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Background: Endometrial cancer can be molecularly classified into POLEmut, mismatch repair deficient (MMRd), p53 abnormal (p53abn), and no specific molecular profile (NSMP) subgroups. We aimed to develop an interpretable deep learning pipeline for whole-slide-image-based prediction of the four molecular classes in endometrial cancer (im4MEC), to identify morpho-molecular correlates, and to refine prognostication. Methods: This combined analysis included diagnostic haematoxylin and eosin-stained slides and molecular and clinicopathological data from 2028 patients with intermediate-to-high-risk endometrial cancer from the PORTEC-1 (n=466), PORTEC-2 (n=375), and PORTEC-3 (n=393) randomised trials and the TransPORTEC pilot study (n=110), the Medisch Spectrum Twente cohort (n=242), a case series of patients with POLEmut endometrial cancer in the Leiden Endometrial Cancer Repository (n=47), and The Cancer Genome Atlas-Uterine Corpus Endometrial Carcinoma cohort (n=395). PORTEC-3 was held out as an independent test set and a four-fold cross validation was performed. Performance was measured with the macro and class-wise area under the receiver operating characteristic curve (AUROC). Whole-slide images were segmented into tiles of 360 μm resized to 224 × 224 pixels. im4MEC was trained to learn tile-level morphological features with self-supervised learning and to molecularly classify whole-slide images with an attention mechanism. The top 20 tiles with the highest attention scores were reviewed to identify morpho-molecular correlates. Predictions of a nuclear classification deep learning model serve to derive interpretable morphological features. We analysed 5-year recurrence-free survival and explored prognostic refinement by molecular class using the Kaplan-Meier method. Findings: im4MEC attained macro-average AUROCs of 0·874 (95% CI 0·856–0·893) on four-fold cross-validation and 0·876 on the independent test set. The class-wise AUROCs were 0·849 for POLEmut (n=51), 0·844 for MMRd (n=134), 0·883 for NSMP (n=120), and 0·928 for p53abn (n=88). POLEmut and MMRd tiles had a high density of lymphocytes, p53abn tiles had strong nuclear atypia, and the morphology of POLEmut and MMRd endometrial cancer overlapped. im4MEC highlighted a low tumour-to-stroma ratio as a potentially novel characteristic feature of the NSMP class. 5-year recurrence-free survival was significantly different between im4MEC predicted molecular classes in PORTEC-3 (log-rank pmut had an excellent prognosis, as do those with true POLEmut endometrial cancer. Interpretation: We present the first interpretable deep learning model, im4MEC, for haematoxylin and eosin-based prediction of molecular endometrial cancer classification. im4MEC robustly identified morpho-molecular correlates and could enable further prognostic refinement of patients with endometrial cancer. Funding: The Hanarth Foundation, the Promedica Foundation, and the Swiss Federal Institutes of Technology.

Slow microbial degradation of organic trace chemicals ("micropollutants") has been attributed to either downregulation of enzymatic turnover or rate-limiting substrate supply at low concentrations. In previous biodegradation studies, a drastic decrease in isotope fractionation of atrazine revealed a transition from rate-limiting enzyme turnover to membrane permeation as a bottleneck when concentrations fell below the Monod constant of microbial growth. With degradation of the pollutant 4-chlorophenol (4-CP) by Arthrobacter chlorophenolicus A6, this study targeted a bacterium which adapts its enzyme activity to concentrations. Unlike with atrazine degradation, isotope fractionation of 4-CP increased at lower concentrations, from epsilon(C) = -1.0 +/- 0.5 parts per thousand in chemostats (D = 0.090 h(-1), 88 mg L-1) and epsilon(C) = -2.1 +/- 0.5 parts per thousand in batch (c(0) = 220 mg L-1) to epsilon(C) = -4.1 +/- 0.2 parts per thousand in chemostats at 90 mu g L-1. Surprisingly, fatty acid composition indicated increased cell wall permeability at high concentrations, while proteomics revealed that catabolic enzymes (CphCI and CphCII) were differentially expressed at D = 0.090 h(-1). These observations support regulation on the enzyme activity level-through either a metabolic shift between catabolic pathways or decreased enzymatic turnover at low concentrations-and, hence, reveal an alternative end-member scenario for bacterial adaptation at low concentrations. Including more degrader strains into this multidisciplinary analytical approach offers the perspective to build a knowledge base on bottlenecks of bioremediation at low concentrations that considers bacterial adaptation.

