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Institut
- Institut für Nachhaltige Chemie und Umweltchemie (INUC) (23) (entfernen)
In der vorliegenden Arbeit werden Untersuchungsergebnisse von niedersächsischen Gewässern auf Triphenylzinn (TPT) präsentiert. Betrachtet werden die Matrices Wasser, Schwebstoff, Sediment und aquatische Organismen, wie Makrozoobenthos und Fische, um eine möglichst umfassende Aussage hinsichtlich des Akkumulationsverhaltens von TPT zu erhalten. Da TPT ein ähnlich endokrin wirksames Potential wie Tributylzinn (TBT) aufweist, über TBT aber wesentlich mehr Informationen und Erkenntnisse als über TPT vorliegen, sind zudem vergleichende Betrachtungen zwischen diesen beiden Organozinnspezies angestellt worden. Die wichtigsten Aussagen dieser Arbeit sind, dass sich TPT in den Kompartimenten Wasser, Schwebstoff und Sediment unauffällig verhält, es jedoch über ein sehr hohes Bioakkumulationsverhalten verfügt. Aus diesen Ergebnissen ist zu fordern, dass Gewässerüberwachungsprogramme unbedingt um die Stufe eines Biomonitorings, in dem aquatische Organismen als Endglieder der Nahrungskette auf Schadstoffe untersucht werden, zu erweitern sind.
Die Emissionen des Kraftfahrzeugverkehrs stellen eine bedeutende Quelle für Luftschadstoffe dar. Um die Luftbelastung durch Kfz zu vermindern, wurden in der Europäischen Gemeinschaft 1970 Grenzwerte für Kraftfahrzeug-Emissionen eingeführt, die sukzessive verschärft werden. Bis 2005 werden die Grenzwerte für Pkw auf ca. 3 % des Ausgangsn iveaus gefallen sein.
Über 90 % der Schadstoffe aus motorischer Verbrennung entstehen in der Kaltstartphase und bei Lastwechseln. Eine Optimierung dieser instationären Betriebszustände des Motors ist notwendig, um zukünftige Emissionsgrenzwerte einhalten zu können Die zur Bestimmung der Abgasemissionen vorgeschriebene Test- und Analyseprozedur ermittelt
lediglich einen integralen Emissionswert über einen vorgeschriebenen Fahrzyklus. Aussagen über den Zeitpunkt der Entstehung und die Höhe einzelner Konzentrationsspitzen werden mit dieser Methode nicht erhalten. Diese Informationen sind jedoch für Entwickler von Motoren und Abgasnachbehandlungssystemen von besonderer Bedeutung. Sie benötigen für die Optimierung eine Analysemethode, die in der Lage ist, dynamische Konzentrationsverläufe von Abgaskomponenten im Rohabgas zu erfassen. Die notwendige Messfrequenz ist abhängig von der Messaufgabe und sollte nach Möglichkeit eine höhere zeitliche Auflösung aufweisen als der zu beurteilende Prozess. Neben der Dynamik des Analysengerätes ist die Ausführung der Probenahme hierbei von ent
scheidender Bedeutung.
In der Umweltanalytik steht die Analyse von potenziellen Schadstoffen im Vordergrund. Häufig ist die negative Wirkungsweise dieser Schadstoffe auf Organismen und Umweltkompartimente bekannt. Dennoch kommt es vor, dass Organismen in einem Ökosystem geschädigt werden, ohne dass dies auf eine bekannte Ursache zurückgeführt werden kann. Der Ansatz der wirkungsspezifischen Analyse greift an diesem Punkt an, da er mit Hilfe von chemisch-analytischen Verfahren die Identifizierung von Schadstoffen mit der Erkenntnis über deren potenzielle Wirkungen auf Organismen mittels Biotests kombiniert. SCHUETZLE UND LEWTAS (1986) stellten fest, dass die Nutzung von Biotests in Verbindung mit analytischen Messungen einen leistungsfähigen Ansatz zur Identifizierung von Umweltschadstoffen darstellt. Sie prägten den Begriff 'Bioassay-Directed Chemical Analysis' (BDCA). Dieses Konzept der 'Biotest-geleiteten chemischen Analyse', oder auch 'Wirkungsspezifische Analyse' genannt, dient folglich der Identifizierung von toxischen Verbindungen in Umweltproben. Es ist verwandt mit dem dreistufigen Konzept 'Toxicity Identification and Evaluation' (TIE) (Toxizität, Identifizierung und Beurteilung), das Ende der 80er Jahre von der amerikanischen Umweltbehörde US-EPA eingeführt wurde.
