Dissertations / Theses on the topic 'Aquatic environment Chemistry'

This thesis studies the chemical reactions of mercury in different oxidations states with several natural methyl-donors present in the aquatic environment. The importance of the abiotic pathway of mercury methylation was assessed by a thorough examination of the kinetics of these reactions in various experimental conditions, relevant to environmental situations. The amount of methylmercury formed in the course of the chemical reactions studied herein shows that the abiotic mercury methylation can be a very significant source of this compound in the environment. The thesis comprises three main chapters which describe the reactions of three major methyl-donors: methyl iodide, methycobalamine and methyl tin compounds with mercury. Reaction of mercuric ions with methyl iodide yields HgI+ and HgI2 as inorganic products and MeOH as the only organic product. The reaction kinetics are biphasic and the reaction rate decreases with pH, increases with temperature and the reaction stops in the presence of complexing agents such as iodide ions. Meanwhile, the reaction of Hg0(aq) with methyl iodide yields 1.1% methylmercury which is a relatively high yield for environmental reactions. We show that the role of methyl iodide in the geochemical cycle of mercury in the aquatic environment is two-fold: it promotes the formation of compounds such as HgI + and HgI2 which are less reactive towards chemical and biological methylation and it methylates Hg0 which is present when Hg2+ is reduced by reducing agents found in the aquatic environment. The reaction of mercuric ions with methylcobalamine is studied using methylaquacobaloxime as a model compound. The mechanism is an electrophilic attack of Hg2+ to the Co-C bond. It results in the cleavage of this bond and formation of Hg-C bond in the structure of methyl mercury. The reaction is first order to mercury and methylcobaloxime concentration and the value of the second-order rate constant is k = (6.8 +/- 0.2) M-1 s-1 at 21.1°C, at a pH of 1.5 and an ionic strength of 0.030 M (HNO3). The reaction rate decreases with pH, and increases with temperature and ionic strength. The yield of methyl mercury formation is as high as 75%. The presence of chloride completely shuts down the reaction. So, abiotic methylation of mercury by methylcobalamin could be a source of methylmercury formation in fresh waters which have low pH and low chloride concentrations. (Abstract shortened by UMI.)

The commercial use of fluorescent whitening agents (FWA' s) in products such as soaps and detergents has resulted in the presence of these compounds in domestic waste waters. A model compound (A) (a possible initial degradation product of a stilbene-s-triazine type FWA) was synthesised and biodegradation studies carried out on this compound in filtered activated sludge solution. During the test period (approximately 6 months) no degradation products were observed. Prior to undertaking biodegradation studies on a purified commercial stilbene-s-triazine FWA, Blankophor REU-P, a method was sought to determine its concentration in aqueous solution. Using ultraviolet absorbance measurements the concentration of the Blankophor could be determined in distilled water. However, this method was unsuitable when the Blankophor was dissolved in filtered activated sludge solution. Attempts to extract the Blankophor from filtered activated sludge solution using solvent extraction and ion-exchange resins were unsuccessful. Using computer modelling (SIMCA), combined with ultraviolet absorbance measurements, it was possible to determine the concentration of the Blankophor in filtered activated sludge solution. Biodegradation studies were undertaken with the Blankophor using this method to monitor the Blankophor concentration. During the test period (six days) the Blankophor concentration fell from 1Oppm to approximately 5. 5ppm. It was possible to deduce that the Blankophor was not being absorbed onto the solid material of the activated sludge and that it had been metabolised and/or isomerised. Two ion-pairing agents, tetraphenyl arsoniurn chloride and oly[oxyethylene(dimethylimino)-ethylene(diethylimino)-ethylene] were examined to try to separate the Blankophor and the metabolites and/or isomers from the filtered activated sludge solution but no successful separation was achieved. Thin layer chromatography was examined briefly but again with no success. Photolysis experiments were undertaken with the Blankophor in distilled water. The concentration of the Blankophor fell from 1Oppm to approximately 7. 5ppm and its ultraviolet spectrum changed shape. This, coupled with the fact that the control spectra remained unaltered, indicated that the Blankophor had undergone photolytic conversion to metabolites and/or isomers. Although it is clear that FWA' s are fairly stable compounds which are slow to bio- and photo-degrade and that their toxicity to man, both directly and by bio-accumulationis is minimal little is still known about the toxicity of possible degradation products.

Mass produced chemicals have revolutionised the way in which humans live and has led to both a significant increase in quality of life and a concomitant change in the way we pollute our habitats. Such chemicals include pharmaceuticals, plasticisers, perfluorinated compounds and metabolites which enter rivers via sources such as sewage treatment works (STW) effluent outfalls. The presence and distribution of these contaminants is of concern due to their increasing use and ability of some to biologically affect non-target aquatic organisms at trace (ng/L) levels. This work investigated the fate and distribution of selected pharmaceuticals, plasticisers, illict drugs, perfluorinated compunds (PFCs) and metabolites are investigated in three rivers of southern England. Specific objectives included establishing spatial distribution patterns of selected contaminants along the entire course of rivers receiving inputs from multiple STWs, their partition between bound (to suspended particulate material) and dissolved phases of river water, accumulation in sediment, bioaccumulation in primary producers including plants and biofilm/ periphyton, bioaccumulation in benthic aquatic organisms, adsorption of studied contaminants to polyethlene microparticles (similar to those used in cosmetic products) both in the lab and in rivers, and adsorption to 'natural' replacements for polyethylene microparticles (MPs). Spatial distribution analysis showed that selected contaminants are ubiquitous in the studied rivers with trace levels of plasticisers and perfluorinated compounds identified in river headwaters and beyond. Within the rivers studied in this work, pharmaceuticals were shown to be exclusively introduced by STW effluent and persisted exclusively in the dissolved phase of river water through the studies areas. Plasticisers and PFCs however were additionally introduced via runoff from streets, at times at higher concentrations than in SFWs effluent outfall and bound to suspended particulate material. Only PFCs and plasticisers were found to be bioaccumulative or very bioaccumulative in aquatic plants, biofilm. periphton and benthic organisms, and accumulated in sediment. Illicit drugs were only found in STW effluent and downstream river flow, almost exclusively in the dissolved phase of collected water. Laboratory assessment of adsorption to polyethylene MPs showed adsorption largely occurred via a linear isotherm and only for PFCs. However, trace levels of pharmaceuticals and an illicit drug urinary metabolite were extracted from polyethylene MPs deployed downstream from STW effluent outfalls in three rivers. Investigation of a 'natural' alternative to polyethyle MPs (walnut husk Mps) showed adsorption to these replacement particles occurred to a greater amount with more of the studied contaminants than to polyethylene MPs. This work significantly contributes to the knowledge of organis contaminant occurrence, bioaccumulation, fate and distribution in the aquatic environment. Future research should focus on elucidating the fate and distribution of conugated pharmaceuticals and metabolites in the aquatic environment, establishing organism-specific contaminant bioaccumulation guideline, the effect of microparticle fragmentation on contaminant adsorption, identification of adsorption-free MPs for use in cosmetic products and developing study designs to incorporate environmental epigenetics with toxicology and chemistry in the aquatic environment.

The thesis comprises four main chapters on chemical reactions and kinetics of some of the processes involved in the global mercury cycle. In the first chapter, the UVA irradiation of aqueous acidic mercuric chloride in the presence of large excess of Fe(III) organic diacid complexes results in partial reduction of the mercuric ion to elemental mercury. The pseudo-first-order rate constant (k) for photoreduction reaction is pH-dependent. Similar results were obtained using visible irradiation although the rates were ca. 10 times slower. The mechanism of photoreduction is inferred to involve reaction of Hg(II) with a secondary photoproduct, the strongly reducing radical anion CO 2-•. No other previous reports have suggested the involvement of this radical in mercury reduction. In the presence of dissolved oxygen, competition for CO2-• between Hg(II) and O2 reduces the rate and efficiency of mercuric ion reduction. The O2-•/HO2 products do not reduce Hg(II). On the contrary, their disproportionation leads to the formation of H2O2 which causes a slow reoxidation of Hg(0). In the second chapter, the reaction rate of UVA photoreduction of Hg(II) ions by fulvic and humic acids was found to have higher values in the pH range of 5 to 6 which is relevant to most aquatic environments, within this pH range, speciation calculations show that most of Hg(II) will bind to DOC. The effects of environmentally relevant parameters such as Hg(II)/HS ratio, and chloride concentration were investigated and the likely mechanism identified. The interaction of DOC with Hg species is not only limited to photoreactions but also the complexation reaction affects the bioavailability and speciation of Hg. This was the topic of the last two chapters. The kinetic stability of Hg-HS and McHg-HS complexes was characterized by different combined techniques; the competitive ligand exchange method (CLEM) combined with inductively coupled plasma-mass spectrometer (CLEM-ICP-MS) and the tangential flow ultrafiltration (TFUF) combined to CLEM-ICP-MS. The Hg-HS complexes can be described by at least two kinetically distinguished components; the more inert (slow) with a dissociation rate constant in the order of 10-5 s -1, and a labile component with a dissociation rate constant in the order of 10-3 s-1, protons (H+) was found to compete with Hg2+ for the strong binding sites, Hg/HS concentration ratio also was an important parameter, when [Hg 2+] was high then the strong binding sites was saturated and the excess Hg bound to the weak sites. (Abstract shortened by UMI.)

