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With 47% land coverage in 2016, agricultural land was one of the largest terrestrial biomes in Germany. About 70% of the agricultural land was cropped area with associated pesticide applications. Agricultural land also represents an essential habitat for amphibians. Therefore, exposure of amphibians to agrochemicals, such as fertilizers and pesticides, seems likely. Pesticides can be highly toxic for amphibians, even a fraction of the original application rate may result in high amphibian mortality.
To evaluate the potential risk of pesticide exposure for amphibians, the temporal coincidence of amphibian presence on agricultural land and pesticide applications (N = 331) was analyzed for the fire-bellied toad (Bombina bombina), moor frog (Rana arvalis), spadefoot toad (Pelobates fuscus) and crested newt (Triturus cristatus) during spring migration. In 2007 and 2008, up to 80% of the migrating amphibians temporally coincided with pesticide applications in the study area of Müncheberg, about 50 km east of Berlin. Pesticide interception by plants ranged between 50 to 90% in winter cereals and 80 to 90% in winter rape. The highest coincidence was observed for the spadefoot toad, where 86.6% of the reproducing population was affected by a single pesticide in winter rape during stem elongation with 80% pesticide interception by plants. Late migrating species, such as the fire-bellied toad and the spadefoot toad, overlapped more with pesticide applications than early migrating species, such as the moor frog, did. Under favorable circumstances, the majority of early migrants may not coincide with the pesticide applications of arable fields during spring migration.
To evaluate the potential effect of pesticide applications on populations of the common frog (Rana temporaria), a landscape genetic study was conducted in the vinicultural area of Southern Palatinate. Due to small sample sizes at breeding sites within viniculture, several DNA sampling methods were tested. Furthermore, the novel repeated randomized selection of genotypes approach was developed to utilize genetic data from siblings for more reliable estimates of genetic parameters. Genetic analyses highlighted three of the breeding site populations located in viniculture as isolated from the meta-population. Genetic differentiation among breeding site populations in the viniculture (median pairwise FST=0.0215 at 2.34 km to 0.0987 at 2.39 km distance) was higher compared to genetic differentiation among breeding site populations in the Palatinate Forest (median pairwise FST=0.0041 at 5.39 km to 0.0159 at 9.40 km distance).
The presented studies add valuable information about the risk of pesticide exposure for amphibians in the terrestrial life stage and possible effects of agricultural land on amphibian meta-populations. To conserve endemic amphibian species and their (genetic) diversity in the long run, the risk assessment of pesticides and applied agricultural management measures need to be adjusted to protect amphibians adequately. In addition, other conservation measures such as the creation of new suitable breeding site should be considered to improve connectivity between breeding site populations and ensure the persistence of amphibians in the agricultural land.
Studies have shown that wastewater treatment plant (WWTP) effluents are the major pathways of organic and inorganic chemicals of anthropogenic use (=micropollutants) into aquatic environments. There, micropollutants can be transferred to ground water bodies - and may finally end up in drinking water - or cause various effects in aquatic organisms like multiple resistances of bacteria. Hence, the upgrading of WWTPs with the aim to reduce the load of those micropollutants is currently under discussion.
Therefore, the primary objective of this thesis was to assess ecotoxicological effects of wastewater ozonation, a tertiary treatment method, using specifically developed toxicity tests with Gammarus fossarum (Koch) at various levels of ecological complexity. Several studies were designed in the laboratory and under semi-field conditions to cope with this primary objective. Prior to the investigations with ozone treated wastewater, the ecotoxicity of secondary treated (=non-ozone treated) wastewater from WWTP Wüeri, Switzerland, for the test species was assessed by a four-week experiment. This experiment displayed statistically significant impairments in feeding, assimilation and physiological endpoints related to population development and reproduction. The first experiment investigating ecotoxicological implications of ozone application in wastewater from the same WWTP displayed a preference of G. fossarum for leaf discs conditioned in ozone treated wastewater when offered together with leaf discs conditioned in non-ozone treated wastewater. This effect seems to be mainly driven by an alteration in the leaf associated microbial community. Another series of laboratory experiments conducted also with wastewater from WWTP Wüeri treated with ozone at the lab- or full-scale, revealed significantly increased feeding rates of G. fossarum exposed to ozone treated wastewater compared to non-ozone treated wastewater. These laboratory experiments also indicated that any alteration in the organic matrix potentially caused by ozone treatment is not related to the effects in feeding as this endpoint showed only negligible deviation in secondary treated wastewater, which contained hardly any (micro)pollutants (i.e. pharmaceuticals), from the same wastewater additionally treated with ozone. Moreover, it was shown that shifts in the dissolved organic carbon (DOC) profile do not affect the feeding rate of gammarids. In situ bioassays conducted in the receiving stream of the WWTP Wüeri confirmed the results of the laboratory experiments by displaying significantly reduced feeding rates of G. fossarum exposed below the WWTP effluent if non-ozone treated wastewater was released. However, at the time the ozonation was operating, no adverse effects in feeding rates were observed below the effluent compared to the unaffected upstream sites. Also population studies in on-site flow-through stream microcosms displayed an increased feeding and a statistically significantly higher population size after ten weeks when exposed to ozone treated wastewater compared to non-ozone treated wastewater.
In conclusion, the present thesis documents that ozonation might be a suitable tool to reduce both the load of micropollutants as well as the ecotoxicity of wastewaters. Thus, this technology may help to meet the requirements of the Water Framework Directive also under predicted climate change scenarios, which may lead to elevated proportions of wastewater in the receiving stream during summer discharge. However, as ozone application may also produce by-products with a higher toxicity than their parent compounds, the implementation of this technique should be assessed further both via chemical analysis and ecotoxicological bioassays.
Field margins are often the only remaining habitats of various wild plant species in agricultural landscapes. However, due to their proximity to agricultural fields, the vegetation of field margins can be affected by agrochemicals applied to the crop fields. The aim of this thesis was to investigate the individual and combined effects of herbicide, insecticide and fertilizer inputs on the plant community of a field margin. Therefore, a 3-year field experiment with a randomized block design including seven treatments (H: herbicide, I: insecticide, F: fertilizer, H+I, F+I, F+H and F+H+I) and one control was conducted on a low-production meadow. Each treatment was replicated 8 times in 8 m x 8 m plots with a distance of 2 m between each plot. The fertilizer rates (25 % of the field rate) and pesticide rates (30 % of the field rate) used for the plot applications were consistent with realistic average input rates (overspray + drift) in the first meter of a field margin directly adjacent to a wheat field.
The study revealed that fertilizer and herbicide misplacements in field margins are major factors that affect the natural plant communities of these habitats. In total, 20 of the 26 abundant species on the study site were significantly affected by the fertilizer and herbicide treatment. The fertilizer promoted plants with high nutrient uptake and decreased the frequencies of small species. The herbicide caused a nearly complete disappearance of three species directly after the first application, whereas sublethal effects (e.g., phytotoxic effects and reduced seed productions of up to 100 %) were observed for the other affected species. However, if field margins are exposed to repeated agrochemical applications over several years, then such sublethal effects (particularly reproduction effects) also reduce the population size of plant species significantly, as observed in this study.
