Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves 87-94. Also available online.

Thesis (Ph. D.)--University of California, Berkeley, 2006. / Includes bibliographical references (leaves 113-117).

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 43-46). Also available on the World Wide Web.

Les compositions isotopiques en Nd, Hf, Pb et Sr des sédiments de rivière sont souvent considérées comme étant représentatives de celles de leurs roches sources. Elles sont donc largement utilisées pour tracer la provenance des sédiments ou pour moyenner les compositions isotopiques des lithologies drainées. L'influence des processus sédimentaires sur les compositions isotopiques de ces sédiments est cependant mal connue. L'objectif de l'étude présentée ici est de caractériser l'ampleur de la variabilité isotopique pouvant être générée par les processus de tri minéralogique au cours du transport des sédiments dans le milieu fluviatile. Pour ce faire, nous avons analysé les concentrations en éléments traces et les compositions isotopiques en Nd, Hf, Pb et Sr dans différents types de sédiments de rivière (bedload, suspended load, bank) échantillonnés à plusieurs endroits dans le système fluviatile du Ganges qui draine une partie de l'orogène Himalayenne. Nous avons également mesuré les compositions chimiques et isotopiques de nombreuses fractions minérales et granulométriques séparées de ces sédiments afin de mieux comprendre l'influence de chaque espèce minérale dans le budget isotopique total d'un sédiment de rivière. Dans le cas où les lithologies drainées sont essentiellement cristallines et sédimentaires, nous montrons que les isotopes du Nd dans les sédiments de rivière sont très peu affectés par les processus de tri minéralogique puisqu'ils sont toujours contrôlés par les mêmes minéraux, à savoir la monazite et l'allanite. Au contraire, les systèmes isotopiques de l'Hf, du Pb et du Sr s'avèrent particulièrement touchés par les processus de tri minéralogique. Les isotopes de l'Hf et du Pb sont tous deux affectés par un effet zircon qui génère de larges variations isotopiques entre les sédiments de fond de rivières et ceux transportés en suspension. Pour le Sr, les variations observées entre les différents types de sédiments résultent des proportions variables de micas et feldspath-K qu'ils contiennent. Dans le cas où les principales lithologies drainées présentent de forts contrastes d'érodabilité i.e. basaltes versus roches cristallines, nous montrons que les effets combinés de l'érosion différentielle dans le bassin de drainage et du tri sédimentaire dans la colonne d'eau sont responsables d'importantes variations isotopiques en Nd, Hf et Pb entre les sédiments de fond de rivière et ceux transportés en suspension. Nos calculs suggèrent que les produits d'érosion basaltique, relativement fins, sont préférentiellement transportés en suspension, proche de la surface de l'eau, alors que les produits d'érosion des roches plus cristallines sont préférentiellement concentrés dans les sédiments de fond de rivière. Enfin, nous suggérons que les variations isotopiques observées entre les différents types de sédiments transportés par les rivières sur les continents pourraient avoir d'importantes implications pour les systématiques isotopiques des sédiments océaniques terrigènes et sur l'évolution à long terme du réservoir mantellique si ces derniers sont recyclés au niveau des zones de subduction. / Nd, Hf, Pb and Sr isotopic compositions of river sediments are often considered to be representative of those of their source rocks. Thus, they are widely used to trace sediment provenance or to average the isotopic compositions of the drained lithologies. The influence of sedimentary processes on the isotopic composition of these sediments is however poorly known. The aim of the present study is to characterize the extent of the isotopic variability that can be generated by mineral sorting process during sediment transport in fluvial system. To do this, we analyzed trace element concentrations and Nd, Hf, Pb and Sr isotopic compositions in river bank, bedload and suspended load sampled at several locations in the Ganga fluvial system draining part of the Himalayan orogen. We also measured the chemical and isotopic compositions of numerous mineral and granulometric fractions separated from