Dyestuffs are widely used industrial chemicals, yet surprisingly little is known about their fate in the environment. The potential modes of transformation and removal of reactive dyes in treatment and in the environment are principally through anaerobic and aerobic biodegradation and photodegradation. The research herein describes the use of LC-MS analysis with laboratory simulations to develop a better understanding of the occurrence and fate of reactive dyes and their degradation products in the aquatic environment. One reason for the lack of information on the environmental fate of reactive dyes has been the paucity of robust analytical methods suitable for the determination of dyes in aqueous samples. Robust analytical methods were optimised to provide LC-MS and MSMS identification of degradation products. Additionally, interpretation of the MSMS spectra of known reactive dyes provided novel characteristic fragment ions indicative of the triazine reactive group of reactive dyes . Fibre reactive dyes are designed to have a degree of photostability and therefore their photodegradation behaviour has not been widely investigated. Little is known of their stability to daylight over prolonged periods of irradiation in dilute aqueous solutions and in the presence of humic substances. The kinetics of photodegradation of an anthraquinone dye (Reactive Blue H4R) and azo dye (Reactive Yellow P5G) were evaluated. The former underwent rapid and extensive degradation 01/2 1.5 h). The major products formed were identified using LC-MSMS and a photodegradation pathway proposed. By comparison, the photodegradation of the azo dye was significantly slower, 01/2 30 h). The addition of humic substancesa ppearedt o have little effect on the rate of photodegradationu nder the conditions used. The reduction of azo dyes under anaerobic treatment has been extensively studied, but the subsequent fate of the initial reduction products when exposed to air are not understood. Three relatively simple azo dyes, Amaranth, Sunset Yellow and Naphthol Blue-Black, were reduced and their autoxidation products identified by LC-MS. These were subsequently used to predict the autoxidation products of a more complex azo reactive dye: Reactive Red 3.1. Additionally, a persistent degradation product from the anaerobicaerobic treatment of Reactive Red 3.1 was identified from LC-MS data. Azo reactive dyes are generally regarded as being resistant to aerobic degradation and there are few published data regarding degradation pathways for reactive anthraquinone dyes. Pure cultures of Pseudomonas docunhae, A 9046 and A texaco and mixed bacterial consortia (semi-continuous activated sludge, SCAS) aerobic degradation of azo and anthraquinone reactive dyes was studied. Two azo dyes were degraded by pure cultures of A docunhae and A 9046, suggesting that azo dyes can be aerobically degraded given favourable conditions. The antraquinone dye was extensively degraded by SCAS and pure culture biodegradation. Metabolites were identified by LC-MS and a degradation pathway proposed.

Photochemical ammonium production and photo-bleaching of chromophoric dissolved organic matter (CDOM) kinetics were studied in a variety of aquatic environments including freshwater samples of peatland origin, Caithness, a Tyne Estuary (NE, U.K.) estuary and the Iberian Sea. The main aims of the study were to assess seasonal variability within the peatland catchments, in conjunction with a study of regional and geographical variability of dissolved organic matter (DOM) and ammonium photo-production. Samples collected from a variety of aqueous environments covered the CDaM .absofPtion coefficient at 350 nm (a350) range 0.3 to 69.0 m-I. Selected, filtered samples (n=21) were exposed to natural and artificial light, in order to study ~+ photo-production CDaM photo-bleaching. The photo-chemical degradation of CDaM, as indicated by decreases in a350 over time, also led to increases in the spectral slope of sample absorbance over the wavelength range 290-350 nm, and losses of total fluorescence intensity. In addition we observed hypsochromic shifts of long-wave, humic-like fluorescence (fluorophore A). Photo-chemical ammonium release was observed in 19 of the total 21 irradiation experiments. However the kinetics of ammonium production were complex with 4 of the 21 samples showing a near-linear increase in NH/ concentration while other samples showed an initial lag phase, followed by production and then a decline in NH/ concentrations. In order to assess possible impacts of ~+ release on N balance we estimated NH4+ photoproduction potentials from concentration differences between the initial values and maximum ~+ values divided by irradiation time (i1t). Thus obtained ~+ photo-production potentials between sites ranged from 0 to 3.57 JIM r1 h-I (mean ± stdev 0.7) under solar noon irradiance levels. Using calculated daily sky irradiance and seasonal correction factors, annual depth integrated ~+ photo-production rates were estimated, ranging from 0.06 to 8.05 JIMNm-2 yrI( mean ± stdev 2.73). The photo-chemical production ofNH/ indicates that photo-chemically induced nitrogen release could potentially be an important source of biologically labile nitrogen to aquatic ecosystems, with severe impacts upon the biogeochemistry and nutrient limitation of these environments when compared to N-reservoir size and other N fluxes. However, compared to N deposition photo-ammonification is not a major source ofN. Key words: Dissolved organic matter, chromophoric dissolved organic matter, photoammonification, peatlands, estuaries, marine, and fluorescence.

The occurrence of microbial pathogens in drinking water sources is recognized as a significant threat to public health. A better understanding of the key processes governing the fate of microbial pathogens in groundwater aquifers can help mitigate the risk of drinking water contamination. The attachment of pathogens to aquifer surfaces and the inactivation of attached and suspended pathogens are key processes that attenuate the concentration of viable pathogens in potable water supplies. Although substantial research effort has been aimed at elucidating the role of various physical, chemical and biological factors on the inactivation rate of microbes suspended in the aqueous phase, our understanding of microbe inactivation when attached to grain surfaces is limited. Thus, the first objective of this work was to develop a fluorescence-based experimental technique for evaluating the inactivation kinetics of bacteria adhered onto a surface in an aqueous environment. The technique was sensitive enough to distinguish between the inactivation kinetics of different representative bacteria attached to either a negatively or a positively charged surface. The new method was then used to characterize bacterial inactivation kinetics when attached to environmentally relevant surface chemistries such as metal oxides over a broad range of groundwater chemistries. X-ray photoelectron spectroscopy (XPS) characterization of bacterial-surface bonding was used to interpret inactivation behavior. It was observed that attachment of cells to metal-oxide surfaces can lead to formation of covalent bonds, specifically O- and C-metal bonds, between the cell and the surface, resulting in reduced bacterial viability (i.e., cell membrane integrity). Surface and near-surface soils in cold climate regions experience low temperature and freeze-thaw (FT) conditions in the winter. Microorganisms that are of concern to groundwater quality may have the potential to survive low temperature and FT in the soil and aqueous environments. Although there is a large body of literature on the survival of pathogenic bacteria at different environmental conditions, little is known about their transport in groundwater environments in low temperatures and after FT. Thus, in the second part of the project, the effect of cold temperature and repeated FT on survival, survival strategies such as motility and biofilm formation, and virulence of selected Gram-negative and Gram-positive bacteria was investigated. The adhesion properties and transport of bacteria exposed to FT were studied using quartz crystal microbalance with dissipation monitoring (QCM-D) and water saturated sand-packed columns. The expression levels of different genes encoding synthesis of flagellin, extracellular matrix production, and virulence factors were measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Our findings demonstrate that bacteria exhibited greater retention onto sand grains after exposure to FT. Moreover, bacteria tend to survive for longer periods of time and may become more virulent at low temperature in higher ionic strength waters thereby posing a potential threat to drinking water supplies.
L'apparition d'agents pathogènes microbiens dans les sources d'eau potable est reconnu comme une menace importante pour la santé publique. Une meilleure compréhension des processus fondamentaux qui régissent le sort des pathogènes microbiens dans les aquifères d'eau souterraine peut contribuer à atténuer le risque de contamination de l'eau potable. L'attachement des agents pathogènes aux surfaces des nappes phréatiques et leur inactivation lorsqu'ils sont attachés et suspendus, sont les processus clés qui atténuent la concentration des pathogènes viables dans l'approvisionnement en eau potable. Bien qu'un effort substantiel de recherche ait été réalisé, visant à élucider le rôle de divers facteurs physiques, chimiques et biologiques sur le taux d'inactivation des microbes en suspension dans la phase aqueuse, notre compréhension de l'inactivation du microbe lorsqu'il est attaché à la surface des grains est limitée. Ainsi, le premier objectif de ce travail était de développer une technique expérimentale basée sur la fluorescence pour évaluer la cinétique d'inactivation de bactéries collées sur une surface dans un environnement aqueux. La technique est suffisamment sensible pour faire la distinction entre la cinétique d'inactivation de différentes bactéries représentatives, montées soit sur une surface chargée négativement ou positivement. La nouvelle méthode a ensuite été utilisée pour caractériser la cinétique d'inactivation bactérienne lorsqu'elle est reliée à la chimie de surface environnementale telle que les oxydes métalliques et ceci sur une large gamme de produits chimiques des eaux souterraines. La caractérisation de la liaison bactérienne de surface par spectroscopie photoélectronique X (XPS) a été utilisée pour interpréter le comportement de l'inactivation. Il a été observé que l'attachement des cellules aux surfaces métal-oxyde peut conduire à la formation de liaisons covalentes, plus précisément des liaisons O- et C-métal, entre la cellule et la surface, ce qui entraîne une réduction de la viabilité bactérienne (i.e. une perte de l'intégrité de la membrane cellulaire).Dans les régions à climat froid, les sols de surface ou proches de la surface subissent de basses températures et des périodes de gel-dégel (GD). Les micro-organismes qui sont des sources de préoccupation pour la qualité des eaux souterraines peuvent avoir le potentiel de survivre à basses températures et aux périodes de GD, dans le sol et les milieux aqueux. Bien qu'il existe une littérature abondante sur la survie des bactéries pathogènes à différentes conditions environnementales, on possède peu d'informations au sujet de leur transport dans les environnements d'eau souterraine à des températures basses et après GD. Ainsi, dans la deuxième partie du projet, l'effet de la température froide et l'effet des périodes GD répétés ont été étudiés sur les stratégies de survie telles que la mobilité et la formation de biofilms ainsi que la virulence des bactéries sélectionnées à Gram négatif et Gram positif . Les propriétés d'adhérence et le transport des bactéries exposées à des périodes de GD ont été étudiés à l'aide d'une microbalance à cristal de quartz avec mesure de la dissipation (QCM-D) et de l'eau contenue dans des colonnes saturées de sable. Les niveaux d'expression des différents gènes codant pour la synthèse de la flagelline, la production de la matrice extracellulaire et des facteurs de virulence ont été mesurés en utilisant la transcription par réaction en chaîne par polymérase inverse quantitative (qRT-PCR). Nos résultats démontrent que les bactéries présentent une plus grande rétention sur les grains de sable après l'exposition aux périodes de GD. En outre, les bactéries ont tendance à survivre pendant de longues périodes de temps et peuvent devenir plus virulent à basse température dans des eaux à plus grande force ionique posant ainsi une menace potentielle pour l'eau potable.