Gemischtkörnige mineralische Abdichtungsmaterialien für Deponieoberflächenabdichtungen wurden hinsichtlich ihres Langzeitverhaltens untersucht. Versuchsreihen mit zyklischer Austrocknung und Wiederbefeuchtung ergaben, dass sich Austrocknungsrisse nach wenigen Zyklen kaum noch verändern und die Wasserdurchlässigkeit niedrig bleibt. Außerdem zeigen diese Materialien ein sehr geringes Schrumpfpotential. Wie die durchgeführten Versuche, zeigen auch numerische Wasserhaushaltsmodelle eine gute Langzeitwirksamkeit dieser Materialien. Mixed-grained sealing materials for surface liners of landfills were assessed regarding their long-term performance. Laboratory investigations under cyclic drying and wetting conditions showed that desiccation cracks remained stable after a few cycles and the water conductivity stayed low. Furthermore, these materials have a very low shrinking potential. Alike the laboratory investigations, numerical water balance models show a good long-term performance of these materials.

Micropollutants are frequently detected in groundwater. Thus, the question arises whether they are eliminated by natural attenuation so that pesticide degradation would be observed with increasing residence time in groundwater. Conventional analytical approaches rely on parent compound/metabolite ratios. These are difficult to interpret if metabolites are sorbed or further transformed. Compound-specific stable isotope analysis (CSIA) presents an alternative for identifying degradation based on the analysis of natural isotope abundances in pesticides and their changes during degradation. However, CSIA by gas chromatography–isotope ratio mass spectrometry is challenged by the low concentrations (ng/L) of micropollutants in groundwater. Consequently, large amounts of water need to be sampled requiring enrichment and clean-up steps from interfering matrix effects that must not introduce artefacts in measured isotope values. The aim of this study was to evaluate the accuracy of isotope ratio measurements of the frequently detected micropollutants atrazine, desethylatrazine and 2,6-dichlorobenzamide after enrichment from large water volumes (up to 100 L) by solid-phase extraction with consecutive clean-up by HPLC. Associated artefacts of isotope discrimination were found to depend on numerous factors including organic matter content and extraction volume. This emphasizes the necessity to perform a careful method evaluation of sample preparation and sample pre-treatment prior reliable CSIA.

In the course of the geotechnical investigations for a new runway at Munich Airport the hydro-mechanical behaviour of organogenic clays was studied. With the aim of an efficient use of materials the organogenic clay shall be used for noise and view barriers. As the organogenic clays have increased arsenic contents the percolation of such structures should be minimized. For the detailed investigation of the hydro-mechanical behaviour and for the determination of seepage quantities, a large scale, 5 m high, 30 m long and 25 m wide test fill was constructed. Due to the low permeability of the organogenic clays in compacted condition a cover design with a drainage mat and a top layer without an additional sealing layer was chosen. Measurements of the water balance were collected since the installation in 2008. The results show very low leachate quantities, although humid climatic conditions with average annual precipitation of approx. 745 mm were present. The low leachate rates can be mainly attributed to the capillary-breaking effect of the drainage geocomposite and the high water retention capacity of the topsoil. Based on the results the presented simple cover system can be considered an efficient and effective solution for minimizing infiltration water into core materials of embankments and noise barriers in road-way design.

