[Truncated abstract] With rapidly increasing population densities along coastlines and rising global sea levels, coastal protection has become a major concern for coastal communities. Predicting sediment transport in nearshore regions, however, is one of the most challenging tasks faced by coastal researchers in designing coastal structures or beach nourishment schemes. Although nearshore sediment transport mainly occurs in the longshore direction, cross-shore sediment transport is crucial in determining the shoreline evolution and beach morphology . . . This study investigated the factors influencing sediment re-suspension and cross-shore suspended sediment flux in the frequency domain through a series of field measurements conducted at several different locations and a numerical model. Only oscillatory flow components were examined and the mean flow components were not considered. Although many different factors such as cross-shore location with respect to breaker line, significant wave height to water depth ratio (Hs/h), normalised horizontal velocity skewness (<u³>/‹u²›³/²), median grain size (d50), breaker type, and wave groupiness appeared to influence the magnitude of cross-shore suspended sediment flux, bed ripples was identified as the major contributing factor in changing the direction of suspended sediment flux due to incident swell waves. Moreover, the direction changed significantly with ripple type. High frequency measurements, obtained to examine the influence of turbulent kinetic energy (TKE) on higher sediment suspension events observed under wave groups indicated that higher TKE was generated at the seabed by approaching wave groups, which in turn resulted in higher suspension events.°1

Beach profile models predict the changes in bathymetry along a line perpendicular to the shoreline. These models are used to forecast bathymetric changes in response to storms, sea level rise or human activities such as dredging and beach nourishment. Process-based models achieve this by simulating the physical processes that drive the sediment transport as opposed to behavior models which simulate observed profile changes without resolving the underlying processes. Some of these processes are wave shoaling and breaking, boundary layer streaming, and offshore-directed undertow currents. These hydrodynamic processes control the sediment processes such as sediment pick-up from the bottom, diffusion of the sediment across the water column and its advection with waves and currents. For this study, newly developed sediment transport and boundary layer models were coupled with existing models of wave transformation, nearshore circulation and bathymetry update, to predict beach profile changes. The models covered the region from the dry land to a depth of 6-8 meters, spanning up to 500 meters in the cross-shore direction. The modeling system was applied at storm time scales, extending from a couple of hours to several days. Two field experiments were conducted at Myrtle Beach, SC, involving the collection of wave, current and bathymetric data as a part of this study. The results were used to calibrate and test the numerical models along with data from various laboratory studies from the literature. The sediment transport model computes the variation of sediment concentrations over a wave period and over the water column, solving the advection-diffusion equation using the Crank-Nicholson finite-difference numerical scheme. Using a new approach, erosion depth thickness and sediment concentrations within the bed were also predicted. The model could predict sediment transport rates for a range of conditions, within a factor of two. It successfully computed the sediment concentration profile over the water column and within the bed and its variation throughout a wave period. Erosion depth and sheet flow layer thickness were also predicted reasonably well. Wave heights across the profile were predicted within ten percent when the empirical wave breaking parameter was tuned appropriately. Mean cross-shore velocities contain more uncertainty, even after tuning. The importance of capturing the location of the maximum, near-bottom, cross-shore velocity when predicting bar behavior was shown. Bar formation, erosion, accretion, onshore and offshore bar movement were all computed with the model successfully

The conceptual subject of this study was to investigate the effects of microbial biofilms of the hyporheic zone of the river Elbe on nutrient dynamics and elimination. This resulted in four aspects, which were carried out separately. One aspect was the investigation of the dynamics of inorganic nitrogen compounds in the upper sediment layers, as highest microbial activity could be expected due to increased import of nutrients. Dissolved oxygen is suggested to control the nitrogen dynamics in the hyporheic zone, as dissolved oxygen in the flowing water varied seasonally and diurnally due to the photosynthetic activity of the algae and infiltrated in the hyporheic zone. The second aspect was the investigation of advective transport of algal cells through porous media. In laboratory columns the retention and retardation of morphological different algae was estimated. In the year 2001, it was possible to use the diving bell of the Office of Water and Navigation Magdeburg. Samples of the river bed at two different sites (Dresden-Übigau and Coswig near Lutherstadt-Wittenberg) were taken. Microbial activity rates, detrital and grain size parameters were detected. This sample material was also used for the detection of the microbial biocoenosis at the two sites. The microorganisms of the flowing water, the interstitial water and associated to the sediment were characterized by means of the fluorescence in situ hybridization (FISH) technique. Multivariate statistical analysis was performed on the FISH data at different spatial and phylogenetic scales. / Das Ziel der vorliegenden Arbeit war die Untersuchung von mikrobiellen Biofilmen in hyporheischen Sedimenten der Elbe sowie deren Auswirkungen auf die Stoffdynamik und die Nährstoffelimination. Daraus ergaben sich vier Teilaspekte, die separat bearbeitet wurden. Ein Aspekt war die Untersuchung der Stickstoffdynamik in den obersten Sedimentschichten, da hier aufgrund des erhöhten Importes von Nährstoffen die höchste mikrobielle Aktivität zu erwarten ist. Wesentliche biologische Steuergröße ist hierbei vermutlich der Gelöstsauerstoff, der saisonal sowie diurnal durch die photosynthische Aktivität der Algen auch die biochemischen Umsätze im hyporheischen Interstitial beeinflußt. Der zweite Aspekt war die Untersuchung des advektiven Transportes von Algen durch poröse Medien. In Laborversuchen wurde die Retention und die Retardation von morphologisch unterschiedlichen Algen untersucht. Im Jahr 2001 konnte der Taucherschacht des Wasser- und Schiffahrtsamtes Magdeburg genutzt werden. Dadurch konnte Probenmaterial aus der Flußmitte an zwei unterschiedlichen Standorten (Dresden-Übigau und Coswig bei Lutherstadt-Wittenberg) entnommen werden. Es wurden mikrobielle Umsatzraten, Detritus- und Korngrößen- Kenngrößen bestimmt. Ebenfalls am Probenmaterial der Taucherschachtaktion wurde die Fluoreszenz in situ Hybridisierung angewendet. Dies ermöglichte eine Bestandsaufnahme der Bakterien sowohl im Freiwasser der beiden Standorte, als auch im Interstitialwasser und den Bakterien assoziiert ans Sediment. Die Ergebnisse wurden auf unterschiedlichen räumlichen und phylogenetischen Ebenen mit multivariaten statistischen Methoden ausgewertet.