Iron oxides and arsenic are prevalent in the environment. With the increase interest in the use of iron oxide nanoparticles (IONPs) for contaminant remediation and the high toxicity of arsenic, it is crucial that we evaluate the interactions between IONPs and arsenic. The goal was to understand the environmental behavior of IONPs in regards to their particle size, aggregation and stability, and to determine how this behavior influences IONPs-arsenic interactions. A variety of dispersion techniques were investigated to disperse bare commercial IONPs. Vortex was able to disperse commercial hematite nanoparticles into unstable dispersions with particles in the micrometer size range while probe ultrasonication dispersed the particles into stable dispersions of nanometer size ranges for a prolonged period of time. Using probe ultrasonication and vortex to prepare IONPs suspensions of different particle sizes, the adsorption of arsenite and arsenate to bare hematite nanoparticles and hematite aggregates were investigated. To understand the difference in the adsorptive behavior, adsorption kinetics and isotherm parameters were determined. Both arsenite and arsenate were capable of adsorbing to hematite nanoparticles and hematite aggregates but the rate and capacity of adsorption is dependent upon the hematite particle size, the stability of the dispersion and the type of sorbed arsenic species. Once arsenic was adsorbed onto the hematite surface, both iron and arsenic can undergo redox transformation both microbially and photochemically and these processes can be intertwined. Arsenic speciation studies in the presence of hematite particles were performed and the effect of light on the redox process was preliminary quantified. The redox behavior of arsenite and arsenate were different depending on the hematite particle size, the stability of the suspension and the presence of environmental factors such as microbes and light. The results from this study are important and have significant environmental implications as arsenic mobility and bioavailability can be affected by its adsorption to hematite particles and by its surface mediated redox transformation. Moreover, this study furthers our understanding on how the particle size influences the interactions between IONPs and arsenic thereby clarifying the role of IONPs in the biogeochemical cycling of arsenic.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references.
The development of three optical instruments for the chemical exploration and characterization of natural waters is described. The first instrument (called LEDIF) employs a novel flowcell, 6 UV LEDs as excitation sources, a wideband lamp, and a spectrometer to measure steady state chemical fluorescence and absorbance. The instrument is packaged aboard an autonomous underwater vehicle (AUV) and demonstrates the ability to map chemical concentrations in three dimensions. The second instrument repackages the sensor components to study dissolved organic matter (DOM) in tropical Southeast Asia peatland rainforests. This instrument is optimized for low power consumption over long deployments to remote locations. Two field trials in Pontianak Indonesia with durations of two and six weeks captured peatland river fluorescence measurements at 20 minute intervals. The results show changes in DOM linked to tidally induced water level fluctuations and provide insight into the complex biogeochemical dynamics of the system. The third instrument increases the chemical sensitivity and specificity of LEDIF with the addition of fluorescence lifetime sensing capabilities. The development of this sensor for AUV deployment required the engineering of a compact, low power, high speed (GHz) data acquisition circuit board. The resulting circuit digitizes data at a rate of 1 gigasample/second and performs user customizable digital signal processing. This board is used along with a 266 nm Q-switch laser, fast photomultiplier tube (PMT), and computer controlled monochromator to build a small fluorescence lifetime instrument. The instrument is tested with solutions of low concentration pyrene to demonstrate its ability to identify small, long-lived fluorescence signals in the presence of large background fluorescence. Results indicate a pyrene limit of detection below environmentally relevant levels. The final overall instrument dimensions allows it to be packaged for future AUV deployments
by Schuyler Senft-Grupp.
Ph. D.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006.
Yiacoumi, Sotira, Committee Chair ; Tsouris, Costas, Committee Co-Chair ; Pavlostathis, Spyros, Committee Member ; Tannenbaum, Rina, Committee Member ; Sherrill, David, Committee Member.

Phosphorus (P) is often the limiting nutrient in lacustrine and brackish eco-systems, and enhanced input of P into an aquatic system might therefore negatively impact the environment. Because modern waste water manage-ment have reduced external P input to surface waters, internal P loading from the sediment has become one of the main P sources to aquatic ecosys-tems, in which relatively unknown organic P compounds seem to be more active in P recycling than previously thought.

This thesis focus is on improving analysis methods for organic P com-pounds in lacustrine and brackish sediments, as well as determining which of these compounds might be degraded, mobilized and subsequently recycled to the water column and on what temporal scale this occur. In both lacustrine and brackish environments, the most labile P compound was pyrophosphate, followed by different phosphate diesters. Phosphate monoesters were the least labile organic P compounds and degraded the slowest with sediment depth. In regulated lakes, it was shown that pyrophosphate and polyphos-phate compound groups were most related to lake trophic status, thus indi-cating their involvement in P cycling. This thesis also indicates faster P turn-over in sediment from the brackish environment compared to sediment from the lacustrine environment.

A comparison of organic P extraction procedures showed that pre-extraction with EDTA, and NaOH as main extractant, was most efficient for total P extraction. Using buffered sodium dithionite (BD) as a pre-extractant and NaOH as main extractant was most efficient for extracting the presuma-bly most labile organic P compound groups, pyrophosphate and polyphos-phate. Furthermore, it was determined that organic P compounds associated with humic substances were more recalcitrant than other P compounds, that the BD step used in traditional P fractionation might extract phosphate monoesters, and that NMR is a statistically valid method for quantification of organic P compounds in sediment extracts.