An alternative to dumping mineral materials containing moderate amounts of contaminants into landfills is to reuse them in road embankments and noise protection barriers. To ensure groundwater protection, seepage of precipitation water through these materials must be omitted or reduced to a minimum. Embankments consisting of both cohesive and coarse-grained soil materials under various designs of cover layers were investigated within six field lysimeters. To gain the understanding of the water balance, quantities of seepage water, as well as runoff in the cover layers and on the surface were monitored. When using moderately contaminated materials in earthworks, reliable prediction of the water balance is crucial. Thus, in this study 2.5 years of the lysimeter experiments were modeled using the finite element software Vadose/W. Results were compared to the experimental data. The unsaturated hydraulic characteristics of the core materials were known from experimental investigations. Those of the topsoil and the shoulder material were estimated from databases of similar soils. A climate boundary condition represented the daily mean of the actual climate data on-site including road runoff. The modeled water balances were in good agreement with the field data for the cohesive core material of low permeability. However, a tendency to overestimate of seepage water was observed, which was even higher in the lysimeters with coarse-grained materials. This is linked to the water-permeability of the shoulder material and demonstrates that the cover layers have a major influence on the water balance of the whole embankment.

Organic contaminant degradation by suspended bacteria in chemostats has shown that isotope fractionation decreases dramatically when pollutant concentrations fall below the (half-saturation) Monod constant. This masked isotope fractionation implies that membrane transfer is slow relative to the enzyme turnover at μg L–1 substrate levels. Analogous evidence of mass transfer as a bottleneck for biodegradation in aquifer settings, where microbes are attached to the sediment, is lacking. A quasi-two-dimensional flow-through sediment microcosm/tank system enabled us to study the aerobic degradation of 2,6-dichlorobenzamide (BAM), while collecting sufficient samples at the outlet for compound-specific isotope analysis. By feeding an anoxic BAM solution through the center inlet port and dissolved oxygen (DO) above and below, strong transverse concentration cross-gradients of BAM and DO yielded zones of low (μg L–1) steady-state concentrations. We were able to simulate the profiles of concentrations and isotope ratios of the contaminant plume using a reactive transport model that accounted for a mass-transfer limitation into bacterial cells, where apparent isotope enrichment factors *ε decreased strongly below concentrations around 600 μg/L BAM. For the biodegradation of organic micropollutants, mass transfer into the cell emerges as a bottleneck, specifically at low (μg L–1) concentrations. Neglecting this effect when interpreting isotope ratios at field sites may lead to a significant underestimation of biodegradation., Please provide a synopsis

In den letzten Jahrzehnten wurden zunehmend Berichte über die Kontamination von Gewässern durch Spurenschadstoffe veröffentlicht. Dabei stellen persistente und polare Spurenschadstoffe ein besonders großes Risiko dar, da sie in das Grundwasser sickern können und somit die Haupt-Trinkwasserquelle vieler europäischer Länder verunreinigen können. Aus diesem Grund ist es im Interesse der Umweltbehörden und der Forschung das Verhalten dieser Spurenschadstoffe in der Umwelt zu untersuchen. Herkömmliche Methoden zur Einschätzung des Umweltverhaltens basieren auf Konzentrationsmessungen eines Schadstoffes, sowie dessen Abbauprodukt. Wird ein Abbauprodukt allerdings nicht nur gebildet, sondern dieses ebenfalls weiter transformiert, können die Resultate über das Abbauverhalten der Muttersubstanz mehrdeutig sein. Neben dem weiteren Abbau des Metaboliten kann es durch unterschiedliche Mobilitäten des Metaboliten und des Ausgangsstoffes, sowie durch wiederholte Remobilisierungen aus dem Boden zu Fehleinschätzungen bezüglich des Abbaus kommen, was eine Risikobeurteilung erschwert. Eine alternative Herangehensweise zur Identifikation von Abbauprozessen ist die substanzspezifische Stabil-Isotopen-Analytik (compound-specific stable isotope analysis, CSIA). Bei dieser Methode wird die natürliche Verteilung der Isotopenhäufigkeit eines Elements (z.B. Kohlenstoff, Stickstoff) analysiert. Bisher