Significant herbicide-fertilizer interaction effects were also detected and could not be extrapolated from individual effects. The fertilizer and herbicide effects became stronger over time, leading to shifts in plant community compositions after three years and to a 15 % lower species diversity than in the control. The insecticide significantly affected the frequencies of two plant species (1 positively and 1 negatively). The results of the experiment suggest that a continuous annual agrochemical application on the study site would cause further plant community shifts and would likely lead to the disappearance of certain affected plants. A clear trend of increasing grass dominance at the expense of flowering herbs was detected. This finding corresponds well with monitoring data from field margins near the study site.
Although herbicide risk assessment aims to protect non-target plants in off-field habitats from adverse effects, reproduction effects and combined effects are currently not considered. Furthermore, no regulations for fertilizer applications next to field margins exist and thus, fertilizer misplacements in field margins are likely to occur and to interact with herbicide effects.
Adaptations of the current risk assessment, a development of risk mitigation measures (e.g., in-field buffers) for the application of herbicides and fertilizers, and general management measures for field margins are needed to restore and conserve plant diversity in field margins in agricultural landscapes.
Assessment of bat activity in agricultural environments and the evaluation of the risk of pesticides
(2013)
Although agriculture dominates with around 50% area much of Europe- landscape, there is virtually no information on how bats use this farmed environment for foraging. Consequently, little is known about effective conservation measures to compensate potential negative effects of agrarian management practice on the food availability for bats in this habitat. Moreover, there are currently no specific regulatory requirements to include bats in European Union risk assessments for the registration of pesticides since no information about pesticide exposure on this mammal group is available. To evaluate the potential pesticide exposure of bats via ingestion of contaminated insects, information about bat presence and activity in agricultural habitats is required. In order to examine bat activity on a landscape scale it was necessary to establish a suitable survey method. Contrary to capture methods, telemetry, and direct observations, acoustic surveys of bat activity are a logistically feasible and cost-effective way of obtaining bat activity data. However, concerns regarding the methodological designs of many acoustic surveys are expressed in the scientific literature. The reasons are the failing of addressing temporal and spatial variation in bat activity patterns and the limitations of the suitability of the used acoustic detector systems. By comparing different methods and detector systems it was found that the set up of several stationary calibrated detector systems which automatically trigger the ultrasonic recording has the highest potential to produce reliable, unbiased and comparable data sets on the relative activity of bats.
By using the proposed survey method, bat diversity and activity was recorded in different crops and semi-natural habitats in southern Rhineland-Palatinate. Simultaneously, the availability of aerial prey insects was studied by using light and sticky traps. In more than 500 sampling nights about 110,000 call sequences were acoustically recorded and almost 120,000 nocturnal insects were sampled. A total of 14 bat species were recorded, among them the locally rare and critically endangered northern bat (Eptesicus nilssonii) and the barbastelle (Barbastella barbastellum), all of them also occurring over agricultural fields. The agricultural landscape of southern Palatinate is dominated by vineyards, a habitat that was shown to be of low quality for most bat species because of the demonstrated low availability of small aerial insects. By surveying bat activity and food availably in a pair-wise design on several rain water retention ponds and neighbouring vineyards it was demonstrated that aquatic insect emergence in artificial wetlands can provide an important resource subsidy for bats. The creation of artificial wetlands would be a possibility to create important foraging habitats for bats and mitigate negative effects of management practice in the agricultural landscape.
In several other agricultural crops, however, high abundances of suitable prey insects and high bat activity levels, comparable or even higher than in the nearby forests and meadows known to be used as foraging habitats were demonstrated. Especially high bat activity levels were recorded over several fruit orchards and vegetable fields where insects were also present. Both crops are known for high pesticide inputs, and, therefore, a pesticide exposure through ingestion of contaminated insects can not be excluded. To follow the current risk assessment approach for birds and mammals pesticide residues were measured on bat-specific food items in an apple orchard following insecticide applications and bat activity was recorded in parallel. The highest residue values were measured on foliage-dwelling arthropods which may results in a reproductive risk for all bat species that, even to a small extent, include this prey group in their diet. The presence of bats in agricultural landscapes that form a majority of the land area in Europe but also on a global scale leads to exposure of bats by contaminated food and depletion of their food resources by pesticide use. So far conservation efforts for bats focussed on securing hibernation sites and the creation of artificial roost sites since especially the latter were thought to be limiting population growth. However the potential pesticide effects might be also crucial for the population persistence in agricultural landscapes of bats and need to be addressed adequately, especially in risk assessment procedures for the regulation of pesticides.
Agricultural pesticides, especially insecticides, are an integral part of modern farming. However, these may often leave their target ecosystems and cause adverse effects in non- target, especially freshwater ecosystems, leading to their deterioration. In this thesis, the focus will be on Insect Growth Regulators (IGRs) that can in many ways cause disruption of the endocrine system of invertebrates. Freshwater invertebrates play important ecological, economic and medical roles, and disruption of their endocrine systems may be crucial, considering the important role hormones play in the developmental and reproductive processes in organisms. Although Endocrine Disruption Chemicals (EDCs) can affect moulting, behaviour, morphology, sexual maturity, time to first brood, egg development time, brood size (fecundity), and sex determination in invertebrates, there is currently no agreement upon how to characterize and assess endocrine disruption (ED). Current traditional ecotoxicity tests for Ecological Risk Assessment (ERA) show limitations on generating data at the population level that may be relevant for the assessment of EDCs, which effects may be sublethal, latent and persist for several generations of species (transgenerational).
It is therefore the primary objective of this thesis to use a test method to investigate adverse effects of EDCs on endpoints concerning development and reproduction in freshwater invertebrates. The full life-cycle test over two generations that includes all sensitive life stages of C. riparius (a sexual reproductive organism) allows an assessment of its reproduction and should be suitable for the investigation of long-term toxicity of EDCs in freshwater invertebrates. C. riparius is appropriate for this purpose because of its short life cycle that enables the assessment of functional endpoints of the organism over several generations. Moreover, the chironomid life cycle consists of a complete metamorphosis controlled by a well-known endocrine mechanism and the endocrine system of insects has been most investigated in great detail among invertebrates. Hence, the full life-cycle test with C. riparius provides an approach to assess functional endpoints (e.g. reproduction, sex ratio) that are population-relevant as a useful amendment to the ERA of EDCs. In the laboratory, C. riparius was exposed to environmentally-relevant concentrations of the selected IGRs in either spiked water or spiked sediment scenario over two subsequent generations.
The results reported in this thesis revealed significant effects of the IGRs on the development and the reproduction of C. riparius with the second (F1) generation showing greater sensitivity. These findings indicated for the first time the suitability of multigenerational testing for various groups of EDCs and strongly suggested considering the full life-cycle of C. riparius as an appropriate test method for a better assessment of EDCs in the freshwater environment. In conclusion, this thesis helps to detect additional information that can be extrapolated at population level and, thus, might contribute to better protection of freshwater ecosystems against the risks of Endocrine Disrupting Chemicals (EDCs.) It may furthermore contribute to changes in the ERA process that are necessary for a real implementation of the new European chemical legislation, REACH (Registration, Evaluation Authorization and Restriction of Chemicals). Finally, significant interactions between temperature, chemical exposure and generation were reported for the first time and, may help predict impacts that may occur in the future, in the field, under predicted climate change scenarios.
