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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.
91

Sustainable use of Baltic Sea natural resources based on ecological engineering and biogas production : System analysis and case study Trelleborg

Karlsson, Sara January 2009 (has links)
Eutrophication is one of the most serious environmental problems in the Baltic Sea due to factors such as nutrient discharges from different sources and long residence time. Eutrophication gives rise to increased primary production, often followed by oxygen depletion and disruption of important ecosystems. An action plan has been created by the Helsinki Commission (HELCOM) in order to achieve good ecological status of the Baltic Sea in the year of 2021. According to the action plan, 21 000 tonnes of nitrogen and 290 tonnes of phosphorus shall be decreased of the annual discharge from Sweden. The aim of methods within ecological engineering is to solve environmental problems, and the applications ranging from the harvesting of existing ecosystems to the construction of new ecosystems. This study evaluates if harvest of algae, reed, and mussels can help meeting the goals of the action plan considerably, in accordance with areas and biomass amounts that need to be harvested, and to assess the efficiency of the three biomasses with regards to nutrient reduction. The potential of harvested biomasses as substrates in biogas production and as fertilizers is investigated, and how much fossil CO2 that can be saved from being released to the atmosphere if net energy benefits, calculated from energy budgets in the biogas process, replaces fossil fuels. Life cycle inventories which extend from the harvest (i.e. from the Baltic coast of Sweden) to the production of biogas have been made in order to investigate the biogas potential of algal, reed, and mussel biomass. Suitability of the three biomasses as fertilizers has been assessed through comparison between nutrient sufficiency of crops and nutrient contents of the three biomasses (i.e. based on quotients of nitrogen). The quantity of biomass in the areas that can be harvested can help meeting the goals of the action plan drawn up by HELCOM, and mussels show to be most efficient with regards to nutrient reduction efficiency. Reed has the highest net energy benefit followed by algae, and both biomasses show potential of further investigation as substrates in the biogas production process. Mussels have low net energy benefit and thus are not a suitable substrate in biogas production. The three biomasses are suitable as fertilizers with respect to contents of nitrogen but the content of phosphorus occurs under the sufficiency levels for the crops (i.e. peas, grain, and sugar beets). For algae and reed, the potassium contents occur above the sufficiency level for peas and grain but under the level for sugar beets, mussels contain lower levels of potassium than the need of the investigated crops. / Eutrofiering är ett av de största miljöhoten i Östersjön och orsakas av faktorer som utsläpp av näringsämnen från olika källor samt lång uppehållstid. Eutrofiering ger upphov till ökad primärproduktion där syrebrist och störning av viktiga ekosystem är vanliga påföljder. En aktionsplan har utformats av HELCOM som fastställer att Sverige ska reducera 21 000 ton kväve och 290 ton fosfor av de årliga utsläppen till Östersjön, med syftet att uppnå god ekologisk status år 2021. Metoder inom ecological engineering innefattar sund skörd av existerande ekosystem med syftet att lösa miljöproblem. I den här studien undersöks om skörd av alger, vass och musslor kan hjälpa till att möta miljömålen med påtaglig effekt, samt mängder och ytor som måste skördas av de tre biomassorna. Effektiviteten med avseende på näringsreducering hos de tre biomassorna jämförs. Potentialen för användning av de skördade biomassorna som substrat i biogasproduktion samt som gödningsmedel undersöks, samt hur mycket CO2 som kan besparas att släppas ut till atmosfären om nettoenergi från energibudgetar i biogasprocessen ersätter fossila bränslen. Energibudgetar som sträcker sig från skörd till biogasproduktion har utformats samt näringsinnehåll av de tre biomassorna jämfördes med näringsbehov hos vissa grödor för att ta reda på biomassornas eventuella potential som gödningsmedel. Beträffande biomassor och areor som finns att skörda visade det sig att metoderna kan möta miljömålen utformade av HELCOM. Musslor visade sig vara den mest effektiva biomassan att skörda med avseende på näringsämnesreducering. Vass erhöll högst nettoenergiutbyte (i.e. baserat på energibudgetarna) följt av alger, därmed finns potential för vidare undersökning av de båda biomassorna som substrat i biogasprocesser. Nettoenergiutbytet i biogasprocessen hos musslor var lågt vilket visar att musslorna inte är lämpligt som substrat. De tre biomassorna uppvisar lämplighet som gödningsmedel med avseende på kväveinnehåll men innehållet av fosfor ligger under näringsbehovet hos de grödor som undersöktes. Alger och vass uppfyller kaliumbehovet hos ärter och spannmål, men inte hos sockerbetor. Musslornas kaliuminnehåll är lägre än näringsbehovet hos samtliga grödor.
92

Hur Biofouling Påverkar Östersjön : En allmän litteraturstudie / How Biofouling Affects the Baltic Sea : A general literature study

Eliasson, Emil, Dahl, William January 2023 (has links)
The aim of this literature study was to investigate the effects of biofouling in the Baltic Sea. This was done to increase environmental awareness and understanding of the importance of a sustainable marine environment. A systematic search in selected databases resulted in the study being based on tio research articles. The overall results of the study show that biofouling demonstrate negative effects, but the effects are not fully understood to date and the focus is still on economic aspects. Furthermore, it was observed that the studied organizations are currently focused on greenhouse gas issues, but they have also been paying attention to biofouling problems in recent time. The literature study provides important insights into the effects of biofouling.
93

An ecological study of the migration, food composition and relative abundance of three-spined stickleback (Gasterosteus aculeatus) in a shallow area in Kalmar Sound.

