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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
451

Energy sources of the future – an explorative scenario analysis of Sweden’s energy security in regard to present energy policy

Ehrling, Axel January 2019 (has links)
Energy has always been an essential commodity, vital for a well-functioning society. Since, the industrialization has fossil fuels been used as man’s main energy source. Consequently, vast amounts of emissions have spread into earth’s atmosphere and lead to an unprecedently quick global warming. Governments are today reacting to climate change, and energy policies to limit the effects are developed. Sweden has since year 2008 established energy policy targets to reduce its emissions. This report looks into outcomes of Swedish energy policy by forecasting scenarios to measure target achievement and effects on Swedish energy security. Energy security has historically been dominated by geopolitical issues and oil, however, today the term has grown to encompass secure access to energy services at a sufficiently low and stable price, in a way that is socially and environmentally acceptable compared to other energy options. Thus, energy security in this report is understood as ‘Ensuring access to affordable, reliable, sustainable and modern energy for all’. From this definition are forecasted scenarios developed and analyzed towards an energy security framework consisting of three subcategorize, affordability, reliability and sustainability. The scenarios are made by linear, exponential and logistic trendlines, to cover different expansion patterns. The general outcome of the scenarios suggests that energy security as defined will become more sustainable and reliable at the cost of affordability for energy consumers. However, even though sustainability is increasing are some of the energy policy targets not likely to succeed if business continues as usual.
452

Is blue mussel farming a potential mitigation tool to combat eutrophication in the Baltic Sea? A synthesis based on stakeholder interviews

Zilinskaite, Emilija January 2019 (has links)
The Baltic Sea is the most polluted sea in the world. Its hydrological conditions and ongoing eutrophication are a high threat for marine biodiversity and ecosystems. Additionally, eutrophication has negative effects on the wellbeing of countries and their societies in the Baltic Sea Region (BSR). Actions to mitigate eutrophication in the Baltic Sea have been implemented through on-land measures in the last 40 years. Although the improvement in the marine environment is notable, it happens very slowly. In order to combat eutrophication, there is a need for a combination of on-land and in-situ measures. In this study, blue mussel farming practices are presented as one of the in-situ measures to combat eutrophication in the Baltic Sea. Blue mussel farming has been implemented in Sweden since the 1980s and has potential to not only mitigate the amounts of nutrients that accumulate in the sea but also brings a circular approach to resource use. In this study, stakeholders from four different sectors that are closely related to blue mussel farming practices and Baltic Sea issues have been interviewed with the aim of making a comprehensive analysis of stakeholder perceptions of blue mussel farming practices in the BSR. Interviewed stakeholders represent four different sectors - academia, entrepreneurs, municipalities and NGOs. A comprehensive analysis of stakeholders’ perceptions on blue mussel farming practises from environmental, social and economic perspective is presented. All interviewed stakeholders are actors in Sweden and represent Swedish perspective on blue mussel farming activities. Potential causes for different perceptions across sectors are discussed.
453

Lakes are browner in the south than in the north of Sweden despite similar levels of dissolved iron

Lindgren, Fredrik January 2019 (has links)
During recent decades many lakes have become browner in the northern hemisphere and more specific in Sweden. This process is called brownification. Brownification of lakes makes it more difficult to clean water to drinking water and may have negative ecological effects on biota. Browning of lakes is generally thought to be caused by an increase of humic substances that consist of organic matter which colour the water brown or yellow. However, more recent studies show that dissolved iron can interact with humic substances in browning lakes. Since the concentrations of dissolved iron have increased during recent years and the mechanisms behind brownification and the contribution of iron to this process is not clearly understood it is important to investigate this subject. In this study 17 lakes in south of Sweden were sampled for iron concentration, dissolved organic carbon (DOC), absorbance (420nm) and pH. Further, data was added about atmospheric sulphur deposition and additional data from 17 lakes in the north part of Sweden. Iron had a stronger significant correlation towards absorbance than DOC had in the south of Sweden. A similar amount of dissolved iron seems to colour lakes differently based on their location in Sweden. This indicates that different mechanisms are involved in the interaction between iron and absorbance. However, pH had a stronger relationship with absorbance than either DOC or iron. Overall results suggested that iron do have a strong browning effect on Swedish fresh water lakes in the presence of DOC and that iron-increase driven processes may be due to a change of pH.
454

