Cette thèse de doctorat concerne l’étude de la distillation membranaire sous vide pour l’élimination de l’arsenic contenu dans les eaux souterraines. En effet, la contamination des nappes phréatiques par l’arsenic est une problématique majeure dans de nombreux pays, et en particulier au Vietnam. Dans ce pays, choisi comme cas d’étude pour ce travail, environ 13% de la population est empoisonnée par des eaux souterraines contaminées par l’arsenic. De plus, ces eaux souterraines présentent des salinités élevées (5-10 g.L-1) dues à des infiltrations d’eau de mer dans les nappes. Ce travail de thèse a permis de démontrer la faisabilité de la distillation membranaire sous vide (DMV) pour éliminer l’arsenic contenu dans ces eaux et réduire leur salinité afin de les rendre propres à la consommation humaine. Les concentrations en As(III) dans le perméat de DMV sont toujours inférieures aux limites de la norme en eau potable (10 μg.L-1), même pour de très fortes concentrations en As(III) dans l’alimentation (jusqu’à 2000 μg.L-1). La DMV ne nécessite pas de pré-oxydation de l’As(III) en As(V), étape nécessaire dans de nombreux procédés conventionnels de traitement. De plus, un couplage entre l’osmose inverse (OI) et la DMV a été étudié : l’étape d’OI permet une pré-concentration en NaCl et As(III), puis ce rétentat est alors sur-concentré grâce à laDMV. La DMV a montré de très bonnes performances pour traiter un concentrat contenant de très fortes concentrations en As(III) (7000 μg/L). La DMV permet toujours de limiter les teneurs en arsenic dans le perméat à des valeurs en-dessous de la norme. Enfin, unesimulation d’un procédé global, incluant OI et DMV, et fonctionnant à un taux de conversion global de 96%, a été effectuée. Ce couplage ouvre la voie vers un traitement global de l’arsenic permettant de générer de très faibles quantités d’effluents finaux / This PhD work deals with vacuum membrane distillation (VMD) for arsenic removal from groundwaters. Contamination of water resources with arsenic was identified in 105 countries. Approximately 150 million people are being exposed to arsenic contamination, and 147 million of these people live in Asia. In Vietnam, chosen as the case study of this work, 13% of the population is being in risk of arsenic poisoning. Drinking water resources present not only high arsenic concentration (1 – 3050 ppb) but also high salinity (5 – 15 g/L). This work allowed demonstrating the feasibility of VMD to remove arsenic and also salts contained in groundwaters. As(III) concentration in the permeate of VMD was always lower than the standard level for drinking water (10 μg.L-1), even for high As(III) concentrations in the feed (up to 2000 μg.L-1). With VMD, a pre-oxidation step was not necessary to convert As(III) into As(V), as it is the case for other conventional treatment processes. Moreover, a coupling between reverse osmosis (RO) and VMD was studied. RO was considered as a first step to concentrate NaCl and As(III) before this retentate stream was further concentrated by the VMD. VMD could work efficiently with 99.9% of As(III) andNaCl rejections at a very high RO retentate concentrations ([NaCl] = 300 g/L and [As(III)] = 7000 ppb). Arsenic in the permeate was still lower than the required standard for drinking water. Finally, a simulation of the coupling was performed. By coupling of RO and VMD, ahigh global recovery of 96% could be achieved

no / The optimal operation policy of flexible RO systems is studied in this work. The design and operation of RO process is optimized and controlled considering variations in water demands and changing seawater temperature throughout the day. A storage tank is added to the system layout to provide additional operational flexibility and to ensure the availability of freshwater to customer at all times. A steady state model for the RO process is developed and linked with a dynamic model for the storage tank. The membrane modules are divided into a number of groups to add flexibility in operation to RO network. The total operating cost of the RO process is minimized in order to find the optimal layout and operating variables at discreet time intervals for three design scenarios. (C) 2013 Elsevier Ltd. All rights reserved.