Polar organic compounds (POCs) are chemicals with polar functional groups in their structure. The functional groups make the compounds hydrophilic and less prone to partition with biota. However, the knowledge of their fate is limited due to difficulties associated with their measurements. Although, the persistence of POCs in the environment is generally low, they are considered to be semi-persistent compounds due to their continuous introduction to the environment via wastewater. Studies have shown that complex mixtures of POCs of different classes may have synergistic toxic effects on biota at environmental concentration levels. Therefore, it is important to develop analytical methods in order to establish the occurrence and fate of POCs in aquatic environments. In Study I, a positive correlation between the sorption of a novel poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC) material and the theoretical logarithmic dissociation partition coefficient (Log D) for seven POCs was observed. The PEVAC material showed an enhanced sorption of the POCs compared to the silicone material. Study II, demonstrated that the PEVAC sampler assess the freely dissolved concentration of POCs in aquatic environments. The results showed that the PEVAC polymer is an attractive alternative to silicone for mimicing the biological uptake of POCs in aquatic environments. Additionally, Study II showed that total extraction is appropriate for determination of the freely dissolved concentration of uncharged POCs with Log KOW < 2.67 in natural water. In study III, a novel bag-solid phase extraction (bag-SPE) technique was compared to a conventional SPE-technique. Despite that the extraction efficiencies for POCs in wastewater were lower using the bag-SPE method, the two methods showed similar detection limits due to the lower ion-suppression experienced with the bag-SPE. In study IV the bag-SPE method was further developed with the aim of lowering the detection limits for POCs. Detection limits (LOD) below 13 ng/L showed that the bag-SPE method was suitable for determination of POCs in surface sea water.
This research was financially supported by European Union (European Commission, FP6 Contract No. 003956) “Novel Methods for Integrated Risk Assessment of Cumulative Stressors in the Environment” (NoMiracle) and by the Swedish research council Formas.

The classical theory of colloids and surface science has universally been applied in modeling and calculations involving solid-liquid interfaces encountered in natural and engineered environments. However, several discrepancies between the observed behavior of charged solid-liquid interfaces and predictions by classical theory have been reported in the past decades. The hypothesis that the mean-field, pseudo-one-component approximation adopted within the framework of the classical theory is responsible for the differences observed is tested in this work via the application of modeling and experimental techniques at a molecular level. Silica and silicon nitride are selected as model charged solid surfaces, and mixtures of symmetric and asymmetric indifferent and non-indifferent electrolytes are used as liquid phases. Canonical Monte Carlo simulations (CMC) of the electrical double layer (EDL) structure of a discretely charged planar silica surface, embedded in solutions of indifferent electrolytes, reveal the presence of a size exclusion effect that is enhanced at larger values of surface charge densities. That effect translates into an unexpected behavior of the interaction forces between a charged planar surface and a spherical particle. CMC simulations of the electrostatic interactions and calculations of the EDL force between a spherical particle and a planar surface, similarly charged, reveal the presence of two attractive force components: a depletion effect almost at contact and a long-range attractive force of electrostatic origin due to ion-ion correlation effects. Those two-force components result from the consideration of discreteness of charge in the interaction of solid-liquid interfaces, and they contradict the classical theory predictions of electrostatic repulsive interaction between similarly charged surfaces. Direct interaction force measurements between a charged planar surface and a colloidal particle, performed by atomic force microscopy (AFM), reveal that, when indifferent and non-indifferent electrolytes are present in solution, surface charge modification occurs in addition to the effects on the EDL behavior reported for indifferent electrolytes. Non-uniformity and even heterogeneity of surface charge are detected due to the action of non-indifferent, asymmetric electrolytes. The phenomena observed explain the differences between the classical theory predictions and the experimental observations reported in the open literature, validating the hypothesis of this work.

The behavior of Deepwater Horizon crude oil and other sources of oil were investigated when exposed to sunlight in aquatic systems under environmentally relevant conditions. This research decoupled the abiotic and biotic weathering modifications of oil by focusing solely on the photochemical transformations of oil in aquatic systems. Photochemical rates and mechanisms were measured through the determination of reactive transients. Total hydroxyl radical formation was studied using high benzoic acid concentrations and varying exposure time. Titanium dioxide (TiO2) nanomaterials were added to the system in an effort to determine if the photocatalyst would enhance oil photodegradation. Photochemical production of singlet oxygen from thin oil films over seawater and pure water was measured with furfuryl alcohol as a selective chemical probe. The loss of furfuryl alcohol and the formation of 6-hydroxy(2H)pyran-3(6H)-one were monitored. Photochemical production of organic triplets from 6 different compositions of petroleum was measured through the cis-trans isomerization of 1,3 pentadiene in Gulf water. The data correlate very well with previously measured singlet oxygen concentrations. The energies were measured in the range of 280-300 kJ/mol. Macondo Well Oil from the Deepwater Horizon (DWH) rig was mixed with pure water and seawater and irradiated with simulated sunlight. After irradiation, the water-soluble organics (WSO) from the dark and irradiated samples were extracted and characterized by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Liquid-liquid extraction yielded two fractions from dark and irradiated water/oil mixtures: acidic WSOs (negative-ion electrospray (ESI)), and base/neutral WSOs (positive-ion ESI). These fractions were analyzed by FT-ICR MS to catalogue molecular-level transformations that occurred to oil-derived WSOs after solar irradiation. The increased abundance of higher-order oxygen classes in the irradiated samples relative to the dark samples indicates that photooxidized components of the Macondo crude oil become water-soluble after irradiation. Time series studies were performed to observe the changes in WSO composition. The predominance of higher-order oxygen classes indicates that multiple photochemical pathways exist that result in oxidation of petroleum compounds. More oxygenated compounds were observed in the WSO acid fraction of oils with higher API gravity.

Phytoremediation as a way to control and lessen nutrient concentrations in landfill leachate is a cheap and environmentally sustainable method. Accumulated nutrients in the plants can then be removed by harvesting and anaerobically digesting the biomass. This study presents two aquatic plants (L. minor (L.) and P. stratiotes (L.)) and one microalgae species (C. vulgaris (L.)), their capacities for growth and nutrient removal in leachate from Häradsudden landfill, Sweden, are investigated. The biogas potential of the two plants is determined via anaerobic digestion in a batch run, followed by a lab-scale reactor run for L. minor only. Results show that growth in leachate directly from the landfill is not possible for the selected species, but at a leachate dilution of 50% or more. Nutrients are removed in leachates with plants to a higher extent than in leachates without, yet the actual amounts do not differ notably between plant species. L. minor proves a better choice than P. stratiotes despite this as growth is superior for L. minor under the experimental conditions of this study. Considering biogas production, L. minor gives more methane than P. stratiotes according to the results from the batch run. The former is however not suitable for large-scale anaerobic digestion unless as an additional feedstock due to practical cultivation issues.

Water quality changes that occur during establishment and maintenance of nitrification in two identical recirculating aquaculture systems containing rainbow trout are described. The time taken for the nitrification process to become established was 40-45 days. Mortality of fish attributed to elevated nitrite concentrations were recorded during the initial conditioning phase of the systems. Un-ionised ammonia concentrations did not attain lethal levels during this period. Nitrate concentrations accumulated slowly throughout the study, while the pH and alkalinity of the water decreased with progressive nitrification. Levels of carbon dioxide, calcium, dissolved and suspended solids remained relatively stable until the carrying capacity of the systems was increased, upon which they increased rapidly and general water quality deteriorated. Permanently elevated concentrations of ammonia and nitrite served as an indication that the carrying capacity of the systems had been exceeded. The use of ozone as a water enhancement treatment in aquaculture systems during one- and six-hour applications was also considered in this study. Ozonation significantly reduced nitrite levels at · low concentrations (0,1 - 0,15 mg/l), although they returned to pre-treatment levels within a few hours of cessation of the treatment. The formation of an unstable, intermediate product that reforms as nitrite in the absence of ozone, rather than the complete oxidation of nitrite to nitrate, is proposed. Ozonation also resulted in decreased dissolved solids, and improved the clarity and odour of the water. Ozone had no effect on ammonia concentrations (at pH > 7,0), or on nitrate or calcium levels, and did not conclusively increase the redox potential of the water. Residual ozone concentrations up to 0,04 mg/l in a sixhour treatment had no harmful effects on rainbow trout, and there were no signs of gas-bubble disease arising from supersaturation of the water with oxygen. Activated carbon filters were effective at removing residual ozone from the water after treatment. Treatment of the water with oxygen alone had no effect on nitrite concentrations.

