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The presence of synthetic chemicals in the environment can affect both ecosystems and
human health. In particular, the increasing contamination of the aquatic environment by
complex mixtures of anthropogenic trace substances has become a major global concern.
Once released into the environment, these compounds can undergo diverse
transformation processes to form a wide range of transformation products (TPs), which
are commonly unknown. Transformation inevitably alters the pattern of contamination and
exposure, as new substances are formed with frequently different physicochemical
properties, environmental behavior and toxicity in comparison to their precursor
compounds. For instance, TPs can exhibit significantly greater persistence and mobility in
the aquatic environment, posing a threat to both aquatic ecosystems and drinking water
resources. Therefore, TPs need to be considered in the risk assessment and authorization
process of chemicals. However, due to a combination of predictive, analytical, and
regulatory challenges, TPs currently remain largely unrecognized and unregulated. By
addressing these challenges, this thesis comprehensively characterizes the entry paths,
occurrence, fate, and (eco)toxicological relevance of selected TPs in the aquatic system in
Germany. These TPs have been largely overlooked in environmental studies and aquatic
monitoring programs for decades, despite their precursors being produced and used in
large quantities on a global scale.
The highly persistent and mobile substance trifluoroacetate (TFA) has garnered
significant attention in recent years due to its diverse sources, widespread occurrence in
the aquatic environment, and the lack of economically viable options to remove TFA from
contaminated waters. One of the most frequently discussed diffuse sources is the
formation of TFA in the atmosphere through the oxidation of volatile precursors and its
subsequent scavenging from the atmosphere by wet deposition. Despite the previously
reported occurrence of TFA in precipitation, the lack of recent and comprehensive data
has severely limited the understanding of the significance of wet deposition as a source of
TFA to the (aquatic) environment. Thus, in the present work, a nationwide field monitoring
campaign covering all precipitation events over a one-year sampling period was
conducted at eight sites across Germany. Samples were analyzed for TFA using ion
exchange chromatography (IC) coupled to negative-ion electrospray tandem mass
spectrometry (ESI-MS/MS). Of the analyzed samples, 16% exhibited TFA concentrations
≥ 1 μg/L. The precipitation-weighted average TFA concentration of 0.34 μg/L highlighted
that wet deposition alone is responsible for approximately 0.3 to 0.4 μg/L of TFA in
surface waters in Germany. The annual wet deposition fluxes ranged from 91 to
400 μg/m², with the highest fluxes observed in densely populated regions. The annual wet
deposition of TFA for Germany during the observation period was estimated to be 68 t.
The sampling revealed a pronounced seasonality, with the highest concentrations and wet
deposition fluxes of TFA observed in summer. Pearson correlation analyses indicated that
the transformation of TFA precursors in the troposphere is enhanced in summer due to
elevated concentrations of photochemically generated oxidants, primarily •OH, which
ultimately results in increased atmospheric TFA deposition. Overall, the study provided the
first published data on TFA in precipitation in Germany since 1995/96. The derived data
serves as a benchmark for future studies. In addition, it allows for the establishment of
mass balances and can be used to develop models to predict the loads of TFA entering
the aquatic environment from multiple sources.
The lack of robust historical data on the wet deposition fluxes of TFA also impeded long-
term trend analyses. Specifically, a postulated increase in atmospheric formation and
deposition of TFA due to substantial emission increases of numerous volatile TFA
precursors in recent decades remained unquantified. To address this knowledge gap,
archived plant samples were analyzed to evaluate the long-term temporal trends in the
atmospheric deposition of TFA in Germany. A robust and highly sensitive analytical
method for TFA in plant matrices was developed and validated. The method
encompassed a three-step sequential extraction procedure followed by the analysis of the
diluted sample extracts using IC-ESI-MS/MS. Subsequently, archived leaf samples of
various tree species and sampling sites from the German Environmental Specimen Bank
(observation period: 1989−2020) were analyzed for TFA. Statistical analysis revealed
significant (p < 0.05) positive trends in TFA concentrations in plant leaves, which is likely
the result of both phytoaccumulation and increasing emissions of gaseous TFA precursors
over the observation period. The concentrations increased by factors of up to 12 from
1989 to 2020. The highest concentrations (up to ∼1,000 μg/kg dry weight) were found in
Lombardy poplar leaves. Overall, the study presents the first trend analysis of TFA in biota
and raises awareness of the escalating atmospheric deposition of TFA over the past three
decades.
Sulfamate has previously been identified as a TP of the artificial sweeteners cyclamate
and acesulfame in wastewater and drinking water treatment. The preliminary results
indicated that sulfamate concentrations in wastewater treatment plant (WWTP) effluent
are substantially higher than those of other wastewater-borne contaminants. However,
despite its high global production and usage, no information was available on the sources,
occurrence, and environmental significance of sulfamate in the aquatic system in
Germany. To close this knowledge gap, a quantitative monitoring approach of different
urban water cycle compartments was conducted. Target analysis based on IC-ESI-MS/MS
revealed exceptionally high concentrations of sulfamate in wastewater (up to 1,900 μg/L),
surface water (up to 580 μg/L), and finished drinking water (up to 140 μg/L) in Germany.
