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<p>Eutrophication from agricultural runoff is a global issue, and can often result in degradation and loss of aquatic habitat. The overall objective of this study is to gain a better understanding of the factors that influence variation in water chemistry of low-order streams in an agricultural watershed. The first chapter finds significant differences between the effects of livestock- vs and crop-based operations on water chemistry while modeling the relationship between independent landscape variables and major water-quality parameters in an agroecosystem. I also determine significant differences exist in dependent variables among seasons and are best described by the agriculturally relevant calendar (ARC). In Chapter 2, I compared the effectiveness of discrete and continuous sampling programs for monitoring the impacts of cattle disturbances on water quality. I found that daily total phosphorus (TP) concentrations (integrated sample taken every 6 hours) were not significantly correlated with precipitation and were significantly lower than discrete water samples. Turbidity readings (recorded every half hour) showed spikes that corresponded with cattle hydration events and increased levels of nutrients through backwash. . In Chapter 3, I find a significant relationship between periphyton growth and the level of primary nutrients (TP, soluble reactive phosphorus, total-ammonia nitrogen). Thus, for low-order streams influenced by small family farms, acrylic rods may be an inexpensive indicator of excess limiting nutrients. In such environments stream length may be a stronger measure of streams than stream order since total nitrogen, TP and pH were significantly correlated with stream length.</p> / Master of Science (MSc)

<p>Coastal wetlands are hydrologically connected to their watershed and the lake. Water levels in Georgian Bay have been at a sustained low for thirteen years and thus connectivity of wetlands to the lake is being threatened as water levels decline. Decreased connectivity has likely caused changes in ecological and chemical characteristics. Future climate change models predict further water declines and potentially increasing the number of wetlands that will be hydrologically disconnected. The over-arching goal of this thesis is to investigate the role of connectivity between the lake and coastal marshes in eastern Georgian Bay on the amount of potential fish habitat, water chemistry and larval amphibian habitat.</p> <p>Bathymetric information is needed in order to estimate fish habitat and two approaches were utilized in order to collect these data. A site-specific method completed in 2009 used an intensive field survey in seven wetlands to create a digital elevation model and calculated the amount of fish habitat at 10 cm increments. A second, regional method, selected 103 sites by using a stratified random sample in 18 quaternary watersheds. In both methods, changes in water levels between 173 and 176 m asl resulted in the most drastic loss of habitat. Approximately 24% of the current fish habitat has already been lost due to low water levels.</p> <p>Water chemistry in coastal marshes is influenced by hydrologic connection. In the summers of 2010 and 2011, 35 coastal marshes were sampled, 17 of which had been impounded and disconnected by a beaver dam. Beaver-impounded marshes resulted in significantly lower pH, conductivity, dissolved oxygen and sulphate concentrations, but had significantly higher soluble reactive phosphors concentrations. These conditions are indicative of the lack of connection and reduced mixing with lake water. This altered habitat was shown to support breeding area for 7 species of amphibians, the most common being green frogs and the least common being American Toads and chorus frogs.</p> / Master of Science (MSc)

The opportunistic pathogen Legionella is the leading cause of reported waterborne disease outbreaks in the United States. Legionella can thrive under the warm, stagnant, low-disinfectant conditions characteristic of premise (i.e., building) plumbing systems, making it challenging to identify effective interventions for its control. Copper (Cu) is a promising antimicrobial that can be dosed directly to water via copper-silver ionization systems or released naturally via corrosion of Cu pipes to help control growth of Legionella and other pathogens. However, prior research has shown that Cu does not always reliably control Legionella and sometimes seems to even stimulate its growth. A deeper understanding of the mechanistic effects of Cu on Legionella, at both pure-culture and real-world scales, is critical in order to inform effective controls for Legionella. The overarching objective of the research embodied by this dissertation was aimed at elucidating the chemical and microbial interactions in premise plumbing that govern efficacy of Cu for Legionella control through a series of complementary bench-, pilot-, and field-scale studies. A critical review and synthesis of the literature identified important knowledge gaps in relation to antimicrobial effects of Cu. In particular, changes in the pH, phosphate corrosion control, and rising levels of natural organic matter (NOM) in distributed water are predicted to be important controlling factors. The type of sacrificial anode rod material employed in water heaters was also identified as an underappreciated factor, which directly affects pH, evolution of hydrogen gas as a microbial nutrient, and release of metals (such as aluminum) that bind copper. Microbiological factors: including growth phase of Legionella (e.g., exponential or stationary), strain-specific Cu tolerance, background microbiome composition, and the possibility that viable but non-culturable (VBNC) Legionella might still cause human disease, were also identified as major confounding factors. These knowledge gaps are addressed from various dimensions across each chapter of the dissertation. The effects of pH, orthophosphate corrosion inhibitor concentration, and NOM were examined in bench-scale pure culture experiments over a range of conditions relevant to drinking water. Cupric