Diving into Blue Carbon : A Review on Carbon Sequestration by Mangrove Forests, Seagrass Meadows and Salt Marshes, and Their Capacity to Act as Global Carbon Sinks

George, Hugo January 2019 (has links)
During the last decade, the academic interest for Earth’s natural carbon sinks and their role concerning climate change has increased. Today, many scientists around the world are trying to calculate different ecosystem’s potential to sequester and store carbon dioxide from the atmosphere. As a newcomer to the scientific arena, the term ‘blue carbon’ has been well received by scientists in the field. ‘Blue carbon’ highlights the carbon captured and stored by productive ecosystems along the world’s coasts. The term refers to coastal wetlands – such as mangrove forests, salt marshes and seagrass meadows – and it came to life as the scientific community recognized these ecosystems’ significant potential as effective carbon sinks. New research indicates that these ecosystems’ complex and vertical root systems can store much larger amounts of carbon in the soil than any other terrestrial ecosystem. By studying this subject, scientists are trying to understand how these ecosystems can help us in the quest of removing excessive carbon dioxide from the atmosphere. The goal of this thesis is to conduct a literature review, aiming to analyse and compile the new research on ‘blue carbon’ that has been published during the last 10 years. The paper aims to investigate whether the ecosystem’s potential as carbon sinks differ from each other, and what threats they will face in the future. It will additionally review if scientists have been able to unite around any predictions about what the future for ‘blue carbon’ – and its role in mitigating climate change – will look like. / Under det senaste decenniet har intresset kring naturliga kolsänkors potential och roll i att mildra klimatförändringar ökat. Idag är det många forskare som arbetar med att beräkna mängden kol som olika ekosystem runt om världen kan lagra i sin biomassa och i jorden under dess rötter. Som en nykomling på den vetenskapliga arenan, har termen ’blue carbon’ blivit väl mottaget av forskare inom området. ’Blue carbon’ syftar på det kol som fixeras och lagras av de produktiva ekosystemen längs världens kuster. Termen refererar till kustbelägna våtmarker – så som mangroveskogar, saltträsk och sjögräsbäddar – och introducerades efter att den vetenskapliga världen erkänt deras imponerande potential som kolsänkor. Ny forskning tyder på att deras avancerade och vertikala rotsystem kan lagra mer koldioxid i marken än vad vanliga terrestra skogar kan. Genom att studera detta ämne försöker forskare att förstå hur dessa ekosystem kan hjälpa oss att avlägsna överskottet av koldioxid från atmosfären. Målet med denna uppsats är att utföra en litteraturstudie och analysera, samt sammanställa den nya forskningen om ’blue carbon’ som publicerats de senaste 10 åren. Uppsatsen kommer undersöka hur stor skillnad det är mellan de olika ekosystemen och vilka hot de står inför i framtiden. Dessutom kommer den undersöka ifall forskare kommit närmre i att enas kring förutsägelser om framtiden för ’blue carbon’, och hur dess roll i att mildra klimatförändringarna kommer se ut.
455

Spatial and Temporal Variations in a Perennial Firn Aquifer on Lomonosovfonna, Svalbard / Rumsliga och tidsmässiga variationer i en flerårig firnakvifer på Lomonosovfonna, Svalbard