war die substanzspezifische Stabil- Isotopen-Analytik allerdings auf die Analyse von Schadstoffen im unteren μg/l Konzentrationsbereich beschränkt. Daher war ein Ziel dieser Arbeit den Anwendungsbereich der substanzspezifischen Stabil-Isotopen-Analytik zu erweitern, um robuste Analysen für umweltrelevante Konzentrationen zu bewerkstelligen. Realisiert wurde dies durch die Entwicklung analytischer Methoden für polare Spurenschadstoffe in Umweltproben, sowie deren Anwendung auf systematische Feldstudien. Zudem wurden die Limitierungen der substanzspezifischen Stabil-Isotopen-Analytik im untern ng/l Konzentrationsbereich untersucht. Dafür wurden indikativ die häufig detektierten Spurenschadstoffe Desphenylchloridazon (DPC), 2,6-Dichlorbenzamid (BAM), Atrazin (ATZ) und Desethylatrazin (DEA) als Modellsubstanzen verwendet. Im zweiten Kapitel dieser Arbeit wurden Methoden zur Kohlen- und Stickstoffisotopenanalyse (δ13C und δ15N) polarer Spurenschadstoffe am Beispiel von DPC entwickelt. Zur Bestimmung der Kohlenstoffisotopenverhältnisse wurde Flüssigchromatographie mit einem Isotopenmassenspektrometer (LC-IRMS) gekoppelt, während für die Bestimmung der Stickstoffisotopenverhältnisse eine Methode mittels Derivatisierung und Gaschromatographie-Isotopenmassenspektrometrie entwickelt wurde. Beide Methoden zeigten reproduzierbare und akkurate δ13C und δ15N Isotopenwerte mit einer Präzisionsgrenze im μg/l Konzentrationsbereich. Dabei waren 996 ng an DPC auf der GC- Säule (on-column) ausreichend für die Kohlenstoffisotopenanalyse. Für die Stickstoffisotopenanalyse musste das DPC zunächst mit einem 160-fachen Überschuss an Trimethylsilyldiazomethan (TMSD) derivatisiert werden. Dabei wurde eine Präzisionsgrenze von 1200 ng DPC auf der GC-Säule bestimmt. Da Spurenschadstoffe in der Umwelt allerdings in einem geringeren Konzentrationsbereich vorkommen (ng/l bis μg/l), war eine Optimierung dieser Methode hinsichtlich ihrer Sensitivität notwendig. Durch die Probeninjektion direkt auf die GC-Säule (on-column Injektion) statt der bisherigen Splitless-Injektionstechnik, konnte für die Bestimmung der Stickstoffisotopenverhältnisse eine Präzisionsgrenze von 100 ng DPC auf der GC-Säule erreicht werden. Danach wurde die Eignung beider Methoden für die Messung von niedrig konzentrierten Umweltproben geprüft. Dafür wurden die Stickstoffisotopenverhältnisse von DPC in mit DPC kontaminiertem Sickerwasser analysiert. Zusätzlich wurde das Sickerwasser mit Chloridazon (CLZ) versetzt, welches sich nach und nach zu DPC abgebaut hat. Die Analyse der Stickstoffisotopenverhältnisse von DPC zeigte Unterschiede in den Isotopensignaturen, was die Differenzierung zwischen unterschiedlichen Eintragungsquellen des DPCs ermöglicht. Nachdem die Methoden zur CSIA polarer Spurenschadstoffe am Beispiel des DPCs in Kapitel 2 entwickelt worden war, wurde eine systematische Feldstudie zum Umweltverhalten des DPC und seiner Ausgangsverbindung CLZ in Lysimetern durchgeführt. Die in Kapitel 3 beschriebene Studie lieferte neue Erkenntnisse über den Abbau von DPC. Dabei wurde der Aspekt der zeitgleichen Bildung und Transformation des Metaboliten betrachtet. Die Erkenntnisse wurden mithilfe zweier analytischer Ansätze ermittelt: der bereits etablierten Methode basierend auf den Konzentrationsverhältnissen von Metabolit zu Ausgangsstoff, und der seit kurzem verfügbaren Kohlenstoff- und Stickstoffisotopenanalytik. Es zeigte sich, dass: (i) DPC in allen Lysimetern mit einer signifikanten 13C und 15N Anreicherung von bis zu +4 ‰ bzw. +3 ‰ transformiert wurde und (ii) das gebildete DPC, welches noch nicht transformiert worden war, den gleichen Stickstoffisotopenwert wie sein Ausgangsstoff CLZ hatte. Nachdem es allerdings weiter abgebaut wurde, konnte eine signifikante Kohlenstoff- und Stickstoffisotopenfraktionierung beobachtet werden. Das Ausmaß der Isotopenfraktionierung wurde teilweise durch die Remobilisierung von nicht-transformiertem DPC abgeschwächt. II Zusammenfassung Zudem zeigte sich, dass das Ausmaß der Isotopenfraktionierung in Abhängigkeit von der Art der Anwendung des Herbizides und des Metaboliten variierte. Dies impliziert den Einfluss von Pflanzen und der präferentiellen Flüsse auf die Bildung und den Abbau von DPC. Zusätzlich konnte gezeigt werden, dass (iii) bei einer Transformation von DPC die Isotopensignatur als Indikator für den Abbau zuverlässiger war, als das Verhältnis von Metabolit zu Ausgangsverbindung. Daher diente CSIA als Indikator für die DPC- Transformation, vorausgesetzt, es findet keine gleichzeitige Bildung und