A fundamental understanding of attachment of engineered nanoparticles to environmentalrnsurfaces is essential for the prediction of nanoparticle fate and transport in the environment.
The present work investigates the attachment of non-coated silver nanoparticles and citraterncoated silver nanoparticles to different model surfaces and environmental surfaces in thernpresence and absence of humic acid. Batch sorption experiments were used for this investigation.
The objective of this thesis was to investigate how silver nanoparticles interactrnwith surfaces having different chemical functional groups. The effect of presence of HA, on the particle-surface interactions was also investigated. In the absence of humic acid, nanoparticle-surface interactions or attachment was influencedrnby the chemical nature of the interacting surfaces. On the other hand, in the presence ofrnhumic acid, nanoparticle-surface attachment was influenced by the specific surface area of the sorbent surfaces. The sorption of non-coated silver nanoparticles and citrate coatedrnnanoparticles to all the surfaces was nonlinear and best described by Langmuir isotherm, indicating monolayer sorption of nanoparticles on to the surfaces. This can be explained as due to the blocking effect generated by the particle-particle repulsion. In the presence of humic acid, sorption of nanoparticles to the surfaces was linear. When the humic acid was present in the interacting medium, both the nanoparticles and surfaces were getting coated with humic acid and this masks the chemical functionalities of the surfaces. This leads to the change in particle-surface interactions, in the presence of humic acid. For the silver nanoparticle sorption from an unstable suspension, the sorption isotherms did not follow any classical sorption models, suggesting interplay between aggregation and sorption. Citrate coated silver nanoparticles and humic acid coated silver nanoparticles showed arndepression in sorption compared to the sorption of non-coated silver nanoparticles. In therncase of citrate coated silver nanoparticles the decrease in sorption can be explained by thernmore negative zeta potential of citrate coated nanoparticles compared to non-coated ones. For humic acid coated nanoparticles the sorption depression can be due to the steric hindrance caused by the free humic acid molecules which may coat the sorbent surface or due to the competition for sorption sites between the nanoparticle and free humic acid molecules present in the suspension. Thus nanoparticle surface chemistry is an important factor that determines the attachment of nanoparticles towards surfaces and it makes the characterization of nanoparticle surface an essential step in the study of their fate in the environment.
Another aim of this study was to introduce the potential of chemical force microscopy for nanoparticle surface characterization. With the use of this technique, it was possible to distinguish between bare silver nanoparticles, citrate coated silver nanoparticles, and humic acid coated silver nanoparticles. This was possible by measuring the adhesion forces between the nanoparticles and five different AFM probes having different chemical functionalization.
Quellen sind hochdiverse Lebensräume mit einer stark spezialisierten Fauna, wobei noch Lücken im Verständnis der besiedlungsrelevanten Faktoren für die aquatische Makrofauna bestehen, so dass die Arbeit einen klärenden Beitrag hinsichtlich anthropogener Veränderungen und ihrer Auswirkungen auf die Besied-lung leisten will. Basierend auf Daten von 334 Quellen aller Grundwasserlandschaften von Rheinland-Pfalz wurden die Quellen morphologisch und faunistisch bewertet. Außerdem wurden die Quellen des Landes morphologisch typisiert, Referenzquellen analysiert und ein Ansatz für die morphologische und faunistische Leitbildentwicklung gegeben. Außerdem wird ein selbst entwickeltes, kompaktes Kartier- und Bewertungsverfahren zur Quellstruktur vorgestellt, wo bislang noch ein Defizit bestand. Das Verfahren erfasst in einem Erfassungsbogen alle ökologisch bedeutsamen Strukturparameter und bewertet in einem 5-stufigen System. Quellen sind hochdiverse Lebensräume mit kleinen Populationen in isolierter Lage. Bei der Untersuchung der 310 Quellen wurden insgesamt 292 Arten bzw. höhere Taxa des Makrozoobenthos nachgewiesen. Es wurden 89 quellassoziierte Taxa gezählt, hiervon waren 24 krenobiont und 65 krenophil. Der Anteil der quellassoziierten Fauna an der Gesamtfauna lag bei über 30%. Es fanden sich 19 Erstnachweise für Rheinland-Pfalz, 9 besondere Nachweise (seltene Arten) und 19 Rote-Liste-Arten. Erstnachweise fanden sich in wenig bearbeiteten Dipterengruppen, vor allem den Psychodidae (13), Limoniidae (5) und ferner den Simu-liidae (1). Bei den Köcherfliegen wurden etliche seltene Arten gefunden, welche bisher in Rheinland-Pfalz kaum gefunden wurden. Häufigere krenobionte Taxa waren Crunoecia irrorata, Bythinella dunkeri, Niphar-gus sp., Pisidium personatum, Salamandra salamandra, Thaumalea sp., Agabus guttatus, Crenobia alpina, Oxycera sp. und Beraea maura. Die durchschnittliche Taxazahl pro Quelle betrug 11, die maximale 62 Taxa. Schüttung und Morphologie der Quellen waren von Naturraum und Grundwasserlandschaft abhängig, so schütteten etwa Buntsandsteinquellen ergiebiger und konstanter als Tonschieferquellen. Quellen spiegeln die Hydrologie ihrer Einzugsgebiete wider, so dass in verschiedenen hydrogeologischen Einheiten die chemischen Parameter differierten. In einzelnen Quellen schwankte die Hydrochemie jahreszeitlich aber nur gering. Der pH-Wert etwa war im Quellwasser versauerungsgefährdeter Gebiete niedrig (Hunsrück, Pfälzer-wald), der Nitratgehalt anthropogen bedingt hoch in intensiv landwirtschaftlich genutzten Räumen. Die morphologische Quelltypologie, welche sich in erster Linie auf gängige Quelltypen stützte, ergab in elf hydrogeologischen Quelltypenräumen vier Basisquelltypen und fünf geochemische Sondertypen. Die Wan-derquelle wurde neu hinzu genommen. Die landesweite Verteilung der Quelltypen ergab bei ungefassten Quellen 57 % Sicker-, 32 % Sturz-, 9 % Tümpel- und über 2 % Wanderquellen. Wanderquellen dürften aber noch öfter vorkommen. Relief und Substrateigenschaften waren entscheidende Faktoren für die Typologie, so dass etwa Sturzquellen vor allem im Buntsandstein häufig waren, während Sickerquellen im Tonschiefer des rheinischen Schiefergebirges dominierten. Es wurden 85 Strukturreferenzquellen als typische, naturnahe Beispiele für einzelne Quelltypenräume genannt. Etwa zwei Drittel aller Quellen waren strukturell beein-trächtigt bis stark geschädigt, 59 % gefasst. Fassungen, Verrohrungen und Betonverbau waren ökologisch besonders bedeutsam. In Regionen mit intensiver Landwirtschaft lagen generell die stärksten Schädigungen vor. Im Forst waren Quellen durch Nadelholzmonokulturen und in den Hochlagen pufferarmer Mittelgebirge durch Versauerung geschädigt. Hinsichtlich der Besiedlung ergaben sich Unterschiede zwischen den Naturräumen, beeinflusst durch die Faktoren Geologie, Hydrochemie, Schüttungsverhältnisse, Landnutzung im Einzugsgebiet sowie die Struk-turvielfalt an der Quelle. Strukturell unveränderte und unversauerte Quellen besaßen im Schnitt höhere Ta-xazahlen. Einzelne Faktoren mit Einfluss auf die Besiedlung wurden in ihrer Auswirkung getestet. In Quel-len ist die Versauerung grundsätzlich besiedlungsbeschränkend