This thesis focuses on the implementation of species-specific isotope dilution (SSID) methodology and stable isotope tracers to determine mercury species occurrence and transformation processes in-situ and during sample treatment. Isotope enriched tracers of methyl-, ethyl- and inorganic mercury were synthesised and applied in different combinations to marine and biological samples. Experimental results were obtained using gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS). Mercury methylation and methylmercury demethylation processes in surface sediments were studied in the brackish Öre River estuary, Bothnian Bay. Uni- and multivariate data evaluation identified the organic material content and mercury methylation potential in the sediments as important factors controlling incipient methylmercury levels. Mercury species distribution in mice treated with the pharmaceutical preservative Thimerosal (ethylmercurithiosalicylate) was studied. The ethylmercury moiety of Thimerosal was observed to rapidly convert to inorganic mercury in the mice during the treatment period as well as during sample treatment, hence necessitating SSID methodology for accurate ethylmercury determinations in biological samples. To facilitate the introduction of SSID as a routine quantitative method in mercury speciation, a methylmercury isotopic certified reference material (ICRM) was produced. Prior to certification, the stability of the material was examined in conventional and isochronous stability studies spanning 12 months, which permitted uncertainty estimation of the methylmercury amount content for two years of shelf-life. Finally, a field-adapted SSID method for methylmercury determinations in natural water samples was developed. The proposed analytical protocol significantly simplified sample storage- and treatment procedures without sacrifices in analytical accuracy.

The in origin intertidal marine brown alga Fucus vesiculosus L. grow permanently sublittoral in the brackish Bothnian Sea, side by side with the recently discovered F. radicans L. Bergström et L. Kautsky. Environmental conditions like salinity, light and temperature are clearly different between F. vesiculosus growth sites in the Bothnian Sea (4-5 practical salinity units, psu; part of the Baltic Sea) and the tidal Norwegian Sea (34-35 psu; part of the Atlantic Ocean). The general aims of this thesis were to compare physiological aspects between the marine ecotype and the brackish ecotype of F. vesiculosus as well as between the two Bothnian Sea species F. vesiculosus and F. radicans. The result in the study indicates a higher number of water soluble organic compounds in the marine ecotype of F. vesiculosus compared to the brackish ecotype. These compounds are suggested to be compatible solutes and be due to an intertidal and sublittoral adaptation, respectively; where the intertidal ecotype needs the compounds as a protection from oxygen radicals produced during high irradiation at low tide. The sublittoral ecotype might have lost the ability to synthesize these compound/compounds due to its habitat adaptation. The mannitol content is also higher in the marine ecotype compared to the brackish ecotype of F. vesiculosus and this is suggested to be due to both higher level of irradiance and higher salinity at the growth site. 77 K fluorescence emission spectra and immunoblotting of D1 and PsaA proteins indicate that both ecotypes of F. vesiculosus as well as F. radicans have an uneven ratio of photosystem II/photosystem I (PSII/PSI) with an overweight of PSI. The fluorescence emission spectrum of the Bothnian Sea ecotype of F. vesiculosus however, indicates a larger light-harvesting antenna of PSII compared to the marine ecotype of F. vesiculosus and F. radicans. Distinct differences in 77 K fluorescence emission spectra between the Bothnian Sea ecotype of F. vesiculosus and F. radicans confirm that this is a reliable method to use to separate these species. The marine ecotype of F. vesiculosus has a higher photosynthetic maximum (Pmax) compared to the brackish ecotype of F. vesiculosus and F. radicans whereas both the brackish species have similar Pmax. A reason for higher Pmax in the marine ecotype of F. vesiculosus compared to F. radicans is the greater relative amount of ribulose-1.5-bisphosphate carboxylase/oxygenase (Rubisco). The reason for higher Pmax in marine ecotype of F. vesiculosus compare to the brackish ecotype however is not due to the relative amount of Rubisco and further studies of the rate of CO2 fixation by Rubisco is recommended. Treatments of the brackish ecotype of F. vesiculosus in higher salinity than the Bothnian Sea natural water indicate that the most favourable salinity for high Pmax is 10 psu, followed by 20 psu. One part of the explanation to a high Pmax in 10 psu is a greater relative amount of PsaA protein in algae treated in 10 psu. The reason for greater amount of PsaA might be that the algae need to