Transformation von DPC statt. Sobald jedoch die DPC-Bildung dominierte, war der Nachweis des DPC-Abbaus durch CSIA nicht mehr eindeutig, da die Änderungen der Isotopenwerte durch den erneuten Eintrag von DPC verringert wurden. Dabei erreichten die Metabolit-zu-Ausgangsstoff- Verhältnisse ein Maximum und konnten somit den Nachweis für die DPC-Bildung erbringen. Das bedeutet, dass sich beide Methoden ergänzen, insbesondere, wenn nur ein teilweiser Abbau des Herbizids stattfindet, denn während das Metabolit-zu-Ausgangsstoff-Verhältnis Informationen über die Remobilisierung eines Analyten liefert, zeigt CSIA die Entwicklung des Abbaus einer Verbindung. Das vierte Kapitel dieser Arbeit befasst sich mit den Herausforderungen der CSIA polarer und persistenter Spurenschadstoffe im natürlichen System Grundwasser. Zur Identifikation und Bewertung der Herausforderungen wurde Grundwasser mit ATZ, DEA und BAM versetzt und die Modellsubstanzen aus großen Volumina extrahiert. Im Gegensatz zu den vorangegangenen Laborversuchen, bei denen die Analyten in Leitungswasser gelöst waren, führte die Extraktion der Substanzen aus dem Grundwasser zu kleinen und nicht reproduzierbaren Wiederfindungsraten. Als Grund für die unvollständige Wiederfindung der Analyten wird der Einfluss der Grundwassermatrix bei der Extraktion angenommen. So können organische Bestandteile des Grundwassers wie z.B. Humin- und Fulvinsäuren mit den Modellsubstanzen ATZ und DEA sogenannte Analyt-Fulvinsäure-Komplexe bilden. Diese Komplexe werden vor allem unter sauren pH-Bedingungen gebildet und das Einstellen eines niedrigen pH- Wertes war Teil dieser Methode. Neben den unvollständigen Wiederfindungsraten wurde bei der großvolumigen Probenanreicherung (Extraktion von bis zu 100 L pro Probe) eine starke Isotopenfraktionierung beobachtet. Die Fraktionierung entsteht durch den Einfluss der Matrix, welche ebenfalls bei der Festphasenextraktion angereichert wurde. Dabei beeinträchtigt die Isotopensignatur der organischen Bestandteile des Grundwassers die Isotopensignatur des Analyten und kann, falls nicht identifiziert, zu einer Fehleinschätzung in der Quantifizierung des Schadstoffabbaus führen. Die Prüfung der in diesem Kapitel vorgestellten Methode zeigt die Notwendigkeit einer kritischen Begutachtung und Identifikation von Fehlerquellen im Vorfeld von künftigen Methodenentwicklungen mit besonderem Augenmerk auch auf Matrixeffekte. Ziel zukünftiger Studien wird es sein, die in diesem Kapitel identifizierten Limitierungen der substanzspezifischen Stabil-Isotopen-Analytik durch die Weiterentwicklung und Optimierung von Methoden und Analysegeräten zu eliminieren. Reports of the contamination of natural water bodies with micropollutants have increased in the last decades. Most importantly, persistent and polar micropollutants are of major concern as they may leach into groundwater, the main source of drinking water in many countries within the European Union. Consequently, for environmental authorities and researchers, it is important to investigate the environmental fate of such micropollutants. Conventional assessment approaches rely on changes in concentrations of the contaminant and its metabolite. This, however, is often inconclusive as the simultaneous formation and transformation of the metabolite, differences in the mobility between parent compound and metabolite, or repeated mobilization may lead to erroneous interpretations. Compound- specific stable isotope analysis (CSIA) is a complementary approach to identify transformation processes based on the analysis of natural isotope abundances of an element (e.g. carbon, nitrogen). As CSIA has so far been limited to the analysis of pollutants in the sub-μg/L range, this thesis aims to broaden the application of CSIA by developing analytical methods for polar micropollutants in environmental samples, applying these for systematic field studies and testing the limits of CSIA in concentrations in the low ng/L range. To this end, the frequently detected micropollutants desphenylchloridazon (DPC), 2,6- dichlorobenzamide (BAM), atrazine (ATZ) and desethylatrazine (DEA) were used as model compounds. In the second chapter of this thesis, methods for carbon- and nitrogen-isotope analysis (δ13C and δ15N) of polar micropollutants were developed using liquid chromatography-isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography-IRMS (GC-IRMS). DPC was used as a representative compound for polar contaminants during method development. Both methods resulted in reproducible and accurate δ13C and δ15N analysis of