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For the coastal aquifers, recent research have shown that the tidal has a significant effect on saltwater intrusion in the near-shore aquifer. However, it is currently unclear how the tidal river contributes to the groundwater flow and salinity distribution in the upstream aquifer of the estuary. This study examined the effects of a tidal river on the dynamic characteristics of groundwater flow and salt transport in a tidal river-coastal aquifer system using field monitoring data and numerical simulations. It was found that changes in tidal-river level led to the reversal of groundwater flow. For a tidal cycle, the maximum area of seawater intrusion is about 41.16 km2 at the end of the high tide stage. Then the area gradually decreased to 39.02 km2 at the end of the low tide stage. More than 2 km2 area variation can be observed in a tidal cycle. Compared to the low tide stage, the area of SWI increased by 5 % at high tide stage. The SWI region was also spreading landward from the tidal river. In addition, we quantified the water exchange and salt flux between the tidal river and aquifer. When the tidal fell below the level of the riverbed, the water exchange rate was stabilized at about −1.6 m/h. The negative value indicated that the river was recharged by the groundwater. With the increasing of tidal water level, the water exchange rate gradually changes from negative to positive and reached the maximum value of 3.2 m/h at the beginning of the falling tide stage. The presence of a physical river dam can amplify the difference in water level between high and low tides, thereby enhancing the influence of a tidal river on water exchange and salt flux. The findings lay the foundation for gaining a comprehensive understanding of the tidal river on groundwater flow and salt transport in upstream aquifers.

Peri-urban interfaces tend to ensure water supply relying on their surrounding’ resources, generating water disputes when asking for collaboration. The urban-rural matrix of the Marina Baja county in southern Spain is characterized by inland irrigation and coastal tourism development, being the most water-intensive activities in Benidorm. This contribution addresses the following research question: Can a better and systematic understanding of stakeholders’ behavior and interactions increase water resilience in urban-rural interfaces? Data were collected from semi-structured interviews and questionnaires to 19 key stakeholders representing government officials, water managers, and the agricultural, tourism, and environmental sectors. Data were analyzed following the SAA and using MaxQDA® Analytics Pro 2020. A triple-loop analysis on water governance has been developed and applied to synthesize stakeholders’ behavior when addressing urban water resilience to face climate change impacts: relevance and representativeness (to be), recognition and assessment (to do), and collaboration (to share). Results highlighted how Benidorm’s urban water resilience is conditioned by four main learnings from stakeholders’ perception and interaction: (1) ‘feeling represented’ is related to stakeholders’ capacity to negotiate decisions, (2) lack of political will and Benidorm’s leading role increase stakeholders’ feelings of underrepresentation, motivating power imbalance, (3) stakeholders’ actions are less valued than stakeholders’ roles and functions, and (4) agreements are benefited by predisposition (willingness), but also by the compatibility of discourses (affinity) and the technical-management facilities (viability).

We have investigated the mechanism of relaxivity for two magnetic resonance imaging contrast agents that both employ a cluster-nanocarrier design. The first system termed Mn8Fe4-coPS comprises the cluster Mn8Fe4O12(L)16(H2O)4 or Mn8Fe4(1) (L = carboxylate) co-polymerized with polystyrene to form ∼75 nm nanobeads. The second system termed Mn3Bpy-PAm used the cluster Mn3(O2CCH3)6(Bpy)2 or Mn3Bpy (2) where Bpy = 2,2′-bipyridine, entrapped in ∼180 nm polyacrylamide nanobeads. Here, we investigate the rate of water exchange of the two clusters, and corresponding cluster-nanocarriers, in order to elucidate the mechanism of relaxivity in the cluster-nanocarrier. Swift-Connick analysis of O-17 NMR was used to determine the water exchange rates of the clusters and cluster-nanocarriers. We found distinct differences in the water exchange rate between Mn8Fe4and Mn8Fe4-coPS, and we utilized these differences to elucidate the nanobead structure. Using the transverse relaxivity from O-17 NMR line widths, we were able to determine the hydration state of the Mn3Bpy (2) cluster as well as Mn3Bpy-PAm. Using these hydration states in the Swift-Connick analysis of O-17 NMR, we found the water exchange rate to be extremely close in value for the cluster Mn3Bpy and cluster-nanocarrier Mn3Bpy-PAm.

Water exchange around a free magnesium ion and magnesium paired with carbonate in aqueous solution was studied using free energy methods. Both a rigid-ion and a polarizable force field based on the AMOEBA model were examined. The parameters were adjusted to accurately reproduce the hydration structures of magnesium and carbonate in aqueous solution. The magnesium carbonate ion pairing free energies calculated with both force fields were found to be in excellent agreement with experimental data. Metadynamics simulations of the water exchange conducted with both models revealed that the formation of a contact magnesium carbonate ion pair significantly decreases the energy barrier for water exchange relative to the free magnesium ion in solution. This finding suggests that the presence of carbonate could accelerate the water exchange around magnesium and constitutes a first step toward a better understanding of the atomic-scale mechanisms involved in the nucleation of magnesium-bearing carbonate minerals.

Peri-urban interfaces tend to ensure water supply relying on their surrounding’ resources, generating water disputes when asking for collaboration. The urban-rural matrix of the Marina Baja county in southern Spain is characterized by inland irrigation and coastal tourism development, being the most water-intensive activities in Benidorm. This contribution addresses the following research question: Can a better and systematic understanding of stakeholders’ behavior and interactions increase water resilience in urban-rural interfaces? Data were collected from semi-structured interviews and questionnaires to 19 key stakeholders representing government officials, water managers, and the agricultural, tourism, and environmental sectors. Data were analyzed following the SAA and using MaxQDA® Analytics Pro 2020. A triple-loop analysis on water governance has been developed and applied to synthesize stakeholders’ behavior when addressing urban water resilience to face climate change impacts: relevance and representativeness (to be), recognition and assessment (to do), and collaboration (to share). Results highlighted how Benidorm’s urban water resilience is conditioned by four main learnings from stakeholders’ perception and interaction: (1) ‘feeling represented’ is related to stakeholders’ capacity to negotiate decisions, (2) lack of political will and Benidorm’s leading role increase stakeholders’ feelings of underrepresentation, motivating power imbalance, (3) stakeholders’ actions are less valued than stakeholders’ roles and functions, and (4) agreements are benefited by predisposition (willingness), but also by the compatibility of discourses (affinity) and the technical-management facilities (viability).

The blood-brain barrier (BBB) is the interface between the blood and brain tissue, which regulates the maintenance of homeostasis within the brain. Impaired BBB integrity is increasingly associated with various neurological diseases. To gain a better understanding of the underlying processes involved in BBB breakdown, magnetic resonance imaging (MRI) techniques are highly suitable for noninvasive BBB assessment. Commonly used MRI techniques to assess BBB integrity are dynamic contrast-enhanced and dynamic susceptibility contrast MRI, both relying on leakage of gadolinium-based contrast agents. A number of conceptually different methods exist that target other aspects of the BBB. These alternative techniques make use of endogenous markers, such as water and glucose, as contrast media. A comprehensive overview of currently available MRI techniques to assess the BBB condition is provided from a scientific point of view, including potential applications in disease. Improvements that are required to make these techniques clinically more easily applicable will also be discussed.

In previous decades, some species of the Orchidaceae family have been found growing in man-made habitats. Neottia ovata is one of the most widespread orchids in Europe, however it is quite rare in Russia and is included in several regional Red Data Books. The purpose of this study was to compare the chemical composition and morphophysiological parameters of N. ovata from two forest communities of the Middle Urals, Russia: natural and transformed (fly ash dump of Verkhnetagil’skaya Thermal Power Station) for determining orchid adaptive features. The content of most of the studied metals in the underground parts (rhizome + roots) of N. ovata was considerably higher than in the leaves, which diminished the harmful effect of toxic metals on the aboveground organs. The adaptive changes in the leaf mesostructure of N. ovata such as an increase in epidermis thickness, the number of chloroplasts in the cell, and the internal assimilating surface were found for the first time. The orchids from the fly ash deposits were characterized by a higher content of chlorophyll b and carotenoids than plants from the natural forest community that evidenced the compensatory response on the decrease in chlorophyll a. The ability of N. ovata from the transformed habitat to maintain a relatively favorable water balance and stable assimilation indexes further contribute to its high viability. The study of orchid adaptive responses to unfavorable factors is necessary for their successful naturalization and introduction into a new environment. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

The blood-brain barrier (BBB) is the interface between the blood and brain tissue, which regulates the maintenance of homeostasis within the brain. Impaired BBB integrity is increasingly associated with various neurological diseases. To gain a better understanding of the underlying processes involved in BBB breakdown, magnetic resonance imaging (MRI) techniques are highly suitable for noninvasive BBB assessment. Commonly used MRI techniques to assess BBB integrity are dynamic contrast-enhanced and dynamic susceptibility contrast MRI, both relying on leakage of gadolinium-based contrast agents. A number of conceptually different methods exist that target other aspects of the BBB. These alternative techniques make use of endogenous markers, such as water and glucose, as contrast media. A comprehensive overview of currently available MRI techniques to assess the BBB condition is provided from a scientific point of view, including potential applications in disease. Improvements that are required to make these techniques clinically more easily applicable will also be discussed.