und überlagert strukturelle Faktoren. Bei niedrigen pH-Werten kommt es zu verminderten Taxazahlen, allerdings sind viele Quellorganismen offen-sichtlich an eine leichte Versauerung angepasst, da in sauren Quellen der Anteil der Quellfauna höher war. Außerdem ergab die Untersuchung, dass neue und intakte Fassungen weniger Taxa und Quelltaxa aufwiesen, während bei alten und verfallenen Fassungen oft eine hohe Quelltaxazahl vorlag, so dass diese als sekundär ökologisch wertvoll zu bezeichnen sind. Die Umfeldnutzung und die Größe des Quellbereichs sind ebenfalls wichtig, so dass Quellen in Laub- und Mischwald sowie in extensivem Grünland am besten besiedelt waren. Die stärksten statistischen Zusammenhänge mit der faunistischen Besiedlung ergaben sich bei den Bewer-tungsergebnissen des Strukturverfahrens, was zeigt, dass das Verfahren realistisch bewertet. Multivariate statistische Methoden dienten der Ermittlung von Besiedlungsfaktoren und der Leitbildentwick-lung. Es ergab sich eine unterschiedliche Besiedlung bei verschiedener Hydrogeologie und Hydrochemie sowie bei verschiedenen Quelltypen. Allerdings waren die Ergebnisse nicht eindeutig, so dass die Trennung der Quelltypen nur teilweise gelang und die Quelltypen von den Grundwasserlandschaften überlagert waren. Die Faunenunterschiede verschiedener Regionen waren größer als die einer Region, so dass morphologische Quelltypen faunistisch nur innerhalb einer hydrogeologischen Einheit von Bedeutung sind. Es wurden regionale faunistische Leitarten für vier Grundwasserlandschaften genannt, wobei sich auf wenige hochstete Quellarten beschränkt wurde. Die Arbeit zeigt, dass faunistisch orientierte Leitbilder nur unter Schwierigkeiten anzugeben sind und vollständige Typuszönosen für größere Gebiete grundsätzlich in Frage zu stellen sind. Sehr häufige grundsätzliche Leitarten für Quellen silikatischer Mittelgebirge in Rheinland-Pfalz sind Crunoecia irrorata und Bythinella dunkeri.
The conservation of groundwater ecosystems requires an assessment and evaluation scheme that shows the state of the ecosystem. Consequently, faunal and microbial criteria are required for groundwater monitoring, in addition to physico-chemical analyses. To proof the adequacy of the application of groundwater organisms for the biological assessment of groundwater quality, an extensive sampling collection of various groundwater systems was accomplished between 2002 and 2009 in Germany. Key aspects were the examination of the indicator potential of groundwater communities towards surface-groundwater interactions and anthropogenic impacts, as well as the analysis of stygofaunal distribution patterns, as a base and reference for a faunal assessment scheme of groundwater systems. The sampling design considered local, regional, and biogeographic conditions. To test the indicator potential of groundwater organisms on a local and regional scale, groundwater systems in Nordrhein-Westfalen (NRW) and Baden-Württemberg (BW) were examined. The faunal and microbial data from unconsolidated aquifers (Erftgebiet, NRW) show the sensitivity of groundwater organisms against land use effects, e.g. extensive agriculture. Data analyses revealed positive correlations of organic material (estimated amount of detritus, TOC) and nitrate with faunal abundance, species richness, diversity and the proportions of stygoxene species. Moreover, the bacterial abundance and diversity in the groundwater of the Erftgebiet was high compared to oligotrophic groundwater systems, indicating an effect of surface influence due to agricultural land use. The groundwater colonization in the Alb-Donau-Kreis (BW) was analyzed for regional effects (landscape, type of aquifer, hydrogeology) and local effects (comparing single wells). The results show that the fauna reflects the strength of the hydrological exchange on different spatial scales. Furthermore, the fauna reflects the interaction of regional and local conditions. Accordingly, the diversity and abundance of groundwater organisms was influenced by the high connectivity of the karst and unconsolidated alluvial aquifers, the type of land use, covering layers of soil, the age of groundwater, and the sampling depths. In general, faunal and microbial data of the Alb-Donau-Kreis are characteristic for oligotrophic, oligoalimonic groundwaters. The large scale analyses of stygofaunal distribution patterns revealed significant biogeographical differences of the communities. These community patterns of the groundwater fauna do not coincide with existing classification schemes defined for surface landscapes or freshwater systems. The largest differences between faunal surface and subsurface distribution patterns were found between the groundwater of northern and southern Germany and the foothills of the central mountain ranges - all of them regions shaped by the last ice ages.
In accordance with the faunal data assessed in groundwater, four different stygoregions were defined that are populated by distinct faunal assemblages. These are 1) the "Northern lowlands", 2) the "Central mountain ranges", 3) the "South-western mountain ranges", and 4) the "Southern mountain ranges and northern alps". The study corroborates that stygofaunal and microbial communities are an adequate tool for the qualitative assessment and monitoring of groundwater ecosystems. The best indicators to detect anthropogenic impacts on groundwater ecosystems are the faunal diversity, abundance, the proportions of stygobitic (obligate groundwater species) and stygoxene species (species not obligate for groundwater), and the bacterial abundance. The development of an ecologically based groundwater assessment and management, is crucial for the conservation of our groundwater ecosystems and thus, healthy drinking water. The defintion of "stygoregions" is an important base for the development of an assessment and reference scheme for groundwater ecosystems. The assessment of the ecological state of groundwater systems must be conducted on local scale, because the strength of the local hydrological influence determines the amount of food and oxygen as well as stygoxene animals within the aquifer, and thus shapes the local groundwater communities. Nevertheless, information of the biogeographic and regional conditions is needed as a reference for the type of species and abundances that potentially can occur in certain groundwater systems.
The increasing application of titanium dioxide nanoparticles (nTiO2) entails an increased risk regarding their release to surface water bodies, where they likely co-occur with other anthropogenic stressors, such as heavy metals. Their co-occurrence may lead to an adsorption of the metal ions onto the particles. These nanoparticles often sediment, due to their agglomeration, and thus pose a risk for pelagic or benthic species. The combined toxicity of nTiO2 and heavy metals is likely influenced by the properties of both stressors (since they may alter their interaction) and by environmental parameters (e.g., organic matter, pH, ionic strength) affecting their fate.
These issues were not yet systematically examined by the recent literature. Therefore, this thesis investigated the influence of nTiO2-products with differing crystalline phase composition on the toxicity of copper (as representative for heavy metals) in presence of different organic matters using the pelagic test organism Daphnia magna.