DPC with a limit of precise isotope analysis in the μg/L concentration range. For carbon isotope analysis 996 ng of DPC on-column were sufficient. Nitrogen isotope analysis was achieved by derivatization of DPC with a 160-fold excess of (trimethylsilyl)diazomethane. To enable the application of CSIA to environmental samples, where micropollutants are present in a concentration range of ng/L to sub-μg/L, more sensitive methods were required. Thus, the nitrogen isotope analysis was optimized using on-column injection, which resulted in accurate δ15N analysis for amounts greater than 100 ng DPC on-column. The feasibility of both methods was proven by measuring the isotopic composition of DPC in DPC-containing environmental-seepage water spiked with chloridazon (CLZ). The analysis indicated that it is possible to distinguish DPC containing different isotopic signatures. After the feasibility of CSIA for polar micropollutants such as DPC was shown, a systematic field study of the DPC and its parent compound CLZ was carried out as detailed in Chapter 3. This study gave new insights into DPC degradation pinpointing the influence of simultaneous formation and transformation of the metabolite using two analytical approaches—the well- established metabolite-to-parent compound ratio and the recently available carbon and nitrogen CSIA. We found that (i) DPC was transformed in all lysimeters, showing a significant enrichment in 13C and 15N by approximately +4 ‰ and +3 ‰, respectively. (ii) Formed DPC, which had not been subject to further transformation yet, showed the same nitrogen isotope value as its precursor CLZ. As further transformation took place, significant carbon and nitrogen isotope fractionation was observed that was partially attenuated when mixing with freshly mobilized DPC from the vadose zone took place. The extent of isotope fractionation varied depending on the method of application of the parent herbicide and metabolite, implying the influence of plants, and the preferential flow on the formation and degradation of DPC. Additionally, we demonstrated that (iii) when DPC was further transformed, the isotopic signature, as an integrated signal of DPC degradation, was more reliable as an indicator of degradation than the metabolite-to-parent-compound ratio. Hence, this study enables the application of CSIA as an indication of DPC transformation, provided that there is no simultaneous formation and transformation of DPC. On the other hand, when DPC formation dominated and evidence from CSIA was not conclusive because changes in isotope values were reduced by the fresh input, metabolite-to-parent-ratios reached a maximum and could provide evidence of DPC formation. This leads to the conclusion that both methods are complementary, in particular when only partial degradation of the herbicide is occurring. While the metabolite-to-parent ratio provides information about the re-mobilization of a compound, CSIA shows the evolution of a compound’s degradation. In Chapter 4 of this thesis, challenges in CSIA of polar and persistent micropollutants in groundwater were identified and critically discussed by evaluating a large volume extraction method of up to 100 L groundwater using ATZ, DEA and BAM as model compounds in low ng/L concentration ranges. It was found that, in contrast to previous laboratory experiments, where tap water was used, extracts from environmental groundwater resulted in low and non- reproducible recoveries. Since groundwater contains organic matter such as humic and fulvic acids, and as acidification was part of the extraction procedure, it is assumed that the change in pH prior to solid-phase extraction (SPE) may favor the formation of analyte-fulvic acid complexes leading to the low recoveries observed. In addition to unsatisfactory recoveries, the extensive sample enrichment also resulted in an extensive isotope fractionation as the isotopic signature of the organic matter interfered with the carbon isotope ratio of the target analytes. Such an interference would lead to an overestimation in the quantification of degradation, if unidentified. Thus, it is essential for future analytical method developments to critically evaluate each method and to include the investigation about a possible influence of sample matrix on the analysis already in the pre-tests. As this study has shown the limitations of CSIA of polar micropollutants in complex sample matrices, future studies may use this as a starting point towards more sensitive isotope analysis by methodological and instrumental advances.