Fish farmers utilize the reversibility of the bioconcentration process to depurate geosmin and other off- flavour causing chemicals from their fish by placing them in clean water just before harvest. To better understand and improve this process, we investigated effects of temperature and water exchange of depuration tanks on geosmin elimination from Atlantic salmon (Salmo salar). Fish loaded with geosmin were depurated for 144 h during which they were subjected to combinations of water exchange (stagnant water or a water exchange rate of ~1200 L/kg fish/d) and temperature (~11.5 or ~14.5 °C) treatments. Model predictions indicated enhanced depuration by water exchange, elevated temperature and interactive effects of these two factors, plus geosmin accumulation in the depuration tank water. The latter was predicted but not observed in the experiment. Furthermore the elevated temperature did not enhance geosmin elimination from Atlantic salmon, possibly because in the tanks with water exchange, temperature treatments did not cause differences in oxygen levels and thus gill ventilation rates. The water exchange significantly increased geosmin elimination from Atlantic salmon, indicating that removal of excreted geosmin from the direct environment of this fish is needed to obtain maximal geosmin elimination from the fish.

Fissures and conduits are main void of karstic aquifer. Karst aquifers are highly vulnerable to contamination as water exchange between fissure system and conduit system greatly influences the karstification of limestone terrains, heterogeneity of karstic aquifer, and spring flow regime. A two-dimensional tank model was constructed, and a corresponding numerical model (MODFLOW-2005 Conduit Flow Process Mode 1, CFPM1) was developed to explore the effects of rainfall intensity and intrinsic structure of karst system (hydraulic conductivity of fissures and conduit diameter) on conduit-matrix water exchange. Nine different scenarios were designed to quantitatively simulate the spatial and temporal variability of water exchange between the fissures and conduits. The study reproduced the area of fissure water recharging to conduit (recharge zone), the area of conduit water discharging to fissure water (discharge zone) and the area of fissure water moving laterally (transport zone) in both physical model and numerical model. The results from rainfall scenarios show a relatively stable ratio of exchange zone (recharge zone and discharge zone) with increasing rainfall intensity, indicating that conduit-matrix water exchange is not sensitive to rainfall intensity, and conduit water discharging to fissure water is just a short-term phenomenon. It is also found that an increase in hydraulic conductivity of fissure system enhances extensiveness of water transport, but restrains conduit-matrix water exchange. However, the enlargement of conduit can prompt the extent of conduit-matrix water exchange. A positive feedback between the extent of conduit-matrix water exchanges and karstification can be confirmed. These findings might be essential for better understanding groundwater flow dynamics in karst aquifers.

Cua Lo river mouth is a coastal inlet connected to an estuary at the central coast of Vietnam. The area is valuable for maritime trade, fishing industries, and tourism development. Natural disasters during the monsoon period are a problem, causing seasonal flooding. In connection to the inlet lies an elongating sand spit which causes erosion and destruction of residential areas on one side of the inlet. The objective was therefore to investigate the dynamics of the sand spit and the inlet, and to describe their long-term morphological development using a fast and simple, yet accurate model. Modelling was done using a process-based numerical approach, where both inlet migration and changes in inlet width were considered. The model base compared the longshore and inlet sediment transport, and exhibited satisfactory performance. A seasonal pattern related to the dry- and monsoon season was observed for the longshore sediment transport. Longshore transport was much larger compared to the inlet transport during the monsoon period. The sediment transport in the inlet had a clear connection to tidal variation. Two scenarios were considered for predicting inlet migration and width evolution. Migration and width evolution were modelled separately due to model limitations, over the period 2020-2049. Scenario 2 allowed for 2000 m migration, with the endpoint being a hard rock boundary. The boundary was not reached during the modelled period as the migration was only 1350 m. Scenario 1 allowed for 980 m of migration before the inlet reached the boundary limited either by longshore sediment transport changes, or a rock boundary. By 2041 the inlet was estimated to reach the boundary if the LST remained unchanged. A very narrow (4-20 m) equilibrium state took place rapidly after the width model was initiated, pointing towards seasonal or permanent closure. A sensitivity analysis on the LST and its effect on the morphological evolution suggested that the inlet could stop migrating, Populärvetenskaplig sammanfattning Långsiktig morfologisk utveckling av Cua Lo mynning i centrala Vietnam - En processbaserad numerisk modellering Nikita Tegenfeldt Orio Johansson En matematisk modell utvecklades för att beskriva hur en flodmynning i centrala Vietnam kommer att flytta sig längs med kusten och hur bredden förändras från nu fram till 2050. Mynningen kopplar ihop havet med en lagun och lokalbefolkningen påverkas negativt av förflyttningen. Platser där hav och floder möts är en av de mest attraktiva platserna för människor att bo och leva vid. Floder bidrar bland annat med vatten för odlingar och hushåll, och transport till inlandet; havet ger möjligheter till långväga handel och fiske. I takt med att samhällen växer kring dessa områden ges ibland mindre utrymme för naturliga processer. Det kan till exempel vara att kustens strandlinje förändras eller att floder och dess mynningar flyttar på sig. En förändrande omgivning kombinerat med relativt fasta bosättningar är längs många kuster ett problem eftersom det är svårt att stoppa förändringarna. Utan åtgärder kan det leda till att bosättningar och byggnader går under i vattnets väg. Sådana problem finns längs kusten i centrala Vietnam, och det är en av dessa platser som har varit huvudämne i detta projekt. Mynningen i fokus, Cua Lo, ligger i ett område med mycket infrastrukturutveckling och ökande turism. En lagun med två öppningar binder samman områdets floder med havet. Cua Lo mynningen har flyttat sig ca 1,7 km sen 1988 och har förstört ett antal hus och fiskodlingar i sin väg. Förflyttningen verkar inte stanna av och kan eventuellt flytta sig 2 km till innan den når solitt berg och då stannar. Det finns även tecken på att öppningen kanske kommer att stängas vilket kan få konsekvenser för vattenkvalitén i lagunen, och därmed även lokalbefolkningen. Hur långt mynningen kommer flytta sig, när den stannar och vad som kommer hända med bredden av öppningen var frågor som detta projekt hade som mål att besv

The Flommen Lagoon system is located in Skanör-Falsterbo, Sweden. It hosts a diverse and sensitive ecosystem. There have been concerns about the water quality in this lagoon due to impaired water exchange. The objectives of this thesis is to determine the current state of the water exchange in the lagoon and investigate possible measures to improve it. These possible measures revolve around the construction of a new inlet, and the potential closing of the inlet Slusan. Flow velocities, especially those in the inlet Slusan, will also be briefly elaborated upon in an effort to gain a better understanding of the sedimentation issues. At present, the sedimentation at the inlet is alleviated by regular dredging. To accomplish these objectives, a hydrodynamic model of the Flommen Lagoon system was created. The modelling software IPH-ECO was used to create the model. This model was used to calculate the flushing time in the lagoon as a measure of the water exchange. Spatially distributed residence time was also calculated and used as a measure to investigate the water quality in different parts of the lagoon. Simulation results indicate a flushing time of 33 days in the current state of the lagoon with Slusan open. Should a new inlet be built to compliment Slusan, then a flushing time of 22 days is expected. But this likely comes at a cost of increased sedimentation issues due to lower flow velocities at Slusan. If instead this new inlet is built and Slusan closed, then a flushing time beyond 60 days can be anticipated. This measure would reduce the costs associated with dredging, but cause a decline in the water quality in the lagoon., Coastal lagoons can be found in the transitional zone between sea and land, constituting water bodies that are connected to the sea by one or several inlets. These inlets allow for water exchange between the lagoon and the sea. The ecosystems found in lagoons are often unique and delicate, functioning as a habitat for many animal species. The health and vitality of these ecosystems very much depend on the water quality of the lagoon. There have been concerns about the water quality in the Flommen Lagoon system due to insufficient water exchange between the lagoon and sea. The current sole existing inlet, Slusan, is crucial for the water quality in the lagoon. Should it be blocked by sediment, then water exchange between the sea and the lagoon will cease, adversely impacting the water quality. The objectives of this thesis was to determine the current water exchange in the Flommen Lagoon system and to investigate different measures that could enhance water exchange with the sea and thus improve water quality in the lagoon. Several conclusions regarding the water quality in the lagoon were accomplished by a mix of computer software and field measurements. These were used to create a working computer model of the lagoon and its behaviour. A combination of calculations and field measurements were then used to verify the reliability of the model. One of the key findings is that the construction of a new inlet to supplement Slusan would aid in improving the water quality of the lagoon. However, this solution would come with one drawback. Increased maintenance costs can be expected to keep both inlets open. Another possible solution investigated would be to close Slusan and rely solely on the new inlet to provide water exchange for the lagoon. The results seem to indicate that this leads to a significant reduction of lagoon water quality over time. Vast differences between water quality in different parts of the lagoon can be seen. Water quality seems to be correlated with

