Eutrophication is a global problem affecting many inland and estuarine waters. Many wetlands on the Swan Coast Plain, in Western Australia, have undergone increasing nutrient enrichment since European settlement of the region in the 1850’s. Problems such as algal blooms and nuisance swarms of non-biting midges (Diptera; Chironomidae) are the consequence of nutrient enrichment in many of these wetlands. The restoration of these degraded wetlands, especially with respect to reducing nutrient enrichment, requires a range of comprehensive and effective techniques including catchment management, diversion or treatment of surface inputs and treatment of enriched sediments. Nitrogen and phosphorus, especially phosphorus, are not the only factors controlling algal biomass in water bodies, but they are the only elements that can be removed efficiently and economically. Internal P cycling from wetland sediments can initiate and sustain eutrophication and related algal blooms and nuisance midge problems even after external sources are diverted or reduced. The aim of this study was to identify an effective material to reduce sediment phosphorus release and thereby the phosphorus concentration of the water column. It was also important to determine the impact of the selected amendment material on phytoplankton and larval midge (chironomid) communities. A range of experiments at increasing scales, from bench-top, to microcosm to outdoor mesocosm experiments were designed to test three hypotheses: 1) Materials which have a high P sorption capacity, over a wide range of P solution concentrations, and low P release rate, are potentially suitable agents to reduce P in wetlands with enriched sediments by inactivating sediment P; 2) A reduction in the abundance of cyanobacteria caused by increasing the N:P ratio of an aquatic ecosystem results in a reduction in the density of nuisance species of Chironomidae. 3) Successful amendment of enriched sediments reduces P in the water column thereby reducing the total phytoplankton biomass and the related density of nuisance species of Chironomidae. The adsorption and desorption experiments were carried out under a range of pH values and P concentrations, with a number of materials including fly ash, red mud, precipitated calcium carbonate, crushed limestone and lime to determine the maximum adsorption capacity and affinity of these materials. A rang of P concentrations (0-1000 µg/L) simulated the P concentration of the water column in a range of wetlands of differing trophic status. Poor fits to the Langmuir equation occurred with both red mud and fly ash due to their high P content. A good fit occurred with lime, with a high P removal rate (90%-96%) over the same range. Fly ash and red mud were eliminated from further investigation due to the possibility that they might release phosphorus rather than absorb when P concentrations in surrounding environment were less than 300 µg/L or 200 µg/L respectively (concentrations which can occur in eutrophic systems). Among the three lime-based, redox-insensitive materials tested in the second mesocosm experiments, precipitated calcium carbonate (PCC) possessed the highest maximum adsorption capacity and lowest desorption rate under a range of pH values (6.2, 7.2 and 10) and P concentrations (0-12 000 µg/L), followed by crushed limestone and lime. The different maximum absorption capacities of the three materials appears to be mainly attributed to their particle size (surface area). Lime was chosen as the amendment material for further investigation because it was the only one of the three available in sufficient quantities within the timeframe of this study. Microcosm experiments showed that lime was effective in reducing sediment P release from intact sediment cores, and the ratio of TN:TP in the treatment cores increased over time compared to the control cores (in which TN: TP decreased slightly). In the first mesocosm experiment a significantly higher density of larval midges was found in the treatments than in the controls. The treatments were aimed to increase N:P ratio in the systems to reduce cyanobacteria and, subsequently, larval midge densities. However even though cyanobacteria were eliminated from the treatments, the nitrogen addition appeared to result in higher phytoplankton biomass overall, which fuelled an increase in larval midge densities. In the second mesocosm experiment, the addition of lime to enriched sediments resulted in a reduction in P in the water column. This reduction was accompanied by a reduction in total phytoplankton biomass, the absence of cyanobacteria, and a less abundant and more species - diverse chironomid fauna in the treatment mesocosms. Sediment P fractionation undertaken for both the microcosm and mesocosm experiments showed that most of the phosphorus adsorbed by lime was in the labile fraction (NH3Cl extractable P and NaOH extractable P). Phosphorus in the HCl extractable fraction was also found to be higher in the treatments due to the presence of inert mineral P in the lime than the formation of new hydroxyapatite from adsorbed P. The two mesocosm experiments suggested that larval midges were non-selective feeders, responding to total phytoplankton biomass, rather than the presence of cyanobacteria. Dissolved oxygen and predation also influenced larval midge densities. In summary, although lime appeared to be a useful material for reducing P release from enriched sediments under controlled laboratory conditions, the effect under field conditions was not as definitive. Further work is required to more fully determine the conditions under which sediment remediation may be used as a means of controlling sediment P release and associated high densities of larval chironomids.