Moreover, the duration of the stressors` interaction (=aging) likely modulates the combined toxicity. Hence, the influence of nTiO2 on copper toxicity after aging as a function of environmental parameters (i.e., organic matter, pH, ionic strength) was additionally investigated.
Finally, the transferability of the major findings to benthic species was examined using Gammarus fossarum. The present thesis discovered a reduction of the copper toxicity facilitated by nTiO2 for all assessed scenarios, while its magnitude was determined by the surface area and structure of nTiO2, the quantity and quality of organic matter as well as the aging of both stressors. The general copper toxicity reduction by nTiO2 was also transferable to benthic species, despite their potentially increased exposure due to the sedimentation of nTiO2 with adsorbed copper. These observations suggest the application of nTiO2 as remediation agent, but potential side effects (e.g., chronic toxicity, reactive oxygen species formation) require further investigations. Moreover, questions regarding the transferability to other stressors (e.g., different heavy metals, organic chemicals) and the fate of stressors adsorbed to nTiO2 in aquatic ecosystems remain open.
New media are continually gaining importance in society. This process also has an increasing influence on developments in the field of education. Due to the use of computers as an integral part of schooling, new possibilities with regard to the organisation of learning processes arise. In this context, it is of great significance that appropriate computer applications for the respective learning group be prepared, so that justifiable use of computers in lessons can take place. Furthermore, efficient integration of computers requires changes in spatial organisation, in teaching methodology and in the role of the teacher. Such reflection and re-orientation are the essential basis for meaningful usage of new media in teaching and learning processes. An initial aim of this thesis is an empirical analysis of the situation regarding the usage of computers in geometry lessons in primary schools, based on a regional survey. The evaluation gives information as to how intensively the computer is used in the learning process and shows us which factors determine the use of computers in geometry lessons.
The results are an empirical foundation for the development of a computer-based learning environment called "Geolizi" (the second aim of my study). Within this learning environment, the pupils should work independently on the topics "mirror-imaged figures" and "the construction of rectangles and squares", with the help of the computer. During this process, hands-on media, traditional drawing instruments and interactive worksheets are available to the pupils. The computer (with its appropriate applications) takes over different functions in this learning process. Testing of this learning environment ("Geolizi") took place in several primary school classes, within the scope of formative and summative evaluation. With the help of questionnaires filled in by the pupils, the usability of the individual elements was tested. Based on a pre-post-investigation design, an attempt has been made to discover possible changes in the attitude of teachers regarding the usage of computers in the teaching of elementary geometry.
The results of this test phase, together with the evaluation of the questionnaires, lead to the founded presumption that usage of the multimedia-based learning environment " Geolizi " could result in greater use of computers in geometry lessons. All in all, the developed learning environment demonstrates an interesting possibility of how to use computers in the teaching of geometry at primary schools, thus making an important contribution to an independent, individualised learning process.
Wild boars belong to the most wide spread ungulates in the world. They are characterized by a well performed adaption to their environment mainly due to their omnivorous dietary. The wild boar population in Germany increased during the past three decades. Nowadays their high density leads to problems in agricultural areas due to damage of crops and plays a significant role as disease vector as the classical swine fever. For an effective population management population size information is of crucial importance. Different traditional methods exist to estimate population sizes as direct sightnings, faecal drop counts or hunting harvest which provide only relative estimates and population trends. Absolute population sizes could be yielded by a Capture-Mark-Recapture (CMR) approach. However, capturing of wild boars is difficult to realize and costly in terms of personnel and field effort.
Furthermore the capture probabilities are heterogeneous due to the variable behaviour of individuals influenced by age, sex, and experience of the animals. Non-invasive genetic methods are a promising complement to the traditional methods for population size estimation particularly for wild boar. These methods reduce stress and capture bias and increase the number of re-captures. Faeces proved to be a suitable DNA source for wild boar genotyping, due to almost equal capture probability. However working with faeces implicates difficulties such as low DNA rnquality and quantity, genotyping errors as dropout and false alleles.
The main aim of the present study was to develop a reliable, cost-efficient, reproducible and practicable method for wild boar genotyping. This method should provide a reliable dataset of genotypes obtained from the collected faeces samples. Individual identification forms the basis for an improved mark-recapture approach. As there is no sound method for absolute population counts in free living wild boar, reference values for the validation of this new approach are missing. Therefore, different routines to reduce and to assess genotyping errors were compared within this thesis. For maximum amplification rate, the storage, the extraction methods and the PCR-procedure were optimised. A step by step procedure was evaluated in order to determine the minimum required microsatellite (MS) number for reliable individual identification including a test with family groups (female and embryo tissue) to distinguish even between close relatives. A multiple-tubes approach, post-amplification checking and different correction procedures were applied to reduce genotyping errors. In order to quantify real genotyping error rates (GER) of datasets derived from sampling in the Palatinate Forest in western Germany, different methods for GER determination were compared with each other, obtaining GERs between 0% and 57.5%. As a consequence, more strict criteria for the multi-tube approach and increased repetition number of homozygous samples were used. An additional method validation was the implementation of a blind test to achieve the reliability of the genotyping and error checking procedure. Finally a strict and practicable proposal for the lab procedure was developed, by beginning with faecal sample collection and ending with a reliable dataset with genotypes of each sample.
The results of the presented method were derived from two sampling periods in a 4000 ha area in the Palatinate Forest in Rhineland-Palatinate in December 2006 and 2007. Both provided high confidence intervals (CI) applying inaccurate estimates (eg. for 2006 population size amounted to 215 with CI 95% of 156-314 and for 2007 population size amounted to 415 with CI 95% of 318-561) due to low sampling sizes (for 2006 n = 141 and for 2007 n = 326), successfully analysed samples (for 2006 n = 89 and for 2007 n = 156) and recapture numbers (for 2006 n = 12 and for 2007 n = 24). Furthermore, the population estimates even for the lowest values were considerably higher than previously assumed by hunting statistics, which implicates an ineffective hunting regime in the study area. For the future prospect, to obtain more precise population size estimations the increase of sampling sizes is inevitable, because absolute and reliable estimates are highly desirable for wildlife management and the control of diseases transmission. Nevertheless, the method for individual genotyping of wild boars evaluated in this thesis could be successfully established resulting in reliable datasets for population estimation modelling with sufficiently low GER.
The transport of pesticides from agricultural land into surface waters via diffuse entry pathways such as runoff is a major threat to aquatic ecosystems and their communities. Although certain risk mitigation measures are currently stipulated during pesticide product authorisation, further approaches might be needed to manage hot spots of pesticide exposure. Such a management is, for example, required by the European Union- directive for the sustainable use pesticides (2009/128/EC).