Desphenylchloridazon (DPC), the main metabolite of the herbicide chloridazon (CLZ), is more water soluble and persistent than CLZ and frequently detected in water bodies. When assessing DPC transformation in the environment, results can be nonconclusive if based on concentration analysis alone because estimates may be confounded by simultaneous DPC formation from CLZ. This study investigated the fate of DPC by combining concentration-based methods with compound-specific C and N stable isotope analysis (CSIA). Additionally, DPC formation and transformation processes were experimentally deconvolved in a dedicated lysimeter study considering three scenarios. First, surface application of DPC enabled studying its degradation in the absence of CLZ. Here, CSIA provided evidence of two distinct DPC transformation processes: one shows significant changes only in C-13/C-12, whereas the other involves changes in both C-13/C-12 and N-15/N-14 isotope ratios. Second, surface application of CLZ mimicked a realistic field scenario, showing that during DPC formation, C-13/C-12 ratios of DPC were depleted in C-13 relative to CLZ, while N-15/N-14 ratios remained constant. Finally, CLZ depth injection simulated preferential flow and demonstrated the importance of the topsoil for retaining DPC. The combination of the lysimeter study with CSIA enabled insights into DPC transformation in the field that are superior to those of studies of concentration trends.

The idiopathic Parkinson's disease (iPD) is a progressive neurodegenerative disorder primarily resulting in impaired movement execution. In the course of the disease symptom fluctuation is common and makes adequate treatment difficult. In this overview the current approaches using modern and especially mobile technologies for diagnosis, monitoring and treatment of iPD are presented. Currently, there are no medical aids ready for point of care application; however, the development of these technologies has great potential for improving care for patients suffering from iPD.

Increasing applications of compound-specific chlorine isotope analysis (CSIA) emphasize the need for chlorine isotope standards that bracket a wider range of isotope values in order to ensure accurate results. With one exception (USGS38), however, all international chlorine isotope reference materials (chloride and perchlorate salts) fall within the narrow range of one per mille. Furthermore, compound-specific working standards are required for chlorine CSIA but are not available for most organic substances. We took advantage of isotope effects in chemical dehalogenation reactions to generate (i) silver chloride (CT16) depleted in 37Cl/35Cl and (ii) compound-specific standards of the herbicides acetochlor and S-metolachlor (Aceto2, Metola2) enriched in 37Cl/35Cl. Calibration against the international reference standards USGS38 (-87.90 ‰) and ISL-354 (+0.05 ‰) by complementary methods (gas chromatography-isotope ratio mass spectrometry, GC-IRMS, versus gas chromatography-multicollector inductively coupled plasma mass spectrometry, GC-MC-ICPMS) gave a consensus value of δ37ClCT16 = -26.82 ± 0.18 ‰. Preliminary GC-MC-ICPMS characterization of commercial Aceto1 and Metola1 versus Aceto2 and Metola2 resulted in tentative values of δ37ClAceto1 = 0.29 ± 0.29 ‰, δ37ClAceto2 = 18.54 ± 0.20 ‰, δ37ClMetola1 = -4.28 ± 0.17 ‰ and δ37ClMetola2 = 5.12 ± 0.27 ‰. The possibility to generate chlorine isotope in-house standards with pronounced shifts in isotope values offers a much-needed basis for accurate chlorine CSIA.