The air-water interface is an important natural boundary layer that has been neglected as an area of environmental field research. This study establishes that comparative microscopy can be an effective environmental method, and establishes that the term metallic surface films, is a more accurate descriptor than iron oxide surface films. This research shows that surface films are complex, often with layered structure, serve as habitat for significant biota, and act as a point of mineralization to several transition metal elements including manganese, iron, copper, nickel and zinc. This study demonstrates that surface films form under several conditions and can have diverse morphology. Activity of biota, microbes, particularly diatoms, suggests that bacteria and cyanobacteria integrate into the film often in patches, represented by forms and casts. Analytical imaging is used to document and compare film morphology and structures, using scanning electron microscopy, photoemission electron microscopy and transmission electron microscopy with elemental analysis by energy dispersive spectroscopy to confirm the hypothesis. Instrument parameters and strengths are reviewed. Component layers of a copper/zinc film were used to confirm metallic layers and elemental distribution. Bacterial casts were used to confirm film interaction, and to show entrainment and enrichment of the film to incorporate autochthonous and allochthonous materials into the films themselves. Most samples were from Oregon selected sites, with some samples from Maryland and Barbados.

Brominated organic compounds (BOCs) of both natural and anthropogenic origin are abundant in the environment. Most compounds are either clearly natural or clearly anthropogenic but some are of either mixed or uncertain origin. This thesis aims to identify some naturally produced BOCs and to develop a method for analysis of the bromine isotopic composition in BOCs found in the environment. Polybrominated dibenzo-p-dioxins (PBDDs) in the Baltic Sea are believed to be of natural origin although their source is unknown. Since marine sponges are major producers of brominated natural products in tropical waters, BOCs were quantified in a sponge (Ephydatia fluviatilis) from the Baltic Sea (Paper I). The results showed that the sponge does not seem to be a major producer of PBDDs in the Baltic Sea. In this study, mixed brominated/chlorinated dibenzo-p-dioxins were however discovered for the first time in a background environment without an apparent anthropogenic source. The use of nuclear magnetic resonance spectroscopy (NMR) is unusual in analytical environmental chemistry due to its sample requirements. Preparative capillary gas chromatography was used to isolate a sufficient amount of an unidentified BOC from northern bottlenose whale (Hyperoodon ampullatus) blubber (Paper II) to enable NMR analysis for identification of the compound. The bromine isotopic composition of BOCs may give information on the origin and environmental fate of these compounds. The first steps in this process are the development of a method to determine the bromine isotope ratio in environmentally relevant BOCs (Paper III) and measuring the bromine isotope ratio of several standard substances to establish an anthropogenic endpoint (Paper IV).
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Irgarol 1051 is a common antifoulant toxic to certain marine organisms. Submerged aquatic vegetation (SAV) are exposed to this herbicide when it leaches into the marine environment from painted structures, making SAVs ideal candidates to function as sentinel indicator of contamination. In the initial stage of this study, Coconut Grove and Key Largo Harbor were assessed for environmental exposure to Irgarol. Water, sediment and SAVs were collected, the latter two subject to automated solid phase extraction, and all samples analyzed by GC/MS-SIM for Irgarol and its metabolite, M1. Of the vegetation analyzed, Halodule and Syringodium had the highest capacity to bioaccumulate Irgarol and M1. The root system and leaf contributed negligibly and significantly, respectively, to Irgarol uptake. In the final stage, a transplant between Coconut Grove and Chicken Key showed that the biota Thalassia and Halodule were able to uptake and depurate Irgarol, respectively, over a period of 30 days.

CAPES
As cianobactérias se proliferam rapidamente em ambientes eutrofizados e podem ser capazes de sintetizar toxinas que inviabilizam a utilização dos recursos hídricos. A espécie Microcystis aeruginosa apresenta ampla distribuição, além de ser potencial produtora de hepatotoxinas denominadas microcistinas. O risco à saúde humana destas substâncias faz com que os métodos para controle destes microrganismos na água adquiram fundamental importância. De forma a verificar possíveis efeitos inibitórios de compostos fitoquímicos produzidos por macrófitas aquáticas sobre o crescimento e a produção de microcistinas da cianobactéria Microcystis aeruginosa, o presente estudo utilizou extratos hidroalcoólicos de sete espécies de macrófitas aquáticas (Eichhornia azurea, Eleocharis cf. acutangula, Ludwigia cf. peruviana, Myriophyllum cf. aquaticum, Pontederia cordata, Sagittaria montevidensis e Typha domingensis). O meio de cultura ASM-1 foi otimizado em relação ao pH, nitrogênio, fósforo e ferro através de planejamento fatorial. Para o preparo dos extratos, as sete espécies de macrófitas aquáticas foram coletadas, processadas e submetidas ao processo de extração com solução hidroetanólica 80% (v/v). Os extratos obtidos foram liofilizados e aplicados em concentrações conhecidas aos cultivos de M. aeruginosa, em meio ASM-1 otimizado. O monitoramento da concentração celular foi realizado a cada 48 h por 10 dias. As diferenças estatísticas foram avaliadas através do método estatístico ANOVA repeated. A determinação da concentração de microcistina-LR foi realizada nas culturas contendo a concentração de extrato de maior efeito inibitório. Para a verificação de efeitos bacteriostáticos e bactericidas, ao final do período testado, os cultivos foram reinoculados em tubos de ensaio contendo apenas o meio de cultura estéril. Os extratos foram avaliados quanto à presença de metabólitos secundários e à toxicidade aguda sobre Daphnia magna. Os experimentos apresentaram valores de crescimento elevados no meio que continha maiores concentrações de P e Fe. Os extratos inibiram significativamente o crescimento da cepa quando foram aplicados na concentração de 500 mg.L-1, com exceção do extrato obtido a partir de S. montevidensis em que o efeito inibitório sobre as células foi o menor observado. O extrato com maior efeito inibitório foi obtido de partes aéreas de M. cf. aquaticum pois a taxa de inibição foi de 99,1% na concentração de 500 mg.L-1. As análises de microcistina evidenciaram que para o extrato de E. cf. acutangula a redução do crescimento foi acompanhada de aumento na produção de microcistina-LR de 216 para 610 ppb. Nos testes com o extrato de S. montevidensis a concentração de toxina sofreu pouca alteração, aumentando de 216 para 222 ppb. Efeitos bactericidas foram verificados para a exposição aos extratos de E. cf. acutangula, L. cf. peruviana e M. cf. aquaticum, uma vez que após reinoculadas não foram verificados crescimentos celulares. Para os extratos de E. azurea, P. cordata e T. domingensis não foram observados efeitos tóxicos, por outro lado, a maior toxicidade ocorreu para S. montevidensis, pois 100% dos organismos apresentaram imobilidade na concentração de 50 mg.L-1. Considerando os dados de inibição e de toxicidade foi possível constatar que o extrato obtido de L. cf. peruviana apresentou maiores vantagens em sua aplicação. Os resultados obtidos indicam a possibilidade futura da aplicação de extratos para a remediação de florações e mostram, também, a necessidade de investigações fitoquímicas e toxicológicas mais detalhadas no sentido de identificar as substâncias ativas no controle de florações, de forma a potencializar a ação destas e minimizar seus efeitos tóxicos.
Cyanobacteria proliferate rapidly in eutrophic environments and may be able to synthesize toxins that block water resources use. The cyanobacterium Microcystis aeruginosa is widely distributed, being a potential producer of hepatotoxins called microcystins. The risks to human health of these substances demands methods to control these microorganisms in water. In order to investigate possible inhibitory effects of phytochemical compounds produced by aquatic macrophytes on the growth and microcystin production of Microcystis aeruginosa, the present study used aquatic macrophytes hydroalcoholic extracts of seven species (Eichhornia azurea, Eleocharis cf. Acutangula, Ludwigia cf. peruviana, yriophyllum cf. aquaticum, Pontederia cordata, Sagittaria montevidensis and Typha domingensis). The culture medium ASM-1 was optimized with respect to pH, nitrogen, phosphorus and iron through a factorial design. For extracts preparation, the seven species of aquatic macrophytes were collected, processed and submitted to extraction process solution ethanol 80% (v/v). The extracts were lyophilized and applied in known concentrations to cultures of M. aeruginosa, in optimized ASM-1 medium. Cell concentration was determined every 48 h for 10 days. Statistical differences were evaluated using ANOVA repeated. The microcystinLR concentration was determined in cultures containing greater inhibitory effect extract concentration. Evaluation of bacteriostatic and bactericidal effects at the end of tested period, the cultures were reinoculated into test tubes containing only sterile culture medium. The extracts were evaluated for the presence of secondary metabolites and acute toxicity on Daphnia magna. The experiments showed high growth rates in medium containing higher concentrations of P and Fe. Hydroalcoholic extracts inhibited the growth of Microcystis aeruginosa strain, more effective when applied at a concentration of 500 mg L-1, except for tests performed with S. montevidensis in that the mean inhibitory effect on the cells was the lowest observed. The extract with the highest inhibitory effect was obtained from aerial parts of M. cf. aquaticum in which the inhibition rate was 99.1%. The analyzes showed that microcystin for the extract of E. cf. acutangula the greatest cellular inhibition was accompanied by an increase in microcystin-LR production from 216 to 610 ppb. In tests with S. montevidensis extract the concentration of toxin was few changed, increasing from 216 to 222 ppb. Bactericidal effects were observed for exposure to extracts of E. cf. acutangula, L. cf. peruviana and M. cf. aquaticum. For extracts of E. azurea, P. cordata and T. domingensis toxic effects were not observed. The major toxicity was observed for S. montevidensis, in which 100% of organisms presented immobility in concentration of 50 mg.L-1. Considering inhibition and toxicity data was found that L cf. peruviana extract showed more advantages on its application. The results indicate the possibility of future application of extracts for blooms remediation and also show the need for detailed toxicological and phytochemical investigations in order to identify the active compounds in blooms control and minimize their toxic effects.