The need for mitigation measures was investigated within the present thesis at stream sites draining an arable and a vineyard region in Germany by characterising pesticide exposure following edge-of-field runoff and (expected) effects on the aquatic macroinvertebrates. The results of these field studies showed, that streams in both regions were exposed to pesticide concentrations suggesting effects on the macroinvertebrate community. In the arable region the observed toxicity was mainly attributed to the insecticides lambda-cyhalothrin (in the water-phase samples) and alpha-cypermethrin (in the suspended particle samples), whereas in the vineyard region fungicides were most important. Furthermore stream water and suspended particles sampled in the vineyard region showed critical copper concentrations, which might cause ecotoxicological effects in the field. In addition to pesticide exposure, in the arable region also the effects on aquatic macroinvertebrates were assessed in the field. Generally, invertebrate fauna was dominated by pesticide-tolerant species, which suggested a high pesticide exposure at almost all sites. The elevated levels of suspended particle contamination in terms of maximum toxic units per sample (logTUMax > -2) reflect also this result. At two sites that received high aqueous-phase entries of the insecticide lambda-cyhalothrin (logTUMax > -0.6), the abundance and number of sensitive species (indicated by the SPEcies At Risk index) decreased during the pesticide application period. In contrast, at sites characterised by low water-phase toxicity (logTUMax < -3.5), no acute significant negative effects on macroinvertebrates were observed. In conclusion these data showed that in both regions the implementation of risk mitigation measures is needed to protect the aquatic communities.
To mitigate runoff-related pesticide entries, riparian buffer strips are often recommended. However, the mitigating influence with increasing buffer strip width could not be demonstrated for riparian buffers which were already present in the arable and vineyard region. This result was attributed in the vineyard region to the high number of paved field paths associated with artificial erosion rills, which concentrate and rapidly transport receiving edge-of-field runoff in stream direction. Consequently the pesticide reduction efficiency of buffer strips is considerably reduced. We assumed that a similar process occurred in the arable region, due to a high number of erosion rills, which complicate a laminar sheet flow of edge-of-field runoff through the riparian buffer strip. Additionally also the presence of ephemeral drainage ditches, which led surface runoff from the agricultural fields to the streams may have contributed to observed pesticide entries despite wide buffers.
Effective risk mitigation measures should address these identified most important input pathways in the study areas. As possible measures the implementation of grassed field paths and vegetated ditches or wetlands were suggested. In general also the improvement of currently present riparian buffer strips regarding their efficiency to reduce pesticide runoff entries should be taken into account. In conclusion the results of the field studies underline the importance that risk mitigation measures are identified specifically for the respective pollution situation in stream catchments. To facilitate this process, a user guide was developed within the present thesis for identifying appropriate mitigation measures at high-risk sites. Based on a survey of exposure relevant landscape parameter a set of risk mitigation measures is suggested that focus on the specific pollution situation. Currently the guide includes 12 landscape- and six application-related measures and presents an overview of these measures" efficiency to reduce pesticide entries via runoff and spray drift, their feasibility and expected acceptability to farmers. Based on this information the user can finally choose the mitigation measures for implementation. The present guide promotes the practical implementation of appropriate risk mitigation measures in pesticide-polluted streams, and thus the protection of aquatic stream communities against pesticide entries.
Worldwide one third to one half of the freshwater crayfish species are threatened with population decline or extinction. Besides habitat deterioration, pollution, and other man-made environmental changes, invasive species and pathogens are major threats to the survival of European crayfish species. Freshwater crayfish are the largest freshwater invertebrates and strongly influence the structure of food webs. The disappearance of crayfish from a water body may change the food web and could have dramatic consequences for an ecosystem.rnOne goal in modern species conservation strategies is the conservation of genetic diversity, since genetic diversity is an advantage for the long-term survival of a species. The main aim of my thesis was to reveal the genetic structure and to identify genetic hotspots of the endangered noble crayfish (Astacus astacus) throughout Europe (part 1 of my thesis). Since the most significant threat to biodiversity of European crayfish species is the crayfish plague pathogen Aphanomyces astaci I studied new aspects in the distribution of A. astaci (part two of my thesis). The results serve as a basis for future conservation programs for freshwater crayfish. In the first part of my thesis I conducted a phylogeographic analysis of noble crayfish using mitochondrial DNA and nuclear microsatellite data. With these methods I aimed to identify its genetic hotspots and to reconstruct the recolonization history of central Europe by this species. I detected high genetic diversities in southestern Europe indicating that noble crayfish outlasted the cold climate phases during the Pleistocene in this region (Appendix 1). Because of the high genetic diversity found there, southeastern Europe is of particular importance for the conservation of noble crayfish. The mitochondrial DNA analysis points to a bifurcated colonization process from the eastern Black Sea basin to a) the North Sea and to b) the Baltic Sea basin (Appendix 2). A second independent refugium that was localized on the Western Balkans did not contribute to the colonization of central Europe. Furthermore, I found that the natural genetic structure is dissolved, probably due to the high human impact on the distribution of noble crayfish (e.g. artificial translocation). In the second part of this thesis using real-time PCR I identified calico crayfish (Orconectes immunis) as the fourth North American crayfish species to be carrier of the agent of the crayfish plague (Appendix 3). Furthermore I detected the crayfish plague pathogen in American spiny-cheek crayfish (Orconectes limosus) and native narrow-clawed crayfish (Astacus leptodactylus) in the lower Danube in Romania (Appendix 4). The distribution of infected spiny-cheek crayfish poses a threat to the native biodiversity in southeastern Europe and shows the high invasion potential of this crayfish species. Moreover, I found that even the native narrow-clawed crayfish in the Danube Delta, about 970 km downstream of the current invasion front of American crayfish, is a carrier of A. astaci (Appendix 5). This finding is of high importance, as the native species do not seem to suffer from the infection. In Appendix 6 I elucidate demonstrate that the absence of the crayfish plague agent is the most likely explanation for the coexistence of populations of European and American crayfish in central Europe. In my thesis I show that the common assumption that all North American crayfish are carrier of A. astaci and that all native crayfish species die when infected with A. astaci does not hold true. The studies presented in my thesis reveal new aspects that are crucial for native crayfish conservation: 1) The genetic diversity of noble crayfish is highest in southeastern Europe where noble crayfish outlasted the last glacial maximum in at least two different refugia. 2) Not all American crayfish populations are carrier of A. astaci and 3) not all Europen crayish populations die shortly after being infected with the crayfish plague pathogen.rnTo conserve native crayfish species and their (genetic) diversity in the long term, further introductions of American crayfish into European waters must be avoided. However, the introduction will only decrease if the commercial trade with non-indigenous crayfish species is prohibited.
The intention of this thesis was to characterise the effect of naturally occurring multivalent cations like Calcium and Aluminium on the structure of Soil Organic Matter (SOM) as well as on the sorption behaviour of SOM for heavy metals such as lead.
The first part of this thesis describes the results of experiments in which the Al and Ca cation content was changed for various samples originated from soils and peats of different regions in Germany. The second part focusses on SOM-metal cation precipitates to study rigidity in dependence of the cation content. In the third part the effects of various cation contents in SOM on the binding strength of Pb cations were characterised by using a cation exchange resin as desorption method.
It was found for soil and peat samples as well as precipitates that matrix rigidity was affected by both type and content of cation. The influence of Ca on rigidity was less pronounced than the influence of Al and of Pb used in the precipitation experiments. For each sample one cation content was identified where matrix rigidity was most pronounced. This specific cation content is below the cation saturation as expected by cation exchange capacity. These findings resulted in a model describing the relation between cation type, content and the degree of networking in SOM. For all treated soil and precipitate samples a step transition like glass transition was observed, determined by the step transition temperature T*. It is known from literature that this type of step transition is due to bridges between water molecules and organic functional groups in SOM. In contrast to the glass transition temperature this thermal event is slowly reversing after days or weeks depending on the re-conformation of the water molecules. Therefore, changes of T* with different cation compositions in the samples are explained by the formation of water-molecule-cation bridges between SOM-functional groups. No influence on desorption kinetics of lead for different cation compositions in soil samples was observed. Therefore it can be assumed that the observed changes of matrix rigidity are highly reversible by changing the water status, pH or putting agitation energy by shaking in there.