produce more ATP, and are able to have a higher flow of cyclic electron transport around PSI to serve a higher rate of CO2 fixation by Rubisco. However, studies of the rate of CO2 fixation by Rubisco in algae treated in similar salinities as in present study are recommended to confirm this theory. / Fucus vesiculosus L. (Blåstång) är en brunalg som i huvudsak växer i tidvattenzonen i marint vatten men arten klarar också att växa konstant under ytan i det bräckta Bottenhavet. Norska havet och den del av Bottenhavet, där algerna är insamlade i denna studie, har salthalterna 34-35 psu (praktisk salthaltsenhet) respektive 4-5 psu. F. radicans L. Bergström et L. Kautsky (Smaltång) är en nyligen upptäckt art (2005) som har utvecklats i Bottenhavet. F. radicans och Bottenhavets ekotyp av F. vesiculosus växer sida vid sida och har tidigare ansetts vara samma art. Sett till hela Östersjön, så ändras ytans salthalt från 25 till 1-2 psu mellan Östersjöns gräns mot Kattegatt och norra Bottenviken. Den låga salthalten i Östersjön beror på det höga flödet av sötvatten från älvarna och på ett litet inflödet av saltvatten i inloppet vid Kattegatt. Salthaltsgradienten är korrelerad med antalet arter som minskar med minskad salthalt. Östersjön är ett artfattigt hav och de arter som finns är till stor del en blandning av söt- och saltvattenarter. Det finns bara ett fåtal arter som är helt anpassade till bräckt vatten och F. radicans är en av dem. Exempel på miljöskillnader för F. vesiculosus i Norska havet och i Bottenhavet är salthalten, tidvattnet, ljuset och temperaturen. Tidvattnet i Norska havet gör att algerna växlar mellan att vara i vattnet och på land, vilket utsätter algerna för stora ljusskillnader, snabba och stora temperaturväxlingar samt även torka. De alger som växer i Bottenhavet har däremot en jämnare och lägre temperatur, istäcke på vintern och mindre tillgång på ljus eftersom de alltid lever under vattenytan. Skillnaderna i miljön mellan växtplatserna leder till skillnader i fysiologiska anpassningar. Anledningen till att F. vesiculosus och F. radicans valdes som studieobjekt i denna avhandling är att de är viktiga nyckelarter i Bottenhavet. F. vesiculosus och F. radicans är de enda större bältesbildande alger som finns i det artfattiga ekosystemet och de används därför flitigt som mat, gömställe, parningsplats och barnkammare för t.ex. fisk. Att de är nyckelarter gör det angeläget att försöka förstå hur algerna är anpassade och hur de reagerar på miljöförändringar för att få veta hur de kan skyddas och bevaras. F. radicans inkluderades även för att se hur en naturlig art i Bottenhavet är anpassad i jämförelse med den invandrade F. vesiculosus. Marin F. vesiculosus inkluderades för att vara en artreferens från artens naturliga växtplats. Studien visar att det finns fler vattenlösliga organiska substanser (finns vissa organiska substanser som har en proteinskyddande funktion) i den marina ekotypen av of F. vesiculosus än i Bottenhavets ekotyp. Anledningen till detta föreslås vara en anpassning till att växa i tidvattenzonen. Vid lågvatten utsätts F. vesiculosus från Norska havet för starkt ljus, uttorkning, och snabba temperatur- växlingar vilket gör att den kan behöva dessa organiska substanser som skydd mot fria syreradikaler som bildas under lågvattenexponeringarna. F. vesiculosus från Bottenhavet har troligen mist förmågan att syntetisera dessa substanser på grund av anpassning till att hela tiden växa under ytan. Mängden mannitol (socker) är högre i den marina ekotypen av of F. vesiculosus än i Bottenhavets ekotyp. Detta föreslås bero på högre fotosyntetiskt maximum i F. vesiculosus från Norska havet jämfört med ekotypen från Bottenhavet. Skillnaden i fotssyntetiskt maximum är bland annat kopplat till ljus- och salthaltskillnaden på algernas växtplatser. Denna teori styrks av att både fotosyntesen och halten av mannitol ökar i Bottenhavets ekotyp när den behandlas i högre salthalt. Studien visar även att båda ekotyperna av F. vesiculosus samt F. radicans har ett ojämnt förhållande mellan fotosystem II och I (PSII och PSI) med en dominans av PSI. Denna slutsats är baserad på fluorescens emissions mätningar vid 77 K (-196 °C) och mätning av den relativa mängden D1 protein (motsvarar PSII) och PsaA protein (motsvarar PSI). F. vesiculosus från Bottenhavet visar ett emission spektrum som pekar mot en jämnare fördelning av PSII och PSI jämfört med den marina ekotypen och F. radicans. Detta stämmer dock inte med förhållandet mellan D1/PsaA som indikerar att alla tre har mer PSI än PSII. Förklaringen till avvikelsen mellan metoderna antas vara att F. vesiculosus från Bottenhavet har större ljus-infångande antennpigment än marin F. vesiculosus och F. radicans. De tydliga skillnaderna i 77 K fluorescens emission spektra mellan Bottenhavets F. vesiculosus och F. radicans visar att denna metod kan användas som säker artidentifiering. Den marina ekotypen av F. vesiculosus har högre fotosyntetiskt