Hawrylak, Monika, Nilsson, Emma January 2019 (has links)
A firn aquifer is a type of englacial water storage that forms when surface meltwater fills up the pore space in porous firn. If the retention time exceeds one year the feature is regarded as perennial. The melt and accumulation rates as well as the available pore space determine the formation and extent of the firn aquifer. Flow of water within the aquifer caused by gradients in hydraulic potential leads to redistribution of water and consequently to a change in the level of the water table. This thesis focuses on a perennial firn aquifer on the Lomonosovfonna ice field on Svalbard. Spatial and temporal variations in the depth to the water table as well as variations in reflectivity strength of the water table are analysed using data from ground penetrating radar surveys along with MATLAB and ArcGIS software tools. The results show a clear connection between surface topography, steepness of its slopes and depth to the water table. It is also proved that the depth varies between different years. During the four years of study, the water table in the area rose closer to the surface. The results also show that the reflections from the top of the water table are stronger and more frequently detected in areas with gentler water table slopes. A similar correlation is true for the surface topography slope, where a gentler slope shows a stronger reflectivity. The results support the previous research done on Holtedahlfonna’s aquifer on Svalbard as well as aquifers on Greenland. / En firnakvifer är en typ av englacial vattenlagring som formas när smältvatten från en glaciärs yta fyller upp porutrymmen i porös firn. När retentionstiden överskrider ett år betraktas akviferen som flerårig. Smält- och ackumulationshastigheten samt det tillgängliga porutrymmet avgör bildningen och utsträckningen av akviferen. Vattenflödet i akviferen orsakad av gradienter i hydraulisk potential leder till omfördelning av vattnet och därmed till förändringar i vattenytans nivå. Denna uppsats fokuserar på en akvifer på isfältet Lomonosovfonna på Svalbard. De rumsliga och tidsmässiga variationerna i djupet till vattenytan samt de rumsliga variationerna i reflektivitetsstyrkan från vattenytan analyseras med hjälp av georadarmätningar samt MATLAB- och ArcGIS-mjukvaror. Resultaten visar ett tydligt samband mellan yttopografin, dess lutning samt djupet till vattenytan. Dessutom är det bevisat att djupet varierar mellan olika år. Under den fyra år långa undersökningssperioden har vattenytan i mätområdet stigit. Vidare visar resultaten att reflektioner från vattenytan är starkare och mer frekvent observerade i områden där vattenytans lutning är svag. En liknande korrelation gäller också för yttopografin, där svagare lutning ger upphov till en starkare reflektivitet. Resultaten stödjer den tidigare forskningen gjord både på akviferen på Holtedahlfonna på Svalbard och akviferer på Grönland.
456

Adoption and sustained use of energy efficient stoves in rural Uganda

Hoigt, Julia January 2019 (has links)
In 2011, Energy saving (mud) stoves were introduced in villages around the Kachung Forestplantation in rural Uganda as part of an effort to support local sustainable development. Initial fieldwork showedthat the stoves had not been adopted as much as the apparent benefits would suggest. This has been a commonissue with improved cooking stove projects around the world. In order to find out why the stoves are notadopted, 67 women in charge of the cooking were interviewed additionally participant observations of cooking,other daily work routines and building stoves conducted, as well as interviews with other relevant stakeholders.Results show that women struggle to find enough firewood and are bothered by the smoke produced whencooking, which makes them generally very interested in improved mud stoves. Indeed many women hadadopted a local version of the mud stove in order to ease the burden of firewood collection. The reason for notadopting a mud stove in general can be mainly attributed to work burden in constructing it. As for the moresophisticated energy saving mud stoves introduced, additional factors were that the implementation strategyshows weaknesses in how the knowledge on how to build the stove is supposed to spread. Further, the stoveintroduced is rather complex in the way it is supposed to be built, which makes it difficult to spread theknowledge of how to build it. The implementation strategy needs to be revised under consideration of the localcircumstances in order to achieve a higher adoption rate.
457

Kartläggning av möjligheten att återanvända takdagvatten för att minska dricksvattenförbrukningen