Microbial and chemical processes in the sediment of standing waters have a big influence on the release of nutrients and the trophic state. Due to the strong interactions between sediment and water body and the storage of materials sediments can be consulted as an important additional source of information for the evaluation of the trophic state and for the estimation of future trophic developments. Because of relatively small fluctuations the parameters in the sediment and pore water are well suitable for a trophic validation. Sediments and pore water of four reservoirs with different trophic characteristics were sampled in regular intervals (Neunzehnhain I - oligotrophic; Muldenberg - oligotrophic, dystrophic; Saidenbach - mesotroph; Quitzdorf - polytrophic). Many chemical and microbial parameters were examined regarding the trophic dependancy and the possibility for including these parameters into a trophic evaluation system. The concentrations of SRP, ammonium, and alkalinity in the pore water and the metal:phosphorus-quotient (Al:P, Fe:P) in the dry sediment showed the biggest trophic dependancy, so that these parameters are applicable for a sediment referred trophic assessment of standing waters. The polytrophic reservoir Quitzdorf has exhibited an extreme abundance of the cyanobacterium Microcystis for years. Investigations of the water body showed that apart from parameters like the water temperature the mass growth of Microcystis in the reservoir is obviously very strongly affected by the nitrogen:phosphorus-quotients in the water body. In laboratory experiments with sediments of this reservoir the phosphorus release from the sediment could be significantly lowered by the addition of aluminum and a part of the phosphorus could be shifted from the reductively soluble iron bound phosphorus fraction into the stable aluminum bound phosphorus fraction. / Die chemischen und mikrobiellen Prozesse im Sediment von Standgewässern haben großen Einfluss auf die Freisetzung von Nährstoffen und die Trophie. Aufgrund der starken Wechselwirkungen zwischen Sediment und Wasserkörper und der Speicherung von Stoffen in den Sedimenten können Gewässersedimente als wichtige zusätzliche Informationsquelle für die Bewertung des Trophiezustandes und zur Abschätzung zukünftiger trophischer Entwicklungen herangezogen werden. Durch relativ geringe Schwankungen sind die Parameter im Sediment und Porenwasser gut für eine Trophieeinschätzung geeignet. Die Sedimente und das Porenwasser von vier Talsperren mit unterschiedlichen trophischen Eigenschaften wurden in regelmäßigen Abständen beprobt (Neunzehnhain I ? oligotroph; Muldenberg ? oligotroph, dystroph; Saidenbach ? mesotroph; Quitzdorf ? polytroph). Es wurden viele chemische und mikrobielle Parameter im Sediment und Porenwasser im Hinblick auf die Trophieabhängigkeit und eine mögliche Einbeziehbarkeit in ein trophisches Bewertungssystem untersucht. Die größte trophische Abhängigkeit konnte bei den Konzentrationen von SRP, Ammonium, und Alkalinität im Porenwasser und den Metall:Phosphor-Quotienten (Al:P, Fe:P) im Trockensediment gefunden werden, sodass diese Parameter gut für eine sedimentbezogene Trophiebewertung von stehenden Gewässern geeignet sind. Die polytrophe Talsperre Quitzdorf weist seit Jahren ein extremes Massenwachstum des Cyanobakteriums Microcystis auf. Untersuchungen des Wasserkörpers haben gezeigt, dass das Microcystis-Massenaufkommen in der Talsperre neben Parametern wie der Wassertemperatur offensichtlich sehr stark von den Stickstoff:Phosphor-Quotienten im Wasserkörper beeinflusst wird. Laborversuche mit Sedimenten dieser Talsperre haben ergeben, dass die P-Freisetzung aus dem Sediment durch die Zugabe von Aluminium signifikant herabgesetzt werden und ein Teil des Phosphors von der reduktiv löslichen eisengebundenen P-Fraktion in die stabile aluminiumgebundene P-Fraktion verlagert werden konnte.