these sediments to better understand the contribution of each mineral species to the bulk isotopic budget of river sediments. When the drained lithologies are mainly crystalline and sedimentary, we show that Nd isotopes are very little affected by mineral sorting processes because, whatever the sediment type, those isotopes are always controlled by the same minerals i.e. monazite and allanite. In contrast, Hf, Pb and Sr isotopic systems are significantly affected by mineral sorting processes. Both Hf and Pb isotopes are affected by a zircon effect that generates large isotopic variations between bedload and suspended load. For Sr, variations between the different sediment types more likely result from variable proportions of K-feldspar and mica. When the main drained lithologies are characterized by strong differences in erodibility i.e. basalts versus crystalline rocks, we show that the combined effects of differential erosion in the drainage basin and sediment sorting in the water column are responsible for significant Nd, Pb and Hf isotopic variations between bedload and suspended load. Our calculations suggest that basaltic erosion products are preferentially transported in suspension, near the water surface, whereas the erosion products of more crystalline rocks are preferentially concentrated in bottom sediments. Finally, we suggest that the isotopic variations observed between bedload and suspended load on continents may have important implications for the isotopic systematics of oceanic terrigenous sediments and the long-term evolution of the mantle if these latters are recycled in subduction zones.

Mudanças na taxa de acumulação e na natureza da matéria orgânica sedimentar, e suas relações com as variações climáticas e flutuações do nível relativo do mar durante os últimos 8.500 anos cal. A.P. foram investigadas em dois testemunhos provenientes do Saco de Ribeira, Enseada do Flamengo, e junto à praia do Lázaro, Enseada da Fortaleza, na região de Ubatuba, litoral norte do Estado de São Paulo. Para o estudo as amostras coletadas foram submetidas a diversas análises - granulometria, teor de CaCO3, teores de Carbono orgânico, Nitrogênio e Enxofre totais, e razões isotópicas de carbono. Datações 14C, calibradas para a idade calendário, permitiram estabelecer um modelo de idades para as variações sedimentares detectadas. Intervalos de clima mais quente, 8.000-6.000 anos cal. A.P., foram acompanhados de um aumento na taxa de acumulação de carbono T.A.C. (10-13 g m-2 ano-1), seguida de diminuição após 5.000 anos cal. A.P., para valores inferiores a 2 g m-2 ano-1. Variações climáticas regionais, possivelmente relacionadas a chuvas torrenciais, próximos ao máximo transgressivo, de 5.100 anos 14C A.P., foram detectadas pelo aumento nos valores de T.A.C. (10-12 g. m- 2 ano-1), aumento nas taxas de acumulação de massa (T.A.M.) e deposição de sedimentos mais grossos, acompanhados de aumento na tendência continental da natureza da matéria orgânica. As maiores tendências continentais da matéria orgânica sedimentar, registradas aproximadamente entre 1.500-1.200 anos cal. A.P., podem ser decorrentes de uma oscilação negativa do nível do mar. No geral, todos os resultados estão de acordo com as curvas de variação do nível relativo do mar, já descritas na literatura. As análises sedimentares da região estudada revelaram um evento regressivo-trangressivo, que ainda não havia sido referido para o Estado de São Paulo. A partir de ~2.000 anos cal. A.P., o mar teria atingido um nível mais baixo que o atual, com o mínimo provavelmente entre 1.500-1.200 anos cal. A.P., e encontra-se em ascensão até os dias atuais. As características anóxicas e a matéria orgânica sedimentar de origem planctônica registradas junto à praia do Lázaro, em meio a condições de energia relativamente mais alta, em ~900 anos cal. A.P., foram consideradas como resultado de condições óxicas das águas, acompanhadas de altas taxas de produtividade, e subseqüente degradação da matéria orgânica, existentes no período anterior. / Changes in the organic carbon accumulation rates (Corg A.R.) and organic matter source characteristics and their relation to climate and relative sea level changes during the last 8.500 cal. yr. B.P. were investigated in two sediment cores from 2 embayments - Flamengo and Fortaleza inlets - northern coast of São Paulo State. Sediment samples were analysed for grain size, organic Carbon, total Nitrogen and Sulphur contents, and ?13C ratio. Radiocarbon datings provided a model age to the sedimentary deposits. The warm climate interval 8.000-6.000 cal. yr. B.P. was accompanied by an increase in the Corg A.R. (10-13 g.m.