В статье рассмотрены вопросы влияния климатических и антропогенных факторов на гидрогеолого-гидрологический режим и водообмен между поверхностными и подземными водами Припятского Полесья. Проведена оценка влияния климатических и антропогенных факторов на экологическое состояние исследуемой территории, включая влияние на гидродинамику грунтовых и подземных вод при разработке Хотиславского карьера строительных материалов. Подробно проанализированы те климатические особенности и антропогенные факторы, влияние которых наиболее вероятно и существенно, что вытекает из анализа состояния природной среды в заданный промежуток времени. При этом, влияние антропогенного фактора может быть оценено величинами отклонений основных показателей от их фоновых, первоначально отражающих природные условия их формирования. Проанализированы гидрогеологические условия и гидрологический режим исследуемого региона. Приводится детальный анализ основных метеорологических факторов и их влияние на экологическое состояние исследуемой территории, расчет испарения разными методами. Приведены основные характеристики природно-климатических условий. Выделены основные техногенные факторы, которые влияют на экологическое состояние исследуемого региона. Одним из самых мощных на сегодняшний день является Хотиславский карьер строительных материалов, расположенный на территории Республики Беларусь на расстоянии 300 м от границы с Украиной, что создает серьезную потенциальную экологическую угрозу пограничной геоекосистемы полесской зоны. Приведены условия формирования озер Припятского Полесья, проанализированы их уровневый режим, источники питания, водный баланс и водообмен. Особое внимание уделено динамике уровня воды озера Свитязь за период 1985–2016 гг. Установлено фактическое влияние на формирование водообмена грунтовых и подземных вод Припятского Полесья как климатических, так и техногенных факторов., The article deals with the issues of influence of climatic and anthropogenic factors on the hydrogeological-hydrological regime and water exchange between surface and underground waters of the reclaimed lands of the Pripyat Polissya. The estimation of the influence of climatic and anthropogenic factors on the ecological condition of the studied territory, including the possible influence on the hydrodynamics of ground and underground waters during the development of the Khotilslavsky building materials career, has been carried out. Detailed analysis of those climatic features and anthropogenic factors, the impact of which is most likely and significant, arising from the analysis of the state of the environment in a given time interval. At the same time, the influence of anthropogenic factor can be estimated by the magnitude of the deviations of the main indicators from their backgrounds, initially reflecting the natural conditions of their formation. Hydrogeological conditions and hydrological regime of the studied region are analyzed. A detailed analysis of the main meteorological factors and their impact on the ecological state of the studied territories, calculation of evaporation by different methods is given. The main characteristics of natural and climatic conditions are given. The main man-made factors that influence the ecological state of the studied region are identified. One of the most powerful at present is the Khotilslav mining building quarry, located on the territory of the Republic of Belarus at a distance of 300 m from the border with Ukraine, which creates a serious potential environmental threat to the border geoecosystem of the Polissya zone. The conditions of formation of lakes of Pripyat Polissya are described, their level regime, power sources, water balance and water exchange are analyzed. Particular attention is paid to the dynamics of the water level of the lake Svityaz for the period 1985–2016. The actual influence on formation of water e, У статті розглянуто питання впливу кліматичних та антропогенних чинників на гідрогеолого-гідрологічний режим та водообмін між поверхневими і підземними водами меліорованих земель Волинського Полісся. Проведено оцінювання впливу кліматичних та антропогенних чинників на екологічний стан досліджуваної території, включаючи можливий вплив на гідродинаміку ґрунтових та підземних вод при розробці Хотиславського кар’єру будівельних матеріалів. Детально проаналізовані ті кліматичні особливості і антропогенні чинники, вплив яких найбільш ймовірний і істотний, що випливає із аналізу стану природного середовища у заданий проміжок часу. При цьому, вплив антропогенного чинника може бути оцінений величинами відхилень основних показників від їх фонових, первісно відображаючих природні умови їх формування. Проаналізовані гідрогеологічні умови та гідрологічний режим досліджуваного регіону. Наводиться детальний аналіз основних метеорологічних чинників та їх вплив на екологічний стан досліджуваної територій, розрахунок випаровування за різними методами. Наведені основні характеристики природно-кліматичних умов. Виокремлені основні техногенні чинники, які впливають на екологічний стан досліджуваного регіону. Одним із найпотужніших наразі є Хотиславський кар’єр будівельних матеріалів, розташований на території Республіки Білорусь на відстані 300 м від кордону з Україною, що створює серйозну потенційну екологічну загрозу прикордонній геоекосистемі поліської зони. Наведено умови формування озер Західного Полісся, проаналізовано їх рівневий режим, джерела живлення, водний баланс та водообмін. Особливу увагу приділено динаміці рівня води озера Світязь за період 1985–2016 рр. Встановлено фактичний вплив на формування водообміну меліорованих земель Волинського Полісся як кліматичних, так і техногенних чинників.

Water-related hazards such as water scarcity may be mitigated by considering interbasin and intersectoral transfers of freshwater, and by promoting the use of non-conventional water resources. This paper deepens on key driving factors able to define the benefits and barriers of a water exchange among agricultural and urban-tourism activities as a mechanism to reduce water scarcity risk in the Marina Baja county, in Alicante (Spain). Thematic analysis through semi-structured interviews with the Marina Baja Water Consortium and the Canal Bajo del Algar irrigators’ community has been conducted based on their role in promoting integrated management of water resources. Results highlighted how water management, water quality, and water charging are the three main issues to be considered when promoting water exchange between agricultural and urban-tourist activities. Learnings could be used to customize interventions at a regional scale when promoting water exchange between confronted water uses in water scarcity regions.

BackgroundA low adenoma detection rate (ADR) increases risks of interval cancers (ICs). Proximal colon flat polyps, e.g. serrated lesions (SLs), are difficult to find. Missed proximal colon flat lesions likely contribute to IC.AimsWe compared chromoendoscopy with water exchange (CWE), water exchange (WE) and air insufflation (AI) in detecting adenomas in screening colonoscopy.MethodsAfter split-dose preparation, 480 veterans were randomized to AI, WE and CWE.ResultsPrimary outcome of proximal ADR (55.6% vs 53.4% vs 52.2%, respectively) were similar in all groups. Adenoma per colonoscopy (APC) and adenoma per positive colonoscopy (APPC) were comparable. Detection rate of proximal colon SLs was significantly higher for CWE and WE than AI (26.3%, 23.6% and 11.3%, respectively, p = 0.002). Limitations: single operator; SLs only surrogate markers of but not IC.ConclusionsWhen an endoscopist achieves high-quality AI examinations with overall ADR twice (61.6%) the recommended standard (30%), use of WE and CWE does not produce further improvement in proximal or overall ADR. Comparable APC and APPC confirm equivalent withdrawal inspection techniques. WE alone is sufficient to significantly improve detection of proximal SLs. The impact of increased detection of proximal SLs by WE on prevention of IC deserves to be studied. This study is registered at ClinicalTrial.gov (NCT#01607255).

The Flommen Lagoon in southern Sweden is surrounded by several natural reserves and is an important bird migration site on the edge of the continent. The protection of this area including water quality in the lagoon and flooding problems in the adjacent area has always been a concern. The objective of this study is to simulate the water level in the Flommen Lagoon and the water exchange between the Flommen Lagoon and the sea with regards to inlet properties, longshore sediment transport and the operation of the sluice gate on the lagoon inlet to minimize the impact of human activities and reach a suitable operation strategy of the sluice gate. An investigation was also performed about the impact of constructing a second inlet between the lagoon and the sea. According to the simulation results, the longshore sediment transport rate is larger in the south of the inlet than in the north which will result in sand accumulation around the inlet. The inlet geometry showed no significant influence on the lagoon water level but affected the water exchange rate. For the simulated time period, halve the cross-section area decreases the gross exchange rate by 39.2% and double cross-section area increases the gross exchange rate by 15.3%. The sluice decreases gross water exchange rate by 31.6%, but it plays an important role in protecting the golf courses around the lagoon from flooding. With two inlets, gross water exchange rate is 15.3% higher than with one inlet, and water level is also slighter higher.

Water-related hazards such as water scarcity may be mitigated by considering interbasin and intersectoral transfers of freshwater, and by promoting the use of non-conventional water resources. This paper deepens on key driving factors able to define the benefits and barriers of a water exchange among agricultural and urban-tourism activities as a mechanism to reduce water scarcity risk in the Marina Baja county, in Alicante (Spain). Thematic analysis through semi-structured interviews with the Marina Baja Water Consortium and the Canal Bajo del Algar irrigators’ community has been conducted based on their role in promoting integrated management of water resources. Results highlighted how water management, water quality, and water charging are the three main issues to be considered when promoting water exchange between agricultural and urban-tourist activities. Learnings could be used to customize interventions at a regional scale when promoting water exchange between confronted water uses in water scarcity regions.

In this study, the flotation characteristics of a cassiterite-bearing fine-grained and complex skarn ore from a deposit in the Ore Mountains is investigated. The tests are performed using an oil-assisted column flotation approach to process very fine ore fractions and avoid losses of cassiterite into the tailings. First, process parameters are obtained for a finely ground artificial mixture of quartz, magnetite and cassiterite, simulating the real ore. Thereby, magnetite is used, as iron oxides can have a detrimental effect on the flotation due to a similar flotation behavior. In addition, they can act as a source of multivalent ions, which are known to reduce the concentration of collector molecules, active for flotation. Based on the results, selected parameters are further tested for cassiterite skarn ore from the Hämmerlein deposit including a pre-conditioning and a water exchange step to remove ionic contaminants. The process response is analyzed in detail by XRF (X-ray fluorescence) and MLA (mineral liberation analysis) to get a better understanding of the behavior of the single ore components. Sulfosuccinamate type surfactant is utilized as the collector, emulsifier and to reduce the froth destabilization through nonpolar oil. Sodium hexafluorosilicate is added as the depressant.

