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Environmental Implications of Cu-Based Nanoparticles and Biocides ProductsTegenaw, Ayenachew G., Ph.D. January 2019 (has links)
No description available.
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Detection of Barium and Strontium Ions in Water Utilizing Functionalized Silver NanoparticlesCobbs, Ashley L. January 2020 (has links)
No description available.
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Localized Corrosion Initiation of Steel in CO2 EnvironmentsGao, Xin 22 September 2020 (has links)
No description available.
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Geological and coastal influences on small bodies of water in subarctic and arctic localitiesStavinga, Janet Maurine January 1992 (has links)
No description available.
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Investigation of the Iron Oxidation Kinetics in Mantua ReservoirLathen, Scott H. 08 May 2007 (has links) (PDF)
Irrigation of the municipal cemetery in Brigham City, Utah resulted in stained headstones in 2001 and 2002. The water used in the irrigation came from Mantua reservoir, a medium sized impoundment situated near the mouth of Box Elder Canyon. In order for Brigham City to establish a city wide secondary pressurized irrigation system using water from Mantua reservoir, the cause and the source of staining problem must be determined. Previous research (Wallace 2006) determined that the source of the staining was the reduction of iron found in Mantua Reservoir sediments that occurred when seasonal variations in the reservoir caused anaerobic conditions. The reduced iron then dissolved in the water and was used in the irrigation system, causing re-oxidation of the iron. The oxidized iron then precipitated out on the headstones causing the staining. The purpose of this investigation is to determine the iron oxidation kinetics after the re-aeration of the water which will help determine appropriate mitigation methods. A secondary purpose is to confirm the Mantua reservoir's capacity to become anaerobic, resulting in the conditions which cause staining. Using laboratory investigations and computer modeling, I determined that on re-aeration, fifty percent of the dissolved iron in the water precipitates in five hours. Using first-order kinetics to model this process, I found the rate constant of the kinetic reaction to be 0.0029 min-1. Fitting a geochemical computer model of the iron oxidation kinetics in Mantua reservoir, which uses a higher-order kinetics model to better model this process, to experimental kinetic data yielded a rate constant of 4x1013 /atm x min. I also recreated the staining process in the laboratory using concrete. This was successful and provided visual evidence that the iron precipitates out of the water and stained the concrete within a couple of hours of application. Field data collected from Mantua reservoir showed that the dissolved oxygen concentration in the reservoir drops regularly below levels consistent with equilibrium to the atmosphere. While my field measurements did not record anaerobic conditions, based on the patterns shown, this study shows that it would be possible for anaerobic conditions to occur during warmer weather.
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Reactor Chemistry in LWR SMRs : Determination of the rate constant for the reaction between boric acid and hydroxyl radicals / Reaktorkemi i vattenkylda små modulära reaktorer (SMR)Petersson, Fredrik January 2023 (has links)
Ett problem vid byggandet av nya kärnkraftverk för elproduktion är de stora investeringskostnaderna samt den långa tiden det att få tillstånd för en reaktor och bygga den. Nyligen färdigställdes den tredje reaktorn vid Olkiluoto I Finland, den tog 18 år att färdigställa exklusive tiden att få tillstånd för reaktorn. Små modulära kärnkraftsreaktorer, SMR är mindre reaktorer med en lägre elektrisk effekt har föreslagits vara en lösning på problemet. Det behövs inte lika stora investeringar för att uppföra en reaktor och de ska också gå snabbare att bygga. Det finns flera fördelar med SMR, de kommer att tillverkas i fabriker vilket minskar konstruktionstiden. Samma reaktormodell behöver bara ett tillstånd för licensering medan stora reaktorer som byggs idag behöver ett nytt för varje reaktor. Det är dessutom billigare att serieproducera reaktorer då kostnaden går ned för varje producerad reaktor. De flesta reaktorer idag använder lättvatten som en moderator och för att kyla ned reaktorn, reaktorerna kallas för lätt vatten reaktorer, LWR. Det finns två vanliga designer, en där vatten kokas inuti reaktorn och driver sedan en turbin, reaktorn kallas för kokvattenreaktor, BWR. Den andra vanliga reaktordesignen är tryckvattenreaktorn, PWR där det är ett högre tryck som gör att vattnet