-2 yr -1) and a decrease (~2 g.m.-2 yr -1) in the last ~5.000 cal. yr. B.P. Regional climate changes, as stormy weather, that may have ocurred near the maximum transgressive period called Santos Transgression at 5.100 yr. B.P., were recorded in the sedimentary profiles by relatively hight T.A.C. and T.A.M. values, coaser grain size sediment delivery, and enhanced terrestrial organic matter source characteristics. Improvement of terrestrial origin of the sedimentary organic matter recorded between 1.500-1.200 cal. yr. B.P in the studied area was mainly related to a negative sea-level oscillation. All the results are in general agreement with the existing sea level change curves. The sedimentary profiles suggest a negative sea-level fall event, that had\'nt been described yet for São Paulo State. It\'s proposed that the negative oscillation would have begun at ~2.000 cal. yr. B.P.and reached a minimum probably between 1.500-1200 cal. yr. B.P. The relative sea level has been rising since then. Anoxic conditions accompanied by algal origins of sedimentary organic matter, observed in the sedimentary profile from Fortaleza inlet at 900 cal. yr. B.P, during a more oxidizing environment are considered as a result of a previous well oxygencontaining water column and high productivity rates.

Concentrações de cádmio (Cd), chumbo (Pb) e mercúrio (Hg) foram determinadas em amostras de água (teores dissolvidos e particulados), sedimento de fundo, peixes e bivalves, coletados em seis bacias hidrográficas do Estado de São Paulo: Alto Paranapanema, Peixe, Aguapeí, São José dos Dourados, Mogi-Guaçu e Piracicaba, as quais apresentam diferentes características quanto ao uso e ocupação da terra. Dentre estas bacias, as dos rios Piracicaba e Mogi-Guaçu apresentam maiores densidades demográficas e industrialização, o que gera, conseqüentemente, maior degradação da qualidade das águas, enfatizando a necessidade de estudos freqüentes nesses sistemas. As amostragens de água e sedimento foram feitas bimestralmente durante o ano de 2001. Os peixes e bivalves foram amostrados no mesmo ano em dois períodos: seca e cheia. As concentrações de Cd e Pb foram determinadas por espectrometria de absorção atômica com atomização eletrotérmica, e as de Hg por espectrometria de fluorescência atômica. Os teores de Cd e Pb na fração trocável do sedimento também foram determinados. Os resultados obtidos mostraram baixas concentrações dos metais Cd e Pb na coluna d’água, tanto nas formas dissolvidas quanto particuladas, no entanto, tais concentrações foram maiores nas bacias dos rios Piracicaba e Mogi-Guaçu. No sedimento de fundo e nos bivalves, as maiores concentrações de Pb foram observadas no rio Mogi-Guaçu, embora este elemento tenha ocorrido em pequenas quantidades na fração trocável do sedimento (<1%). O Cd ocorreu em maiores teores no sedimento e no material particulado do rio Piracicaba. Por outro lado, as maiores concentrações de Pb nos bivalves foram detectadas no rio Mogi-Guaçu. Na fração trocável do sedimento, o Cd ocorreu em altas proporções (até 76%), principalmente, nos rios Itapetininga (Bacia do Alto Paranapanema), Piracicaba e Mogi-Guaçu. Em algumas amostras de água e sedimento de fundo ocorreram quantidades relativamente elevadas de Hg. Por outro lado, nos bivalves os teores do elemento foram sempre baixos. No entanto, nenhuma tendência significativa de distribuição espacial ou temporal de Hg ocorreu nas amostras. Portanto, acredita-se que os altos teores registrados para algumas amostras foram resultantes de fontes de origem difusa não-pontual, como deposição atmosférica e fontes originárias da agricultura. Nos peixes, as concentrações de Cd e Pb foram sempre inferiores aos limites de detecção (0,005 e 0,08 µg/g peso seco, respectivamente). Por outro lado, peixes carnívoros coletados no reservatório de Jurumirim (bacia do Alto Paranapanema) apresentaram altas concentrações de Hg (média: 1,14 +/- 0,54 µg/g peso úmido) e metilmercúrio (média: 1,04 +/- 0,51 µg/g peso úmido). Este último, representou