In this study, the flotation characteristics of a cassiterite-bearing fine-grained and complex skarn ore from a deposit in the Ore Mountains is investigated. The tests are performed using an oil-assisted column flotation approach to process very fine ore fractions and avoid losses of cassiterite into the tailings. First, process parameters are obtained for a finely ground artificial mixture of quartz, magnetite and cassiterite, simulating the real ore. Thereby, magnetite is used, as iron oxides can have a detrimental effect on the flotation due to a similar flotation behavior. In addition, they can act as a source of multivalent ions, which are known to reduce the concentration of collector molecules, active for flotation. Based on the results, selected parameters are further tested for cassiterite skarn ore from the Hämmerlein deposit including a pre-conditioning and a water exchange step to remove ionic contaminants. The process response is analyzed in detail by XRF (X-ray fluorescence) and MLA (mineral liberation analysis) to get a better understanding of the behavior of the single ore components. Sulfosuccinamate type surfactant is utilized as the collector, emulsifier and to reduce the froth destabilization through nonpolar oil. Sodium hexafluorosilicate is added as the depressant.

Surface PEGylation of nanoparticles designed for biomedical applications is a common and straightforward way to stabilize the materials for in vivo administration and to increase their circulation time. This strategy becomes less trivial when MRI active porous nanomaterials are concerned as their function relies on water/proton-exchange between the pores and bulk water. Here we present a comprehensive study on the effects of PEGylation on the relaxometric properties of nanozeolite LTL (dimensions of 20 × 40 nm) ion-exchanged with paramagnetic GdIII ions. We evidence that as long as the surface grafting density of the PEG chains does not exceed the “mushroom” regime (conjugation of up to 6.2 wt % of PEG), Gd-LTL retains a remarkable longitudinal relaxivity (38 s–1 mM–1 at 7 T and 25 °C) as well as the pH-dependence of the longitudinal and transverse relaxation times. At higher PEG content, the more compact PEG layer (brush regime) limits proton/water diffusion and exchange between the interior of LTL and the bulk, with detrimental consequences on relaxivity. Furthermore, PEGylation of Gd-LTL dramatically decreases the leakage of toxic GdIII ions in biological media and in the presence of competing anions, which together with minimal cytotoxicity renders these materials promising probes for MRI applications., BT/Biocatalysis

The flotation characteristics of a cassiterite bearing fine grained and complex skarn ore from the Ore Mountain region is investigated. A sulfosuccinamate type collector is used and sodium hexafluorosilicate is added as depressant. The objective of the experiments is a better understanding of the cassiterite flotation performance as influenced by different pre-processing operations as magnetic separation, gravity separation, sulphide flotation and desliming. Therefore, structure and composition of the feed, the different concentrates and the tailings of each process are analysed in detail by XRF and MLA to get a better understanding of the behaviour of the single ore components in the different processing steps. Problematic minerals (e.g. chlorites) have a negative effect on the selectivity of cassiterite flotation. Therefore, particular attention is payed to the behaviour of these minerals during flotation. Furthermore, the effect of the particle size due to the change in liberation on the flotation process is investigated. Three critical factors are found to greatly influence the flotation performance, namely: (1) particle size; (2) Fe oxides content; and (3) ions in the solution.

The flotation characteristics of a cassiterite bearing fine grained and complex skarn ore from the Ore Mountain region is investigated. A sulfosuccinamate type collector is used and sodium hexafluorosilicate is added as depressant. The objective of the experiments is a better understanding of the cassiterite flotation performance as influenced by different pre-processing operations as magnetic separation, gravity separation, sulphide flotation and desliming. Therefore, structure and composition of the feed, the different concentrates and the tailings of each process are analysed in detail by XRF and MLA to get a better understanding of the behaviour of the single ore components in the different processing steps. Problematic minerals (e.g. chlorites) have a negative effect on the selectivity of cassiterite flotation. Therefore, particular attention is payed to the behaviour of these minerals during flotation. Furthermore, the effect of the particle size due to the change in liberation on the flotation process is investigated. Three critical factors are found to greatly influence the flotation performance, namely: (1) particle size; (2) Fe oxides content; and (3) ions in the solution.

Surface PEGylation of nanoparticles designed for biomedical applications is a common and straightforward way to stabilize the materials for in vivo administration and to increase their circulation time. This strategy becomes less trivial when MRI active porous nanomaterials are concerned as their function relies on water/proton-exchange between the pores and bulk water. Here we present a comprehensive study on the effects of PEGylation on the relaxometric properties of nanozeolite LTL (dimensions of 20 × 40 nm) ion-exchanged with paramagnetic GdIII ions. We evidence that as long as the surface grafting density of the PEG chains does not exceed the “mushroom” regime (conjugation of up to 6.2 wt % of PEG), Gd-LTL retains a remarkable longitudinal relaxivity (38 s–1 mM–1 at 7 T and 25 °C) as well as the pH-dependence of the longitudinal and transverse relaxation times. At higher PEG content, the more compact PEG layer (brush regime) limits proton/water diffusion and exchange between the interior of LTL and the bulk, with detrimental consequences on relaxivity. Furthermore, PEGylation of Gd-LTL dramatically decreases the leakage of toxic GdIII ions in biological media and in the presence of competing anions, which together with minimal cytotoxicity renders these materials promising probes for MRI applications., BT/Biocatalysis

Surface PEGylation of nanoparticles designed for biomedical applications is a common and straightforward way to stabilize the materials for in vivo administration and to increase their circulation time. This strategy becomes less trivial when MRI active porous nanomaterials are concerned as their function relies on water/proton-exchange between the pores and bulk water. Here we present a comprehensive study on the effects of PEGylation on the relaxometric properties of nanozeolite LTL (dimensions of 20 × 40 nm) ion-exchanged with paramagnetic GdIII ions. We evidence that as long as the surface grafting density of the PEG chains does not exceed the "mushroom" regime (conjugation of up to 6.2 wt % of PEG), Gd-LTL retains a remarkable longitudinal relaxivity (38 s-1 mM-1 at 7 T and 25 °C) as well as the pH-dependence of the longitudinal and transverse relaxation times. At higher PEG content, the more compact PEG layer (brush regime) limits proton/water diffusion and exchange between the interior of LTL and the bulk, with detrimental consequences on relaxivity. Furthermore, PEGylation of Gd-LTL dramatically decreases the leakage of toxic GdIII ions in biological media and in the presence of competing anions, which together with minimal cytotoxicity renders these materials promising probes for MRI applications.

[Abstract] Two macrocyclic ligands containing a cyclen unit, a methyl group, a picolinate arm, and two acetate pendant arms attached to two nitrogen atoms of the macrocycle either in trans (1,7-H3Medo2 ampa = 2,2′-(7-((6-carboxypyridin-2-yl)methyl)-10-methyl-1,4,7,10-tetraazacyclododecane-1,4-diyl)diacetic acid) or in cis (1,4-H3Medo2 ampa) positions are reported. These ligands provide eight-coordination to the Ln3+ ions, leaving a coordination position available for a water molecule that occupies a capping position in the twisted square antiprismatic polyhedron (1,4-H3Medo2 ampa) or one of the positions of the square antiprism (1,7-H3Medo2 ampa). The charge neutral [Gd(1,7-Medo2 ampa)] complex presents an unprecedentedly low water-exchange rate (kex298=8.8×103 s−1), whereas water exchange in [Gd(1,4-Medo2 ampa)] is three orders of magnitude faster (kex298=6.6×106 s−1). These results showcase the labile capping bond phenomenon: A ligand occupying a capping position is hindered by the environment and thus is intrinsically labile.

There is great interest worldwide to reconnect floodplain wetlands to their rivers. Whilst the surface water connection between rivers and wetlands is fairly well understood, the linkages via groundwater are not well known. In this study, it is hypothesized that the significance of the groundwater pathways between rivers and wetlands is largely determined by the geomorphic setting of the riverine corridor. This was tested by measuring the response of water levels and temperatures in floodplain groundwater and in wetlands to river pulses in two geomorphologically distinct riverine corridors in Southern Québec. In the De la Roche River (DLR; 145 km2), the floodplain is narrow and the alluvial sediments consist of sandy silt (wetland A; abandoned meander) or clayey silt (wetland B; stable floodplain), depending on the location. During within-channel floods, exchanges of water between the river and the floodplain are limited to some bank recharge where the alluvial sediments are permeable, and over-bank storage where the sediments are finer. Water levels in the DLR floodplain wetlands were controlled by a combination of over-bank flow and groundwater discharge from adjacent uplands. In the Matane River (1678 km2), the floodplain substrate is coarser, and the floodplain is wider and has a meandering planform geometry. The response of the Matane River wetland during floods shows storage of water due to a groundwater flood wave. This response of the wetland to within-channel flood pulses could play a role in downstream flood attenuation. In this river, the presence of river infiltration in this floodplain was also illustrated by the warming of floodplain groundwater during flood pulses. This study has shown with three distinct examples how riverine wetlands can be connected to their rivers via either a surface or subsurface pathway depending on the geomorphic setting of the riverine corridor.