Der Seehund wird in Monitoring-Programmen zum Zustand des Ökosystems Wattenmeer (z.B. TMAP) als ein Indikatororganismus genutzt. Aufgrund der Position im Nahrungsnetz (Top-Prädatoren) und der langen Lebensspanne sind Seehunde besonders stark mit Schadstoffen belastet, u.a. mit Polychlorierten Biphenylen (PCB) und Perfluoroctansulfonat (PFOS). Zahlreiche Studien deuten darauf hin, dass die Schadstoffbelastung die Gesundheit der Seehunde beeinträchtigt. Das Ziel unserer Arbeitsgruppe ist die Identifizierung neuer Biomarker, die im Lebendmonitoring von Seehunden eingesetzt werden können. Ziel der vorliegenden Arbeit war die Ausarbeitung und Etablierung eines Zellkulturmodells, welches in weiterführenden Arbeiten die Identifizierung der Biomarker ermöglicht. Als Biomarker sollen Proteinmuster verwendet werden, die eine Früherkennung von schadstoffbedingten Veränderungen in der Seehundpopulation ermöglichen. Da Hepatozyten an der Metabolisierung von Xenobiotika beteiligt sind, werden sie für das Zellkulturmodell verwendet. Von den Hepatozyten werden in vivo Plasmaproteine synthetisiert, die bei in vitro Experimenten im Zellkulturmedium nachweisbar sind. Diese Proteine könnten anschließend als Biomarker in einem Lebendmonitoring (Blutproben) an Seehunden eingesetzt werden. Für das Zellkulturmodell wurden primäre Seehund-Hepatozyten mit Schadstoffen (PCB, PFOS) in umweltrelevanten Konzentrationen inkubiert. Als Kontrolle dienten Zellen, die nur mit dem jeweiligen Lösungsmittel inkubiert wurden (Isooctan für PCB; DMSO für PFOS). Da in der Literatur bisher keine Isolierung von Hepatozyten aus marinen Säugern beschrieben wurde, musste eine geeignete Isolierungsmethode etabliert werden. Die Methode musste die Isolierung vitaler Hepatozyten aus bereits verstorbenen Tieren in ausreichend hoher Menge ermöglichen. Es wurden verschiedene Isolierungsmethoden getestet von denen sich nur die Leberbiopsie Perfusion eignete. Sämtliche Parameter müssen mit den sich anschließenden Proteomanalysen kompatibel sein. Die Hepatozyten müssen ihre Vitalität nach der Isolierung und während der Kultivierung beibehalten. Zur Analyse der Vitalität wurden der XTT- und LDH-Test (allgemeiner Stoffwechsel und Membranintegrität) angewendet sowie die Harnstoffsynthese (leberspezifischer Stoffwechsel) beurteilt. Mit Hilfe der Zelltests wurde die Vitalität der Hepatozyten im Verlauf einer dreitägigen Kultivierung untersucht und der Einfluss einer Schadstoffinkubation auf die Zellvitalität analysiert. Die Schadstoffe sollen in den eingesetzten Konzentrationen keinen Einfluss auf die Zellvitalität oder Morphologie haben. Die Ergebnisse aus den Vitalitätstests zeigten, dass die verwendeten PCB-Konzentrationen keinen signifikanten Einfluss auf die Vitalität hatten. Eine Aussage zum Einfluss einer PFOSInkubation auf die Zellen (XTT- und Harnstoff-Test) konnte nicht gemacht werden, da die DMSO-Konzentration in den Proben zu hoch gewählt wurde. Die PFOSInkubation hatte keinen signifikanten Einfluss auf die Membranintegrität. Anhand erster Testreihen, die in unserer Arbeitsgruppe realisiert wurden, konnte die Funktionalität des Zellkulturmodells überprüft werden. Hierzu wurden Proteomanalysen von Seehund-Hepatozyten durchgeführt, die mit PCB inkubiert wurden. Erste Ergebnisse zeigten, dass es zu einer signifikanten Hochregulierung der Expressionslevel einiger Proteine kam, die am Schadstoffabbau beteiligt sind. In der vorliegenden Arbeit wurde erfolgreich ein Zellkulturmodell mit primären Seehund-Hepatozyten entwickelt, welches die Identifizierung neuer Biomarker für Seehunde ermöglicht.