maximum än de båda arterna från Bottenhavet. Mätningar av den relativa mängden av enzymet Rubisco, viktigt för upptaget av koldioxid hos växter och alger, visar att mängden enzym är en sannolik förklaring till skillnaden i fotosyntetiskt maximum mellan den marina ekotypen av F. vesiculosus och F. radicans och detta är troligen en normal artskillnad. Mängden Rubisco kan dock inte förklara skillnaden i fotosyntetiskt maximum mellan de båda ekotyperna av F. vesiculosus. För att undersöka vad skillnaden mellan dessa två beror på så föreslås istället mätningar av Rubisco’s koldioxidfixeringshastighet. Det är en ökning av fotosyntetiskt maximum i Bottenhavets ekotyp av F. vesiculosus när den behandlas i högre salthalt (10, 20 och 35 psu) och det högsta fotosyntetiska maximumet uppmättes i alger som behandlats i 10 psu. Denna ökning beror inte på ökning i den relativa mängden av Rubisco. Ökningen i fotosyntesen speglas dock av en ökning av den relativa mängden PsaA. Detta antas bero på att det behövs mer energi i form av ATP och att en ökning av detta kan ske på grund av att mer PsaA kan driva den cykliska elektrontransporten i fotosyntesreaktionen. Ökat behov av ATP antas bero på en ökning av Rubisco aktiviteten men mätning av aktiviteten krävs för att bekräfta detta.

O Complexo Lagunar de Jacarepaguá, localizado no município do Rio de Janeiro, região sudeste do Brasil, é formado pelas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi. Estas lagunas estão interligadas ao mar pelo canal da Joatinga e têm como afluentes rios e canais que vertem dos maciços da Tijuca e da Pedra Branca. Recebem esgotos sanitários e efluentes industriais, além de contribuições difusas de águas de drenagem e circulação das massas de águas de várias origens, com elevada carga de poluição. A eutrofização cultural aliada aos processos de evolução de ecossistemas costeiros produziu um estado de degradação destas águas com constantes florações de cianobactérias potencialmente tóxicas. O presente estudo tem como objetivo avaliar a ocorrência das cianobactérias (Classe Cyanophyceae) no Complexo Lagunar de Jacarepaguá e corroborar a hipótese de serem boas indicadoras de qualidade ambiental de águas salobras. Foi realizado um monitoramento ambiental nas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi, nos anos de 2004 a 2006, sendo analisados parâmetros físicos, químicos e biológicos. Os resultados obtidos demonstraram a dominância e a persistência das cianobactérias em elevadas concentrações de nutrientes, caracterizando a hipereutrofização dessas lagunas. As estratégias ecológicas das cianobactérias garantiram sua dominância em quase todo o período amostral e demonstraram ser um refinado sensor das variáveis ambientais. A salinidade não foi um fator de limitação ao desenvolvimento desses microorganismos. Desta forma, este estudo, oferece subsídios para gestão de recursos hídricos, corroborando com a legislação CONAMA 357/05-MMA, na sugestão de indicação deste parâmetro de qualidade ambiental também para ambientes salobros na classe 1. / The Jacarepaguá Lagoon Complex, located in the state of the Rio of Janeiro, in Southeast of Brazil, is formed by the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi. These lagoons are interconnected to the sea by the Joatinga canal and receive contribution from tributary rivers and channels that come from Tijuca and Pedra Branca massifs. They receive industrial and domestic effluents, including diffuse contributions of the drainage basin, as well as water circulation from several origins, with a high pollution load. The cultural eutrophication associated with coastal ecosystems evolution processes, have produced a state of degradation of these waters with frequent waterblooms of potentially toxic cyanobacteria. The objective of the present study is to evaluate the presence of Cyanobacteria (Class Cyanophyceae) in the Jacarepaguá Lagoon Complex and also to corroborate the hypothesis of using them as a good bioindicators of environmental quality in brackish waters. An environmental monitoring program has been carried out in the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi from 2004 to 2006, including physical, chemical and biological parameters analysis. The results showed the dominance and persistence of Cyanobacteria at high concentrations of nutrients, characterizing the hypereutrofication of these lagoons. The ecological strategies of Cyanobacteria were responsible for their dominance in almost the whole period of study and demonstrated that they can be used as a good sensor of environmental variables. The salinity did not demonstrate to be a limiting factor to the development of these microorganisms. In this way, this study provides subsidies for water resources management, corroborating with Brazilian legislation (CONAMA 357/05- MMA) suggesting the inclusion of Cyanobacteria as a parameter of environmental quality in brackish environments classified as Class 1.