Hydrologic interaction between surface and subsurface water systems has a significant impact on water quality, ecosystems and biogeochemistry cycling of both systems. Distributed models have been developed to simulate this function, but they require detailed spatial inputs and extensive computation time. The SWAT model is a semi-distributed model that has been successfully applied around the world. However it has not been able to simulate the two way exchanges between surface water and groundwater. In this study, the SWAT-LU model – based on a catena method that routes flow across three landscape units (the divide, the hillslope and the valley) – was modified and applied in the floodplain of the Garonne River. The modified model was called SWAT-LUD. Darcy's equation was applied to simulate groundwater flow. The algorithm for surface water level simulation during flooding periods was modified and the influence of flooding on groundwater levels was added to the model. Chloride was chosen as a conservative tracer to test simulated water exchanges. The simulated water exchange quantity from SWAT-LUD was compared with the output of a 2D distributed model, 2SWEM. The results showed that simulated groundwater levels in the LU adjoining the river matched the observed data very well. Additionally, SWAT-LUD model was able to reflect the actual water exchange between the river and the aquifer. It showed that river water discharge has a significant influence on the surface-groundwater exchanges. The main water flow direction in the river/groundwater interface was from groundwater to river, water flowed in this direction accounted for 65 % of the total exchanged water volume. The water mixing occurs mainly during high hydraulic periods. Flooded water was important for the SW-GW exchange process, it accounted for 69 % of total water flowed from the river to the aquifer. The new module also provides the option of simulating pollution transfer occurring at the river/groundwater int

Background Lagoons are shallow coastal water bodies which occupy 13 % of the world’s total coastlines. Healthy lagoons have a rich aquatic fauna and can provide an economic benefit for the people living in its vicinity. Due to anthropogenic activities, the water quality in many lagoons is deteriorating. The Mundaú-Manguaba Estuarine-Lagoon System is no exception. BOD-rich water from the nearby sugar plantations along with large amount of untreated sewage from the nearby city of Maceió are contributing to the deteriorating water quality in the lagoon system. A computerized model can be a useful tool in terms of forecasting the effects of different actions taken to improve the water quality. Such a model already exists, called IPH-ECO, but uses data collected in 1984 and consequently needs a thorough overhaul. The morphology of the lagoon system has changed mainly due to sediment infilling; therefore the model needs to be updated regarding bathymetry and sediments. Objectives The purpose of this master thesis is to construct an updated hydrodynamic model over the Mundaú-Manguaba Estuarine-Lagoon System in Brazil. In order to achieve this, bathymetry and sediment information needs to be collected, analyzed and finally digitized. A field camping will be executed where data regarding depth and salinity variation in the lagoons will be collected. Two scenarios will be tested with the newly calibrated model to demonstrate the usability of the model. Procedure This thesis was initiated in September 2013 with a literature review where lagoons in general and the Mundaú-Manguaba Estuarine-Lagoon System in particular were studied. Data collection and field measurements were carried out in Maceió, Brazil, between January and March 2014. During this time a new field campaign was carried out in order to get updated data concerning depth and salinity. To run the IPH-ECO model the boundary conditions had to be updated. That includes tidal fluctuations, river flows, bathymetry and Ch

Bonding of the Ni2+(aq) complex is investigated with an unprecedented combination of resonant inelastic X-ray scattering (RIXS) measurements and ab initio calculations at the Ni L absorption edge. The spectra directly reflect the relative energies of the ligand-field and charge-transfer valence-excited states. They give element-specific access with atomic resolution to the ground-state electronic structure of the complex and allow quantification of ligand-field strength and 3d-3d electron correlation interactions in the Ni2+(aq) complex. The experimentally determined ligand-field strength is 10Dq = 1.1 eV. This and the Racah parameters characterizing 3d-3d Coulomb interactions B = 0.13 eV and C = 0.42 eV as readily derived from the measured energies match very well with the results from UV-vis spectroscopy. Our results demonstrate how L-edge RIXS can be used to complement existing spectroscopic tools for the investigation of bonding in 3d transition-metal coordination compounds in solution. The ab initio RASPT2 calculation is successfully used to simulate the L-edge RIXS spectra.

We report here new data and a mass balance model for I-129 in the Baltic Proper and the Bothnian Sea covering the period from November-December 2009. The results showed that the general I-129 concentrations in the Bothnian Sea were two-four folds lower than in the Baltic Proper for both surface and deep water. Water exchange between the two basins based on the I-129 mass balance model suggests fluxes from the Baltic Proper to the Bothnian Sea and vice versa at 980 km(3)/y (600-1400 km(3)/y) and 1180 km(3)/y (780-1600 km(3)/y) respectively. Water retention time (residence time) in the Bothnian Sea was estimated at up to 4 years. Applying the I-129 exchange model, an estimate of total phosphorus and nitrogen inflow from the Baltic Proper to the Bothnian Sea indicates values of 20 +/- 7 x 10(3) tons/y and 300 +/- 50 x 10(3) tons/y respectively. The values for the outflow from the Bothnian Sea to the Baltic Proper hold 12 +/- 3 x 10(3) tons/y for total phosphorus and 283 +/- 55 x 10(3) tons/y for total nitrogen. These data and application of I-129 as a tracer of water masses provide information on small scale salinity changes which are vital for accurate understanding of the Baltic Sea ecosystems evolution through time.

129I is a radioactive isotope (T1/2= 15.7 million years) produced through natural and anthropogenic pathways, but the anthropogenic production is presently dominating the Earth’s surface environments. Sparse data from previous investigations in the Baltic Sea clearly indicated the occurrence of 129I at levels 3-4 orders higher than natural pre-atomic era (before 1940) without comprehensive evaluation of distribution and inventory. In this thesis extensive data on the distribution and inventory of iodine isotopes, 129I and 127I, and their species in waters of the Baltic Sea, Kattegat and Skagerrak are presented and used for estimation of water masses exchange and impact on the environment. To fulfill these objectives seawater samples were collected in August 2006 and April 2007 in the Baltic Proper, Kattegat and Skagerrak as well as in December 2009 in the Bothnian Sea. After elaborative chemical separation of total iodine and iodine species, the analysis was performed using ICP-MS for 127I and AMS for 129I. The results reveal considerable differences in 129I concentration in terms of spatial and temporal variability and expose relatively high concentrations in the deep waters. Inventory estimates show higher amounts of 129I in August 2006 (24.2 ±15.4 kg) than in April 2007 (14.4± 8.3 kg) within the southern and central Baltic Proper, whereas almost a constant inventory is found in the Kattegat Basin. Relatively high 127I-/127IO3- and 129I-/129IO3- values in water of the Baltic Proper suggest effective reduction of iodate at a maximum rate of 8×10-7 (127IO3-) and 6×10-14 (129IO3-) (g/m3.day). The combination of 129I and 127I as tracers of water circulation in the Baltic Sea suggest that upwelling deep basinal water occurs into the surface along the Gotland deep and intrusion of North Atlantic water into southern Baltic. Furthermore, 129I-based model inventory reveals inflow of 330 km3/y (230-450 km3/y) water from the Kattegat into the Baltic Proper. Water exchange

129I is a radioactive isotope (T1/2= 15.7 million years) produced through natural and anthropogenic pathways, but the anthropogenic production is presently dominating the Earth’s surface environments. Sparse data from previous investigations in the Baltic Sea clearly indicated the occurrence of 129I at levels 3-4 orders higher than natural pre-atomic era (before 1940) without comprehensive evaluation of distribution and inventory. In this thesis extensive data on the distribution and inventory of iodine isotopes, 129I and 127I, and their species in waters of the Baltic Sea, Kattegat and Skagerrak are presented and used for estimation of water masses exchange and impact on the environment. To fulfill these objectives seawater samples were collected in August 2006 and April 2007 in the Baltic Proper, Kattegat and Skagerrak as well as in December 2009 in the Bothnian Sea. After elaborative chemical separation of total iodine and iodine species, the analysis was performed using ICP-MS for 127I and AMS for 129I. The results reveal considerable differences in 129I concentration in terms of spatial and temporal variability and expose relatively high concentrations in the deep waters. Inventory estimates show higher amounts of 129I in August 2006 (24.2 ±15.4 kg) than in April 2007 (14.4± 8.3 kg) within the southern and central Baltic Proper, whereas almost a constant inventory is found in the Kattegat Basin. Relatively high 127I-/127IO3- and 129I-/129IO3- values in water of the Baltic Proper suggest effective reduction of iodate at a maximum rate of 8×10-7 (127IO3-) and 6×10-14 (129IO3-) (g/m3.day). The combination of 129I and 127I as tracers of water circulation in the Baltic Sea suggest that upwelling deep basinal water occurs into the surface along the Gotland deep and intrusion of North Atlantic water into southern Baltic. Furthermore, 129I-based model inventory reveals inflow of 330 km3/y (230-450 km3/y) water from the Kattegat into the Baltic Proper. Water exchange