inte kokar i reaktorn, i stället kokar det varma vattnet från reaktorn vatten i en sekundär vattenloop i en ånggenerator. Det är ångan i sekundär loopen som sedan driver turbinen. Det finns även flera reaktorkoncept som inte använder lättvatten. De SMR koncept som är närmast att påbörja konstruktion är alla LWR eftersom det är där den största erfarenheten från tidigare reaktordesigner finns. Genom att undersöka sju SMR koncept, sex PWR och en BWR är bilden att många är väldigt lika reaktorerna som finns idag, däremot så har många tagit bort komplicerade system och infört passiva säkerhetssystem som bland annat naturlig cirkulation för att få en passiv kylning. Materialen som används är också material som tidigare har används. En av de föreslagna förenklingarna är borttagandet av en löst neutronabsorbent i PWR reaktorer, i stället ska kontroll stavar och neutron gift i bränslet användas i en större grad. Den vanligaste neutronabsorbenten som används i lösning är borsyra eftersom bor har ett högt neutrontvärsnitt. Användandet av borsyra i reaktorn leder till lägre pH vilket ökar korrosionen, borsyran påverkar även radiolysen av vatten. I det här arbetet har hastighetskonstanten för reaktionen mellan borsyra och hydroxylradikalen som bildas genom radiolys av vatten undersökts. I experimenten användes coumarin-3-karboxylsyra som en radikalinfångare för att studera reaktionshastigheten genom tävlingskinetik. Den hydroxylerade produkten som bildas har detekterats genom fluorescens. Hastighetskonstanten mättes till 1.25 ∙ 106 M-1 s-1 vilket är högre än tidigare litteraturvärden. Skillnaden kan delvis förklaras genom närvaron av motbasen till borsyra, borat samt trimeren tetraborat som bildas vid höga koncentrationer av borsyra. / One problem with building new nuclear reactors for electricity production is the large investment costs and the long time needed for permissions and construction. Most recently is the Olkiluoto nuclear power plant in Finland where a third reactor was built, it took 18 years to finalize the reactor, and this is not including the time of handling the licencing application. Small modular nuclear reactors, SMR which is a smaller reactor with a reduced effect has been proposed to reduce the cost of investment and the time it takes from license application to finalized reactor. The SMR reactors have many advantages. It will be fabricated in factories reducing the time of construction, since reactor units are the same, the same reactor design only needs one licencing for all reactors. Compared to large reactors built today, where every single reactor needs a new licencing. Smaller reactors lead to shorter construction times and lower investment. It is also less expensive to produce reactors in series where the cost per unit decreases for every unit produced. Most reactors in operation today use light water as a moderator and coolant and are called light water reactors, LWR. Two designs are common, one where the water is boiled in the reactor and goes directly to the turbine, this reactor is called a boiling water reactor, BWR. The other common reactor is a pressurized water reactor, PWR where a higher pressure does not allow the water to boil. Instead, it is heated and boils water in a steam generator that then turns the turbine blades. There are other reactor concepts which do not use light water as a moderator and coolant, The SMR concepts that are the closest to construction are all LWR because it is where most experience from previous reactor designs is. By investigating seven SMR reactor concepts, six PWR and one BWR, it was concluded that they are similar to reactors operating today, but with some simplification and passive safety systems like natural circulation for many of them. The materials that will be used are also materials that have previously been used. One of the simplifications for several of the reactor concepts is the removal of a soluble neutron absorber in PWR reactors and instead, the use of control rods and burnable neutron poison to a larger extent. The soluble neutron absorber is usually boric acid which has a high neutron cross-section. The use of boric acid will reduce the pH in the reactor which increases corrosion, and it also affects the radiolysis of water. This work has investigated the rate constant for the reaction of boric acid with hydroxyl radicals formed in the radiolysis of water. In the experiments, coumarin-3-carboxylic acid was used as a probe to study the reaction rate using competition kinetics. The hydroxylated product formed has been detected using fluorescence. The rate constant measured was 1.25 ∙ 106 M-1 s-1 which is higher than previous literature values. Some of the discrepancies could be explained by the presence of the counter base, borate and the tetraborate that is formed at high concentrations.