O Complexo Lagunar de Jacarepaguá, localizado no município do Rio de Janeiro, região sudeste do Brasil, é formado pelas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi. Estas lagunas estão interligadas ao mar pelo canal da Joatinga e têm como afluentes rios e canais que vertem dos maciços da Tijuca e da Pedra Branca. Recebem esgotos sanitários e efluentes industriais, além de contribuições difusas de águas de drenagem e circulação das massas de águas de várias origens, com elevada carga de poluição. A eutrofização cultural aliada aos processos de evolução de ecossistemas costeiros produziu um estado de degradação destas águas com constantes florações de cianobactérias potencialmente tóxicas. O presente estudo tem como objetivo avaliar a ocorrência das cianobactérias (Classe Cyanophyceae) no Complexo Lagunar de Jacarepaguá e corroborar a hipótese de serem boas indicadoras de qualidade ambiental de águas salobras. Foi realizado um monitoramento ambiental nas lagunas de Jacarepaguá, Camorim, Tijuca e Marapendi, nos anos de 2004 a 2006, sendo analisados parâmetros físicos, químicos e biológicos. Os resultados obtidos demonstraram a dominância e a persistência das cianobactérias em elevadas concentrações de nutrientes, caracterizando a hipereutrofização dessas lagunas. As estratégias ecológicas das cianobactérias garantiram sua dominância em quase todo o período amostral e demonstraram ser um refinado sensor das variáveis ambientais. A salinidade não foi um fator de limitação ao desenvolvimento desses microorganismos. Desta forma, este estudo, oferece subsídios para gestão de recursos hídricos, corroborando com a legislação CONAMA 357/05-MMA, na sugestão de indicação deste parâmetro de qualidade ambiental também para ambientes salobros na classe 1. / The Jacarepaguá Lagoon Complex, located in the state of the Rio of Janeiro, in Southeast of Brazil, is formed by the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi. These lagoons are interconnected to the sea by the Joatinga canal and receive contribution from tributary rivers and channels that come from Tijuca and Pedra Branca massifs. They receive industrial and domestic effluents, including diffuse contributions of the drainage basin, as well as water circulation from several origins, with a high pollution load. The cultural eutrophication associated with coastal ecosystems evolution processes, have produced a state of degradation of these waters with frequent waterblooms of potentially toxic cyanobacteria. The objective of the present study is to evaluate the presence of Cyanobacteria (Class Cyanophyceae) in the Jacarepaguá Lagoon Complex and also to corroborate the hypothesis of using them as a good bioindicators of environmental quality in brackish waters. An environmental monitoring program has been carried out in the lagoons of Jacarepaguá, Camorim, Tijuca and Marapendi from 2004 to 2006, including physical, chemical and biological parameters analysis. The results showed the dominance and persistence of Cyanobacteria at high concentrations of nutrients, characterizing the hypereutrofication of these lagoons. The ecological strategies of Cyanobacteria were responsible for their dominance in almost the whole period of study and demonstrated that they can be used as a good sensor of environmental variables. The salinity did not demonstrate to be a limiting factor to the development of these microorganisms. In this way, this study provides subsidies for water resources management, corroborating with Brazilian legislation (CONAMA 357/05- MMA) suggesting the inclusion of Cyanobacteria as a parameter of environmental quality in brackish environments classified as Class 1.