Air quality models are important tools which are utilized for a large field of application. When combined with data from observations, models can be employed to create a comprehensive estimation of the past and current distribution of pollutants in the atmosphere. Moreover, projections of future concentration changes due to changing emissions serve as an important decision basis for policymakers. For the determination of atmospheric concentrations of air pollutants by means of numerical modelling it is essential to possess a model which is able to create anthropogenic and biogenic emissions with a temporally and spatially high resolution. The emission data is needed as input for a chemistry transport model which calculates transport, deposition, and degradation of air pollutants. To evaluate the impact of changing emissions on the environment a flexible emission model with the capability to create diverse emission scenarios is needed. Further, it is important to always take into account a variety of different species to properly represent the major chemical reactions in the atmosphere (e.g. ozone chemistry, aerosol formation). Currently there are only a few high resolution emission datasets available for Europe. The amount of substances included in these datasets, however, is limited. Moreover, they can not be used as basis for the creation of new emission scenarios. To enable the creation of emission scenarios in the course of this doctoral thesis the American emission model SMOKE was adopted and modified. On the basis of a multitude of different georeferenced datasets, official statistics, and further model results the newly created emission model “SMOKE for Europe” is capable of creating hourly emission data for the European continent with a spatial resolution of up to 5x5km2. In order to demonstrate the universal applicability of the emission model the carcinogenic species benzo[a]pyrene (BaP) was exemplarily implemented into the model. BaP belongs to the group of polycyclic aromatic hydrocarbons. Because of its high toxicity the European Union introduced an annual target value of 1 ng/m3 in January 2010. SMOKE for Europe was used to create a variety of emission scenarios for the years 1980, 2000, and 2020. These emission scenarios were then used to determine the impact of emission changes on atmospheric concentrations of BaP and to identify regions which exceed the European target value. Additionally the impact of different legislation and fuel use scenarios on the projected atmospheric concentrations in 2020 was investigated. Furthermore, additional use cases for a flexible emission model are pointed out. The SMOKE for Europe model was used to simulate the transport of volcanic ash after the eruption of the Icelandic volcano Eyjafjallajokull in March 2010. By comparison of modelled concentrations for different emission scenarios with observations from remote sensing and air plane flights distribution and concentration of the volcanic ash over Europe was estimated. The results of this thesis have been presented in four scientific papers published in international peerreviewed journals. The papers are reprinted at the end of this thesis.
Uranine (sodium fluorescein, UR) has been routinely used in hydrological research to monitor surface and subsurface water flow, transport and mixing processes since the end of nineteenth century. Based on such obtained data, further conclusions can be drawn on the spread and behavior of pollutants (partly on models). Use of UR for qualitative (visual) studies of underground contamination is common, however data available on its environmental behavior (e.g., conversion, degradation or formation and fate of the transformation products, TPs) are incomplete or not readily comparable. UR observations of biodegradation are still speculative. S-metolachlor (SM) is a popular worldwide chloroacetamide herbicide, which highly correspond to the global pesticide use. It is offered on the French market as an effective multicrop herbicide against annual grasses and certain broadleaf weeds under the trade name Mercantor Gold (MG). Photodegradation contributes to the fate of SM in the aquatic environment. TPs were already found in surface and groundwater. However, further fate and assessment of the TPs was not done. Moreover, adjuvants in MG´s formula can affect the solubility, biodegradation, photolysis and sorption properties of the active compound SM. TPs can have different properties (e.g. more mobile, toxic or present at higher concentrations) that enable them to reach the environmental compartments not affected by the parent compound (PC) itself. To assess the ecological impact of pesticides, tracers, and their respective TPs on water organisms, their behavior can be investigated in laboratory screening biodegradation tests. Yet, incomplete data was available on SM, MG and UR transformation or their photo- TPs´ fate in surface and water-sediment systems. The combination of photolysis with aerobic biodegradation in order to identify persistent photo-TPs could provide new insight into the environmental behavior of the selected compounds. Therefore, principle of this thesis