ions and antimicrobial effects were drastically reduced at pH >7.5, especially in the presence of phosphate, which precipitates copper, or NOM, which complexes the Cu in a form that is less bioavailable. Chick-Watson disinfection models indicated that soluble Cu was the most robust correlate with observed Cu antimicrobial effects across a range of tested waters. This new knowledge suggests that measuring soluble rather than total Cu would be much more informative to guide practitioners in dosing. The research also demonstrated that changes in pH or orthophosphate that have been made to control corrosion over the last few decades, have significantly altered Cu chemistry in buildings, undermining antimicrobial capacity and increasing likelihood of Legionella growth. Pilot-scale experiments confirmed that soluble Cu is an effective indicator of Cu antimicrobial capacity, even in more complex environments represented by realistic hot water plumbing systems. In particular, dosing of orthophosphate, which is widely added by drinking water utilities to control corrosion, directly reduces soluble copper and overall antimicrobial capacity. In some cases, Cu added together with orthophosphate apparently promoted the growth of Legionella, providing an example of at least one circumstance where Cu addition can induce interactive effects that elevate Legionella compared to a control system with trace Cu. It was also demonstrated for the first time that different water heater sacrificial anode types are subject to different corrosion processes, which indirectly influence Cu antimicrobial capacity. Specifically, aluminum ions released from aluminum anode corrosion at 1 mg/L can form an Al(OH)3 gel, which can remove >80% of the soluble Cu from water and reduce Cu antimicrobial effects by >2-log at pH=7. Corrosion from magnesium anodes was found to dramatically increase the pH from 6.8 to >8, which correspondingly reduces Cu antimicrobial capacity. Cu deposition further increased the anode corrosion rate and promoted evolution of hydrogen gas, which is a potent electron donor that stimulates autotrophic microbial growth especially with a magnesium anode. Electric powered anodes did not release metals or alter pH and thus did not diminish Cu antimicrobial capacity. Still, across the pilot-scale experiments, even very high levels of Cu (>1.2 mg/L) at low pH (<7) failed to fully eradicate culturable Legionella. The much lower than expected antimicrobial efficacy of Cu in the pilot-scale hot water plumbing systems was found to be partially explained by the properties of the strain that colonized the systems. Based on fitting the data to a Chick-Watson disinfection model, the outbreak-associated strain that was inoculated into the systems was estimated to be 7 times more tolerant to Cu compared to the common lab strain applied in the bench-scale tests. Further, exponential growth phase L. pneumophila were found to be 2.5 times more susceptible to Cu relative to early stationary phase cultures. It is important to also recognize that, in the pilot-scale systems, drinking water biofilms and the amoeba hosts that colonize them can further shield Legionella from the antimicrobial effects of Cu. Application of shotgun metagenomic sequencing offered the opportunity to more deeply examine the response of Legionella and other pathogens to Cu dosed to the pilot-scale hot water systems in the context of the broader microbiome. It was found that metagenomic analysis provided a sensitive indication of the bioavailability of Cu to the broader microbial community inhabiting the hot water systems, further confirming that the outbreak-associated strain of Legionella that colonized the rigs was relatively tolerant of Cu. Functional gene analysis provided further insight into the mechanistic action of Cu, suggesting multi-modal action of both membrane damage and interruption of nucleic acid replication. The metagenomic analysis further revealed that protozoan host numbers tended to increase in the pilot-scale systems with time, and this could also increase the potential for Legionella proliferation with time. Additional pure culture studies aiming to further assess the mechanistic action of Cu provided strong evidence that Cu can induce a VBNC state for Legionella. This is a concern, given that other studies have indicated that VBNC Legionella are still capable of causing legionellosis. However, VBNC cells are not detected by conventional culturing. Multiple lines of evidence supported the conclusion that Cu induced a VBNC state for Legionella, including membrane integrity, enzyme activity, ATP generation, and Amoebae resuscitation assays applied to two different strains of L. pneumophila. After exposure to Cu, up to a 5-log (99.999%) reduction in culturable Legionella was observed, whereas corresponding reductions in the various viability measures were only by <1-log (90%). In other words, conventional culturing may miss up to 99.99% of the Legionella that is still capable of causing disease. To our knowledge, this is the first study that has assessed the potential for Cu-induced VBNC Legionella. Additional research is needed to further quantify the contribution of VBNC status to challenges in effective Cu-based control of Legionella in premise plumbing. This research further examines, for the first time, the proteomic response of Legionella to Cu, comparing both presumably VBNC and culturable cells. Functional annotation of proteins that were differentially produced by the cells in response to Cu addition revealed that VBNC L. pneumophila modulated its proteome to favor cell membrane- and motility-related proteins, while reducing production of other proteins related to primary metabolism compared to culturable cells. These observations are consistent with the metagenomic-based observations and support the hypothesis that Cu inactivates cells by damaging the cell membrane. The findings also confirmed reduced general cell metabolism that is characteristic of a VBNC state. This dissertation highlights the important and complex effects of Cu on Legionella growth in potable water systems as modified by water chemistry, water heater anode