Mercury -contaminated sediments often act as a sink of mercury and produce methyl-mercury, an acute neurotoxin which readily bio accumulates, due to the presence of bacterial communities hosted by the sediment. One common remediation approach to manage methyl-mercury is to amend the sediment by capping or directly mixing with a sorbent. This thesis aims to assess the capabilities of some calcium-based sorbent to act in that capacity. Laboratory experiments were implemented to simulate mercury fate and behavior in geochemical conditions that capping would likely create. Well-mixed slurries showed that gypsum materials were disparate and their behavior was similar from sand to organocaly. Mercury sorption capacities of these gypsums were poor with a sorption coefficient approximately equal to 300 L/kg. Reduction of methylmercury was minimal and even increased in two of the three materials. Therefore, the three gypsums, which tend to be more cohesive when wetted, doesn’t constitute a viable material for sediment capping. / text

Contaminated aquatic sediments pose health risks to fish, wildlife, and humans and can limit recreational and economic uses of surface waters. Technical and cost effective in situ approaches for sediment management and remediation have been identified as a research need. Subaqueous in situ capping is a promising remedial approach; however, little is known regarding its impact on underlying sedimentary processes and the feasibility of bioaugmented caps at sites subject to contaminated groundwater seepage. This work specifically addresses (1) the impact of capping on biogeochemical processes at the sediment-water interface, (2) the ability and degree to which indigenous sediment microorganisms colonize an overlying cap, (3) the effect of advective flow direction on redox conditions within a cap, (4) natural contaminant bioattenuation processes within capped sediment, and (5) limitations toward a functional bioreactive in situ cap. Laboratory-scale experiments with capped sediment columns demonstrated that emplacement of a sand-based in situ cap induced an upward, vertical shift of terminal electron accepting processes into the overlying cap while simultaneously conserving redox stratification. Upflow conditions simulating a groundwater seep compressed anaerobic processes towards the cap-water interface. Microorganisms indigenous to the underlying sediment colonized cap material and spatial population differences generally reflected redox stratification. Downflow of oxic surface water through the cap, simulating tidally-induced recharge, created fully oxic conditions within the cap, demonstrating that flow direction strongly contributes to redox conditions. Experiments simulating capped sediment subject to contaminated groundwater seepage revealed a reduction of natural bioattenuation processes with time, stemming from the elimination of labile organic matter deposition to the sediment and a subsequent lack of electron donor. Thus, parent contaminants within groundwater seeps will be subject to minimal biotransformations within the sediment before entering a reducing cap. A bioreactive cap, inoculated with microorganisms capable of reductive dehalogenation, was established to reductively dechlorinate tetrachloroethene present in the groundwater; however electron donor amendments to sediment effluent were required to achieve complete dechlorination of tetrachloroethene to non-toxic ethene. Results from this work improve understanding of biogeochemical and bioattenuation processes within capped aquatic sediments and should aid in the development of active capping technologies.