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Mechanisms of Iron Carbonate Formation on Mild Steel in Controlled Water Chemistry ConditionsIeamsupapong, Supat, January 2016 (has links)
No description available.
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Groundwater chemistry and supplementary sources of freshwater in Arid environments : groundwater salinisation, solar desalination & fog collectionShanyengana, Shanyengana E. 03 1900 (has links)
Thesis (DPhil)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Freshwater is the most fundamental of all life-supporting resources that determine our
social, economic and political wellbeing. It is, however, only a small percentage of
the world's water resources and is also unevenly distributed. Arid regions make-up
about forty percent of the world's land area and have a large proportion of the world
population, however, they only have a small fraction of the freshwater compared to
other areas.
Conventional freshwater sources in arid environments such as surface water in rivers,
lakes and dams are often seasonal, available mainly during the rainy season. Equally,
only a small part of the rain (0 - 5% of rainfall) infiltrates into groundwater reserves,
and even this groundwater displays high rates of salinisation such that the end-water
is too saline for human consumption.
The poor quality of groundwater in arid regions is generally understood, however, it is
always assumed that this is mainly a problem in areas where surface water does not
occur. The study investigates seasonal groundwater salinisation in ephemeral
(seasonal) river sources in some parts of Namibia and aims to derive a better
understanding of the nature of this problem and how it affects people in these areas.
It also looks at some possible solutions to the problem with the aim of informing
water managers and scientists who are responsible for formulating solutions for water
supply to areas in arid regions. These solutions are designed to take advantage of available opportunities in the study
areas namely; the abundant supply of solar energy, alternative sources of freshwater
such as fog and general atmospheric moisture, and adaptations for water collection in
animals that inhabit these regions.
The results show that groundwater in shallow ephemeral river sources of the Namib
Desert and the Cuvelai delta in North central Namibia display high seasonal variation
in Total Dissolved Solids (TDS) and chemical composition. The lowest TDS values
are recorded during the rainy season, mainly after the first rains in the high rainfall
areas and only after flood events in the lower rainfall regions. The groundwater
salinity increases during the remainder of the year and in most cases becomes too
saline for drinking purposes.
The investigations of possible solutions indicate that small-scale photovoltaic reverse
osmosis; solar distillation and fog collection could be used to address the seasonal
shortage of potable water in these areas. The low-pressure (6 bar) reverse osmosis
desalination experiments show that it is possible to operate the unit on a solar-driven
pump to produce enough water to cover the typical daily water demand of a village in
the Namib Desert. This unit would produce about 4600 litres per day (l/day) of 500-
mg/l TDS product water, which exceeds the water production of similar world-leading
small-scale RO units in Australia and The Canary Islands.
The results also show that the cost of solar distillation units (solar stills) can be
reduced sufficiently to make them a viable option for water supply to individual
households in these rural areas. The study also found that fog is a feasible alternative source of freshwater in some of
the study areas. The fog water is generally of 'A' quality drinking water according to
the WHO-derived Namibian Drinking Water Quality Guidelines (NDWQG) and can
be used directly or mixed with the saline groundwater to provide potable water.
Mixing of the above-mentioned waters is particularly suitable in the Central Namib
Desert because the period of high groundwater salinity coincides with that of peak fog
deposition.
The results also show that fog water can be collected with vanous polymeric
greenhouse shade netting that can be easily obtained, and provides guidelines on the
correct percentage shade coefficient and weave of possible fog collector mesh to
intending users of fog collection technology in areas where the polypropylene mesh
that is used in Standard Fog Collectors is not available.