This study focused on development of a continuous watershed-scale modelling approach capable of evaluating sediment removal performance of vegetative filter strips (VFS). This was done by integrating the single-event hydrologic and sediment transport model AGNPS with the event-based VFS model (VFSMOD) applying the methodology developed by Sebti and Rudra (2010), and also through the development and incorporation of sub-models capable of describing changes in hydrologic conditions between rainfall events into the integrated models. For modeling purposes, the buffer zone is divided to segments called “buffer cells”. The upstream source area corresponding to each buffer cell and the flow-path connecting the area to the stream are identified, and runoff and sediment generated within each area is simulated for each event applying AGNPS. Using VFSMOD, performance analysis of VFS is conducted for each buffer cell. By applying the developed “continuous simulation” sub-models the hydrologic conditions prior to each event were determined.

During high flow rates, the acceleration of flow and turbulence around bridge foundations lead to scouring, defined as the removal of bed sediments. Due to the interparticle physico-chemical forces of clay particles, erodibility and transport mechanisms for fine sediments are different from those for coarse sediments, and the capability to predict the erosion resistance of fine sediments is still in question. In this study, silt-clay soil mixtures with different kaolin contents were prepared by mixing ground silica and Georgia kaolin with tap water. Geotechnical tests were carried out to obtain the physical properties of the specimens. The critical shear stress and yield stress of the soil mixtures were determined through hydraulic flume experiments and rheometer tests, respectively. Particle associations of the soil specimens were observed using the technique of scanning electron microscopy (SEM). From the laboratory work and data analysis, relationships among the critical shear stress, yield stress, and the soil physical properties were developed from multiple regression analysis. Specifically, values of the critical shear stress, yield stress, and their dimensionless form can be predicted by the soil properties including bulk density, clay content, and water content. Finally, a single relationship is obtained to predict the Shields parameter as a function of the corresponding dimensionless yield stress in this study. The results can be used to provide a methodology for engineering applications requiring the value of critical shear stress such as estimating fine sediment bed stability and assessing the erosion risk of river beds in proximity to bridge foundations and other flow obstructions.

This thesis presents the development of a novel numerical model capable of evaluating suspended sediment dynamics under breaking waves, and is based in the open source Computational Fluid Dynamics software, OpenFOAM®. The hydrodynamics were determined by solving the incompressible, Reynolds-Averaged Navier-Stokes equations for a two-phase fluid using the Finite Volume method, along with a Volume of Fluid scheme that modelled the interface between the air and water phases. A new library of five turbulence models was developed to include weakly compressible effects through the introduction of density variations in the conservation equations. This library was thoroughly evaluated against existing physical data for surf zone dynamics. A skill score was applied, based on the MSE, to rank the models, with the nonlinear k−ε performing best overall, and the k−ω predicting turbulent kinetic energy most accurately. Furthermore, the numerical model was shown to predict the near-bed hydrodynamics well, through comparison with new in-house physical data obtained in the COAST laboratory. Suspended sediment concentrations were determined using an advection-diffusion methodology, with near-bed processes modelled using a flux based approach that balances entrainment and deposition. The model was validated against existing experimental data for steady state flow conditions, as well as for regular and breaking waves. The agreement was generally good, with the results indicating that the model is capable of capturing complicated processes such as sediment plumes under plunging breakers. The validated model was applied to investigate the properties of the sediment diffusivity, which is a vital parameter in suspended sediment dynamics. In physical experiments, sediment diffusivity is commonly estimated implicitly, based on the vertical concentration profile. In this work, this approach was applied to the numerical concentration predictions, and compared with the value directly determined within the model. The estimated value was generally acceptable providing that large horizontal concentration gradients were not present, and diffusion dominated flow advection. However, near the breaking point of waves, large errors were observed at mid-depth of the water column, which strongly correlates with a region of large flow advection relative to diffusion. Therefore, when using this estimation, caution is recommended since this approach can potentially lead to substantial discrepancies.