Cumulative effects from multiple anthropogenic stressors over the past three centuries have severely impacted estuarine and coastal habitats, with cascading effects on the species that rely upon them. Pacific salmon (Oncorhynchus sp.) are migratory species that use estuaries as juveniles and as adults and deliver critical nutrients to coastal ecosystems as they move between fresh and marine waters. Many once abundant salmon populations have been extirpated or are in severe decline relative to historic levels, yet the strength of the relationship between habitat loss and population productivity has been challenged. In this dissertation, I applied field studies, otolith analyses, and conservation decision science tools to investigate the relative importance of estuarine habitat to salmon populations, with the aim of advancing effective management solutions for these species and their habitats. First, I conducted a two-year field survey of fish communities in the Fraser River estuary, British Columbia, Canada comparing the species richness and relative catch amongst three distinct habitats. I found that this impacted estuary still supported a rich community of migratory marine and anadromous fishes, as well as resident estuarine fish species. Each habitat supported some unique fish assemblages, with eelgrass supporting the highest catch and diversity of fishes overall but brackish marsh supporting the highest and most consistent catch of salmonids. Next, I used otolith analyses to quantify the residency and growth of juvenile Chinook salmon in the estuary. I found that for one of the only two remaining Chinook salmon stocks abundant enough to still support limited harvest in the Fraser River, the estuary provides vital rearing habitat, with juveniles residing in the estuary for an average of 6 weeks, during which time they had mean daily growth rates of 0.57 mm fork length, approximating growth in healthier estuarine systems. The use of these habitats by juvenile Chinook salmon had not been quantified previously, so these findings directly inform management of this population, which was recently designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada. Finally, I applied Priority Threat Management, a conservation decision science framework, to predict the future status of Pacific salmon in the lower Fraser River and identify the most cost-effective conservation solutions out of a suite of alternative management strategies. On our current trajectory none of these populations were predicted to be assessed as ‘green’ or healthy status at the end of 25 years. In contrast, implementation of broad scale habitat restoration, protection, and watershed management could considerably improve the viability of the lower Fraser to support these salmon, such that many (14/19) of these populations would have a >50% likelihood of being assessed as healthy. Together, this research provides novel evidence of active and selective use of estuarine habitats by juvenile salmon, reliance on estuarine habitat for early marine growth by juvenile Chinook salmon, and a direct link between habitat health and population status for lower Fraser River salmon populations. / Graduate / 2023-04-13

Dynestadsjön in Gamleby, Västervik municipality, has a history of collapses due to lack ofoxygen and high levels of salt, nitrogen and phosphorus. The high levels of nutrients havegiven rise to deteriorating living conditions for aquatic organisms. At the times when a collapsehas occurred, the upper water layer has become oxygen-free, which has led to a large part oflife in the water being lost. During the collapses, a powerful stench of sulfur was spread. Theaccumulated amounts of nutrients in the lake are assumed to have arisen due to the inflow ofbrackish water that occurs at regular intervals from Gamlebyviken. In recent years, numerousmeasures have been taken to reduce the nutrient load in the lake in order to improve its waterquality. A more innovative, and thus less proven measure, has been to pump water from thebottom layer of Dynestadsjön and use these volumes to irrigate crops. The volumes that arepumped contains significant amounts of the undesirable nutrients and thereby reduce thestress of the lake and its organisms. In order to perform this and other possible measures ona larger scale, it is necessary to be aware of the mass balance of salt and nutrients that existsin the lake. The aim of this study has been to map out the various flows that make up the massbalance and recreate it in the form of a simulation model in the programs MATLAB andSimulink. Also, an evaluation of the effects of the withdrawn volumes through pumping hasbeen performed and a discussion of what affects the inflow and outflow from Dynestadsjön'soutlet has been made.From the results it can be stated that the exchange of water that takes place at the lake's outletstrongly affects the mass balance of salt and nutrients in Dynestadsjön. It can also be statedthat the change in the amount of nutrients in the lake largely follows the same pattern as itsvolume. When inflow of