was to 1) identify the impact of MG´s adjuvants on the biodegradation, photolysis (Xe lamp) and sorption compared to the SM alone, 2) examine the photolysis and biodegradability of UR 3) monitor the primary elimination (photolysis) of the PCs by HPLC (-UV, -FLD) and measure the degree of mineralization by means of nonpurgeable organic carbon (NPOC) 4) elucidate the photo-TPs of SM, MG and UR by using LCMS/ MS 5) analyze biodegradability of the photo-TPs in order to determine their fate and persistence in aquatic environment 6) conduct in silico toxicity predictions (pesticides) in human (carcinogenicity, genotoxicity and mutagenicity) and eco-toxicity (microtoxicity, bioconcentration factor and toxicity in rainbow trouts). SM, MG and UR were found not readily biodegradable in Closed Bottle test (CBT), Manometric Respiratory test (MRT) and in water-sediment test (WST). Chemical analysis of photolysis samples showed higher elimination of SM in MG compared to SM alone whereas UR displayed high primary elimination rate in general. The overall low degree of mineralization indicated that abundant photo-TPs were formed. Furthermore, the photo-TPs were found not biodegradable in performed biodegradation tests. Only small degradation rates for UR could be observed in the CBT and WST. Additionally, in the MRT and WST new bio-TPs were generated from the photo-TPs of SM and SM in MG. Obtained results suggest that the MG formulation did not significantly affect the biodegradation, however it influenced the diffusion of the active substance (SM) to sediment and potentially affected the photolysis efficiency, which might result in faster formation of photo-TPs in the environment. In silico predictions showed that for many endpoints, biotransformation might lead to an increased toxicity in humans and to water organisms compared with the parent compound SM. No indications were found for UR toxicity. Still, target-oriented investigations on long term impacts of photo-TPs from UR are warranted. The present work demonstrates that a combination of laboratory tests, analytical analysis and in silico tools result in valuable information regarding environmental fate of the TPs from selected compounds. Furthermore, it was shown that photo-TPs formed in the aquatic environment should be taken into account not only the parent compound and its decay.
In the discourse on pharmaceuticals in the environment, hardly any attention has been paid to anticancer drugs. Because of their none-selective modes of action, that is, because they affect both cancerous and healthy cells, these drugs are regarded as potentially carcinogenic, genotoxic, mutagenic, and teratogenic substances. It is, however, not known how and to what extent these substances affect organisms and the environment in the long run. For this reason, this dissertation evaluated, addressing several endpoints and using organisms from different trophic levels and in silico predictions, the fate (bio- and photo degradation) and ecotoxicity of these substances. Four anticancer drugs (cyclophosphamide (CP), 5-fluorouracil (5-FU), methotrexate (MTX), and imatinib (IM) were selected. None of these anticancer compounds can be classified as ´readily biodegradable,´ a classification that indicates that biodegradation will only play a minor role in the elimination of these compounds and that they cannot be removed by the conventional processes used in sewage treatment plants and will most likely remain in the water cycle. Despite the high degrees of mineralization achieved in advanced (photo)oxidation processes, it was not possible to fully mineralize the compounds, a result that indicates that transformation products were created during these reactions. The ecotoxicity assays performed with V. fischeri indicated that 5-FU was, of all the substances tested, likely to be the most toxic (very toxic), followed by MTX (toxic) and IM (toxic/harmful), whereas CP was nontoxic. MTX presented the highest phytoxicity activity in the Lactuca sativa assay, followed by 5-FU, IM, and CP. The results of the tests performed with A. cepa showed cytotoxic (5-FU, MTX, and CP) and genotoxic effects (5-FU, CP, and IM) and mutagenic activity (5-FU, MTX, CP, and IM) of the compounds. Photo transformation products (PTPs) of CP, MTX, and 5-FU were nontoxic towards V. fischeri. However, some PTPs formed during the photodegradation of 5-FU led to positive mutagenic and genotoxic alerts in several in silico models. Not one of the compounds examined in this dissertation is likely to be fully eliminated from the water cycle by (natural) photolysis and/or advanced oxidation. Moreover, some of the treatments resulted in the formation of stable intermediates that were even less biodegradable than parent compounds. This finding shows that it is not enough to focus on primary elimination because TPs are not necessarily better biodegradable than their respective parent compounds. As indicated by the genotoxic and mutagenic positive alerts presented by different in silico models, the PTPs observed here are likely to require, despite their lower toxicity in comparison to the parent compounds, screening after treatments.