Climate change is one of the largest problems facing this generation. Anthropogenically caused increases of greenhouse gas emissions is a significant culprit to this problem. Although the obvious problems such as cars, industry, and urbanism garnish a significant amount of the criticism, natural sources such as wetlands are also beginning to contribute to this issue. This is becoming increasingly significant as wetlands shift from being sinks of greenhouse gases to becoming sources as various anthropogenic impacts, including global warming itself, begin to affect the health of the wetlands. The aim of this project is to look at four common types of wetlands, being tropical mangroves, temperate coastal marshes, inland meadows, and subarctic peatlands, all located in different climactic areas of the world, and by doing a meta-analysis of available data of greenhouse gas production for each wetland type, observe how differences in their greenhouse gas production may contribute or be affected by climate change and global warming. Results of the meta-analysis revealed that the most significant production of the potent greenhouse gas nitrous oxide occurs in coastal wetlands such as tropical mangroves and coastal marshes, while the greenhouse gas methane is seen to be produced most in subarctic peatlands. These contributions of wetlands to global greenhouse gas production are not as significant as other anthropogenic contributions. However, subarctic wetlands contribute to more than half of the global methane emissions, and the most important aspect of wetland greenhouse gas production is that they are producing more greenhouse gases than they would normally be sequestering, contributing more than the basic greenhouse gas production data can display. Global climate changes such as temperature increase and sea level rise could also make these levels of greenhouse gas production become worse, although measures to decrease the effects of this such as regulations on anthropogenic nitrogen input, macrophyte presence, and prevention of peat burning.

Use of arsenic-rich groundwater for crop irrigation can increase the arsenic (As) content in food crops and act as a carcinogen, compromising human health. Using aquatic plant based phytofiltration is a potential eco-technique for removing arsenic from water. The aquatic moss species Warnstorfia fluitans grows naturally in mining areas in northern Sweden, where high concentrations of arsenic occur in lakes and rivers. This species was selected as a model for field, climate chamber and greenhouse studies on factors governing arsenic removal and arsenic phytofiltration of irrigation water. The arsenic and silicon (Si) concentrations in soil, water and plant samples were measured by AAS (atomic absorption spectrophotometry), while arsenite and arsenate species were determined using AAS combined with high pressure liquid chromatography (HPLC) with an anion exchange column. The arsenic content in grains of hybrid and local aromatic rice (Oryza sativa) cultivars with differing arsenic accumulation factor (AF) values was investigated in an arsenic hotspot in Bangladesh. The results showed that arsenic AF was important in identifying arsenic-safer rice cultivars for growing in an arsenic hotspot. The study based on silicon effect on arsenic uptake in lettuce showed that arsenic accumulation in lettuce (Lactuca sativa) could be reduced by silicon addition. The aquatic moss had good phytofiltration capacity, with fast arsenic removal of up to 82% from a medium with low arsenic concentration (1 µM). Extraction analysis showed that inorganic arsenic species were firmly bound inside moss tissue. Absorption of arsenic was relatively higher than adsorption in the moss. Regarding effects of different abiotic factors, plants were stressed at low pH (pH 2.5) and arsenic removal rate was lower from the medium, while arsenic efflux occurred in arsenate-treated medium at low (12°C) and high (30°C) temperature regimes. Besides these factors, low oxygenation increased the efficiency of arsenic removal from the medium. Finally, combining W. fluitans as a phytofilter with a lettuce crop on a constructed wetland significantly reduced the arsenic content in edible parts (leaves) of lettuce. Thus W. fluitans has great potential for use as an arsenic phytofilter in temperate regions.

QC 20170323

Diese Dissertation beschäftigt sich mit der passiven Probenahme von hydrophoben organischen Schadstoffen in Oberflächengewässern: Polyaromatische Kohlenwasserstoffe (PAK), polychlorierte Biphenyle (PCB), polybromierte Biphenylether (PBDE), Organochlorpestizide (u. a. HCH, DDX) und weitere hydrophobe Pestizide. Die Zielstellung dieser Arbeit lag bei der Validierung des Silikonstabs als Alternativmethode im Gewässermonitoring zu konventionellen Probenahmetechniken wie Schöpf- und Wochenmischproben der Wasserphase sowie Schwebstoffanalysen. Die Probenahme mit dem Silikonstab erfolgte durch dessen Exposition im Gewässer für einen Zeitraum zwischen einer Woche und mehreren Monaten. Nach Einholung wurden die im Silikonstab akkumulierten Schadstoffe (Analyten) mittels instrumenteller Analytik quantifiziert. Die Probenaufgabe erfolgte ohne vorherige Lösungsmittelextraktion durch direktes Erhitzen des Silikonstabs, wodurch die Analyten vom Polymer desorbieren (Thermodesorption). Die durch Hitze freigesetzten Analyten wurden direkt auf eine chromatographische Trennsäule gegeben und massenspektroskopisch quantifiziert. Nach Erhalt der Ergebnisse der Silikonstab-Analytik gibt es verschiedene Herangehensweisen für die Berechnung der zeitgemittelten Analytkonzentrationen im Gewässer, die in dieser Arbeit vorgestellt und diskutiert werden. Dazu gehören die Verwendung von experimentellen Daten aus Kalibrierversuchen und Berechnungen auf Grundlage von physikochemischen Eigenschaften der Analyten wie dem Sammler-Wasser-Verteilungskoeffizienten. Im Zuge dieser Arbeit wurde die Aufnahmekinetik des Silikonstabs bei verschiedenen Temperaturen und Fließgeschwindigkeiten mit Hilfe von Kalibrierversuchen untersucht. Die gewonnenen experimentellen Daten wurden für die Entwicklung von Rechenmodellen herangezogen, mit denen das Aufnahmeverhalten vorgesagt werden soll. Es wurden Sammler-Wasser-Verteilungskoeffizienten für den Silikonstab u. a. mit der Kosolvenzmethode bestimmt und als Parameter für die Berechnung von zeitgemittelten Analytkonzentrationen des Gewässers verwendet. Für die Validierung wurde der Silikonstab in zwei Gewässergütemessstationen der Fließgewässer Mulde (Dessau) und Elbe (Magdeburg) in Durchflussbehältern exponiert und die zeitgemittelten Analytkonzentrationen mit verschiedenen Rechenmodellen bestimmt. Die erhaltenen Werte werden mit gleichzeitig entnommenen Wochenmischproben der Wasserphase sowie monatlichen Schwebstoffproben verglichen und die Eignung des Silikonstabs als alternative Probenahmemethode für das Umweltmonitoring von Oberflächengewässern diskutiert.

Coastal forest retreat in the Florida Keys during the 20th century has been attributed to a combination of sea level rise and hurricane storm surge impacts, but the interactions between these two disturbances leading to forest decline are not well understood. The goal of my research was to assess their effects over a period spanning more than two decades, and to examine the relationships between these press and pulse disturbances and freshwater availability in pine rockland, hardwood hammock, and supratidal scrub communities. Impacts and recovery from two storm surges, Hurricanes Georges (1998) and Wilma (2005), were assessed with satellite-derived vegetation indices and multiple change detection techniques. Impacts were greater at lower elevations, and in hardwood hammock, spectral signatures indicative of plant stress and productivity returned to pre-disturbance levels within a few years. In pine rockland, impacts were predominately related to Hurricane Wilma, however, a similar return to pre-disturbance conditions was absent, suggesting that trajectories of disturbance recovery differed between the two communities. Long-term monitoring of forest composition, structure, and groundwater salinity showed that compositional shifts in the low shrub stratum were associated with salinization of the freshwater resource attributable to sea level rise. Throughout the course of twelve months of climate and groundwater monitoring (2011-2012), groundwater salinity generally decreased in response to large precipitation events. Modeling of geophysical data indicated that groundwater salinity was an important predictor of community type. Isotopic analysis of d18O in plant stem water and foliar d13C was used to determine temporal and spatial patterns in water use and plant stress in two community dominants, slash pine, Pinus elliottii var. densa, and buttonwood, Conocarpus erectus. Both species relied heavily on groundwater, and plant stress was related to increasing groundwater salinity. The results of this work suggest that the interaction of press and pulse disturbances drive changes in community composition by causing mortality of salt-sensitive species and altering the freshwater resource.