em média 92% do mercúrio total determinado no músculo dos peixes. Tais concentrações foram maiores que o máximo permitido pela legislação brasileira para peixes predadores (1 µg/g peso úmido) e, provavelmente, foram resultante de altos teores de metilmercúrio produzido no reservatório devido aos processos de produção e liberação de mercúrio a partir da vegetação e solos inundados. Portanto, concluiu-se que os peixes do reservatório de Jurumirim estavam contaminados com Hg, recomendando-se que novos estudos sejam realizados para se identificar as fontes e processos responsáveis por tais contaminações. As bacias dos rios do Peixe, Aguapeí, Alto Paranapanema e São José dos Dourados apresentaram baixas quantidades de todos os elementos estudados. Por outro lado, foram observadas concentrações relativamente elevadas de Cd no rio Piracicaba, e Pb e Cd no rio Mogi-Guaçu, os quais devem ser periodicamente avaliados. / Concentrations of cadmium (Cd), lead (Pb), and mercury (Hg) were determined in water (dissolved and particulate), bottom sediment, fish, and bivalves sampled in six watersheds located in the State of São Paulo (Southeast, Brazil): the Alto Paranapanema, the Peixe, the Aguapeí, the São José dos Dourados, the Mogi-Guaçu, and the Piracicaba. These watersheds show different levels of land-use. Among these basins, the Piracicaba and the Mogi-Guaçu River Basins show highest population and industrialization rates. Such features lead, consequently, to a higher degradation of water, thus decreasing its quality. These facts emphasize the need of new and frequent studies in those systems. Water and sediment samplings were carried out bimonthly during 2001. Fish and bivalves samples were collected twice a year: at the end of the rainy and dry season. Cd and Pb concentrations were determined through electrotermal atomic absorption spectrometry, whereas Hg through atomic fluorescence spectrometry. In addition, exchangeable Cd and Pb were determined in sediment. The results showed low concentrations of Cd and Pb in water (dissolved and particulate). However, these concentrations were higher in the Piracicaba and the Mogi-Guaçu River Basins. Pb concentrations in sediment and bivalves were the highest in the Mogi-Guaçu River, even so this element occurred in low levels in the exchangeable fraction of sediment (< 1%). The highest Cd concentrations in sediment and particulate suspended matter were related to the Piracicaba River, although the highest levels for bivalves occurred in the Mogi-Guaçu River. High Cd concentrations in the exchangeable fraction of sediment (up to 76%) were observed, mainly in the Itapetininga (the Alto Paranapanema Basin), the Piracicaba, and the Mogi-Guaçu River. High concentrations of Hg were detected in some water and sediment samples, whereas in bivalves Hg was always in low levels. However, no significant tendency of temporal and/or spatial distribution was observed for Hg, so it is belived that the high levels reported for some samples were a result from diffuse non-point source pollution, such as atmospheric deposition and residues from agricultural practices. Cd and Pb concentrations in fish were always lower than the detection limit (0.005 and 0.08 µg/g dry wt, respectively). On the other hand, high concentrations of Hg (1.14 +/- 0,54 µg/g wet wt) and methylmercury (1.04 +/- 0.51 µg/g wet wt), which represented 92% of the total mercury, were found in carnivorous fish samples from the Jurumirim Reservoir (the Alto Paranapanema Basin). These concentrations were higher than the maximum limit permitted by Brazillian legislation for predatory fish (1 µg/g wet wt) and, probably, were a result from high methylmercury levels produced and released in the reservoir supported by inundated soil and vegetation. Hence, we concluded that carnivorous fish from the Jurumirim Reservoir were contamined with Hg, therefore new research sould be carried out in that area in order to identify the sources and processes responsible for high levels of mercury. The Peixe, the Aguapeí, the Alto Paranapanema, and the São José dos Dourados River Basins showed relatively low concentrations of all elements studied. Conversely, high Cd concentrations were determined in the Piracicaba River, and Pb and Cd in the Mogi-Guaçu River, pointing out that these areas should be frequently monitored.