<p>U radu je ispitana distribucija metala u sistemu sediment/voda na najugroženijim vodotocima u<br />AP Vojvodini. Na osnovu dobivenih podataka urađena je procena rizika na osnovu analize<br />porne vode, kiselog volatilnog sulfida i simultano ekstrahovanih metala i sekvencijalne<br />ekstrakcione procedure. Procena mobilnosti metala u sistemu sediment/voda određena je<br />promenom fizičko-hemijskih uslova u realnom sistemu (vodotok) i u laboratorijskim uslovima.<br />Ispitana je efikasnost in-situ (aeracijom sistema sediment/voda) i ex-situ remedijacije<br />sedimenta metodama termičkog tretmana i solidifikacije/stabilizacije.<br />Rezultati su ukazali da u svakom vodotoku i za&scaron;tićenoj zoni postoji lokacija u kojoj je sediment<br />barem po jednom metalu klasifikovan (holandski sistem klasifikacije sedimenata) kao zagađen<br />(klasa 3) ili izuzetno zagađen sediment (klasa 4). Generalno, kvalitet sedimenta manjih<br />vodotoka (Krivaja, Nadela, Kudo&scaron;, Veliki Bački kanal i Begej) je lo&scaron;iji u odnosu na ostale<br />ispitivane vodotoke.<br />Procena dostupnosti metala u sedimentu Velikog Bačkog kanala ukazala je da na svakom<br />ispitivanom profilu postoji minimum jedan metal i jedna metoda koja defini&scaron;e sediment kao<br />visoko rizičan. Takođe je zaključeno da je sediment na delu od 2+000 do 4+900 km zagađeniji,<br />jer postoji veći broj metala i metoda koji ga defini&scaron;u kao visoko rizičnim. Ovako dobijeni<br />rezultati ukazuju da nije dovoljan jednostavan i samo jedan pristup u oceni kvaliteta sedimenta<br />i proceni rizika koji metali mogu da ispolje u akvatičnom ekosistemu.<br />Ukazano je da pomeranje sedimenta (npr. otvaranja ustave), dovodi do promene fizičkohemijskih<br />uslova u sistemu sediment/voda, resuspenzije i transporta sedimenta. Usled ovih<br />promena povećava se dostupnost metala i dolazi do povećanja njihove koncentracije u vodenoj<br />fazi čime se znatno povećava rizik i mogućnost ispoljavanja negativnih efekata na akvatični<br />ekosistem.<br />U slučaju resuspenzije sedimenta u sistemu sediment/voda pronađena je zavisnost između<br />koncentracije metala u suspendovanim materijama i vodi od sadržaja određenih frakcija u<br />suspendovanim materijama (sadržaj organskih materija i frakcije do 63 &mu;m).<br />Remedijacione tehnike često su ekonomski neprihvatljive zbog velike zapremine zagađenog<br />sedimenta. Ukazano je da primena in-situ aeracije, omogućava smanjenje količine sedimenta<br />(čime se smanjuju tro&scaron;kovi eventualno naknadnog tretmana sedimenta), a da je tretman<br />solidifikacije/stabilizacije sedimenta sa glinom i termičke remedijacije zadovoljavjući sa<br />aspekta izluživanja metala. Dobijeni rezultati izvedenih testova izluživanja ukazali su na<br />moguću primenu ovih tretmana u pogledu re&scaron;avanja problema sedimenta koji je zagađen<br />metalima, bilo u pogledu sigurnog odlaganja na deponiju ili u smislu njegove upotrebe kao<br />dodatka pri proizvodnji građevinskog materijala (opeke), osnove za puteve, uređenje obale<br />(nasipa) itd. Na taj način mogu se znatno umanjiti tro&scaron;kovi izmuljivanja i manipulacije<br />kontaminiranog sedimenta, a sama remedijacija učiniti mnogo prihvatljivijom</p> / <p> This work investigates the distribution of metals in the sediment / water systems of the most<br /> endangered rivers in Vojvodina. Utilizing the data obtained, risk assessments are carried out<br /> based on analysis of pore water, acidic volatile sulphides and simultaneously extracted metals<br /> and sequential extraction procedure. The assessment of metal mobility in the sediment / water<br /> system is determined by the changing physical and chemical conditions in real systems<br /> (waterways) and under laboratory conditions. The effectiveness of in-situ (aeration of sediment<br /> / water) and ex-situ remediation of sediment by thermal treatment methods and solidification /<br /> stabilization are investigated.<br /> The results show that in each waterbody and protected area, certain locations have sediment<br /> which for at least one metal, is classified (by the Dutch system of sediment classification ) as<br /> polluted (class 3) or highly polluted (class 4). In general, the quality of sediment in smaller<br /> rivers (Krivaja, Nadela, Kudo&scaron;, Veliki Bački canal and Begej) is inferior to the other rivers<br /> studied.<br /> Assessment of the metals availability in the sediments of the Veliki Bački canal indicates that<br /> in each profile examined, at least one metal and one method defines the sediment as very<br /> hazardous. It is also shown that the sediment at the section from 2 +000 to 4 +900 km is the<br /> most polluted, with a number of metals and methods that define it as a high risk. The results<br /> indicate that it is inadequate to have a simple singular approach to sediment quality assessment<br /> and the assessment of the risks posed by metals detected in aquatic ecosystems.