type, characteristics of the surrounding microbiome, and Legionella strain characteristics and growth status. The findings raise important questions about how to measure disinfectant efficacy and provide fundamental new knowledge that can help to better optimize the application of Cu as an antimicrobial to drinking water systems and better protect public health. / Doctor of Philosophy / The opportunistic pathogen Legionella is the leading cause of reportable waterborne disease outbreaks in the United States. Legionella is capable of growing in drinking water plumbing systems in homes, hospitals, hotels, and other buildings. Legionella is spread by inhaling tiny droplets of water that are suspended in the air when using the water, for example when showering, resulting in a severe and deadly form of pneumonia called Legionnaires' Disease. Copper is a promising antimicrobial that can be dosed directly into a building's water system by installing a copper-silver ionization system. There is also interest in understanding whether copper released naturally from copper pipes could help control Legionella. However, prior research indicates that copper sometimes inhibits, sometimes has no effect, and sometimes even seems to stimulate Legionella growth. The purpose of this dissertation was to better understand how the chemical properties of the drinking water, such as pH, presence of corrosion inhibitors that are commonly added to the water by utilities, and natural organic matter impact the ability of copper to kill Legionella. Impacts of the design of the drinking water system were also examined, for example, the material used in the anodes of water heaters to prevent corrosive damage to other system components was hypothesized to change the water chemistry in such a way that could also interfere with copper disinfection. Finally, the effect of the strain of Legionella, its growth phase (exponential or stationary), and culturability status (culturable versus viable but non-culturable) was also examined. Experiments were conducted over a wide range of conditions, from bench-scale pure culture experiments of a few days to full-scale plumbing systems over a period of 3.5 years. The complementary approaches maximize the strength of scientific conclusions about approaches that can more effectively control Legionella. Several discoveries were made as a result of this research that can help to improve the use of copper for controlling Legionella in drinking water systems. In particular, it was found that it is best to keep the pH less than 7.5, because above pH 7.5 copper reacts with orthophosphate corrosion inhibitor or natural organic matter in the water in a manner that makes it less potent to microbes. Through disinfection modeling it was found that soluble copper was the best predictor of the ability to kill Legionella. Therefore, it is recommended from this research that practitioners should monitor soluble copper instead of total copper for the purpose of assessing Legionella control. From the pilot-scale experiments, it was further found that the type of anode installed in the water heater can affect the ability of copper to kill Legionella. Magnesium anodes performed the worst, likely because they raised the pH above the recommended level of 7.5. Aluminum anodes were also a problem because aluminum ions released form an aluminum hydroxide gel that can remove more than 80% of the soluble copper from water. Electric powered anodes did not reduce copper antimicrobial effects by raising pH or forming a gel, but they are much less commonly used. A surprising finding throughout this study was that very high levels of copper (>1.2 mg/L) were required to measurably reduce Legionella in the pilot-scale systems. In the pure culture experiments, it was found that the outbreak-associated strain from Quincy, IL, that was inoculated into the system was highly copper tolerant. This demonstrated that the strain of Legionella that colonizes a particular drinking water system could be the reason why copper is sometimes less effective. Pure culture experiments also found that stationary phase Legionella are more difficult to kill than exponential phase Legionella, which could explain some discrepancies among lab studies reported in the literature. A particularly noteworthy discovery of this research was that copper can make it appear as if Legionella have been killed, because the traditional culture media indicate that there is no growth on the Petri dish; however, they are in fact still alive and capable of causing human disease. This is referred to as a "viable but non-culturable (VBNC)" state. The VBNC state of Legionella was confirmed using an array of techniques (membrane integrity, enzyme activity, ATP generation, and amoebae resuscitation) for two strains of L. pneumophila. We also examined how VBNC Legionella cellular functions were impacted by copper using whole cell proteome, i.e., analysis of all of the proteins extracted from Legionella. Copper induced VBNC Legionella modulated its proteome to favor cell membrane and motility related proteins, and reduced others related to primary metabolism compared with culturable cells. These results were consistent with those obtained via shotgun metagenomic analysis of the microbial community DNA in the pilot-scale water systems. Given the potential for VBNC organisms to prevail in systems disinfected with copper, it is recommended to supplement culture-based monitoring with molecular-based monitoring, e.g., with quantitative polymerase chain reaction. This dissertation highlights the important and complex effects of copper on Legionella growth in potable water systems. The findings help to inform guidance on how to improve the antimicrobial effect of copper, through adjusting the water chemistry, selecting appropriate water heater anodes, and optimizing the overall hot water system design. The dissertation also helps to inform improved strategies for monitoring the efficacy of copper for killing Legionella in real-world systems. Overall, the findings can help to improve policy and practice aimed at reducing the incidence of Legionnaires' Disease and protecting public health.