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As substâncias húmicas aquáticas possuem grande importância ambiental por terem a capacidade de complexar íons metálicos presentes no ambiente influenciando a disponibilidade dos mesmos, tornando-os geralmente menos tóxicos para a biota. As Metalotioneínas (MT) apresentam a característica de regular metais nos organismos aquáticos, sendo induzidas na presença de metais e outros compostos e, portanto utilizadas como biomarcador ambiental. O benzo[a]pireno é oriundo de fontes biogênicas, pirogênicas e petrogênicas e seu efeito na indução de MT em tilápias é desconhecido. Neste contexto, foi avaliada a indução de MT em peixes expostos a metais tóxicos individualmente e na mistura, na ausência e presença de substâncias húmicas aquáticas (SHA), bem como na presença de benzo[a]pireno. Neste trabalho foram feitas a otimização e padronização do método para quantificação de metalotioneínas em fígado e brânquias de peixes empregando a técnica de Cromatografia Líquida de Alta Eficiência com Detector de Fluorescência (HPLC-FD). Também foi avaliada a influência do tempo de duração dos ensaios na indução de metalotioneínas em peixes expostos a metais de interesse ambiental durante 3, 7 e 14 dias. Tilápias do Nilo (Oreochromis niloticus) foram alocadas em aquários individuais e submetidas à exposição a concentrações regulamentadas pela resolução Conama 357/2005 para rios Classe 2, Classe 3 e 5 vezes Classe 3 de Cádmio, Cobre, Chumbo, Ferro e Benzo[a]pireno isoladamente, bem como a mistura dos metais na presença e ausência de SHA. A concentração de metal “livre” foi acompanhada durante os experimentos de exposição empregando o Sistema de Ultrafiltração com Fluxo Tangencial. Em todas as amostras de água dos experimentos de exposição e no tecido muscular dos peixes utilizados foram realizadas a...
The aquatic humic substances have great environmental importance to have the ability to complex metal ions present in the environment influencing their availability, making them generally less toxic to biota. Metallothioneins (MT) have the characteristic of regular metals on aquatic organisms being induced in the presence of metals and other compounds and therefore used as a biomarker environment. Benzo[a]pyrene is formed by biogenic sources, pyrogenic and petrogenic and its effect on the induction of MT in tilapia is unknown. In this context, we evaluated the induction of MT in fish exposed to toxic metals (Fe, Cu, Cd and Pb) individually and all these metal combined in the absence and presence of humic substances (SHA), as well as in the presence of benzo[a]pyrene. In this work we made the optimization and standardization of the method for quantification of metallothionein in liver and gills of fish employing the technique of High Performance Liquid Chromatography with Fluorescence Detector (HPLC-FD). We also evaluated the influence of the duration of the tests in the induction of metallothionein in fishes exposed to metals of environmental interest for 3, 7 and 14 days. Nile tilapia (Oreochromis niloticus) were placed in individual aquaria and subjected to exposure to concentrations regulated by CONAMA 357/2005 Resolution for rivers Class 2, Class 3 and 3 fold the concentrations to Class 3 for Cadmium, Copper, Lead, Iron and Benzo[a]pyrene separately, and all these metals combined in the presence and absence of SHA. The concentration of free metal was monitored during the exposure experiments using a Tangential Flow Ultrafiltration System (TFUS). In all samples of water exposure experiments and in the muscle tissue of fishes were quantified total metal employing a Graphite Furnace Atomic Absorption Spectrophotometer... (Complete abstract click electronic access below)

Dissertação de Mestrado em Ecologia apresentada à Faculdade de Ciências e Tecnologia
O presente Projeto de Mestrado pretende contribuir para a caracterização do risco do uso agrícola da mandipropamida, um fungicida cujo risco para os organismos aquáticos foi considerado baixo pela EFSA, para o compartimento água. Para tal foram delineados três objetivos: a) desenvolver e validar um método analítico para determinar a mandipropamida na matriz água, b) determinar os níveis de exposição ambiental da mandipropamida, e c) determinar os efeitos do princípo ativo mandipropamida e da sua formulação comercial Revus®. Os resultados mostram que a mandipropamida dissolvida determinada em amostras do rio Tejo está abaixo do limite de quantificação de 0.05 μg L-1, logo abaixo do valor máximo admissível de acordo com o Decreto-Lei 236/98, indicando as boas práticas agrícolas desenvolvidas no vale do tejo. Tanto o principio ativo como a formulação Revus® apresentam baixa toxicidade para os organismos aquáticos, não tendo sido possível determinar EC50 (concentração com 50% de efeito). Dos seis organismos testados, o crustáceo Thamnocephalus platyurus é a espécie mais sensível, pois foi possível determinar um LC20 (concentração que mata 20% dos organismos testados), e a bactéria Vibrio fischeri o organismo menos sensível. Usando os dados de toxicidade encontrados na literatura, foi possível derivar dois valores de proteção ambiental, um pelo método determinístico (37 μg L-1) e outro pelo método probabilístico (93 μg L-1). Uma vez que a concentração ambiental máxima determinada em amostras de água superficial foi de 0.24 μg L-1, os quocientes de risco são inferiores a um, indicando que a caracterização de risco prospectiva foi apropriada para classificar a mandipropamida como sendo de baixo risco, uma vez que não são esperados efeitos adversos para os organismos aquáticos da aplicação agrícola deste fungicida.
The present Master Project aims to contribute towards the evaluation of the potential hazard of the agricultural application of mandipropamid, a fungicide whose prospective risk to aquatic organisms was considered low, to the aquatic environment. To attain this main goal, three specific objectives were delineated: a) to develop and validate an analytical method to determine mandipropamid in the water matrix, b) to determine mandipropamid environmental exposure levels, and c) to determine the effects of both mandipropamid as an active ingredient and its commercial formulation Revus®. The gathered results showed that the dissolved mandipropamid levels in the river Tagus, the selected study area, were below the method quantification limit of 0.05 μg L-1, thus below the maximum acceptable value for individual pesticides according to Decree-Law 236/98, indicating good agricultural practices in the Tagus valley. Both mandipropamid and Revus® showed low toxicity to aquatic organisms, and no EC50 (half effect concentration) value could be determined. Nevertheless, from the six tested organisms, the crustacean Thamnocephalus platyurus seems to be the most sensitive species, as a LC20 (20% lethal concentration) could be determined, and the bacteria Vibrio fischeri was the least sensitive species. Using the toxicity data reported in literature, two environmental quality standard values were derived for freshwater ecosystems: one using the deterministic method (37 μg L-1), and the other using the statistical extrapolation model species sensitivity distribution (93 μg L-1), and as expected the value based on the lowest EC50 (deterministic method) was lower than the one obtained through the SSD method. Since the maximum environmental concentration found in surface waters is 0.24 μg L-1, risk quotients below one were determined using both approaches, indicating that the prospective risk process was appropriate for mandipropamid, and no adverse effects are expected for aquatic organisms from the agricultural use of this fungicide.
Outro - PT2020 e COMPETE 2020