Simultaneous in-situ measurements of waves, currents, water depth, suspended sediment concentrations and bed profiles were made in a rip channel on Perranporth Beach, Cornwall, UK. Perranporth is a high energy beach (annual offshore Hs = 1.6 m) which is macro-tidal (mean spring range = 6.3 m) and the grain size is medium sand (D50 = 0.28 – 0.34 mm). It can be classified as a low tide bar – rip beach and exhibits a relatively flat inter-tidal zone with pronounced rhythmic low tide bar - rip morphology. Data were collected over two field campaigns, totalling 14 tidal cycles and including 27 occurrences of rip currents, in a range of offshore wave heights (Hs = 0.5 – 3 m). The in-situ measurements were supplemented with morphological beach surveys. Sediment samples were taken for grain size analysis. The rip current was found to be tidally modulated. The strongest rip flow (0.7 m/s) occurred at mid to low tide, when waves were breaking on the adjacent bar. Rip flow persisted when the bar had dried out at the lowest tidal elevations. The rip was observed to pulse at a very low frequency (VLF) with a period of 15 - 20 minutes, which was shown to be influenced by wave breaking on the adjacent bar. The rip was completely in-active at high tide. Bedforms were ubiquitous in the rip channel and occurred at all stages of the tide. Visual observations found bedforms to be orientated shore parallel. When the rip was active, mean bedform length and height was 1.45 m and 0.06 m respectively. The size and position of the bedforms in the nearshore suggested that they were best classified as megaripples. When the rip was not active, the mean bedform length and height was 1.09 m and 0.06 m respectively. In rip conditions, with typical mean offshore flow rates of > 0.3 m/s, the bedforms migrated in an offshore direction at a mean rate of 0.16 cm/min and a maximum rate of 4.6 cm/min. The associated mean bedform sediment transport rate was 0.0020 kg/m/s, with a maximum rate of 0.054 kg/m/s. In the rip, migration rates were correlated with offshore directed mean flow strength. In non-rip conditions, bedform migration was onshore directed with a mean rate of 0.09 cm/min and a maximum rate of = 2.2 cm/min. The associated mean bedform transport rate was 0.0015 kg/m/s, with a maximum rate of = 0.041 kg/m/s. The onshore bedform transport was correlated with incident wave skewness, and was weakly correlated with orbital velocity. Over a tidal cycle, the offshore directed bedform transport was only marginally larger in rip currents than when it was when onshore directed in non-rip conditions. Sediment suspension in the rip current was shown to be dependent on the presence of waves. Suspended sediment transport was dominated by the mean flux. The mean flux contributed > 70% of total suspended transport on 19 out of the 27 observed rip current occurrences. The net contribution of the oscillatory flux was small compared to the mean flux. Within the oscillatory component, a frequency domain partitioning routine showed that the VLF motion was an important mechanism for driving offshore directed sediment transport. This was balanced by onshore directed sediment transport at incident wave frequency of a similar magnitude. Depth integration showed that the mean total suspended sediment transport was in the range of 0.03 kg/m/s to 0.08 kg/m/s. At high tide, when the rip was inactive suspended sediment transport rates were minimal compared to when the rip was active. Bedform transport was (on average) 6% of the total suspended sediment transport in a rip current. The new results presented here show that rip currents make an important contribution to offshore directed sediment transport. The magnitudes of transport indicate that future improvements to morphology change models should include rip driven offshore sediment transport.

Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant correlation between sediment toxicity and sediment characteristics (organic carbon, cation exchange capacity, particle size distribution, particle surface area). Fluoranthene amended sediments with similar organic carbon contents do not yield similar toxicities due to sorbed fluoranthene and thus do not support the organic carbon normalization approach for evaluating sediment quality or for sediment criteria development.

The Tibbitt-to-Contwoyto Winter Ice Road (TCWR) is the sole overland route servicing diamond mines north of Yellowknife, Northwest Territories (NWT), Canada. The road is 568 km long, 85% of which extends over frozen lakes. As such, its operational season is highly dependent upon the length of the winter season. This was exemplified in 2006, when an El Niño event caused an unusually short ice road season and resulted in a costly reduction of shipments to the mines. For future use and development of the TCWR, a comprehensive understanding of past regional climate variability is required. This study is an integral component of a larger-scale study designed to develop a comprehensive database of high-resolution paleoclimate data for the NWT, using a variety of proxies. As part of the larger study, freeze cores were taken from numerous lakes along the TCWR and sliced at 1-mm intervals using a custom-designed sledge microtome. Bulk 13C and 15N isotope analysis was completed at preliminary 1-cm intervals through the cores of two lakes on opposite sides of the tree line. Results from this analysis show clear trends with distinct transitions in both cores, whose closely-matched timing suggests regional-scale climate events. These results indicate that the Early Holocene was warm and dry, with a sudden shift to wetter conditions around 7200-6900 cal yr BP. Another shift to cooler conditions occurred at 4000 cal yr BP, and a final transition to even cooler temperatures occurred around 755-715 cal yr BP, coinciding with the Little Ice Age. Additionally, a modern lake survey was completed using surface sediments of numerous lakes throughout the Arctic and Subarctic. This survey verifies the strong influence of boreal forest vs. tundra conditions in affecting various environmental properties within lakes, including carbon and nitrogen isotopes. Lastly, time-series analysis was completed on two sections of Danny’s Lake core at high resolution (up to 2 mm), in order to determine short-term climate cycles. These results highlight specific climate frequencies which may be related to the Pacific Decadal Oscillation. These results offer insight to short-term climate phenomena in the Northwest Territories which will allow future climate modellers to make more accurate predictions of future climate and its impact on the ice road.

<p>Od primenjenih elektrokinetičkih tehnika:<br />konvencionalna, elektrodijalitička (uz primenu CEM), zatim tretman<br />uz izmenu polariteta na elektrodama, primena pomeranja anode ka<br />katodi, bipolarnih elektroda kao i povećane dužine katodnog prostora,<br />na uzorku Ni zagađenog kaolina (model matriks) najveću efikasnost<br />uklanjanja Ni pokazale su primena pomeranja anode ka katodi (51%<br />odnosno 82% bez uračunavanja katodnog regiona kaolina) i primena<br />bipolarnih elektroda uz povećani katodni prostor (45%).<br />Primenom bipolarnih elektroda uz povećan katodni prostor kao<br />unapređene EK tehnike preči&scaron;ćavanja sedimenta sa visokim ANC<br />postignute su efikasnosti od 44% za uklanjanje Ni odnosno 36%,<br />42% i 43% za uklanjanje Ni, Cd i Pb u sme&scaron;i, redom. Ove efikasnosti<br />su približno dvostruko veće u odnosu na efikasnosti konvencionalnih<br />tretmana, a uviđa se neznatni uticaj prisustva Cd i Pb na efikasnost<br />uklanjanja Ni. Procena rizika na osnovu različitih kriterijuma utvrdila<br />je da je sediment zagađen Ni nakon tretmana siguran za okolinu.