Water chemistry and fluid velocity are factors that can perpetuate certain types of non-uniform pitting corrosion in copper tube, specifically in waters with high chlorine and a high pH. These two parameters can further act synergistically to alter pitting propensities in copper pipes subjected to this type of water. A preliminary short-term experiment considered pitting propensity in copper pipe as a function of water chemistry. This study used a water chemistry that had been documented to promote and sustain pitting in copper tube that further developed into fully penetrating pinhole leaks. Modifications to this base water chemistry found that dosing a chloramine disinfect (rather than free chlorine) or the addition of silica greatly reduced corrosion activity and pitting propensity on copper pipes. In another short-term experiment, copper pitting propensity was considered as a function of fluid velocity. A number of different fluid velocities were tested in several different pipe diameters using the same documented pitting water. Velocity was observed to significantly increase pitting propensity in all pipe diameters considered. At the highest fluid velocity tested (11.2 fps) a pinhole leak formed in ¼â tubing after only 2 months of testing. Larger pipe diameters were also found to increase the likelihood of forming deeper pits on the pipe surface at the same fluid velocity. Chlorine was a driving factor in corrosion for preliminary tests conducted using this pitting water. The reduction of chlorine to chloride is believed to be the primary cathodic reaction limiting the overall rate of corrosion in this type of water. As such, a subsequent study considered the relationship between the rate of chlorine reduction and corresponding corrosion activity. Chlorine reduction or demand rates were found to be good indicators for pitting propensity and corrosion activity for this particular type of water. All preceding work led to the development and design of a large scale, long-term, copper pitting study. A matrix of 21 unique conditions tested various water chemistries, flow conditions, corrosion inhibitors, and galvanic connections of copper pipes to other metallic plumbing materials. The severity of pitting corrosion was observed to be dramatically decreased by lower free chlorine residual concentrations, high alkalinity, and sufficient doses of copper corrosion inhibitors such as natural organic matter, silica, and orthophosphate. Pitting severity was consequently observed to increase at a low alkalinity, indicating that this parameter has a significant effect on corrosion reactions. Furthermore, the addition of aluminum solids to the base pitting water chemistry dramatically increased the formation of tubercle mounds on the inside of the copper pipes in contact with the waster. Aluminum solids have been observed to be a vital constituent for sustaining pit growth in this specific water at lower pHs, however, the role of this constituent at the high pH levels tested in this study was previously unknown. From simple visual observation, aluminum solids appear to increase the aggressiveness of this water even at higher pHs. / Master of Science

As demand for alternative water sources intensifies, increased use of reclaimed water is important to help achieve water sustainability. In addition to treatment, the manner in which reclaimed water is distributed is a key consideration as it governs the water quality at the point of use. In this work, simulated reclaimed water distribution systems (SRWDSs) were operated for more than two years to examine the role of system design, biofiltration, residual disinfectant type (i.e., chlorine, chloramine, no residual) and temperature on important aspects of chemistry and microbial regrowth under laboratory-controlled conditions. Turbidity decreased to 0.78 NTU after biofiltration and chlorinated treatments from 10.0-12.6 NTU for conditions with chloramine and no residuals. SRWDSs were susceptible to sediment accumulation, which occupied 0.83-3.2% of the volume of the first pipe segment (1 day of hydraulic residence time), compared to 0.32-0.45% volume in the corresponding chlorinated SRWDSs. The mass of accumulated sediment positively correlated (R2 = 0.82) with influent turbidity. Contrary to experiences with potable water systems, chlorine was found to be more persistent and better at maintaining biological stability in the SRWDSs than chloramine, especially at the higher temperatures >22°C common to many water scarce regions. The severe nitrification at the warmer temperatures rapidly depleted chloramine residuals, decreased dissolved oxygen, and caused elevated levels of nitrifiers and heterotrophic cell counts. A metagenomic taxonomic survey revealed high levels of gene markers of nitrifiers in the biofilm samples at 22°C for the chloraminated system. Non-metric multidimensional