The morphodynamics of an inlet channel draining an estuary or bay are governed by a complex system of temporally and spatially varying physical processes, including wind, waves, tides, sediment transport, and both tide and wave driven currents. In addition, sediment availability and characteristics in conjunction with underlying geologic framework bear on the morphology and morphologic behavior of an inlet system. This study examines the morphodynamics, sediment transport patterns and time-series morphologic change of John’s Pass and Blind Pass, two structured tidal inlets that collectively make up a dual-inlet system sharing the tidal prism of northern Boca Ciega Bay, in Pinellas County, Florida. To quantify wave and tidal forcing and response mechanisms an array of hydrodynamic sensors were deployed over a 12 month period at both inshore and offshore locations. In order to capture morphologic changes and quantify volumetric changes within the inlets, bathymetric surveys of the inlets were conducted in 2010, 2011, 2012, and 2014. Similarly, bi-monthly beach survey data for the same range of time was acquired in order to quantify volumetric changes along adjacent stretches of beach. In addition to gaining insights into sediment pathways based on morphologic and volumetric variability, those data were also used to develop a regional sediment budget along the studied stretch of coast. To gain insights into the morphodynamics of the dual-inlet system, bathymetric and hydrodynamic data was used to develop a numerical model of the dual inlet system. Numerical model simulations based on existing or baseline conditions were compared with numerical simulations employing synthetic bathymetric and hydrodynamic conditions in order to examine inlet behavior under a range of different morphological and hydrodynamic conditions. John’s Pass is the dominant of the two inlets. It exhibits mixed-energy straight morphology and captures ca 81% of the available tidal prism. The inlet has a well-developed mature ebb shoal, and actively bypasses sediment from one side of the inlet to the other supplying sediment to the downdrift littoral system. Blind Pass captures less than 20% of the available tidal prism, and while also exhibiting mixed-energy morphologic characteristics has a less well developed ebb shoal that currently has not fully established a sediment bypassing system. Both inlets channels and ebb shoals have been dredged on multiple occasions to provide sediment for the nourishment of nearby chronically eroding stretches of beach. Dredge pits excavated along the distal margins of the ebb shoals are infilling at rates substantially slower than expected due to limited sediment transport along those regions of the ebb shoal, while inlet channel dredge pits infill at rapid and expected rates. The objective of this study was to characterize the morphodynamics of the dual-inlet system with the aim of identifying sediment pathways and bypassing mechanisms, and quantify a balanced regional sediment budget in order to design more sustainable approaches to inlet management.

<p>Predmet&nbsp; istraživanja&nbsp; ove&nbsp; doktorske&nbsp; disertacije&nbsp; je&nbsp; procena&nbsp; potencijalno&nbsp; biodostupne&nbsp; frakcije odabranih&nbsp; prioritetnih&nbsp; organskih&nbsp; polutanata&nbsp;&nbsp; (pentahlorbenzena,&nbsp; heksahlorbenzena,&nbsp; lindana, trifluralina, 4-oktilfenola i 4-nonilfenola) u sedimentu, ispitivanje biodegradacionog potencijala ovih&nbsp; jedinjenja&nbsp; u&nbsp; sedimentu&nbsp; u&nbsp; različitim&nbsp; uslovima,&nbsp; kao&nbsp; i&nbsp; procena&nbsp; potencijala&nbsp; stabilizacije<br />sedimenta&nbsp; dodatkom&nbsp; ugljeničnih&nbsp; sorpcionih&nbsp; agenasa.&nbsp; U&nbsp; cilju&nbsp; razvoja&nbsp; metoda&nbsp; za&nbsp; određivanje biodostupnosti odabranih organskih polutanata ispitivane su i&nbsp; optimizovane metode vi&scaron;estepene i jednostepene parcijalne ekstrakcije primenom sledećih hemijskih agenasa:&nbsp; Tenaks&nbsp; smole, XAD-4&nbsp; smole&nbsp; i&nbsp; rastvora&nbsp; ciklodekstrina&nbsp; (2-hidroksipropil-&beta;-ciklodekstrina,&nbsp; &beta;-ciklodekstrina&nbsp; i&nbsp; metil-&beta;-ciklodekstrina).