Considering the limited data on short-term ecotoxicity, approximately 30% of the
sulfamate concentrations detected in groundwater and surface water samples exceeded
the derived predicted no-effect concentration (PNEC) of sulfamate. Therefore, the
potential impact of sulfamate on the aquatic ecosystem in Germany cannot be excluded.
Municipal WWTP effluent was identified as the primary source of sulfamate for the aquatic
system, as its concentrations correlated positively (r > 0.77) with the municipal wastewater
tracer carbamazepine in samples from different waterbodies. Ozonation and activated
sludge experiments demonstrated that sulfamate can be formed through chemical and
biological degradation of various precursors containing a sulfonamide group.
Nevertheless, the transformation of precursors to sulfamate in WWTPs and receiving
waters was found to be quantitatively insignificant, due to the substantial direct use of
sulfamic acid as a descaling agent in domestic and industrial applications. Laboratory
batch experiments, in conjunction with the findings from the sampling conducted at full-
scale waterworks, demonstrated that the commonly applied drinking water treatment
techniques, including ozonation and activated carbon filtration, are largely ineffective in
removing sulfamate. Bank filtration was identified as the only option to efficiently eliminate
sulfamate from contaminated raw water resources (removal: 62% to 99%). Overall, the
study presents the first comprehensive analysis of sulfamate in the urban water cycle and
suggests that there may be other high production volume inorganic chemicals that are
currently overlooked in environmental studies and monitoring programs.
Despite pantoprazole (PPZ) being one of the most widely prescribed human
pharmaceuticals globally, consistently low concentrations of this proton-pump inhibitor in
environmental water samples have been documented. This can be attributed to the
extensive metabolism of PPZ within the human body, with only minor amounts of the
parent compound being excreted. Since environmental monitoring and risk assessment
for regulatory purposes focus on the parent substances of pharmaceuticals, it was
assumed that the current environmental exposure associated with the use of PPZ is
considerably underestimated. In the presented thesis, 4′-O-demethyl-PPZ sulfide (M1)
was identified as the most relevant PPZ metabolite for environmental analysis. This was
achieved by applying reversed-phase high-performance liquid chromatography (RP-
HPLC) coupled to high-resolution mass spectrometry (HRMS) to urine samples of a PPZ
user, as well as to municipal wastewater. M1, which had not been investigated in previous
monitoring studies, was found to be ubiquitous in WWTP influent and effluent (max.:
3 μg/L, detention frequency: 100%) as well as in surface water (max.: 1.2 μg/L; detection
frequency: 97%) in Germany. Its average surface water concentration was approximately
30 times higher than that of the parent compound PPZ. Moreover, quantitative structure-
toxicity relationship (QSTR) modeling indicated a lower preliminary freshwater PNEC for
M1 (4.8 μg/L) compared to PPZ (28 μg/L). The analysis of archived suspended particulate
matter (SPM) samples from the Rhine at Koblenz revealed that the concentrations of M1
increased significantly from 2005 to 2015 and were positively correlated with the
prescription volume of PPZ. Conventional biological wastewater treatment was found to
be insufficient to remove M1 (average removal: 22%). Laboratory-scale experiments and
the analysis of samples taken after different treatment steps of an advanced full-scale
WWTP demonstrated that post-treatment with activated carbon as well as ozonation can
significantly improve the removal of M1 and PPZ during wastewater treatment, thereby
reducing their release to the aquatic environment. During ozonation, a rapid oxidation of
M1 was observed, accompanied by the formation of several ozonation products, which
were proposed for the first time. The identity of the main ozonation TPs of M1 was
confirmed through the synthesis of reference compounds. Their detection in samples
collected after the ozonation step of a full-scale WWTP demonstrated the transferability of
the laboratory-scale ozonation experiments. M1 was found to be sufficiently removed from
contaminated source waters (max. raw water concentration: 0.25 μg/L) by bank filtration
under different redox conditions (removal ≥ 80 %) and by other commonly applied
purification processes in drinking water production. In summary, this study revealed that
the environmental exposure and risk associated with the use of PPZ have been previously
underestimated, which likely extends to other human pharmaceuticals. Therefore, these
findings call for more sophisticated approaches to environmental monitoring and risk
assessment of pharmaceuticals that take TPs into account.
This thesis provides an in-depth understanding of the entry paths, occurrence, fate, and
environmental significance of selected TPs in the aquatic system in Germany. It
significantly advances our understanding of the introduction of TFA into the water cycle,
by characterizing the source of wet deposition and elucidating long-term temporal trends
of atmospherically deposited TFA. Additionally, the thesis gives comprehensive insights
into the formation, behavior, removability, and potential (eco)toxicological risks of
sulfamate, PPZ and its TPs. The thesis addresses key challenges in assessing and
integrating TPs into chemical management and presents solutions to overcome these
challenges. Finally, it highlights the urgent need for increased focus on TPs in research,
aquatic monitoring, and regulation to safeguard the environment and human health.