129I is a radioactive isotope (T1/2= 15.7 million years) produced through natural and anthropogenic pathways, but the anthropogenic production is presently dominating the Earth’s surface environments. Sparse data from previous investigations in the Baltic Sea clearly indicated the occurrence of 129I at levels 3-4 orders higher than natural pre-atomic era (before 1940) without comprehensive evaluation of distribution and inventory. In this thesis extensive data on the distribution and inventory of iodine isotopes, 129I and 127I, and their species in waters of the Baltic Sea, Kattegat and Skagerrak are presented and used for estimation of water masses exchange and impact on the environment. To fulfill these objectives seawater samples were collected in August 2006 and April 2007 in the Baltic Proper, Kattegat and Skagerrak as well as in December 2009 in the Bothnian Sea. After elaborative chemical separation of total iodine and iodine species, the analysis was performed using ICP-MS for 127I and AMS for 129I. The results reveal considerable differences in 129I concentration in terms of spatial and temporal variability and expose relatively high concentrations in the deep waters. Inventory estimates show higher amounts of 129I in August 2006 (24.2 ±15.4 kg) than in April 2007 (14.4± 8.3 kg) within the southern and central Baltic Proper, whereas almost a constant inventory is found in the Kattegat Basin. Relatively high 127I-/127IO3- and 129I-/129IO3- values in water of the Baltic Proper suggest effective reduction of iodate at a maximum rate of 8×10-7 (127IO3-) and 6×10-14 (129IO3-) (g/m3.day). The combination of 129I and 127I as tracers of water circulation in the Baltic Sea suggest that upwelling deep basinal water occurs into the surface along the Gotland deep and intrusion of North Atlantic water into southern Baltic. Furthermore, 129I-based model inventory reveals inflow of 330 km3/y (230-450 km3/y) water from the Kattegat into the Baltic Proper. Water exchange

The Maha Oya river mouth, located on the west coast of Sri Lanka, is seasonally closed by a sand bar formed at the river mouth due to little rainfall and thus little river discharge. A new Outlet, located just north of the Maha Oya river mouth, was created by the 2004 tsunami. The Outlet remains open all year because of its location in the lee of an offshore breakwater. When the Maha Oya river mouth is closed, the river discharge flows out to sea through this new Outlet via the connecting Dutch Canal. For this thesis field measurements were undertaken over nine weeks during the dry season in Sri Lanka. The measured data included salinities, water levels and discharges for three cross sections close to the above mentioned tsunami Outlet. The main objective of this thesis was to investigate how the water exchange in estuaries and river mouths is affected by sedimentation in the coastal areas of Sri Lanka, using the Maha Oya as an experimental site. A mathematical model, HEC-RAS, was used to calculate water surface elevations and discharges at given points for the investigated area. The model was calibrated with the measured data. Simulations were then carried out for different openings of the river mouth with varying discharges in Maha Oya in order to quantify the effect on the water exchange through the Outlet. As expected, the result of the study showed that the water exchange in the Outlet was considerably higher for a closed river mouth than for a completely open river mouth due to the decrease of runoff in the Dutch Canal. When the river mouth was just a few meters open and the discharge from Maha Oya was strong the water exchange in the Outlet was large due to increased runoff in the Dutch Canal. Overall, the Outlet created by the tsunami does not seem to have a large impact on the water exchange in Maha Oya. However its existence might facilitate the everyday life for the people living in the area, providing them with a passage to the sea for the periods when t

The effect of dissolved humic substances (DHS) on the rate of water–gas exchange of two volatile organic compounds was studied under various conditions of agitation intensity, solution pH and ionic strength. Mass-transfer coefficients were determined from the rate of depletion of model compounds from an apparatus containing a stirred aqueous solution with continuous purging of the headspace above the solution (dynamic system). Under these conditions, the overall transfer rate is controlled by the mass-transfer resistance on the water side of the water–gas interface. The experimental results show that the presence of DHS hinders the transport of the organic molecules from the water into the gas phase under all investigated conditions. Mass-transfer coefficients were significantly reduced even by low, environmentally relevant concentrations of DHS. The retardation effect increased with increasing DHS concentration. The magnitude of the retardation effect on water–gas exchange was compared for Suwannee River fulvic and humic acids, a commercially available leonardite humic acid and two synthetic surfactants. The observed results are in accordance with the concept of hydrodynamic effects. Surface pressure forces due to surface film formation change the hydrodynamic characteristics of water motion at the water–air interface and thus impede surface renewal.

129I is a radioactive isotope (T1/2= 15.7 million years) produced through natural and anthropogenic pathways, but the anthropogenic production is presently dominating the Earth’s surface environments. Sparse data from previous investigations in the Baltic Sea clearly indicated the occurrence of 129I at levels 3-4 orders higher than natural pre-atomic era (before 1940) without comprehensive evaluation of distribution and inventory. In this thesis extensive data on the distribution and inventory of iodine isotopes, 129I and 127I, and their species in waters of the Baltic Sea, Kattegat and Skagerrak are presented and used for estimation of water masses exchange and impact on the environment. To fulfill these objectives seawater samples were collected in August 2006 and April 2007 in the Baltic Proper, Kattegat and Skagerrak as well as in December 2009 in the Bothnian Sea. After elaborative chemical separation of total iodine and iodine species, the analysis was performed using ICP-MS for 127I and AMS for 129I. The results reveal considerable differences in 129I concentration in terms of spatial and temporal variability and expose relatively high concentrations in the deep waters. Inventory estimates show higher amounts of 129I in August 2006 (24.2 ±15.4 kg) than in April 2007 (14.4± 8.3 kg) within the southern and central Baltic Proper, whereas almost a constant inventory is found in the Kattegat Basin. Relatively high 127I-/127IO3- and 129I-/129IO3- values in water of the Baltic Proper suggest effective reduction of iodate at a maximum rate of 8×10-7 (127IO3-) and 6×10-14 (129IO3-) (g/m3.day). The combination of 129I and 127I as tracers of water circulation in the Baltic Sea suggest that upwelling deep basinal water occurs into the surface along the Gotland deep and intrusion of North Atlantic water into southern Baltic. Furthermore, 129I-based model inventory reveals inflow of 330 km3/y (230-450 km3/y) water from the Kattegat into the Baltic Proper. Water exchange

A modelling approach is proposed to evaluate the environmental dynamics of coastal lagoons. The water, heat and salt balances are addressed simultaneously, providing a better estimation of evaporation and water exchanges. Compared to traditional approaches, the model presented accounts for the effects of water salinity, heat storage and net energy advected in the water body. The model was applied daily to the Mar Menor coastal lagoon (SE Spain) from 2003 through 2006. Water exchanges with the Mediterranean Sea were estimated based on the monthly trend of the lagoon salinity and were correlated with monthly averages of wind speed. The mean daily water exchange with the sea was 1.77 hm3 d 1. This exchange accounted for only 1% of the heat losses in the lagoon heat balance, and it is the most important flow in the water balance. The mean annual evaporation flux amounted to 101.3 W m-2 (3.55 mm d-1), while the sensible heat flux amounted to 19.7 W m-2, leading to an annual Bowen ratio on the order of 0.19. To validate the model, daily water temperatures were predicted based on the daily heat balance of the water body and were compared with remote sensing data from water surface standard products.

A characterization of hyporheic exchange for dry and wet season baseflow, as well as partially dewatered discharge, was done in Prieta Creek, a first-order cascade in northern Honduras. The cascade had discharges from 1 to 15 1 s(-1), had average slopes of 12%, pool spacing of 3 m, and shallow substrate of sand and gravel. Tracer tests were conducted in a 15-m sub-reach, a length considered to be adequate for the experiment based on the DaI test, a ratio of exchange and transport processes. In the three tests, between 9 and 18% of tracer was not recovered, possibly due to entrainment in flowpaths passing beneath the downstream monitoring location. Tracer data were analysed by the one-dimensional transport with inflow and storage (OTIS) transient storage model (TSM) to derive standard exchange parameters, and by the solute transport in rivers (STIR) model to examine hyporheic residence time distributions (RTDs). The best fit of the observed tracer breakthrough curves was obtained by using the STIR model with a combination of two exponential RTDs to represent hyporheic retention. With increasing discharge, the OTIS model predicted increasing storage exchange fluxes and exchange coefficients and decreasing storage zone areas and transient storage times, which are trends supported by riparian and streambed piezometric head data. Riparian water levels rose during the transition from the dry to wet season, which could constrict the hyporheic storage zone. Thirteen of the 19 streambed piezometers recorded seasonal changes in hydraulic gradients and flux direction, with fewer yet stronger upwelling zones during higher discharges. The MODFLOW model missed the observed seasonal changes, possibly due to subtle changes in the seasonal change in water surface profiles. We conclude that partially dewatered dry season exchange, compared to wet season exchange, was initiated and terminated with smaller pressure gradients and, in different streambed locations, was smaller in volume, QC 20120214