Die Arbeit stellt die Frage nach den Effekten einer tertiären Präventionsmaßnahme in Bezug auf Schmerzbewältigung und Schmerzveränderung bei chronischen Lumbalgiepatienten. Im Rahmen der Überprüfung werden ausdifferenzierte psychophysische Interventionsmaßnahmen aus den Bereichen der Physiotherapie/Krankengymnastik und Psychologie eingesetzt. Die Gruppenunterteilung erfolgt in eine behandelte Versuchsgruppe und eine unbehandelte Warte-Kontrollgruppe mit jeweils 100 Probanden (N=200). Die Ergebnisse der tertiären Präventionsmaßnahme zeigen statistisch und klinisch relevante sowie positive Veränderungen in den Bereichen der Schmerzbewältigung und Schmerzveränderung.
Fate and effects of insecticides in vegetated agricultural drainage ditches and constructed wetlands
(2006)
Studies have shown that runoff and spray-drift are important sources of nonpoint-source pesticide pollution of surface waters. Owing to this, public concern over the presence of pesticides in surface and ground water has resulted in intensive scientific efforts to find economical, yet environmentally sound solutions to the problem. The primary objective of this research was to assess the effectiveness of vegetated aquatic systems in providing buffering between natural aquatic ecosystems and agricultural landscape following insecticide associated runoff and spray-drift events. The first set of studies were implemented using vegetated agricultural ditches, one in Mississippi, USA, using pyrethroids (bifenthrin, lambda-cyhalothrin) under simulated runoff conditions and the other in the Western Cape, South Africa using the organophosphate insecticide, azinphos-methyl (AZP), under natural runoff and spray-drift conditions. The second set of studies were implemented using constructed wetlands, one in the Western Cape using AZP under natural spray-drift conditions and the other in Mississippi, USA using the organophosphate MeP under simulated runoff conditions. Results from the Mississippi-ditch study indicated that ditch lengths of less than 300 m would be sufficient to mitigate bifenthrin and lambda-cyhalothrin. In addition, data from mass balance calculations determined that the ditch plants were the major sink (generally > 90%) and/or sorption site for the rapid dissipation of the above pyrethroids from the water column. Similarly, results from the ditch study in South Africa showed that a 180 m vegetated system was effective in mitigating AZP after natural spray drift and low flow runoff events. Analytical results from the first wetland study show that the vegetated wetland was more effective than the non-vegetated wetland in reducing loadings of MeP. Mass balance calculations indicated approximately 90% of MeP mass was associated with the plant compartment. Ninety-six hours after the contamination, a significant negative acute effect of contamination on abundances was found in 8 out of the 15 macroinvertebrate species in both wetland systems. Even with these toxic effects, the overall reaction of macroinvertebrates clearly demonstrated that the impact of MeP in the vegetated wetland was considerably lower than in the non-vegetated wetland. Results from the constructed wetland study in South Africa revealed that concentrations of AZP at the inlet of the 134 m wetland system were reduced by 90% at the outlet. Overall, results from all of the studies in this thesis indicate that the presence of the plant compartment was essential for the effective mitigation of insecticide contamination introduced after both simulated and natural runoff or spray-drift events. Finally, both the vegetated agricultural drainage ditch and vegetated constructed wetland systems studied would be effective in mitigating pesticide loadings introduced from either runoff or spray-drift, in turn lowering or eliminating potential pesticide associated toxic effects in receiving aquatic ecosystems. Data produced in this research provide important information to reduce insecticide risk in exposure assessment scenarios. It should be noted that incorporating these types of best management practices (BMPs) will decrease the risk of acute toxicity, but chronic exposure may still be an apparent overall risk.
Biodiversity is not only threatened by habitat loss, climate change and pollution, but also by invasive species. The impact of introduced species is immense and causes substantial ecological and economical costs worldwide. With the start of domestications of the African wildcat (Felis lybica) in the Near East, the transport of house cats (Felis catus) around the world as a commensal and domesticate began. The general aim of my thesis was to investigate the impact of invasive feral cats on native species as well as underlying population genetic structures, diversity and phylogeography. This was studied in the context of the demographic history in Australia and Hawai'i. My studies confirmed that the main introductions of cats to Australia began in the 19th century via ships of European settlers, traders and workers. Similarly, I was able to confirm cat introductions to Hawai'i by European traders and explorers; which has to the present a devastating effect on Hawaiian endemic species. Likewise, cats are widespread across Australia, can be found on most islands and are recognized as one of the major threats to Australian native species. A selective feeding behaviour by invasive predators was found in one of my studies. This study additionally gives an indication for possible population recovery of small Western Australianrnvertebrate species after predator removal. Advancement and the combination of various management techniques allow, if adequately funded, a more efficient planning and implementation of eradication campaigns. Population genetic approaches are able to give insights into population genetic structure, diversity and kinship, thereby enabling management campaigns to be more cost effective and successful. No pattern of isolation by distance between populations of Hawai"i and Australia indicated that trade routes, such as the "Golden Round" of the maritime fur trade, facilitated a link between far off global cat populations. Multiple introductions to Australia and intermixing with domestic breed cats resulted in feral cat populations which showrnno signs of reduced genetic variability. My studies also revealed the advantages of bioproxies in combination with phylogeography, which enable the inference and reconstruction of introduction routes, history and origin of invasive species. Genetic signals of historically introduced genotypesrnare still discernible on islands with low number of introductions over time and thereby low intermixing with domestic fancy breeds. Feral cats' adaptability as an invader was reconfirmed and possible underlying genetic mechanisms enabling their success as a global invader ("global supercat") are discussed. Research into the feralisation process of cats will provide new information regarding the domestication of cats, the genetic basis of feralisation and allow additional insights into cats" adaptive potential.