&nbsp; Optimalni&nbsp; agens&nbsp; za&nbsp; procenu&nbsp; biodostupne&nbsp; frakcije&nbsp; odabranih&nbsp; organskih zagađujućih&nbsp; materija&nbsp; sa&nbsp; sedimenta&nbsp; XAD-4&nbsp; smola,&nbsp; a&nbsp; optimalno&nbsp; vreme&nbsp; ekstrakcije&nbsp; primenom jednostepenih&nbsp; ekstrakcija&nbsp; je&nbsp; oko&nbsp; 8&nbsp; h.&nbsp; Procena&nbsp; biodegradacionog&nbsp; potencijala&nbsp; odabranih prioritetnih&nbsp; organskih&nbsp; zagađujućih&nbsp; materija&nbsp; u&nbsp; sedimentu&nbsp; ispitana&nbsp; je&nbsp; u&nbsp; različitim&nbsp; aerobnim&nbsp; i anaerobnim uslovima uz optimizaciju uslova putem biostimulacije i bioaugmentacije. Pokazano je&nbsp; da&nbsp; svih&nbsp; &scaron;est&nbsp; odabranih&nbsp; jedinjenja&nbsp; poseduju&nbsp; značajan&nbsp; potencijal&nbsp; biodegradacije&nbsp; u&nbsp; anaerobnoj sredini&nbsp; pri&nbsp; čemu&nbsp; u&nbsp; slučaju&nbsp; lindana&nbsp; i&nbsp; trifluralina&nbsp; dolazi&nbsp; do&nbsp; potpunog&nbsp; uklanjanja&nbsp; biodostupne količine&nbsp; jedinjenja&nbsp; primenom&nbsp; sva&nbsp; četiri&nbsp; ispitana&nbsp; inokuluma.&nbsp; Aerobni&nbsp; potencijal&nbsp; u&nbsp; ispitanim uslovima&nbsp; pokazali&nbsp; su&nbsp; samo&nbsp; alkil&nbsp; fenoli,&nbsp; gde&nbsp; je&nbsp; takođe&nbsp; uklonjena&nbsp; skoro&nbsp; celokupna&nbsp; količinabiodostupne&nbsp; frakcije&nbsp; jedinjenja&nbsp; u&nbsp; sedimentu&nbsp; (78-85%).&nbsp; Potencijal&nbsp; remedijacije&nbsp; sedimenta dodatkom&nbsp; ugljeničnih&nbsp; materijala&nbsp; ispitan&nbsp; je&nbsp; sa&nbsp; aspekta&nbsp; odabira&nbsp; ugljeničnih&nbsp; sorpcionih&nbsp; agenasa (aktivni&nbsp; ugalj,&nbsp; biougalj&nbsp; i&nbsp; humus);&nbsp; određivanja&nbsp; optimalne&nbsp; količine&nbsp; materijala;&nbsp; isptivanja dugoročnih i kratkoročnih efekata dodatka ovih agenasa na biodostupnost organskih zagađujućih materija&nbsp; kako&nbsp; bi&nbsp; se&nbsp; ispitao&nbsp; efekat&nbsp; starenja &nbsp; i&nbsp; toksičnosti&nbsp; dobijenih&nbsp; sme&scaron;a.&nbsp; Rezultati&nbsp; stabilizacije zagađujućih&nbsp; supstanci&nbsp; u&nbsp; sedimentu&nbsp; pokazuju&nbsp; da:&nbsp; (1)&nbsp; povećanje&nbsp; doze&nbsp; sva&nbsp; tri&nbsp; sorpciona&nbsp; agensa dovodi&nbsp; do&nbsp; povećanja&nbsp; efikasnosti&nbsp; imobilizacije&nbsp; i&nbsp; smanjenja&nbsp; biodostupne&nbsp; frakcije&nbsp; odabranih organskih jedinjenja; (2) starenjem sme&scaron;a sedimenta i&nbsp; sorbenata u toku prvih 90 dana dolazi do daljeg smanjenja biodostupne frakcije svih jedinjenja, nakon čega se biodostupna koncentracija ispitivanih&nbsp; jedinjenja&nbsp; primenom&nbsp; aktivnog&nbsp; uglja&nbsp; ne&nbsp; menja,&nbsp; dok&nbsp; primenom&nbsp; biouglja&nbsp; i&nbsp; humusa&nbsp; dolazi&nbsp; do&nbsp; porasta&nbsp; biodostupne&nbsp; frakcije&nbsp; jedinjenja.&nbsp; Testovi&nbsp; fitotoksičnosti&nbsp; su&nbsp; pokazali&nbsp; da&nbsp; je&nbsp; <em>Zea mays&nbsp; </em>akumulirao&nbsp; značajno&nbsp; veće&nbsp; količine&nbsp; ispitivanih&nbsp; jedinjenja&nbsp; iz&nbsp; netretiranog&nbsp; sedimenta&nbsp; u poređenju sa&nbsp; <em>Cucurbita pepo</em>&nbsp; i&nbsp;<em> Lactuca sativa. </em>Toksičnost sme&scaron;a sedimenta sa aktivnim ugljom i humusom&nbsp; procenjena&nbsp; na&nbsp; osnovu&nbsp; inhibicije&nbsp; luminiscencije&nbsp; na&nbsp; <em>Vibrio&nbsp; fischeri</em>&nbsp; kao&nbsp; i&nbsp; ispitivanjem <em>Zea&nbsp; mays&nbsp; </em>germinacije&nbsp; i&nbsp; produkcije&nbsp; biomase&nbsp; je&nbsp; pokazala&nbsp; značajno&nbsp; smanjenje&nbsp; u&nbsp; odnosu&nbsp; na netretirani&nbsp; sediment.&nbsp; Akumulacija&nbsp; ispitivanih&nbsp; jedinjenja&nbsp; u&nbsp; biomasi&nbsp; <em>Zea&nbsp; mays&nbsp; </em>u&nbsp; netretiranom sedimentu je bila značajno veća u odnosu na sve sme&scaron;e sedimenta i aktivnog uglja i humusa. Sva tri&nbsp; sorbenta&nbsp; pokazala&nbsp; su&nbsp; veliki&nbsp; remedijacioni&nbsp; potencijal&nbsp; za&nbsp; sediment&nbsp; zagađen&nbsp; organskim zagađujućim supstancama, ali je aktivni ugalj pokazao najbolje performance.