The chemistry of actinides in aqueous solution is important, and it is essential to build adequate conceptual models and develop methods applicable for actinide systems. The complex electronic structure makes benchmarking necessary. In the thesis a prototype reaction of the water exchange reaction for uranyl(VI), for both ground and luminescent states, described with a six-water model, was used to study the applicability of density functional methods on actinides and different solvation models. An excellent agreement between the wave function methods CCSD(T) and MP2 was obtained in the ground state, implying that near-minimal CASPT2 can be used with confidence for the reaction in the luminescent state of uranyl(VI), while density functionals are not suited to describe energetics for this type of reaction. There was an ambiguity concerning the position of the waters in the second hydration sphere. This issue was resolved by investigating a larger model, and prop- erly used the six-water model was found to adequately describe the water exchange reaction. The effect of solvation was investigated by comparing the results from conductor-like polarizable continuum models using two cavity models. Scattered numbers made it difficult to determine which solvation model to use. The final conclusion was that the water exchange reaction in the luminescent state of uranyl(VI) should be addressed with near-minimal CASPT2 and a solvation model without explicit cavities for hydrogens. Finally it was shown that no new chemistry appears in the luminescent state for this reaction. The thesis includes a methodological investigation of a multi-reference density functional method based on a range separation of the two-electron interaction. The method depends on a universal parameter, which has been determined for lighter elements. It is shown here that the same parameter could be used for actinides, a prerequisite for further development of the method. The results are in that sense promisin

The chemistry of actinides in aqueous solution is important, and it is essential to build adequate conceptual models and develop methods applicable for actinide systems. The complex electronic structure makes benchmarking necessary. In the thesis a prototype reaction of the water exchange reaction for uranyl(VI), for both ground and luminescent states, described with a six-water model, was used to study the applicability of density functional methods on actinides and different solvation models. An excellent agreement between the wave function methods CCSD(T) and MP2 was obtained in the ground state, implying that near-minimal CASPT2 can be used with confidence for the reaction in the luminescent state of uranyl(VI), while density functionals are not suited to describe energetics for this type of reaction. There was an ambiguity concerning the position of the waters in the second hydration sphere. This issue was resolved by investigating a larger model, and prop- erly used the six-water model was found to adequately describe the water exchange reaction. The effect of solvation was investigated by comparing the results from conductor-like polarizable continuum models using two cavity models. Scattered numbers made it difficult to determine which solvation model to use. The final conclusion was that the water exchange reaction in the luminescent state of uranyl(VI) should be addressed with near-minimal CASPT2 and a solvation model without explicit cavities for hydrogens. Finally it was shown that no new chemistry appears in the luminescent state for this reaction. The thesis includes a methodological investigation of a multi-reference density functional method based on a range separation of the two-electron interaction. The method depends on a universal parameter, which has been determined for lighter elements. It is shown here that the same parameter could be used for actinides, a prerequisite for further development of the method. The results are in that sense promisin

Periods of hypoxia are a recurring issue in Brunnsviken. Main factors that trigger hypoxia in Brunnsviken are eutrophication due to anthropogenic emission of nutrients, stratification in the water column due to salinity and temperature differences that prevents mixing and a sill inlet that prevents water exchange. As an attempt to improve the oxygen levels, bottom water is pumped from Brunnsviken causing aerated surface water to flow back into the basin. The objective of this Master’s thesis was to study the change in dissolved oxygen levels due to pumping. Since the question is complex, two areas were chosen to focus on; oxygen variability and the impact of water exchange on dissolved oxygen. Conductivity, temperature, depth and oxygen measurements, which were performed by Stockholm Vatten, were studied. This type of data set, with high resolution, is very rare and the data set from Brunnsviken has not been evaluated thoroughly before. The result of the evaluation was that high resolution data of oxygen are required in order to describe the dynamics of oxygen in Brunnsviken and other aquatic systems properly. Measurements of oxygen once a month is not sufficient. For that reason, it is not possible to use monthly measurements to evaluate the effect of the pumping. However, high resolution data for approximately one year were available. Episodes of hypoxia occurred during that period. This was not surprising, as the main purpose of the pumping was to keep the oxycline as deep as possible. The water exchange was determined from a water balance of Brunnsviken and compared with oxygen data. The water exchange did not seem to influence the oxygen level in Brunnsviken. The reason for this is most likely that the density of inflowing water was less than the density of the bottom water in Brunnsviken during most of the period studied. This result in combination with the fact that the pump flow is small compared to the water exchange sugges, Perioder av syrebrist är ett återkommande problem i Brunnsviken. De faktorer som i huvudsak ger upphov till utbredningen av syrefria områden i viken är övergödning orsakad av antropogena utsläpp av näringsämnen, en tröskel vid inloppet som hindrar vattenutbyte samt skiktning i vattenkolumnen till följd av salinitets- och temperaturskillnader som hämmar vertikal omblandning. I ett försök att förbättra syrgasförhållandena pumpas bottenvatten ut ur viken i syfte att syrerikare vatten ska strömma in. I detta examensarbete undersöktes pumpningens effekt på syrgashalten. Då detta är en komplex fråga lades fokus på att utreda syrets variabilitet samt vilken effekt vattenutbytet har på syrgashalten. I Brunnsviken pågår sedan omkring ett år tillbaka konduktivitet-, temperatur-, djup- och syremätningar med hög tidsupplösning. Dataserien är en av mycket få serier i sitt slag och någon grundlig utvärdering av dessa mätningar har inte gjorts tidigare. Resultatet av utvärderingen visade att syremätningar måste göras mycket ofta för att beskriva syredynamiken i Brunnsviken och andra akvatiska system på ett korrekt sätt, eftersom syrgashalten varierar mycket på kort tidsskala. Det är därför inte möjligt att använda månadsmätningar för att utvärdera vilken effekt pumpningen har haft på syrgashalten i Brunnsviken. Högupplösta data visade att syrebrist inte varit möjligt att undvika i Brunnsviken. Detta var heller inte att vänta då målet med pumpningen främst varit att hålla ner oxyklinen. Vattenutbytet beräknades utifrån Brunnsvikens vattenbalans och jämfördes med syredata. Någon effekt på syrgashalten orsakad av vattenutbytet har inte gått att påvisa. Det beror troligen på att densiteten på det inströmmande vattnet varit lägre än densiteten på bottenvattnet i Brunnsviken under nästan hela den studerade perioden. Detta i kombination med att pumpflödet är mycket litet i förhållande till det naturliga vattenutbytet gör att det viktigaste med pumpningen är att s

The chemistry of actinides in aqueous solution is important, and it is essential to build adequate conceptual models and develop methods applicable for actinide systems. The complex electronic structure makes benchmarking necessary. In the thesis a prototype reaction of the water exchange reaction for uranyl(VI), for both ground and luminescent states, described with a six-water model, was used to study the applicability of density functional methods on actinides and different solvation models. An excellent agreement between the wave function methods CCSD(T) and MP2 was obtained in the ground state, implying that near-minimal CASPT2 can be used with confidence for the reaction in the luminescent state of uranyl(VI), while density functionals are not suited to describe energetics for this type of reaction. There was an ambiguity concerning the position of the waters in the second hydration sphere. This issue was resolved by investigating a larger model, and prop- erly used the six-water model was found to adequately describe the water exchange reaction. The effect of solvation was investigated by comparing the results from conductor-like polarizable continuum models using two cavity models. Scattered numbers made it difficult to determine which solvation model to use. The final conclusion was that the water exchange reaction in the luminescent state of uranyl(VI) should be addressed with near-minimal CASPT2 and a solvation model without explicit cavities for hydrogens. Finally it was shown that no new chemistry appears in the luminescent state for this reaction. The thesis includes a methodological investigation of a multi-reference density functional method based on a range separation of the two-electron interaction. The method depends on a universal parameter, which has been determined for lighter elements. It is shown here that the same parameter could be used for actinides, a prerequisite for further development of the method. The results are in that sense promisin

Analysis on the hydrologic characteristics of the main stream of the Yangtze River and Poyang Lake were studied to discuss the water exchange between the main stream of the Yangtze River and Poyang Lake before and after the operation of Three Gorges Reservoir, as well as in the typical dry year of 2006. The annual runoff distribution for dry season of Hukou station, located at the outlet of Poyang in 2000s has increased, compared to previous years. And the percentage of runoff in September and October has also increased, compared to 1990s in last century. The water exchange coefficient was 0.51 in the year 2006, which means nearly stable effect between the Yangtze River and the Poyang Lake. Meanwhile, the Poyang Lake provide water supply up to 1564 × 108m3, accounts for about 23% of the Datong runoff in the same period, and 5% more than the normal year. This is the main reason that the discharge maintained more than 10000m3/s at Datong all over the year 2006, reaching a positive phenomenon of ‘no drought in dry season’., Hydraulic Engineering, Civil Engineering and Geosciences