The investigations of surface properties of fog-harvesting beetles and experiments
with various prototype collectors show that it is possible to increase water production
in fog collectors existing today. The hydrophobic surface conditions as were found
on the cuticles of fog-basking beetles (Onymaeris unguicularis and Onymacris
bieolor) would enhance formation and runoff of large fog droplets on the collector
surface. The prototype extractor-fan- and cooling system-based collectors show that
it is possible to increase fog collection on polymeric meshes about three times and
also that a comparable volume of atmospheric moisture can be collected even when
there is no fog, up to a relative humidity of about 40%. In conclusion the study emphasizes that groundwater salinity in arid regions is at
times a seasonal problem that should be considered in water supply strategies for
these regions. Also that atmospheric moisture is a feasible alternative source of
freshwater in some arid regions that often exceeds rainfall several times and should be
considered as an important aspect of the strategies to address water problems in these
areas. The study strongly recommends that scientists, engineers and water managers
in these regions should always investigate the available opportunities such as climatic
conditions (e.g. fog deposition) and adaptations for water collection/conservation that
are found in the endemic plants and animals in order to develop sustainable solutions
to this problem. They should also constantly update themselves on
developments/opportunities that arise in the larger water industry that could be of
benefit to water supply initiatives for remote areas in developing countries.
Lastly, the study serves to better the understanding of the nature of groundwater
salinity in arid environments that are dependent on seasonal surface flow for water
supply as well as to contribute to the formulation of solutions to this problem in these
areas, particularly in west coast hyper arid environments where conventional sources
of freshwater are most inadequate. It also emphasises the role of materials science
(polymers) and environmental engineering as well as that of UNESCO associated
scientific institutions in the formulation of sustainable solutions to some of the current
water problems in arid regions.
Keywords: Arid lands, hydrochemistry, sources of freshwater, desalination,
atmospheric moisture / AFRIKAANSE OPSOMMING: Vars water is die mees fundamentele van aIle lewensonderhoudende natuurlike
hulpbronne wat ons sosiale, ekonomiese, en politieke welstand bepaal. Dit is egter
slegs 'n klein gedeelte van die totale waterbronne van die wereld, en is boonop baie
oneweredig versprei. Natuurlike waterarm gebiede (woestyne en halfwoestyne)
beslaan ongeveer veertig persent van die landoppervlakte van die aarde en word
bewoon deur 'n relatief groot persentasie van die wereldbevolking, maar beskik oor
slegs 'n klein gedeelte van die varswater in vergelyking met ander gebiede.
Konvensionele bronne van varswater in waterarm gebiede, soos oppervlaktewater in
riviere, mere en darnme, is dikwels seisoenaal, en slegs beskikbaar gedurende die
reenseisoen. Verder beland slegs 'n klein gedeelte van die reenval (0 - 5%) in die
ondergrondse waterreserwes, en selfs hierdie grondwater vertoon 'n hoe mate van
versouting, sodat die eindproduk te brak is vir menslike gebruik. Die swak gehalte
van grondwater in waterarm gebiede word algemeen verstaan, maar daar is tot nog toe
aanvaar dat dit oor die algemeen slegs 'n probleem is in gebiede waar
oppervlaktewater me voorkom nie. Hierdie studie ondersoek seisoenale
grondwaterverbrakking in seisoenale rivierbronne in sekere dele van Namibie en
beoog om 'n beter begrip te formuleer van die aard van die probleem en hoe dit die
inwoners van hierdie gebiede raak. Daar word ook ondersoek ingestel na moontlike
oplossings vir die probleem, met die doel om 'n inligtingsbron vir waterbestuurders
en wetenskaplikes wat verantwoordelik is vir die formuleer van oplossings vir
watervoorsiening in waterarm gebiede daar te stel. Hierdie oplossings is ontwerp om voordeel te trek uit die beskikbare geleenthede in
die ondersoekgebiede, naamlik; die oorvloedige beskikbaarheid van sonenergie,
altematiewe bronne van varswater soos mis (Eng. "fog") en atmosferiese vog in die
algemeen en aanpassings (Eng. "adaptations") vir die opvang van water wat voorkom
by diere, veral insekte, in hierdie gebiede. Die resultate toon dat grondwater in die
vlak seisoenale rivierbronne van die Namibwoestyn en die Cuvelai-delta in noordsentraal
Namibie hoe seisoenale variasie in totale opgeloste stowwe (TVS) en
chemiese samestelling vertoon. Die laagste TVS-waardes word waargeneem tydens
die reenseisoen, hoofsaaklik na die eerste reen in die hoe-reenvalgebiede en eers na
vloede in die lae-reenvalgebiede, Die soutgehalte van die grondwater neem toe
gedurende die res van die jaar en in die meeste gevalle verbrak die water tot
ondrinkbare vlakke.