</p> / <p>The&nbsp; aim&nbsp; of&nbsp; the&nbsp; research&nbsp; in&nbsp; this&nbsp; PhD&nbsp; dissertation&nbsp; is&nbsp; the&nbsp; assessment&nbsp; of&nbsp; the&nbsp; potentially biodegradable&nbsp; fraction&nbsp; of&nbsp; selected&nbsp; organic&nbsp; pollutants&nbsp;&nbsp; (pentachlorbenzene,&nbsp; hexachlorobenzene, lindane,&nbsp; trifluraline,&nbsp; 4-octylphenol&nbsp; and&nbsp;&nbsp;&nbsp; 4-nonylphenol)&nbsp; in&nbsp; the&nbsp; sediment,&nbsp; estimation&nbsp; of&nbsp; the biodegradation potential of these compounds in sediment in different conditions, as well as the assessment&nbsp; of&nbsp; the&nbsp; stabilization&nbsp; potential&nbsp; sediment&nbsp; by&nbsp; the&nbsp; sediment&nbsp; amendment&nbsp; with&nbsp; of&nbsp; carbon rich sorption agents. In order to develop and optimise&nbsp; methods for the bioavailability assessment of&nbsp; the&nbsp; selected&nbsp; organic&nbsp; pollutants,&nbsp; methods&nbsp; of&nbsp; multistage&nbsp; and&nbsp; single-step&nbsp; non&nbsp; exhaustive extraction&nbsp; were&nbsp; studied&nbsp; using&nbsp; the&nbsp; following&nbsp; chemical&nbsp; agents:&nbsp; Tenax&nbsp; resin,&nbsp; XAD -4&nbsp; resin&nbsp; and&nbsp; a cyclodextrin&nbsp; solution&nbsp; (2-hydroxypropyl- &beta;-cyclodextrin,&nbsp; &beta;-cyclodextrin&nbsp; and&nbsp; methyl-&beta;-cyclodextrin).&nbsp; Results&nbsp; showed&nbsp; that&nbsp; optimal&nbsp; agent&nbsp; for&nbsp; estimating&nbsp; the&nbsp; bioavailable&nbsp; fraction&nbsp; of selected organic pollutants from the sediment is XAD-4 resins, and that the optimum extraction time using single-step extraction is about 8 h. The assessment of the biodegradation potential of selected&nbsp; priority&nbsp; organic&nbsp; pollutants&nbsp; in&nbsp; the&nbsp; sediment&nbsp; was&nbsp; examined&nbsp; in&nbsp;&nbsp; various&nbsp; aerobic&nbsp; and anaerobic&nbsp; conditions,&nbsp; with&nbsp; the&nbsp; optimization&nbsp; of&nbsp; conditions&nbsp; through&nbsp; biostimulation&nbsp; and bioaugmentation.&nbsp; It&nbsp; has&nbsp; been&nbsp; shown&nbsp; that&nbsp; all&nbsp; six&nbsp; selected&nbsp; compounds&nbsp; possess&nbsp; significant biodegradation&nbsp; potential&nbsp; in&nbsp; the&nbsp; anaerobic&nbsp; environment,&nbsp; where&nbsp; in&nbsp; the&nbsp; case&nbsp; of&nbsp; lindane&nbsp; and trifluraline there is complete removal of the bioavailable amount of the compound&nbsp;&nbsp; using all four inoculum tested. Aerobic potential under the applied conditions has been showen only for alkyl phenols,&nbsp; where&nbsp; almost&nbsp; all&nbsp; of&nbsp; the&nbsp; bioavailable&nbsp; fraction&nbsp; of&nbsp; the&nbsp; compound&nbsp; in&nbsp; the&nbsp; sediment&nbsp; was removed (78-85%). The potential of sediment remediation with the amendment of sediment withcarbon&nbsp; rich&nbsp; materials&nbsp; was&nbsp;&nbsp; examined&nbsp; from&nbsp; the&nbsp; aspect&nbsp; of&nbsp; selecting&nbsp; carbon&nbsp; sorption&nbsp; agents (activated carbon, biochar and humus); estimation the optimal material doses; the long -term and short-term effects of the addition&nbsp; of these agents on the bioavailability of organic pollutants&nbsp; in order to examine the effect of aging and the toxicity of the resulting mixtures. The results of the stabilization of pollutants in the sediment show that: (1)&nbsp; increasing the dose of all three&nbsp;&nbsp; sorption agents&nbsp; leads&nbsp; to&nbsp; an&nbsp; increase&nbsp; in&nbsp; the&nbsp; immobilization&nbsp; efficiency&nbsp; and&nbsp; reduction&nbsp; of&nbsp; the&nbsp; bioavailable fraction of the selected&nbsp; organic compounds; (2) aging of the amended sediment during the first 90 days results in a further reduction of the biodegradable fraction of all compounds, after which the&nbsp; biodegradable&nbsp; concentration&nbsp; of&nbsp; the&nbsp; selected&nbsp; compounds&nbsp; remain&nbsp; the&nbsp; same&nbsp; in&nbsp; the&nbsp; case&nbsp; of activated carbon amendment, while the bioavailable fraction of&nbsp; the compound increases with the use&nbsp; of&nbsp; biohar&nbsp; and&nbsp; humus.