Periods of hypoxia are a recurring issue in Brunnsviken. Main factors that trigger hypoxia in Brunnsviken are eutrophication due to anthropogenic emission of nutrients, stratification in the water column due to salinity and temperature differences that prevents mixing and a sill inlet that prevents water exchange. As an attempt to improve the oxygen levels, bottom water is pumped from Brunnsviken causing aerated surface water to flow back into the basin. The objective of this Master’s thesis was to study the change in dissolved oxygen levels due to pumping. Since the question is complex, two areas were chosen to focus on; oxygen variability and the impact of water exchange on dissolved oxygen. Conductivity, temperature, depth and oxygen measurements, which were performed by Stockholm Vatten, were studied. This type of data set, with high resolution, is very rare and the data set from Brunnsviken has not been evaluated thoroughly before. The result of the evaluation was that high resolution data of oxygen are required in order to describe the dynamics of oxygen in Brunnsviken and other aquatic systems properly. Measurements of oxygen once a month is not sufficient. For that reason, it is not possible to use monthly measurements to evaluate the effect of the pumping. However, high resolution data for approximately one year were available. Episodes of hypoxia occurred during that period. This was not surprising, as the main purpose of the pumping was to keep the oxycline as deep as possible. The water exchange was determined from a water balance of Brunnsviken and compared with oxygen data. The water exchange did not seem to influence the oxygen level in Brunnsviken. The reason for this is most likely that the density of inflowing water was less than the density of the bottom water in Brunnsviken during most of the period studied. This result in combination with the fact that the pump flow is small compared to the water exchange sugges, Perioder av syrebrist är ett återkommande problem i Brunnsviken. De faktorer som i huvudsak ger upphov till utbredningen av syrefria områden i viken är övergödning orsakad av antropogena utsläpp av näringsämnen, en tröskel vid inloppet som hindrar vattenutbyte samt skiktning i vattenkolumnen till följd av salinitets- och temperaturskillnader som hämmar vertikal omblandning. I ett försök att förbättra syrgasförhållandena pumpas bottenvatten ut ur viken i syfte att syrerikare vatten ska strömma in. I detta examensarbete undersöktes pumpningens effekt på syrgashalten. Då detta är en komplex fråga lades fokus på att utreda syrets variabilitet samt vilken effekt vattenutbytet har på syrgashalten. I Brunnsviken pågår sedan omkring ett år tillbaka konduktivitet-, temperatur-, djup- och syremätningar med hög tidsupplösning. Dataserien är en av mycket få serier i sitt slag och någon grundlig utvärdering av dessa mätningar har inte gjorts tidigare. Resultatet av utvärderingen visade att syremätningar måste göras mycket ofta för att beskriva syredynamiken i Brunnsviken och andra akvatiska system på ett korrekt sätt, eftersom syrgashalten varierar mycket på kort tidsskala. Det är därför inte möjligt att använda månadsmätningar för att utvärdera vilken effekt pumpningen har haft på syrgashalten i Brunnsviken. Högupplösta data visade att syrebrist inte varit möjligt att undvika i Brunnsviken. Detta var heller inte att vänta då målet med pumpningen främst varit att hålla ner oxyklinen. Vattenutbytet beräknades utifrån Brunnsvikens vattenbalans och jämfördes med syredata. Någon effekt på syrgashalten orsakad av vattenutbytet har inte gått att påvisa. Det beror troligen på att densiteten på det inströmmande vattnet varit lägre än densiteten på bottenvattnet i Brunnsviken under nästan hela den studerade perioden. Detta i kombination med att pumpflödet är mycket litet i förhållande till det naturliga vattenutbytet gör att det viktigaste med pumpningen är att s

The chemistry of actinides in aqueous solution is important, and it is essential to build adequate conceptual models and develop methods applicable for actinide systems. The complex electronic structure makes benchmarking necessary. In the thesis a prototype reaction of the water exchange reaction for uranyl(VI), for both ground and luminescent states, described with a six-water model, was used to study the applicability of density functional methods on actinides and different solvation models. An excellent agreement between the wave function methods CCSD(T) and MP2 was obtained in the ground state, implying that near-minimal CASPT2 can be used with confidence for the reaction in the luminescent state of uranyl(VI), while density functionals are not suited to describe energetics for this type of reaction. There was an ambiguity concerning the position of the waters in the second hydration sphere. This issue was resolved by investigating a larger model, and prop- erly used the six-water model was found to adequately describe the water exchange reaction. The effect of solvation was investigated by comparing the results from conductor-like polarizable continuum models using two cavity models. Scattered numbers made it difficult to determine which solvation model to use. The final conclusion was that the water exchange reaction in the luminescent state of uranyl(VI) should be addressed with near-minimal CASPT2 and a solvation model without explicit cavities for hydrogens. Finally it was shown that no new chemistry appears in the luminescent state for this reaction. The thesis includes a methodological investigation of a multi-reference density functional method based on a range separation of the two-electron interaction. The method depends on a universal parameter, which has been determined for lighter elements. It is shown here that the same parameter could be used for actinides, a prerequisite for further development of the method. The results are in that sense promisin

Analysis on the hydrologic characteristics of the main stream of the Yangtze River and Poyang Lake were studied to discuss the water exchange between the main stream of the Yangtze River and Poyang Lake before and after the operation of Three Gorges Reservoir, as well as in the typical dry year of 2006. The annual runoff distribution for dry season of Hukou station, located at the outlet of Poyang in 2000s has increased, compared to previous years. And the percentage of runoff in September and October has also increased, compared to 1990s in last century. The water exchange coefficient was 0.51 in the year 2006, which means nearly stable effect between the Yangtze River and the Poyang Lake. Meanwhile, the Poyang Lake provide water supply up to 1564 × 108m3, accounts for about 23% of the Datong runoff in the same period, and 5% more than the normal year. This is the main reason that the discharge maintained more than 10000m3/s at Datong all over the year 2006, reaching a positive phenomenon of ‘no drought in dry season’., Hydraulic Engineering, Civil Engineering and Geosciences

The chemistry of actinides in aqueous solution is important, and it is essential to build adequate conceptual models and develop methods applicable for actinide systems. The complex electronic structure makes benchmarking necessary. In the thesis a prototype reaction of the water exchange reaction for uranyl(VI), for both ground and luminescent states, described with a six-water model, was used to study the applicability of density functional methods on actinides and different solvation models. An excellent agreement between the wave function methods CCSD(T) and MP2 was obtained in the ground state, implying that near-minimal CASPT2 can be used with confidence for the reaction in the luminescent state of uranyl(VI), while density functionals are not suited to describe energetics for this type of reaction. There was an ambiguity concerning the position of the waters in the second hydration sphere. This issue was resolved by investigating a larger model, and prop- erly used the six-water model was found to adequately describe the water exchange reaction. The effect of solvation was investigated by comparing the results from conductor-like polarizable continuum models using two cavity models. Scattered numbers made it difficult to determine which solvation model to use. The final conclusion was that the water exchange reaction in the luminescent state of uranyl(VI) should be addressed with near-minimal CASPT2 and a solvation model without explicit cavities for hydrogens. Finally it was shown that no new chemistry appears in the luminescent state for this reaction. The thesis includes a methodological investigation of a multi-reference density functional method based on a range separation of the two-electron interaction. The method depends on a universal parameter, which has been determined for lighter elements. It is shown here that the same parameter could be used for actinides, a prerequisite for further development of the method. The results are in that sense promisin

It is necessary to improve our understanding of the exchange of dissolved constituents between surface and subsurface waters in river systems in order to better evaluate the fate of water-borne contaminants and nutrients and their effects on water quality and aquatic ecosystems. Here we present a model that can predict hyporheic exchange at the bed-form-to-reach scale using readily measurable system characteristics. The objective of this effort was to compare subsurface flow induced at scales ranging from very small scale bed forms up to much larger planform geomorphic features such as meanders. In order to compare exchange consistently over this range of scales, we employed a spectral scaling approach as the basis for a generalized analysis of topography-induced stream-subsurface exchange. The spectral model involves a first-order approximation for local flow-boundary interactions but is fully three-dimensional and includes the lateral hyporheic zone in addition to the flow directly beneath the streambed. The primary model input parameters are stream velocity and slope, sediment permeability and porosity, and detailed measurements of the stream channel topography. The primary outputs are the distribution of water flux across the stream channel boundary, the resulting pore water flow paths, and the subsurface residence time distribution. We tested the bed-form-exchange component of the model using a highly detailed two-dimensional data set for exchange with ripples and dunes and then applied the model to a three-dimensional meandering stream in a laboratory flume. Having spatially explicit information allowed us to evaluate the contributions of both gravitational and current-driven hyporheic flow through various classes of stream channel features including ripples, dunes, bars, and meanders. The model simulations indicate that all scales of topography between ripples and meanders have a significant effect on pore water flow fields and residence time distributions. F, QC 20110501

Thirty-three snowpack models of varying complexity and purpose were evaluated across a wide range of hydrometeorological and forest canopy conditions at five Northern Hemisphere locations, for up to two winter snow seasons. Modeled estimates of snow water equivalent (SWE) or depth were compared to observations at forest and open sites at each location. Precipitation phase and duration of above-freezing air temperatures are shown to be major influences on divergence and convergence of modeled estimates of the subcanopy snowpack. When models are considered collectively at all locations, comparisons with observations show that it is harder to model SWE at forested sites than open sites. There is no universal "best'' model for all sites or locations, but comparison of the consistency of individual model performances relative to one another at different sites shows that there is less consistency at forest sites than open sites, and even less consistency between forest and open sites in the same year. A good performance by a model at a forest site is therefore unlikely to mean a good model performance by the same model at an open site (and vice versa). Calibration of models at forest sites provides lower errors than uncalibrated models at three out of four locations. However, benefits of calibration do not translate to subsequent years, and benefits gained by models calibrated for forest snow processes are not translated to open conditions., QC 20100525