<br /> This work shows that sediment movement (e.g. from opening a sluice gate) leads to changes in<br /> the physical-chemical conditions of the sediment / water system, with resuspension and<br /> sediment transport. These changes increase metals availability and increase their<br /> concentrations in the aqueous phase, significantly increasing the posed risk and the possibility<br /> of adverse effects on aquatic ecosystems.<br /> In the case of sediment resuspension in the sediment / water system, a relationship was found<br /> between the concentration of metals in suspended matter and the concentration in the water for<br /> certain fractions of suspended matter (organic matter content and the fraction up to 63 &mu;m).<br /> Remediation techniques are often not economically viable due to the large volume of<br /> contaminated sediments involved. It is shown that the implementation of in-situ aeration<br /> reduces the amount of sediment (which reduces the costs of subsequent sediment treatment),<br /> and that solidification / stabilization treatment with clay and thermal remediation results in<br /> satisfactory remediation with respect to metals leaching. Leaching test results show the<br /> potential of these treatments to solve the problem of sediments which are contaminated with<br /> metals, either in terms of safe disposal in landfill or in terms of its use as a supplement in the<br /> production of building materials (brick), as road foundation, or for river bank reinforcement<br /> (dams), etc.. Thus, the costs of dredging and manipulating contaminated sediments can be<br /> significantly reduced, making remediation itself much more applicable.</p>

Great Lakes Areas of Concern (AOC) are designated geographical locations within the Great Lakes Basin with particularly degraded environmental conditions. There is a consensus among diverse sectors in the Great Lakes Basin that contaminated sediment is a major environmental problem and a key factor in many of the impairments of the human and nonhuman uses (beneficial uses) of the Great Lakes. This case study examines Randle Reef in the Hamilton Harbour (AOC) which is the largest Canadian contaminated sediment site in the Great Lakes containing 695,000 m3 of sediment contaminated with polycyclic aromatic hydrocarbons (PAH) and metals. The cleanup of the Randle Reef site is a major step in the process to restore Hamilton Harbour and remove it from the list of AOCs. The Randle Reef sediment remediation project is finally coming to fruition after more than thirty years of study, discussion, collaborations, and debate. As in the case of Randle Reef, environmental decisions are often complex and multi-faceted and involve many stakeholders with competing (sometimes conflicting) priorities or objectives representing exactly the type of problem that humans are poorly equipped to solve unaided. When professionals encounter complex issues, they often attempt to use approaches that simplify the complexity so that they can manage the problem at hand. During this process, valuable information may be lost, opposite points of view may be ignored and elements of uncertainty may be overlooked. A systematic methodology that combines both quantitative and qualitative data from scientific or engineering studies of risk, cost, and benefit, as well as stakeholder objectives and values to rank project alternatives, has yet to be fully developed for contaminated sediment decision-making. The main goal of this Ph.D. research was to develop a Decision Support System (DSS) framework to aid the complex decision-making in sediment remediation. The proposed DSS framework incorporates the five key themes that, through research, were found to be the most relevant for sediment remediation projects. These themes are 1)participation of appropriate actors with common objectives; 2)funding and resources; 3)decision-making process; 4)research and technology development; and 5)public and political support. There was a need to gather relevant information and data from various sources to develop the required DSS framework. For this purpose, expert interviews were conducted, responses were collected through a public survey, Qualitative Document Analysis (QDA) was performed on available policy and research documents, and a review was undertaken of how other jurisdictions have employed DSS to aid their decision-making process. The final DSS framework has six key components as follows: 1)data module; 2)communication module; 3)document module; 4)knowledge module; 5)tools module; and 6)DSS optimization module. This generic framework can assist practitioners in developing more systematic and structured decisions for sediment remediation by incorporating an Integrated Information Management System (IIMS) along with a DSS optimization module. This IIMS+DSS method can aid the decision-making process by making it documented, reproducible, robust, transparent and provide a coherent framework to explore and analyze available alternatives in an attempt to reach the preferred solution promptly. / Thesis / Doctor of Philosophy (PhD)