Andersson, Linnea January 2019 (has links)
Dricksvatten är vårt viktigaste livsmedel. I takt med klimatförändringarna kommer temperaturen öka och vädret bli mer extremt vilket gör vår tillgång till dricksvatten mer sårbar. Redan idag finns problem med dricksvattenförsörjningen i vissa delar av Sverige. Ett sätt att minska dricksvattenförbrukningen är att samla in regnvatten och använda det till processer med lägre kvalitetskrav än dricksvatten. Swedavia jobbar aktivt med att få mer miljövänliga flygplatser och som en del av detta minska dricksvattenförbrukningen. Detta projekt utreder möjligheten att samla upp regnvatten på takytor för att använda till processer som idag använder dricksvatten. Projektet är koncernövergripande och applicerbart på samtliga av Swedavias flygplatser även om arbetet utförs på Stockholm Arlanda Airport. I detta examensarbete har kvaliteten på vattnet från fem olika typer av tak studerats. Taken valdes bland annat utifrån tidigare utförda studier där föroreningsgraden på vattnet från olika sorters tak undersökts. Även faktorer som förekomst på flygplatserna spelade in. Provtagning utfördes vid två tillfällen där avrunnet regnvatten samlades in från de fem olika taken samt ett referensprov på rent regnvatten. Fem näringsämnen, löst organiskt material, suspenderat material och sex olika tungmetaller analyserades. Tre av taken gav så pass höga värden att de överskred satta gränsvärden. Det gröna taket gav höga halter fosfor och löst organiskt material. Taket med TRP-stål gav höga zinkhalter vilket tros bero på den zinkbeläggning som taket har. Taket med PVC-plastduk gav också höga zinkhalter vid en av provtagningarna, men inte lika höga som på TRP-ståltaket. Taken med FPO-plast, som är en mer miljövänlig plastduk, och taket med takpapp gav låga värden och överskred inte några satta gränsvärden. Referensprovet på regnvatten gav hög halt suspenderat material vid en av provtagningarna samt höga blyhalter som överskred gränsvärdena. Slutsatserna av detta projekt är att gröna tak, tak med TRP-stål och tak med PVC-plastduk riskerar att överskrida gränsvärden vilket gör att de lämpar sig sämre för uppsamling av regnvatten än de resterande taken. Resultatet baseras på de två provtagningar som utfördes vilket gör att fler provtagningar bör utföras för att kunna dra den definitiva slutsatsen att dessa tre typer av tak inte lämpar sig för detta ändamål. Taken med FPO-plast och takpapp överskrider inga gränsvärden och kan, utifrån de analyserade parametrarna, lämpa sig för uppsamling av regnvatten. Det är dock viktigt att poängtera att för att kunna återanvända vattnet och garantera att det håller en tillräckligt bra kvalitet behöver fler parametrar analyseras, något som inte kunde genomföras i detta projekt. / Drinking water is vital for our daily life. With climate change comes increasing temperatures and more extreme weather which can jeopardize our access to drinking water. One way to reduce our drinking water consumption is to collect rainwater and use it for processes which have lower quality demands than drinking water. Swedavia is constantly working on making their airports more environmentally friendly and as a part of this reducing the drinking water consumption. This project examines how water can be collected at Swedavia’s airports. The project results should be of intent to all of Swedavia’s airports even if the project is performed at Stockholm Arlanda Airport. In this project the water quality from five different types roofs has been studied. The different kind of roofs were chosen based on previous studies where pollutants in roof-harvested rainwater were studied. Other aspects such as location on the airports were also considered. Samplings were collected at two different occasions where water was collected from the different roofs. One sample of clean rainwater was collected as a reference. Five nutrients, dissolved organic matter, suspended matter and six heavy metals were analyzed. Three of the roofs gave water with high values that exceeded the quality limits. The samples from the green roof showed high levels of phosphorus and dissolved organic matter. The steel roof gave high levels of zink which may origin from its zink coating. The roof with PVC plastic also gave high levels of zink, but not as high as the steel roof. The roof with FPO plastic, a more environmentally friendly plastic, and the roof with roof paper gave low values and did not exceed any quality limits. The reference sample of clean rainwater gave high values of suspended matter at the second occasion and high values of lead that exceeded the quality limits. The conclusions of this project are that roof-harvested rainwater from green roofs, steel roofs and roofs with PVC plastic may exceed quality limits which makes them less suitable for collecting and re-use. The results are based on the two sampling occasions which means that sampling at more occations needs to be done to make definitive conclusions. The roofs with FPO plastic and roof paper do not exceed any quality limits and can therefore, according to the analyzed parameters, be suitable for collecting rainwater. It is important to note that to be able to reuse the water and guarantee that the quality of the water does not exceed any quality limits more parameters should be analyzed.
458

Seasonality of resource limitation of stream biofilm : Nutrient limitation of an arctic stream in northern Sweden