scaling analysis confirmed distinct taxonomic and functional microbial profiles between the chlorine and chloramine SRWDSs. Reflecting on multiyear experiences operating two different SRWDSs reactor designs, including thin tubes (0.32-cm diameter) and pipe reactors (10.2-cm), illustrated strengths and weaknesses of both approaches in recreating key aspects of biochemical changes in reclaimed water distribution systems. It is clear that approaches deemed successful with drinking water distribution systems may not always directly transfer to simulating reclaimed distribution systems, or to proactively managing full-scale reclaimed systems that have long periods of stagnation and where minimally-treated wastewater with high levels of nutrients and turbidity are used. / Doctor of Philosophy / Increasing water scarcity is creating an impetus for creating more sustainable water supplies. Wastewater effluent is increasingly viewed as in important resource that can reduce both water and energy demand. Reclaiming moderately to minimally-treated secondary wastewater effluent for non-potable reuse (NPR) applications; such as agricultural irrigation, landscaping, and toilet flushing, helps reduce demand for higher quality potable water sources. NPR presently accounts for more than 50% of total reuse and is projected to become increasingly important. While NPR is attractive, important knowledge gaps remain in terms of managing water quality and safety as it is transported through distribution pipes to the point of use. A comprehensive literature review revealed that NPR distribution systems are distinct from conventional drinking water distribution systems (DWDSs) and that it is doubtful if our current understanding of DWDSs would directly transfer to NPR systems. Unlike drinking water systems, NPR systems are currently unregulated at the national level and corresponding state-to-state regulations vary widely. The levels of water treatment can vary from simply distributing untreated effluent from wastewater treatment plants to very high-level treatment with membranes that produces water of equal or even higher quality than many existing tap waters. A common treatment train for minimally-treated NPR involves biologically activated carbon (BAC) filtration and the use of disinfectants (e.g., chlorine or chloramine) to control microbial water quality to the point of use. Prior studies from DWDSs have demonstrated water quality degradation in terms of disinfectant loss, bacterial growth, and aesthetic problems, with the settling of trace particulate matter producing sediment within pipe distribution systems. In particular, accumulated sediment can become a hotspot for water quality deterioration. Considering that minimally-treated reclaimed water can have much higher levels of particulate matter and nutrients than drinking water, it was predicted that NPR distribution systems could suffer from faster water quality degradation than corresponding drinking water systems, especially at the warmer temperatures common in water-scarce regions. This work was the first multi-year attempt to examine the effects of disinfectant (i.e. free chlorine, chloramine, no residual), BAC filtration versus no filtration, water age (up to 5-d versus 28-min), and temperature (14°C, 22°C, 30°C) in different types of lab-scale reactors. Two simulated reclaimed water distribution systems (SRWDSs) including 4-in. diameter Pipe SRWDSs versus 1/8-in. diameter Tube SRWDSs, were designed to study key aspects of full-scale NPR systems and were operated for more than two years to study chemical and microbial changes as distributed water traveled through the two systems. The Pipe SRWDSs were designed to assess the impacts on final water quality after long-term operation that allowed sediment to slowly accumulate, whereas the complementary Tube SRWDS design did not allow sediment to accumulate and only held the water for 28 minutes. Water was sampled regularly to track the trends of key water quality parameters, including disinfectant residuals, dissolved oxygen, nitrogen compounds involved in nitrification reactions, and various types of bacteria of interest. Sequencing of the biological genetic materials on selected samples was conducted to understand the types of bacteria present and their functions under the different circumstances. High levels of sediment were found to accumulate near the beginning of the Pipe SRWDSs, which caused loss of oxygen and disinfectants at the bottom of the pipes. Chlorine was more persistent and better at preventing bacteria growth as water traveled through the distribution system. In contrast, a type of bacteria that used ammonia as a nutrient (i.e., nitrifying bacteria) were observed in the pipes with chloramine (i.e., ammonia plus chlorine) as the disinfectant. The nitrifying bacteria caused rapid depletion of chloramine residuals, especially