Die ondersoek na moontlike oplossings dui aan dat kleinskaalse fotovoltaiesgedrewe
tru-osmose, sondistillasie en die opvang van mis (Eng."fog collection") aangewend
kan word om die seisoenale tekort aan drinkwater in hierdie gebiede aan te spreek.
Die laedruk (6 bar) tru-osmose-ontsoutingseksperimente wys dat dit moontlik is om
die eenheid met behulp van 'n sonkraggedrewe pomp te bedryf en voldoende water te
lewer vir die tipiese daaglikse drinkwaterbehoeftes van 'n nedersetting in die
Namibwoestyn. Hierdie eenheid sal sowat 4600 liter per dag (l/d) water, met 'n TVSwaarde
van 500 mg/I, lewer. Dit is aansienlik meer as die lewering van soortgelyke
eenhede in Australie en die Kanariese Eilande.
Die resultate wys ook dat die koste van sondistillasie-eenhede genoegsaam verminder
kan word om dit 'n lewensvatbare opsie vir watervoorsiening aan enkelhuishoudings in die plattelandse gebiede te maak. Die studie het ook bevind dat die opvang van mis
'n toepaslike alternatiewe bron van varswater is in sekere van die studiegebiede. Die
miswater is oor die algemeen 'A' -gehalte drinkwater vol gens die Namibiese
gehalteriglyne Vir drinkwater (gebasseer op bepalings van die
Wereldgesondheidsorganisasie) en dat dit net so, of vermeng met brak grondwater,
gebruik kan word as drinkwater. Vermenging is besonder geskik in die sentrale
Namibwoestyn, aangesien die periode van hoe grondwaterverbrakking saamval met
die piek van benutbare misneerslag.
Die resultate toon ook aan dat miswater opgevang kan word met verskeie tipes
polimeriese skadunet, wat maklik verkrygbaar is, en verskaf riglyne vir die optimale
skadu-koeffisient en weefpatroon van moontlike misvangsnette vir voomemende
gebruikers van misvangstegnologie in gebiede waar die polipropileennet wat in die
standaard miskollekteerders gebruik word nie, beskikbaar is nie. Die ondersoek van
oppervlakeienskappe van mis-koesterkewers (Eng. "fog harvesting beetles") en
eksperimente met verskeie prototipe versamelaars toon dat dit moontlik is om die
waterproduksie van bestaande kollekteerders te verhoog. Die hidrofobe
oppervlaktetoestande soos gevind op die opperhuid van die mis-koesterkewers
(Onymacris unguicularis en Onymacris bicolor) bevorder die vorming en afloop van
groot misdruppels op die versameloppervlak.