brackish water from Gamlebyviken occurs, the amount of saltincreases and thus also the salinity. The runoff which contains a relatively low salinitycontributes to a diluting factor of salinity. This flow, on the other hand, supplies the lake withundesirable amounts of nitrogen and phosphorus as a result of a catchment area where theland use mainly consists of forestry and agriculture. The volumes extracted from the bottomlayer have contributed with a clearly reduced amount of nutrients relative to the startingamounts. The amounts that have been added to the layer through sedimentation and stratifyingis however unknown. High levels of salt are pumped out with the irrigation water. If theseamounts are enriched in the soil, it may cause problems in future harvests. The constant shiftsin the direction of flow at the outlet of Dynestadsjön are assumed to be due to so-called wateroscillation arising on the coast because of strong winds. The deep, long, narrow Gamlebyvikenwith its open inlet towards the sea is considered to have great potential for this phenomenonto occur. Variations in air pressure are also considered to affect the flow. For the time periodexamined, the variations of the air pressure have been evaluated. These variations correspondto large changes in the water level compared with the lake's location above sea level. / Dynestadsjön i Gamleby, Västerviks kommun, har en historia av kollapser till följd av syrebristsamt höga halter havssalt, kväve och fosfor. De höga halterna näringsämnen har gett upphovtill försämrade levnadsförhållanden för fisk och andra vattenlevande organismer. Då sjönkollapsar stiger syrefritt bottenvatten upp till ytskiktet och orsakar fiskdöd. Vid kollapserna haräven en kraftfull stank av svavel spridit sig intill sjön. De ackumulerade mängderna salter i sjönantas uppkommit på grund av inflöde av bräckt vatten från Gamlebyviken till Dynestadsjön.Flertalet åtgärder har utförts för att minska näringsbelastningen från land till sjön för attförbättra vattenkvaliteten. Dessa åtgärder har främst varit anläggning av fosfordammar,tvåstegsdiken samt våtmarker. En mer nytänkande, och därmed mindre beprövad åtgärd äratt pumpa vatten från sjöns bottenskikt för att sedan använda detta näringsrika vatten tillbevattning av grödor. Tanken är att volymerna som pumpas upp ska återföra näringsämnentill land och skapa en återcirkulation av det näringsrika vattnet. För att kunna utföra detta samtandra eventuella åtgärder i större skala krävs det förståelse om den massbalans avnäringsämnen som råder i sjön. Syftet med arbetet har varit att utföra mätningar för attkartlägga de olika flödena som utgör massbalansen och återskapa denna i form av en modelli programmen MATLAB och Simulink. En utvärdering kring effekten av de uttagna volymernagenom pumpning har utförts samt en diskussion kring vad som påverkar in- och utflödet urDynestadsjöns utlopp har genomförts.Resultatet visar att det utbyte av vatten som sker vid sjöns utlopp kraftigt påverkarmassbalansen av salt, kväve och fosfor i Dynestadsjön. Vid inflöden av bräckt vatten frånGamlebyviken till Dynestadsjön ökar mängden salt. Tillrinningen från land och andravattendrag har en relativt låg salthalt och bidrar med en utspädande faktor. Flödet förserdäremot sjön med oönskade mängder kväve och fosfor som ett resultat av ettavrinningsområde där markanvändningen till största del består av skogs- och jordbruk.Simuleringarna visar att de uttagna volymerna från bottenskiktet har bidragit till att minskamängden näringsämnen med 25 % relativt de ursprungliga mängderna. Hur stora mängdersom tillkommit skiktet genom sedimentation och skiktning är dock oklart. Höga halter av salthar pumpats upp med bevattningsvattnet. Om mängderna anrikas i marken kan det påverkamarkbördigheten och orsaka problem vid framtida skördar. De ständiga skiftningarna avflödets riktning vid Dynestadsjöns utlopp antas delvis bero av vattenpendling uppkommen vidkusten som ett resultat av kraftiga vindar. Den djupa, långsmala Gamlebyviken anses ha godpotential för att detta fenomen ska kunna inträffa. Även variationer i lufttrycket anses påverkaflödet. För den undersökta tidsperioden har variationerna av lufttrycket utvärderats. Dessavariationer motsvarar förändringar av vattenståndet av samma storleksordning som sjönsbelägna nivå över havet.

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From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / A direct osmosis plant can reclaim twenty to thirty thousand acre feet of Wellton-Mohawk brackish drainage water using no more nitrogen fertilizer than is normally used in the Yuma, Coachella valley, Imperial Valley and the bordering Mexican areas. On a per-acre basis ammonium sulfate-driven direct osmosis can reclaim about one percent of the total irrigation requirement from 3000 ppm brackish water. In addition to the ammonium sulfate-driven direct osmosis efficiency, the by-product energy recovery of the manufacture of the fertilizer and the low technology inherent in direct osmosis processes make direct osmosis an appealing water reclaiming process.