Diese Dissertation beschäftigt sich mit der passiven Probenahme von hydrophoben organischen Schadstoffen in Oberflächengewässern: Polyaromatische Kohlenwasserstoffe (PAK), polychlorierte Biphenyle (PCB), polybromierte Biphenylether (PBDE), Organochlorpestizide (u. a. HCH, DDX) und weitere hydrophobe Pestizide. Die Zielstellung dieser Arbeit lag bei der Validierung des Silikonstabs als Alternativmethode im Gewässermonitoring zu konventionellen Probenahmetechniken wie Schöpf- und Wochenmischproben der Wasserphase sowie Schwebstoffanalysen. Die Probenahme mit dem Silikonstab erfolgte durch dessen Exposition im Gewässer für einen Zeitraum zwischen einer Woche und mehreren Monaten. Nach Einholung wurden die im Silikonstab akkumulierten Schadstoffe (Analyten) mittels instrumenteller Analytik quantifiziert. Die Probenaufgabe erfolgte ohne vorherige Lösungsmittelextraktion durch direktes Erhitzen des Silikonstabs, wodurch die Analyten vom Polymer desorbieren (Thermodesorption). Die durch Hitze freigesetzten Analyten wurden direkt auf eine chromatographische Trennsäule gegeben und massenspektroskopisch quantifiziert. Nach Erhalt der Ergebnisse der Silikonstab-Analytik gibt es verschiedene Herangehensweisen für die Berechnung der zeitgemittelten Analytkonzentrationen im Gewässer, die in dieser Arbeit vorgestellt und diskutiert werden. Dazu gehören die Verwendung von experimentellen Daten aus Kalibrierversuchen und Berechnungen auf Grundlage von physikochemischen Eigenschaften der Analyten wie dem Sammler-Wasser-Verteilungskoeffizienten. Im Zuge dieser Arbeit wurde die Aufnahmekinetik des Silikonstabs bei verschiedenen Temperaturen und Fließgeschwindigkeiten mit Hilfe von Kalibrierversuchen untersucht. Die gewonnenen experimentellen Daten wurden für die Entwicklung von Rechenmodellen herangezogen, mit denen das Aufnahmeverhalten vorgesagt werden soll. Es wurden Sammler-Wasser-Verteilungskoeffizienten für den Silikonstab u. a. mit der Kosolvenzmethode bestimmt und als Parameter für die Berechnung von zeitgemittelten Analytkonzentrationen des Gewässers verwendet. Für die Validierung wurde der Silikonstab in zwei Gewässergütemessstationen der Fließgewässer Mulde (Dessau) und Elbe (Magdeburg) in Durchflussbehältern exponiert und die zeitgemittelten Analytkonzentrationen mit verschiedenen Rechenmodellen bestimmt. Die erhaltenen Werte werden mit gleichzeitig entnommenen Wochenmischproben der Wasserphase sowie monatlichen Schwebstoffproben verglichen und die Eignung des Silikonstabs als alternative Probenahmemethode für das Umweltmonitoring von Oberflächengewässern diskutiert.:I ZUSAMMENFASSUNG ...................................................................................................... 2 II INHALTSVERZEICHNIS .................................................................................................. 3 III ABBILDUNGSVERZEICHNIS .......................................................................................... 5 IV TABELLENVERZEICHNIS ................................................................................................ 6 V GLEICHUNGSVERZEICHNIS ............................................................................................ 7 VI ABKÜRZUNGSVERZEICHNIS........................................................................................... 9 0 VIELEN DANK AN … ...................................................................................................... 11 1. EINLEITUNG ................................................................................................................ 12 1.1 Wasser, seine Nutzung und Verschmutzung ............................................................ 12 1.2 Das Wasser und seine Schadstoffe .......................................................................... 15 1.3 Monitoring von Oberflächengewässern .................................................................... 17 1.3.1 Entnahme konventioneller Schöpfproben .............................................................. 17 1.3.2 Entnahme von Mischproben (integrative oder Kompositproben) ........................... 18 1.3.3 Probenahme des Schwebstoffanteils in der Wasserphase .................................... 19 2. PASSIVSAMMLER IN DER WASSERANALYTIK ................................................................ 21 2.1 Theoretische Grundlagen ......................................................................................... 21 2.1.1 Allgemeiner Aufbau von Passivsammlern ............................................................... 23 2.1.2 Die einzelnen Schritte von der Wasser- in die Sammelphase ................................ 25 2.1.3 Adsorptive und absorptive Akkumulation des Analyten in der Sammelphase ........ 26 2.2 Passivsammlersysteme in der Wasseranalytik ......................................................... 28 2.2.1 Absorbierende Passivsammler für hydrophobe Analyten ....................................... 28 2.2.1.1 Semipermeable membrane device (SPMD) .......................................................... 28 2.2.1.2 LDPE-Streifen (LDPE strips) ................................................................................ 29 2.2.1.3 Silikonplatten (silicone sheets) ........................................................................... 30 2.2.1.4 Chemcatcher ...................................................................................................... 31 2.2.1.5 Lösungsmittelfreie Passivsammler (MESCO / Silikonstab) .................................. 32 2.2.2 Absorbierende Passivsammler für polare Analyten ............................................... 35 2.2.2.1 Polar organic integrative Sampler (POCIS) ......................................................... 35 2.2.2.2 Chemcatcher ...................................................................................................... 35 2.3 Auswertung von Passivsammlerdaten ..................................................................... 35 2.3.1 Gleichgewichtssammler ......................................................................................... 36 2.3.2 Laborkalibrierung .................................................................................................. 37 2.3.3 In-situ-Kalibrierung mit Performance Reference Compounds (PRC) ...................... 38 2.3.4 Validierung von Passivsammlern............................................................................ 39 3. LÖSLICHKEIT UND THERMODYNAMISCHES GLEICHGEWICHT ...................................... 41 3.1 Freie Enthalpie und chemisches Potential ................................................................ 41 3.2 Lineare freie Energie-Beziehungen (LFER) für die Abschätzung von KSW ................ 41 3.3 Kosolvenzmodelle für die Modellierung von KSW ...................................................... 43 3.3.1 Log-Linear-Modell von Yalkowsky .......................................................................... 43 3.3.2 Freie Enthalpie-Ansatz (Khossravi-Connors-Modell) .............................................. 44 3.3.3 Jouyban-Acree-Modell ............................................................................................ 44 4. MATERIAL UND METHODEN ......................................................................................... 45 4.1 Präparation der verwendeten Passivsammler .......................................................... 45 4.2 Laborkalibrierung zur Bestimmung von Sammelraten ............................................... 45 4.2.1 Beschreibung der Versuche für die Silikonstab-Kalibrierung .................................. 45 4.3 Experimentelle Bestimmung von Sammler-Wasser-Verteilungskoeffizienten KSW ... 48 4.3.1 Zeitabhängige KSW-Bestimmung in der Wasserphase .......................................... 48 4.3.2 KSW-Bestimmung mit der Kosolvenzmethode ....................................................... 50 4.4 Validierung des Silikonstabs an limnischen Gewässergütemessstationen ............... 52 5. ERGEBNISSE UND DISKUSSION ................................................................................... 55 5.1 Sammelraten RS für den Silikonstab aus Kalibrierversuchen .................................... 55 5.1.1 Temperaturabhängigkeit ....................................................................................... 58 5.1.2 Einfluss der Hydrodynamik auf die Aufnahmekinetik von PAK ................................ 59 5.1.3 Modellierung von Sammelraten .............................................................................. 62 5.1.3.1 Polynomisches Modell nach Vrana [137] ............................................................. 62 5.1.3.2 Diffusionsmodell nach Booij [71] ......................................................................... 64 5.1.3.3 Diffusionsmodell nach Rusina [85] ...................................................................... 66 5.1.4 Wahl der geeigneten In-situ-Kalibrierung am Beispiel eines Kalibrierversuchs ..... 67 5.1.4.1 Berechnung von In-situ-Sammelraten mit RS-Modellen ...................................... 68 5.1.4.2 Berechnung von In-situ-Sammelraten über Eliminierung von PRCs .................... 69 5.1.4.3 Vergleich Modelle und PRCs mit experimentellen Sammelraten .......................... 70 5.2 Experimentelle Bestimmung des Sammler-Wasser-Verteilungskoeffizienten KSW ... 73 5.2.1 Zeitabhängige KSW-Bestimmung in der Wasserphase .......................................... 73 5.2.2 Zusammenfassung KSW(t)-Versuche in der Wasserphase .................................... 81 5.2.3 KSW-Bestimmung mit der Kosolvenzmethode ....................................................... 81 5.2.3.1 Kosolvenzmodelle ............................................................................................... 83 5.2.4 Zusammenfassung ................................................................................................ 90 5.3 Empirische Modelle zur Abschätzung von KSW-Werten ............................................ 92 5.3.1 Lineare Korrelation des KSW mit physikochemischen und Molekülparametern ...... 92 5.3.2 Berechnung mit Mehrparameter-Regression (LSER) .............................................. 95 5.3.3 Zusammenfassung Abschätzung von KSW-Werten für den Silikonstab ................. 97 5.4 Freilandvalidierung des Silikonstab-Passivsammlers ................................................ 97 5.4.1 Ausbringung an Gewässergütemessstationen....................................................... 97 5.4.1.1 Validierung des Silikonstabs mit Wasserproben ............................................... 100 5.4.1.2 Validierung des Silikonstabs mit Sedimentproben ............................................ 102 5.4.2 Validierung des Silikonstabs bei Laborvergleichsstudien ..................................... 105 6. ERGEBNISSE UND AUSBLICK ..................................................................................... 105 VII LITERATURVERZEICHNIS ......................................................................................... 107 VIII ANHANG ................................................................................................................. 116