Hydrophobic organic contaminants (HOCs) often reside in sediments sorbed to particles, most tightly to particles with high content of organic carbon. If persistent, such pollutants can accumulate in the sediment for many years and constitute a contamination risk for sediment-living organisms and organisms at higher trophic levels, including humans. Since traditional remediation techniques are associated with complications (e.g. release of contaminants during dredging operations, disturbance of benthic faunal communities), or constraints (handling of large amounts of contaminated sediment and water, limitations due to depth and size of the area, high costs), there is a need for new alternative methods. In situ remediation through thin-layer capping (a few centimeter cover) with a sorbing material such as activated carbon (AC) has been proposed as an alternative remediation method. Compared to traditional remediation techniques, AC amendment in a thin layer means less material handling and lower costs and is assumed to be less disruptive to benthic communities. The objectives of this thesis were to investigate the ecological effects from thin layer capping as well as the efficiency in contaminant retention. Thin layer capping amended with AC proved to reduce availability of HOCs to the tested organisms, the gastropod Nassarius nitidus (Paper II), the clam Abra nitida (Paper III) and to polychaete worms  (Paper II and III). The remediation technique also decreased the sediment-to-water fluxes of the contaminants (Paper II and III). However, AC amended thin-layer capping was also found to cause negative biological effects. In laboratory studies with only a few species the negative effects were minor, or difficult to discern with the endpoints used (Paper II and III). In a larger multi-species mesocosm (boxcore) study, on the other hand, the negative effects were more prominent (Paper I) and in a large scale field study the benthic community was found to be profoundly disturbed by the AC amendment, with the effects persisting or even worsening ca one year (14 months) post amendment (Paper IV). / <p>At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 3: Manuscript; Paper 4: Manuscript.</p> / Carbocap / Opticap / Thinc

Made available in DSpace on 2016-06-02T19:31:43Z (GMT). No. of bitstreams: 1 2493.pdf: 1820155 bytes, checksum: c4fbdc0a3fdb7a9316ba5c6c6a6905c8 (MD5) Previous issue date: 2009-05-15 / Universidade Federal de Sao Carlos / The objective of the present dissertation was to make a toxicity assessment of the application of calcium nitrate solution as a remediation procedure for sediments of a eutrophic aquatic ecosystem. The study was carried out using microcosms with superficial sediments and water from sediment-water interface of the Ibirité Reservoir located in the metropolitan area of Belo Horizonte (Minas Gerais, SE Brazil). The experiment lasted 135 days and the following treatment or incubation periods were applied: t=0, t=5, t=10, t=25, t=50, t=85 and t=135 days. In each period, one controlmicrocosm and three treatment-microcosms were disassembled and, chemically and ecotoxicologically analyzed. The organisms Ceriodaphnia silvestrii and Vibrio fischeri (Microtox® System) were used for the acute toxicity assessment of the water from sediment-water interface and the pore water of sediments, whereas the organism Chironomus xanthus was used for the toxicity assessment of bulk sediment. The toxicity tests were run in parallel with chemical analyzes of dissolved inorganic nitrogen species (nitrate, nitrate and ammonium), sulfate, and metals in the interface sediment-water and interstitial water samples. Acid volatile sulfide (AVS), simultaneously extracted metal (SEM) and potentially bioavailable metals were analyzed in bulk sediment. The overall results indicate that nitrate whose concentration reached 1,200 mg N-NO3 - L-1 in sediment pore water samples from treatment-microcosms is the most probable compound causing toxicity to the tests organisms. For Chironomus xanthus sediments were deleterious to the exposed organisms in all microcosm run, except in the period of t= 135 days. For the experimental conditions of this work, the application of calcium nitrate as a remediation procedure for sediments from Ibirité Reservoir indicated to be inadequate from the ecotoxicological pint of view. / O presente trabalho visou à avaliação da toxicidade da aplicação de solução de nitrato de cálcio, como procedimento de intervenção para remediação de sedimentos de um ambiente aquático eutrofizado. O estudo foi realizado através de microcosmos com sedimento e água de interface sedimento-água da Represa Ibirité, situada