Hauptmann, Demian January 2019 (has links)
Arctic ecosystems are sensitive to climate change and this biome is experiencing accelerated warming. Climate change in the arctic is projected to further alter precipitation and temperature patterns, which may influence land-water interactions in the future. Such changes have the potential to affect aquatic biofilm communities (i.e., algae, bacteria, and fungi) that form the base of riverine food webs, yet are sensitive to changes in thermal and light regimes, and are potentially limited by macronutrients like carbon (C), nitrogen (N) and phosphorus (P). This study investigated the patterns of resource limitation for autotrophic and heterotrophic biofilms in the Arctic using nutrient diffusing substrata (NDS) in a river network in northern Sweden (Miellajokka). Continuous NDS deployments (March until September) in a birch forest stream were combined with a spatial survey of nutrient limitation in late summer across 20 sites that encompassed a variety of nutrient, light, and temperature combinations. Results show that nutrient limitation of autotrophic processes was common during summer, but also that light inhibited algal growth in early season, and that temperature accelerated rates of activity throughout the growing season. By comparison, heterotrophic processes were less influenced by temperature, unless experimentally supplied with N and P. Alongside persistent N limitation, co-limitation by macronutrients (NP: autotrophic and heterotrophic biofilm, or CNP: heterotrophic biofilm) dominated the overall pattern of limitation over time and space. However, results from the spatial survey suggested that the identity of the primary limiting nutrient can change from N to P, based on differences in chemistry that arise from varying catchment features. As arctic studies are often conducted at individual sites during summer, they may miss shifts in the drivers of stream productivity that arise from variable nutrient, temperature, and light regimes. This study attempted to capture those changes and identify conditions where one might expect to see transitions in the relative importance of physical and chemical factors that limit biofilm development. These results also highlight the challenge of identifying the single most important limiting nutrient (e.g., N versus P) in streams and rivers across the Arctic, as I found that both nutrients could play this role within a single, relatively small drainage system.
459

Lake water chemistry and the changing arctic environment : Topographic or climatic control?

Gydemo Östbom, Viktor January 2019 (has links)
The arctic is expected to be one of the regions most affected by ongoing climate change, with relative changes in air temperatures significantly higher than the global mean. Lakes are recognized for their potential role in the global climate system and as ecosystems of importance for local societies. As such, there is a scientific interest regarding how arctic lakes and their geochemistry will respond to climatic changes. Lakes around Kangerlussuaq (66.99 N, 51.07 W), south-west Greenland, are known for their unique geochemical composition, including oligosaline lakes, of which some are enriched in colourless dissolved organic carbon (DOC). The origin of this DOC and the importance of local catchment properties for the general water chemistry is currently being debated. This thesis aimed at: i) exploring the extent and effect of catchment morphology on lake-water chemistry in the Kangerlussuaq area; ii) determine the predominant origin of DOC, aquatic or terrestrial. I used a remote-sensing approach based on satellite imagery and digital elevation model (DEM) in deciding landscape influence on water chemistry (pH, alkalinity, conductivity, base cations, sulphate, nitrogen and absorbance). To trace the origin of the organic sources behind DOC lake water and sediments, I used a hydrogen isotope tracing method. The remote sensing approach revealed that morphological characteristics serving as proxies for lake water residence time and hydrologic connectivity (e.g. lake altitude difference and absence of outlets) explained up to 77% of the variations in lake water chemistry. The hydrogen isotopic signature of the DOC indicated a predominantly autochthonous origin, i.e. 59 to 78% was estimated to originate from algae. I conclude that lake water chemistry of the lakes in the study area is primarily controlled by the precipitation : evaporation balance, enhanced by static catchment characteristics regulating water age. Thus, the examined lake water chemical properties are likely to remain across future climatic scenarios, providing the current precipitation : evaporation balance prevails.
460

‘Hot Planet, Cool Athletes’: A Case Study of Protect Our Winters and the Role of Ski Activism in Combating Climate Change

Mihala, Ioana January 2019 (has links)
Despite the high vulnerability of alpine environments to climate change, adaptation and mitigation within the winter sport industry have only recently received consideration. However, the focus has been mainly on the adaptation measures of the ski resort operators (supply side), not taking into consideration other actors (demand side) or attempts aiming for a sustainable form of winter tourism. Through a case study of Protect Our Winters (POW), an environmental group started by a professional snowboarder, this research aims at investigating the role of a new social movement, ski activism, in combating climate change. Interviews with active members of POW Austria and participant observations at events and meetings of this same organisationwere conducted and analysed to gain an overview on the matter. Results show that empirical knowledge of climate change consequences and the concern about the future of lifestyle sports such as skiing and snowboarding can motivate activist behaviour. Furthermore, the variety of outreach tools of an organisation like POW can help raise awareness and inspire to join the ski activist movement. Because the study deals with a new type of movement, further research is needed to explore the effects of this alternative climate mitigation attempt and to analyse more initiatives and organisations started by the demand side of the winter sport industry.

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