&nbsp; Phytotoxicity&nbsp; tests&nbsp; showed&nbsp; that&nbsp; <em>Zea&nbsp; mays&nbsp;</em> accumulated&nbsp; significantly higher amount of selected organic pollutants from unamended sediment, comparing to&nbsp; <em>Cucurbita pepo&nbsp;</em> and <em>Lactuca sativa</em>. Toxicity of activated carbon and humus amended sediment assessed by <em>Vibrio&nbsp; fischeri&nbsp;</em> luminescence&nbsp; inhibition&nbsp; test&nbsp; and&nbsp; by&nbsp; measuring&nbsp; <em>Zea&nbsp; mays&nbsp; </em>germination&nbsp; and biomass yield was significantly reduced in the amended sediment samples. Accumulation of the selected&nbsp; organic&nbsp; pollutants&nbsp; in&nbsp; the&nbsp; <em>Zea&nbsp; mays</em>&nbsp; biomass&nbsp; in&nbsp; the&nbsp; unamended&nbsp; sediment&nbsp; were&nbsp; a significantly&nbsp; higher&nbsp; than&nbsp; in&nbsp; the&nbsp; humus&nbsp; and&nbsp; activated&nbsp; carbon&nbsp; amended&nbsp; sediment.&nbsp; Both&nbsp; sorbents show&nbsp; potential&nbsp; to&nbsp; be&nbsp; used&nbsp; as&nbsp; remediation&nbsp; agents&nbsp; for&nbsp; organically&nbsp; contaminated&nbsp; sediment,&nbsp; but activated carbon exhibited the better performance.</p>

<p>Predmet izučavanja ove disertacije, osim poređenja različitih metoda procene rizika na&nbsp;osnovu karakterizacije kvaliteta sedimenta vodotokova Vojvodine, bilo je i ispitivanje&nbsp;mogućnosti imobilizacije te&scaron;kih metalau sedimentu primenom različitih remedijacionih&nbsp;tehnika kao i određivanje njihove efikasnosti (npr. solidifikacija/stabilizacija silikatnim&nbsp;materijalima, portland cementom, kalcijum-oksidom itd.) u zavisnosti od brojnih faktora.&nbsp;Osim pseudo-ukupnog sadržaja metala određene su i specifičnije frakcije metala sa posebnim<br />osvrtom na određivanje potencijalno biodostupnih frakcija.</p><p>Rezultati su ukazali da je naosnovu holandskih preporuka sediment pojedinih vodotokova&nbsp;Vojvodine (Begej, DTD-kanal,Nadela, Sava-&Scaron;abac) zagađen metalima (klasa 4) i da je&nbsp;neohodno izmuljivanje i remedijacija. Prema USEPA i kanadskim preporukama, neki uzorci&nbsp;su potencijalno toksični, ali nije zabeležena akutna toksičnost za test vrste u pornoj vodi. Za&nbsp;neke uzorke, i pored visoke pseudo-ukupne koncentracije (klasa 4), nije potvrđena&nbsp;potencijalna toksičnost na osnovu odnosa kiselog volatilnog sulfida i simultano ekstrahovanih&nbsp;metala. Dok se ne primene skuplje metode remedijacije i tretmana sedimenta, najbolje re&scaron;enje&nbsp;je izolovano skladi&scaron;tenje na specijalnim&nbsp; deponijama. Naredni koraci bi trebali da budu&nbsp;usresređeni na kontrolu i sprečavanje zagađenja kako bi se obezbedilo da revitalizacija ovih&nbsp;vodotoka ima trajni pozitivan uticaj na životnu sredinu i nesmetanu i bezbednu plovidbu, kao&nbsp;i na primenu određenih remedijacionih metoda. Poređenje rezultata koji su dobijeni različitim&nbsp;procenama kvaliteta sedimenta pokazalo je da ponekad nije dovoljan jedan pristup i da je&nbsp;potrebno je uključiti metode procene biodostupnosti, biotestove i aspekt radioaktivnosti. U&nbsp;uzorku sedimenta koji je kori&scaron;ćen za ispitivanje efikasnosti remedijacionih tretmana,&nbsp;pokazano je da cink, nikal i olovo imaju visok rizik po okolinu, jer seprocenat metala u&nbsp;izmenljivoj i karbonatnoj fazi kretao od 40.1 do 45.2%. Cr i Cd imaju umeren rizik, dok je&nbsp;bakar prisutan u ovim frakcijama u koncentraciji koja predviđa nizak rizik (5.3%). Ovo je u&nbsp;skladu i sa rezultatima analize porne vode i simultano ekstrahovanih metala i kiselog&nbsp;volatilnog sulfida.</p><p>Istraživanje prikazano u radu je dalo odgovor na pitanje da li remedijacija može uspe&scaron;no da&nbsp;ukloni zagađenje, u smislu imobilizacije metala u stanje kada oni vi&scaron;e neće biti opasnost po&nbsp;okolinu. Svi primenjeni tretmani doveli su dosmanjenja procenta kumulativno izluženih&nbsp;metala iz S/S sme&scaron;a, ali nijedna sme&scaron;a tretiranog sedimenta i ispitivanih imobilizacionih&nbsp;agenasa ne pripada grupi inertnog otpada ukoliko se kumulativne izlužene koncentracije&nbsp;metala porede sa koncentracijama koje za otpad propisuje Evropska Unija (2003/33/EC).&nbsp;Ukoliko nam je cilj dobijanje nehazardnog otpada onda moramo primeniti u tretmanu&nbsp;sedimenta kontaminiranog metalima najmanje 30% imobilizaconih agenasa (cementa,&nbsp;kalcijum-oksida). Najveća efikasnost u imobilizaciji metala postignuta je kori&scaron;ćenjem&nbsp;cementa i kalcijum-oksida u sme&scaron;i (30% cementa i 10% kalcijum-oksida) i primenom termičkog tretmana na vi&scaron;oj temperaturi (1100⁰C) sa glinom (20% gline) &scaron;to je zaključeno na osnovu koeficijenata difuzije i indeksa izlužljivosti. Dominantan mehanizam izluživanjametala iz ovih sme&scaron;a je difuzija.