The polysaccharide hydration phenomenon is nowadays the subject of intense research. The interaction of native and modified polysaccharides and polysaccharides-based bioconjugates with water has an important influence on their functional behaviour. Notwithstanding that the hydration phenomenon has been studied for decades, there is still a lack of awareness about the influence of hydration water on the polysaccharide´s structure and consequences for industrial or medicinal applications. The hydration of polysaccharides is often described by the existence of water layers differing in their physical properties depending on the distance from the polysaccharide. Using the differential scanning calorimetry (DSC) such water layers were categorized according their properties upon cooling in hyaluronan (HYA, sodium salt of ß-1,4-linked units of ß-1,3-linked D-glucuronic acid and N-acetyl-D-glucosamine), a model polysaccharide in the present work. The amount of non-freezing water, i.e. water in close proximity of HYA chain which does not freeze et all, was determined around 0.74gH2O/gHYA for HYA with molecular weight from 100 to 740kDa and 0.84gH2O/gHYA for molecular weight of 1390kDa. The amount of freezing-bound water, the water pool which is affected by presence of HYA but freezes, was determined in the range from 0.74 to 2gH2O/gHYA. Above this value only non-freezing and bulk water are present since melting enthalpy measured above this concentration reached the same value as for pure water. Since this approach suffers from several experimental problems, a new approach, based on the evaporation enthalpy determination, was suggested. The analysis of the evaporation enthalpies revealed an additional process associated with apparent energy release taking part below the water content of 0.34gH2O/gHYA. Existence of this phenomenon was observed also for protonated form of HYA. The existence of energy compensating process was confirmed with the Kissinger-Akahira-Sunose method which allowed determination of actual water evaporation/desorption enthalpies in all stages of the evaporation process. In fact, the apparent evaporation enthalpy value increased until water content of 0.34gH2O/gHYA, and then dropped down to lower values which were, still higher than the value of the pure water evaporation enthalpy. By the use of time domain nuclear magnetic resonance (TD-NMR) technique it was revealed that this phenomenon is the plasticisation of HYA.
Further, it was revealed that the non-freezing water determined by the use of DSC consists of two water fractions, i.e. 15% of water structurally integrated, interacting directly with polar sites, and 85% of water structurally restricted, embedded in-between the HYA chains. The occurrence of plasticisation concentration close to equilibrium moisture content provided the possibility to influence the HYA physical structure during the drying. In this way three samples of native HYA, dried under various conditions were prepared and their physical properties were analyzed. The samples differed in kinetics of rehydration, plasticisation concentration, glass transitions, and morphology. The properties of water pool were studied in solutions of 10"25mg HYA/mL as well. The fast filed cycling (FFC) NMR relaxometry showed the existence of three water fractions which correlation times spanned from 10"6 to 10"10 seconds, progressively decreasing in dependency on its distance from HYA chain. The formation of a weak and transient intramolecular water bridge between HYA chains was observed. It was shown that, unlike the inorganic electrolytes, polyelectrolytes hydration is a dynamic process which reflects not only the technique used for the analysis, experimental conditions but also the conformation of the polysaccharide and its "thermal" and "hydration" history.
It was demonstrated that some native polysaccharide structures can be easily modified by manipulation of preparation conditions, giving fractions with specific physicochemical properties without necessity of any chemical modification.
Engineered nanoparticles are emerging pollutants. Their increasing use in commercial products suggests a similar increase of their concentrations in the environment. Studying the fate of engineered colloids in the environment is highly challenging due to the complexity of their possible interactions with the main actors present in aquatic systems. Solution chemistry is one of the most central aspects. In particular, the interactions with dissolved organic matter (DOM) and with natural colloids are still weakly understood.
The aim of this work was to further develop the dedicated analytical methods required for investigating the fate of engineered colloids in environmental media as influenced by DOM. Reviewing the literature on DOM interactions with inorganic colloids revealed that a systematic characterization of both colloids and DOM, although essential, lacks in most studies and that further investigations on the fractionation of DOM on the surface of engineered colloids is needed. Another knowledge gap concerns the effects of DOM on the dynamic structure of colloid agglomerates. For this question, analytical techniques dedicated to the characterization of agglomerates in environmental media at low concentrations are required. Such techniques should remain accurate at low concentrations, be specific, widely matrix independent and free of artefact due to sample preparation. Unfortunately, none of the currently available techniques (microscopy, light scattering based methods, separation techniques etc.) fulfills these requirements.
However, a compromise was found with hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry (HDC-ICP-MS). This method has the potential to size inorganic particles in complex media in concentration ranges below ppb and is element specific; however, its limitations were not systematically explored. In this work, the potential of this method has been further explored. The simple size separation mechanism ensures a high flexibility of the elution parameters and universal calibration can be accurately applied to particles of different compositions and surface chemistries. The most important limitations of the method are its low size resolution and the effect of the particle shape on the retention factor. The implementation of HDC coupled to single particle ICP-MS (HDC-SP-ICP-MS) offers new possibilities for the recognition of particle shape and hence the differentiation between primary particles and homoagglomerates. Therefore, this coupling technique is highly attractive for monitoring the effects of DOM on the stability of colloids in complex media. The versatility of HDC ICP MS is demonstrated by its successful applications to diverse samples. In particular, it has been used to investigate the stability of citrate stabilized silver colloids in reconstituted natural water in the presence of different types of natural organic matter. These particles were stable for at least one hour independently of the type of DOM used and the pH, in accordance with a coauthored publication addressing the stability of silver colloids in the River Rhine. Direct monitoring of DOM adsorption on colloids was not possible using UV and fluorescence detectors. Preliminary attempts to investigate the adsorption mechanism of humic acids on silver colloids using fluorescence spectroscopy suggest that fluorescent molecules are not adsorbed on silver particles. Several solutions for overcoming the encountered difficulties in the analysis of DOM interactions are proposed and the numerous perspectives offered by further developments and applications of HDC-(SP)-ICP-MS in environmental sciences are discussed in detail.
Leaf litter breakdown is a fundamental process in aquatic ecosystems, being mainly mediated by decomposer-detritivore systems that are composed of microbial decomposers and leaf-shredding, detritivorous invertebrates. The ecological integrity of these systems can, however, be disturbed, amongst others, by chemical stressors. Fungicides might pose a particular risk as they can have negative effects on the involved microbial decomposers but may also affect shredders via both waterborne toxicity and their diet; the latter by toxic effects due to dietary exposure as a result of fungicides’ accumulation on leaf material and by negatively affecting fungal leaf decomposers, on which shredders’ nutrition heavily relies. The primary aim of this thesis was therefore to provide an in-depth assessment of the ecotoxicological implications of fungicides in a model decomposer-detritivore system using a tiered experimental approach to investigate (1) waterborne toxicity in a model shredder, i.e., Gammarus fossarum, (2) structural and functional implications in leaf-associated microbial communities, and (3) the relative importance of waterborne and diet-related effects for the model shredder.
Additionally, knowledge gaps were tackled that were related to potential differences in the ecotoxicological impact of inorganic (also authorized for organic farming in large parts of the world) and organic fungicides, the mixture toxicity of these substances, the field-relevance of their effects, and the appropriateness of current environmental risk assessment (ERA).
In the course of this thesis, major differences in the effects of inorganic and organic fungicides on the model decomposer-detritivore system were uncovered; e.g., the palatability of leaves for G. fossarum was increased by inorganic fungicides but deteriorated by organic substances. Furthermore, non-additive action of fungicides was observed, rendering mixture effects of these substances hardly predictable. While the relative importance of the waterborne and diet-related effect pathway for the model shredder seems to depend on the fungicide group and the exposure concentration, it was demonstrated that neither path must be ignored due to additive action. Finally, it was shown that effects can be expected at field-relevant fungicide levels and that current ERA may provide insufficient protection for decomposer-detritivore systems. To safeguard aquatic ecosystem functioning, this thesis thus recommends including leaf-associated microbial communities and long-term feeding studies using detritus feeders in ERA testing schemes, and identifies several knowledge gaps whose filling seems mandatory to develop further reasonable refinements for fungicide ERA.