Die prototipe suigwaaier- en verkoelerstelselgebasseerde versamelaars toon dat dit
moontlik is om die misvogversameling op polimeriese nette tot drie maal te verhoog
en dat 'n vergelykbare volume atmosferiese vog versamel kan word, selfs in die
afwesigheid van mis, tot by 'n relatiewe humiditeit van ongeveer 40%. Ten slotte benadruk die studie dat grondwatersoutgehalte in waterann gebiede soms
'n seisoenale probleem is, en dat dit in ag geneem moet word in
watervoorsieningstrategiee vir sulke gebiede. Dit benadruk ook dat atmosferiese vog
'n bruikbare alternatiewe bron van varswater kan wees in sekere areas, waar dit
dikwels verskeie male meer is as reenval, en gesien behoort te word as 'n belangrike
aspek in strategiee om waterprobleme in hierdie gebiede aan te spreek. Die studie
beveel sterk aan dat wetenskaplikes, ingenieurs en waterbestuurders in hierdie
gebiede altyd die beskikbare geleenthede soos klimaatstoestande (bv. misneerslag) en
aanpassings vir vogvangslbewaring wat voorkom by inheemse plante en diere sal
navors om sodoende onderhoudbare oplossings vir die probleem te vind. Hulle
behoort deurlopend op hoogte te bly met ontwikkelings/geleenthede wat ontstaan in
die wyer waterindustrie, wat van waarde kan wees in by waterverskaffmgsinisiatiewe
vir afgelee gebiede in ontwikkelende lande.
Laastens dien die studie om 'n beter begrip daar te stel van die aard van
grondwatersoutvlakke in waterarm gebiede wat afhanklik is van seisoenale
oppervlaktevloei vir watervoorsiening sowel as om 'n bydrae te lewer tot die
formuleer van oplossings tot die probleem in hierdie gebiede, veral in die hiperdroe
omgewings aan die Namibiese weskus, waar konvensionele waterbronne mees
onvoldoende is. Dit benadruk ook die rol van materiaalkundige wetenskappe
(polimere) en omgewingsingenieurswese sowel as die UNESCO-geassosieerde
wetenskaplike instellings in die formulering van volhoubare oplossings vir sommige
van die huidige waterprobleme in waterann gebiede.
Sleutelwoorde: Waterarm gebiede, hidrochemie, bronne van varswater, ontsouting,
atmosferiese vog
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INTEGRATED HYDROCHEMICAL MODELING OF AN ALPINE WATERSHED: SIERRA NEVADA, CALIFORNIAWolford, Ross A. 12 1900 (has links)
Seasonally snow covered alpine areas play a larger role in the hydrologic cycle than their area
would indicate. Their ecosystems may be sensitive indicators of climatic and atmospheric change.
Assessing the hydrologic and bio- geochemical responses of these areas to changes in inputs of water,
chemicals and energy should be based on a detailed understanding of watershed processes. This dissertation
discusses the development and testing of a model capable of predicting watershed hydrologic
and hydrochemical responses to these changes. The model computes integrated water and chemical
balances for watersheds with unlimited numbers of terrestrial, stream, and lake subunits, each of which
may have a unique, variable snow -covered area. Model capabilities include 1) tracking of chemical
inputs from precipitation, dry deposition, snowmelt, mineral weathering, basefiow or flows from areas
external to the modeled watershed, and user -defined sources and sinks, 2) tracking water and chemical
movements in the canopy, snowpack, soil litter, multiple soil layers, streamflow, between terrestrial
subunits (surface and subsurface movement), and within lakes (2 layers), 3) chemical speciation,
including free and total soluble species, precipitates, exchange complexes, and acid -neutralizing capacity,
4) nitrogen reactions, 5) a snowmelt optimization procedure capable of exactly matching observed
watershed outflows, and 6) modeling riparian areas. Two years of data were available for fitting and
comparing observed and modeled output. To the extent possible, model parameters are set based on
physical or chemical measurements, leaving only a few fitted parameters. The effects of snowmelt rate,
rate of chemical elution from the snowpack, nitrogen reactions, mineral weathering, and flow routing
on modeled outputs are examined.
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Impact of land reclamation on hydrogeochemical processes in coastal aquifer systems: a case study in Shenzhen,China陳扣平, Chen, Kouping. January 2008 (has links)
published_or_final_version / abstract / Earth Sciences / Doctoral / Doctor of Philosophy
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