as elevation, exposure, and their interaction with siliceous rock substrata. Targeted PCR and Sanger sequencing revealed the presence of toxin-encoding genes, particularly for ndaF/mcyE fragments, which may encode microcystin and/or nodularin biosynthesis, while specific genes for microcystins, anatoxins, and cylindrospermopsins were rather rare. Metabarcoding analysis identified 11 cyanobacterial families, with Chroococcaceae, Nostocaceae, and Leptolyngbyaceae being the most abundant. Complementary high-resolution mass spectrometry confirmed the occasional presence of nodularins and microcystins, alongside more frequent detection of other bioactive peptides such as anabaenopeptins and cyanopeptolins. Overall, these findings provide the most comprehensive insight to date into Tintenstrich-associated cyanobacteria, underscoring their environmental significance given their genetic and metabolic potential.

Cyanobacteria produce toxic and bioactive secondary metabolites, posing risks to ecosystems and human health, yet their transformation pathways in surface waters remain unclear. We assessed biotransformation for 40 cyanopeptides including microcystins, anabaenopeptins and cyanopeptolins in surface waters and in situ enriched biofilm suspensions. In surface waters, most cyanopeptides did not degrade significantly over the course of 7 days. A wide range of biodegradability across cyanopeptides was apparent in biofilm suspensions from three rivers. Increasing the biofilm density shortened the lag time and increased initial removal of cyanopeptides. Increasing the initial cyanopeptide concentration lengthened the lag time and decreased their initial removal, supporting inhibitory effects of cyanopeptides toward enzymes involved in their own transformation. Transformation kinetics and product analysis demonstrated a structure–reactivity relationship across and within cyanopeptide classes. Anabaenopeptins were hydrolyzed at the C-terminus when arginine, tyrosine and (iso)leucine were present, but not when phenylalanine or tryptophan was present. Microcystins showed tetrapeptide formation when adda linked to arginine but not when it linked to alanine, leucine, or tyrosine. Oxidation of tyrosine and deamination of arginine residues showed an interdependence across cyanopeptide classes. These novel insights into biotransformation products and pathways of a wide range of cyanopeptides facilitate assessment of exposure scenarios in surface waters and inform about kinetics and product formation in biological water treatment.

Wastewater-based epidemiology is an established approach for monitoring population-level illicit drug use. Standard methods rely on 24-hour composite samples collected from treatment plant influent. While suitable for assessing long-term consumption patterns, composite samples obscure diurnal information on daily load dynamics - valuable for understanding substance sources and normalization strategies. Currently, the required, high manual effort limits the feasibility of diurnal monitoring applications.
In this study, we deployed a transportable, automated liquid chromatography-mass spectrometry system (MS²Field) at the influent of the wastewater treatment plant in Zurich, Switzerland (serving 471,000 people). Over an eight-week period from July to September 2023 - including school holidays and two major public events - samples were analyzed every 36 min (1909 total). Loads of five exogenous population biomarkers, six common illicit drug markers, and the cocaine adulterant levamisole were quantified. In parallel, hourly mobile phone data were used to estimate de facto population size and demographic composition in the catchment.
Automated analysis enabled the detection of consistent, weekday-specific intraday patterns for individual substances. Population biomarkers exhibited distinct temporal profiles: paraxanthine remained stable during working hours, while candesartan declined even at peak population times - highlighting implications for normalization, particularly with day visitors. Mobile phone-based occupancy data aligned with general trends but diverged during large events, likely due to mobile toilet use, whereas chemical markers directly reflected the contributing population.
During the special events, MDMA, ketamine, and amphetamine loads rose with distinct profiles - one event showing a gradual overnight rise, the other a morning peak. Daily MDMA loads were 20-fold higher during one event than typical weekends. Ketamine showed irregular spikes, possibly due to a smaller user base, rapid excretion, or direct input. Levamisole loads rose on weekends and during events, mirroring benzoylecgonine, indicating continued presence as harmful cocaine adulterant.
Automated analysis reveals short-term intraday trends, providing additional insights into the sources of chemical marker loads - such as consumption, excretion, and contributions from transient populations - that are typically averaged out in standard 24-hour composite samples.

Global climate change is increasing the frequency and intensity of heat waves, posing a significant threat to ectothermic organisms. Concurrently, chemical pollution, including heavy metals and pesticides, remains a pervasive environmental stressor. This study investigates the effects of sub-lethal copper and fluazinam exposure on the thermal tolerance of the soil-dwelling springtail, Folsomia candida. Using a thermal death time (TDT) framework, we assessed how pre-exposure to these toxicants at two acclimation temperatures (20°C and 24°C) influenced survival under heat stress. Our findings indicate that toxicant exposure reduced heat tolerance at moderately high temperatures (32.5°C) but had negligible effects at extreme temperatures (37°C). Acclimation at 24°C mitigated the negative effects of both toxicants, suggesting an enhanced capacity for cellular homeostasis under warm conditions. Additionally, soil type influenced thermal tolerance, highlighting the importance of environmental context in multiple stressor interactions. These findings highlight the need to integrate realistic thermal exposure scenarios in ecotoxicological assessments to improve predictions of organismal vulnerability under climate change.