na região metropolitana de Belo Horizonte (Minas Gerais, Brasil). Os experimentos tiveram a duração total de 135 dias, divididos nos tempos de tratamento ou incubação de: t=0, t=5; t=10; t=25; t=50; t=85 e t=135 dias. Em cada tempo de tratamento foram analisados um microcosmo-controle e três microcosmostratamento. Os organismos Ceriodaphnia silvestrii e Vibrio fischeri (Sistema Microtox®) foram utilizados para avaliação da toxicidade aguda das águas de interface sedimento-água e intersticial dos sedimentos, enquanto o organismo Chironomus xanthus para avaliação do sedimento integral. Em paralelo aos testes de toxicidade foram realizadas análises químicas da série nitrogenada (nitrato, nitrito e amônia), sulfato, e metais nas amostras de água de interface sedimento-água e intersticial dos sedimentos, sulfetos volatilizáveis por acidificação (SVA), metais extraídos simultaneamente (MES) e metais potencialmente biodisponíveis nos sedimentos. Os resultados mostraram que o nitrato, chegando a concentração superior a 1.200 mg N-NO3 - L-1 nas amostras de água intersticial dos sedimentos dos microcosmos-tratamentos, foi considerado o causador mais provável da toxicidade das amostras dos microcosmos-tratamento para os organismos-teste empregados. Para o organismo Chironomus xanthus, os sedimentos em tratamento foram deletérios aos organismos expostos em todos os tempos de incubação, exceto no tempo t=135 dias. Estritamente do ponto de vista ecotoxicológico e para as condições experimentais deste trabalho, a aplicação do nitrato como forma de intervenção para remediação dos sedimentos da Represa Ibirité não se mostrou adequada.

<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>

Persistent organic pollutants (POPs) are hydrophobic substances that readily sorb to organic matter in particles and colloids instead of being freely dissolved in the water phase. This sorption affects the bio­availability and environmental transport of the POPs. The major part of this thesis concerns the role of sediments as secondary sources of POPs. As the primary emissions decrease, contaminated sediments where POPs have accumulated can become the main source of contamination. If the contaminated sediment by time becomes covered with cleaner layers, the POPs are buried and no longer in contact with the aquatic environment. Experiments in this thesis showed, however, that new invading species can alter the sediment-water dynamics as a result of their bioturbation, i.e. mixing of sediment particles and pore-water. Marenzelleria spp., invading species in the Baltic Sea that burrow deeper than native species, were found to increase the remobilization of buried contaminants. The sediment-to-water flux was inversely related to the burial depth (2-10 cm) of the POP congeners (polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers) and also inversely related to the hydrophobicity of the congener. The flux was therefore most pronounced for less hydrophobic contaminants, which was linked to the bioirrigating behaviour of these species. Marenzelleria spp. also accumulated the buried POPs and increased concentrations in surface sedi­ment. Contaminants previously considered buried at a ’safe’ depth can thus be remobilized as a result of the invasion of Marenzelleria spp. in the Baltic Sea. One method to decrease the remobilization of contaminants from sediments is ’capping’, i.e. a layer of clean material is placed as a cap on the sediment. By amending the cap with active materials, which sequester the POPs and decrease their availability, thinner layers can be used (’active capping’ or ’thin-layer capping’). Results from an experiment with thin-layer capping using different active materials (activated carbon (AC) and kraft lignin) showed that both the sediment-to-water flux and the bioaccumulation by benthic species of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), hexachlorobenzene (HCB) and octachlorostyrene (OCS) decreased with increased thick­ness of the cap layer (0.5-5 cm). Amendments with active materials further increased the cap efficiency. AC was more efficient than kraft lignin, and a 3 cm cap with 3.3% AC reduced the flux and bioaccumulation with ~90%. The reduction of the sediment-to-water flux was inversely related to the hydrophobicity of the POP, and reductions in the flux had similar magnitudes as reductions in the concentration in deep-burrowing polychaetes, demonstrating the importance of bioturbation for sediment-to-water transport. In a one-year study on the levels of PCDD/Fs, PCBs, and HCB in a coastal area of the Baltic Sea, the correlations between the POP levels and the levels of particles and organic carbon in the water were found to differ for POPs of different structure and hydrophobicity. The levels of PCDD/Fs decreased to one third in May, which could be related to the increased sedimentation, i.e. water-to-sediment transport, during spring bloom.