at temperatures above 22°C. At 30°C both chlorine and chloramine were almost immediately consumed in the pipe reactors. Nitrification is known to trigger water quality problems in chloraminated DWDSs, and we expect that chloraminated RWDSs would be even more susceptible to nitrification and associated water quality degradation issues in Compare the Tube SRWDSs to the Pipe SRWDSs, aside from heavy accumulations of sediment in the pipes versus no sediment in the thin tubes, the tubes clogged repeatedly from formation of thick biofoulants in the systems treated with no disinfectant and chloramine, whereas they remained relatively free of biofoulants and clogging in the tubes with chlorine. Even in just 28 minutes, it took water to move from the start to the end of the tube, both chlorine and chloramine were almost completely consumed in the tubes, due to the unrealistically high pipe surface area to the small flow volume inherent to this reactor design. As NPR becomes increasingly common to help achieve water sustainability, it will be important to deploy laboratory simulations, that are capable of testing and revealing key chemical and microbial processes that affect the operation of these systems and water safety at the point of use. The insights from this first long-term effort of simulating RWDSs highlight some unique characteristics and challenges of RWDSs, and reveals key concepts to help guide future research.

For decades, cement mortar relining has been used successfully to extend the life of drinking water pipelines, although, few quantitative data exist on the short-term water quality impacts of this process. This study investigated mortar lining impacts on disinfectant by-product formation, alkalinity, metal leaching, pH and disinfectant consumption, and odor generation shortly after in-situ installation. The experimental design used a 30-day, coupon immersion procedure that simulated a relined 4-inch diameter pipe located in a low-flow system. Four water regimes were utilized; no disinfectant, chlorine (2 mg/L at pH 6 .5 and 8), and chloramines. Flavor Profile Analysis panels evaluated odors of samples and controls. Additionally, the affects of three different phosphate-based corrosion prevention additive regimes were evaluated. Cement mortar leachates impacted water quality significantly during the first week of exposure. Alkalinity, hardness and pH increased dramatically after initial exposure, rising to approximately 600 mg/L as CaCO3 alkalinity, 770 mg/L as CaCO3 hardness, and pH 12 in the first two days. Sharp declines in alkalinity and hardness did not occur until after day 9 when the cement mortar was substantially cured and release of calcium hydroxide lessened. Chlorinated water residual disinfectant decay rate was increased substantially during the initial 24 hours and remained elevated until day 9. After day 1, there was not a significant increase in the formation of regulated haloacetic acids or trihalomethanes. Significant levels of aluminum (< 700 ug/L) and chromium (< 75 ug/L) were released at various times during the test period but their concentrations did not exceed USEPA water quality standards. Cement odor intensity levels were significantly higher than controls, persisted for 14 days, and were of an intensity that would be readily noticeable to consumers. The polyphosphate-based corrosion preventative resulted in less severe water quality effects than other phosphate additives or water without added phosphate. / Master of Science

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COMPARATIVE STUDY OF FLUVIAL LAKES IN FLOODPLAINS OF THE ELBE, LUŽNICE AND SVRATKA RIVERS Petra Havlíková ABSTRACT The aim of the thesis was to specify key differences in chemistry and biota (zooplankton communities) among fluvial lakes in three regions of Czech Republic: "střední Polabí" (central part of the Elbe River on the territory of Bohemia), "Horní Lužnice" (the upper part of the Lužnice River on the territory of Bohemia), and the Svratka River near Milovy (upper part of the Svratka River). The 10 studied lakes of the three regions differ in size, geology, shading, the influence of the river, and the level of anthropogenic impact. The following hypotheses were tested: 1) The chemical composition of the water in fluvial lakes is significantly different in different areas (floodplains). In the central Elbe River floodplain, there are the highest values of conductivity and concentrations of organic matter and nutrients. Fluvial lakes of the Svratka River floodplain near Milovy show the lowest level of these parameters, and fluvial lakes of the upper Lužnice River occur between the two previous regions. 2) The chemistry of fluvial lakes that have contact with the river through surface connection is significantly influenced by the river, and differs from the chemistry in fluvial lakes without any direct...