<br />Sediment zagađen Ni, Cd i Pb je prema sadržaju Ni i Pb siguran po<br />okolinu, ali se poređenjem različitih kriterijuma procene rizika koji su<br />kori&scaron;ćeni u toku rada dobijaju informacije koje se u manjoj ili većoj<br />meri potvrđuju &scaron;to ukazuje na neophodnost postojanja jedinstvenih i<br />sveobuhvatnih kriterijuma procene rizika. Navedeno potvrđuje da je<br />primena bipolarnih elektroda uz povećan katodni prostor efikasna<br />tehnika preči&scaron;ćavanja sedimenta koji je zagađen Ni i Pb pri<br />koncentracijama koje su navedene u radu.<br />Primenom pomeranja anode ka katodi uz povećan katodni<br />prostor kao unapređene EK tehnike preči&scaron;ćavanja sedimenta sa<br />niskim ANC postignute su efikasnosti od 25% za uklanjanje Ni<br />odnosno 17%, 24% i 62% za uklanjanje Ni, Cd i Pb u sme&scaron;i, redom.<br />Ove efikasnosti su približne za Ni odnosno dvostruko i trostruko veće<br />za Cd i Pb, redom u odnosu na efikasnosti konvencionalnih tretmana.<br />Može se utvrditi da je efikasnost unapređenog procesa značajno<br />povećana, ali poređenjem krajnih koncentracija metala u sedimentu<br />nakon tretmana sa kriterijumima procene rizika, utvrđeno je da jedino<br />prema sadržaju Pb sediment se može smatrati sigurnim po akvatičnu<br />sredinu dok prema sadržaju ostalih metala spada u visoko rizičnu<br />klasu (&gt;50%).</p> / <p> As the result of applying electrokinetic techniques:<br /> conventional, electrodialytic, treatment with electrode polarity<br /> exchange, moving anode, using bipolar electrodes and increased<br /> cathodic compartment length, on Ni contaminated kaolin (model<br /> matrix) the most efficient were moving anode technique (51% or<br /> 82% without calculating the cathode region of kaolin) and using<br /> bipolar electrodes and increased cathodic compartment length (45%).<br /> Using bipolar electrodes and increased cathodic compartment<br /> length as enhanced EK technique for remediation of sediment with<br /> high ANC resulted in 44% of Ni removal and 36%, 42% i 43% for<br /> removal of Ni, Cd and Pb, respectively. This technique nearly<br /> doubled efficiency after conventional treatment and there is slight<br /> influence of Cd and Pb on Ni removal. Risk assessment based on<br /> different criteria determine that Ni contaminated sediment is safe for<br /> the environment after EK treatment. According to Dutch standards it<br /> is classified as Class 1/2. Ni, Cd and Pb contaminated sediment is<br /> safe for the environment according to Ni and Pb content after EK<br /> treatment according to Dutch standards but comparing the risk<br /> assessment arise from different criteria in some cases it do not<br /> provide the same information. This indicates that it is of great<br /> importance to develop unique risk assessment criteria. According to<br /> the results using bipolar electrodes and increased cathodic<br /> compartment is efficient EK remediation technique of Ni and Pb<br /> contaminated sediment at the concentrations used for these<br /> investigations.<br /> Using the moving anode technique and increased cathodic<br /> compartment length as enhanced EK technique for remediation of<br /> sediment with low ANC resulted in 25% of Ni removal and 17%,<br /> 24% and 62% for removal of Ni, Cd and Pb, respectively. It can be</p> <p> concluded that efficiencies after enhanced technique compare to<br /> conventional treatments are significantly increased but the final metal<br /> concentrations (except Pb) in sediment after treatment according to<br /> risk assessment criteria are highly hazardous for the environment<br /> (&gt;50%).</p>