</p> / <p>This work is concerned with the comparison of the different methods of metal risk assessment&nbsp;in sediments based on examination of the qualityof water courses in Vojvodina. Besides, it&nbsp;deals with the possibility of applying remediation treatments of contaminated sediment and&nbsp;with the efficiency of the different methods, that is the techniques, for immobilization of&nbsp;sediment heavy metals by applying S/S and thermal treatments. A dominant mechanism is&nbsp;proposed for the process of leaching ofthe metals from treated mixtures.</p><p>Comparison of the results obtained by the different methods of sediment quality assessment&nbsp;showed that in some cases one approach to solving this problem is not &nbsp;sufficient. Metal&nbsp;concentrations in particular sediment samples (the Begej, the DTD Canal, the Nadela, the&nbsp;Sava at &Scaron;abac) indicate the presence of contamination, the analyzed samples being of Class 4.&nbsp;According to the Dutch regulations, a sedimentof &nbsp;Class 4 is of unacceptable quality and&nbsp;requires urgent intervention in the sense of sediment dredging, disposal into special depots,&nbsp;and, if possible, remediation. For some samples, despite a high pseudo-total concentration&nbsp;(Class 4), no potential toxicity was confirmed onthe basis of the ratioof the acidic volatile&nbsp;sulfide and simultaneously extracted metals. The results showed that, apart from chemical&nbsp;analyses, biological tests are also necessary, but also sequential extraction analysis, which can&nbsp;more clearly define the way of metal binding to the particular sediment fractions, to allow a&nbsp;more reliable prediction of metal mobility, potential toxicity and bioavailability. In the&nbsp;analysis of sediment quality it is also necessary toinclude the aspect of radioactivity, as it has&nbsp;been shown that the results of this analysis can, not only confirm some of the results of the&nbsp;other analyses, but also indicate the sediment age, origin of contamination and potential&nbsp;toxicity.The subsequent steps should be directed to the control and prevention of&nbsp;contamination, in order to ensure that the water course reviatalization has a lasting positive&nbsp;effect on the environment, an unimpared and safe navigation and application of remediation&nbsp;methods.</p><p>In the sediment sample (Class 4) that was usedfor the examination of the efficiency of it&nbsp;appeared that zinc, nickel and lead exhibit a high risk, as the percentages of these metals in&nbsp;the exchangeable and carbonate phases were in the range from 40.1 &nbsp;to 45.2%. On the other&nbsp;hand, chromium and cadmium exhibited a moderaterisk, whereas copperin these fractions&nbsp;was present at the levels corresponding to a low risk (5.3%). This is alsoin agreement with&nbsp;the results of pore water analysis and simultaneously extracted metals and acid volatile&nbsp;sulphide examinations.</p><p>The investigations presented in this work provided an answer to the question whetehr the&nbsp;remediation can successfully remove the contamination in the sense of the immobilization of&nbsp;metals in a state that will not be harmful tothe environment. All the treatments applied&nbsp;yielded a decrease of the percentage of cumulatively leached metals from the S/S mixtures,&nbsp;but none of the mixtures of treated sediments with the tested immobilization agents belongs to&nbsp;the group of inert materials if the cumulative leached concentrations are compared with the&nbsp;concntrations for the wastes given by the EU legislation (2003/33/EC). Ifthe goal is to obtain a non-hazardous material it is necessary to treat the contaminatedsediment with at least 30% of the immobilizing agent (cement or calcium oxide). Based on the diffusion coefficients and leachability index, the highest immobilization efficiency was achieved using a mixture of cement and calcium oxide (30% of cement and 10% of CaO) and by applying thermal treatment at a higher temperature (1100⁰C) with clay (20%). A dominant mechanism of leaching metals from these mixtures is diffusion.</p>