Compound-specific isotope analysis (CSIA) is a valuable tool for assessing the fate of organic pollutants in the environment. However, the requirement of sufficient analyte mass for precise isotope ratio mass spectrometry combined with prevailing low environmental concentrations currently limits comprehensive applications to many micropollutants. Here, we evaluate the upscaling of solid-phase extraction (SPE) approaches for routine CSIA of herbicides. To cover a wide range of polarity, a SPE method with two sorbents (a hydrophobic hypercrosslinked sorbent and a hydrophilic sorbent) was developed. Extraction conditions, including the nature and volume of the elution solvent, the amount of sorbent and the solution pH, were optimized. Extractions of up to 10 L of agricultural drainage water (corresponding to up to 200000-fold pre-concentration) were successfully performed for precise and sensitive carbon and nitrogen CSIA of the target herbicides atrazine, acetochlor, metolachlor and chloridazon, and metabolites desethylatrazine, desphenylchloridazon and 2,6-dichlorobenzamide in the sub-g L-1-range. C-13/C-12 and N-15/N-14 ratios were measured by gas chromatography-isotope ratio mass spectrometry (GC/IRMS), except for desphenylchloridazon, for which liquid chromatography (LC/IRMS) and derivatization-GC/IRMS were used, respectively. The method validated in this study is an important step towards analyzing isotope ratios of pesticide mixtures in aquatic systems and holds great potential for multi-element CSIA applications to trace pesticide degradation in complex environments.

The widespread application of herbicides impacts surface water and groundwater. Metabolites (e.g., desphenylchloridazon from chloridazon) may be persistent and even more polar than the parent herbicide, which increases the risk of groundwater contamination. When parent herbicides are still applied, metabolites are constantly formed and may also be degraded. Evaluating their degradation on the basis of concentration measurements is, therefore, difficult. This study presents compound-specific stable isotope analysis (CSIA) of nitrogen- and carbon-isotope ratios at natural abundances as an alternative analytical approach to track the origin, formation, and degradation of desphenylchloridazon (DPC), the major degradation product of the herbicide chloridazon. Methods were developed and validated for carbon- and nitrogen-isotope analysis (delta C-13 and delta N-15) of DPC by liquid chromatography-isotope-ratio mass spectrometry (LC-IRMS) and derivatization gas chromatography-IRMS (GC-IRMS), respectively. Injecting standards directly onto an Atlantis LC-column resulted in reproducible delta(13)-isotope analysis (standard deviation 100 ng of DPC with 160-fold excess of (trimethylsilyl)diazomethane. Application of the method to environmental-seepage water indicated that newly formed DPC could be distinguished from "old" DPC by the different isotopic signatures of the two DPC sources.

The suitability of two different tracers to mimic the behavior of pesticides in agricultural soils and to evidence the potential for preferential flow was evaluated in outdoor lysimeter experiments. The herbicide atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] was used as a model compound. Two tracers were used: a nonadsorbing tracer (bromide) and a weakly adsorbing dye tracer (uranine). Two soils that are expected to show a different extent of macropore preferential flow were used: a well‐drained sandy‐loamy Cambisol (gravel soil) and a poorly drained loamy Cambisol (moraine soil). Conditions for preferential flow were promoted by applying heavy simulated rainfall shortly after pesticide application. In some of the experiments, preferential flow was also artificially simulated by injecting the solutes through a narrow tube below the root zone. With depth injection, preferential leaching of atrazine occurred shortly after application in both soil types, whereas with surface application, it occurred only in the moraine soil. Thereafter, atrazine transport was mainly through the porous soil matrix, although contributions of preferential flow were also observed. For all the application approaches and soil types, after 900 d