After being administrated to humans or animals, pharmaceuticals may be metabolized by a variety of mechanisms and pathways within the body. Once these compounds and/or their metabolites are excreted, they may undergo degradation in the aquatic environment. Unfortunately, a rapid and complete mineralization cannot always be guaranteed, whereas relatively stable transformation products (TPs) may be formed. The largest part of older studies focused on investigation of the elimination kinetics of parent compounds without considering the amount and chemical structure of individual TPs. Only recently, there is an increasing trend to deliver such information. Nevertheless, since drugs are defined as significant environmental pollutants, it is not only important to elucidate their TPs, but also necessary to investigate whether these formed compounds preserve the same mode of action as the parent compound or are even more toxic. Thus, two main objectives of this thesis can be formulated. Firstly, to highlight the concern originated by metabolites and transformation products of pharmaceuticals that contaminate the environment. Hereby, the already-published knowledge on TPs within a certain selection of drugs is assessed to exemplify the number and quality of the existing information on their TPs. Secondly, to particularly investigate the fate of the antibiotic ciprofloxacin (CIP). This is done by (a) evaluating the suitability and sustainability of the photolytic decomposition as an advanced water treatment technique, (b) monitoring the course of genotoxicity of the irradiated mixtures using a battery of genotoxicity and cytoxicity in vitro assays, and (c) considering the potential genotoxicity for CIP´s individual TPs by the employment of in silico approaches using quantitative structure activity relationships (QSAR) models. This thesis based on the results and conclusions of five articles, which can be found in the appendix. A systematic literature review was conducted on the current state of knowledge on pharmaceuticals and its derivatives in the environment. Two groups, namely antibiotics and anticancer drugs, were considered more closely with respect to the availability of chemical structures for their TPs. Furthermore, the photodegradation of CIP as well as a preliminary toxicity assessment of its identified TPs were investigated in three research papers. An extensive review with a table at its core shows the existing data on 158 TPs, which already have an assigned registry number in chemical abstracts service (CAS-RN), was presented. In total, 294 TPs, identified with chemical structures in the literature, were found for 15 compounds out of the 21 that were selected as target compounds. Eleven TPs, created from CIP, were identified by high-performance liquid chromatography/high-resolution multiple-stage mass spectrometry. It was detected that the transformation of CIP mainly occurred through substitution of fluorine, defluorination, hydroxylation of the quinolone core and the breakdown of the piperazine ring. Some of the identified TPs of CIP were predicted as genotoxic by QSAR analysis, while the experimental testing for a few genotoxic and cytotoxic endpoints showed that the potential of the resultant mixtures could be primarily dependent on the concentration of residual CIP. In contrast, irradiation mixtures were neither mutagenic in the Ames Test nor genotoxic in the in vitro Micronucleus Test. It is possible that the effect of the TPs was masked by antagonistic mixture interactions and/or they were not formed at effectively concentrations. Nevertheless, all of the identified TPs of CIP still retained the core quinolone moiety, which is responsible for the biological activity. Thus, a more comprehensive assessment, encompassing more genotoxic endpoints, chemical analysis characterization and exposure analyses, needs to be conducted. Information available on TPs demonstrates that already slight changes in treatment conditions and processes result in the formation of different TPs. Nevertheless, most of the transformation products could neither be identified nor fully assessed regarding their toxicity. This, in turn, presents a major challenge for the identification and assessment of TPs. Hence, from a practical and sustainability point of view, limiting the input of pharmaceuticals into effluents as well as improving their (bio)degradability and elimination behavior, instead of only relying on advanced effluent treatments, is urgently needed. Solutions that focus on this