Söderling, Peter January 2013 (has links)
The populations of three–spined sticklebacks (Gasterosteus aculeatus) in the Baltic Sea have increased tenfold over the last decade. A large increase in abundance can alter the offshore and coastal food webs. Despite of these facts, there are large gaps in the knowledge about the stickleback ecology in the Baltic and the possible effect they might have on their environment. Earlier investigations state that stickleback mainly occupy the deeper areas offshore, and only migrate to the shallow areas during May–July to spawn. Observations by recreational fishermen indicate that this may be incorrect, and that some adult sticklebacks are present in the shallow areas even during the winter. One aim of this study was to investigate the timing of stickleback migration to a shallow coastal area in Kalmar Sound. The study also aimed to examine the relative abundance in two adjacent shallow areas in the archipelago south of Kalmar, where one of the areas is a pike spawning ground. A one month long test fishing with fyke nets was started on the first day after ice break. Results show that the sticklebacks are present in the bays immediately after the ice break, and that high abundances coincide with the pike spawning period. Stomach analyses showed that sticklebacks consumed a large proportion of crustaceans, but also fish eggs were found. These results shed new light on the management actions for many of the coastal spring spawning fish species that have shown decreasing abundances during the last decades. / Bestånden av storspigg (Gasterosteus aculeatus) i Östersjön har ökat markant, data visar på en tiofaldig ökning under det senaste decenniet. Ökningen kan medföra att bl.a. näringsväven, till havs och längs kusterna förändras. Trots vetskapen om detta finns det kunskapsluckor kring spiggens ekologi och dess möjliga påverkan på sin omgivning. Litteratur säger att spiggen till största del bara befinner sig inne längs kusterna under maj-juli. Observationer från sportfiskare tyder på att detta inte stämmer, och att vuxen storspigg befinner sig inne längs kusten och i skärgårdsvikar året om. Ett syfte med studien var att undersöka när spiggen kom in till de grunda vikarna i Kalmarsund. Studien jämförde även spiggtätheterna mellan två närliggande områden där den största skillnaden var födan. Ett månadslångt provfiske inleddes den första isfria dagen i två skyddade vikar söder om Kalmar, där en av lokalerna var en dokumenterad leklokal för gäddor. Resultaten visade att spiggen fanns i vikarna direkt efter islossningen, och vid fisket sammanföll de största spiggfångsterna med gäddleken. Maganalyser visade att en stor andel av födan bestod av olika kräftdjur, men även romkorn hittades. Resultaten tyder på andra förutsättningar för många av de hårt ansatta vårlekande fiskarterna än vad som tidigare är dokumenterat.
94

Gråsälen - en skyddsvärd art, ett problem eller en resurs? : En rättsvetenskaplig undersökning om artskydd, säljakt och handel med sälprodukter i EU / The Grey Seal - a species worthy of protection, a problem or a resource? : A study in legal science on species protection, seal hunting and trade in seal products in the EU

Woivalin, John January 2021 (has links)
No description available.
95

En undersökning av potentiellt odlingsbara makroalger i Hanöbukten, Östersjön

Persson, Beatrice January 2023 (has links)
In the future, the cultivation of algae for food may become increasingly important in Sweden. But this area is still new in Europe and most of the harvest today comes from wild stocks. In Sweden, cultivation is only available on the west coast, but research is underway to see if it is possible to start cultivating macroalgae in the Baltic Sea as well. The Baltic Sea has completely different biological conditions than the west coast, and one of the challenges is the low salinity, which limits the species that can live in the Baltic Sea. This is something that the Marine Center in Simrishamn is also researching in the project Tångkusten, of which this study is a part of. The purpose of this study is to use a literature study to compile available knowledge about which algae that has the potential to be cultivated in the future and what the life cycles of these algae look like. An inventory of the macroalgae found locally in Hanöbukten was also carried out. Based on this information, possible cultivation methods and the advantages of each species are discussed, but also the challenges that may arise.  The results showed that the most abundant species were filamentous brown algae, bladder wrack and saw wrack . The species deemed most cultivable are gut weed and sea lettuce. Clawed fork weed, bladder wrack and saw wrack are also considered to have some cultivation potential. Among the biggest challenges are the growth of epiphytic algae and finding a suitable site for cultivation. / Projektet Tångkusten på Marint centrum i Simrishamn
96

En kanons värde : En undersökning av svårigheterna och nyttan med att bärga och förmedla senmedeltida kanoner på museum / A gun’s worth : Investigating the gains and difficulties in recoveringand displaying late medieval guns in a museum setting

Jansson, Michael January 2023 (has links)
Marinarkeologiska föremål är en icke desto mera undersökt underkategori i museisamlingar. De skiljer sig frånandra typer av föremål i samlingar då de genom sin fyndplats är mera krävande. Det är också värt att etableravad föremålet har för värden efter utgrävningen. Som en del av värde och förmedling tas föremålenskonservering och utgrävning också upp.Genom att undersöka bärgade tre kanoner från tre vrak från perioden 1480 till 1580 ef. kr försöker uppsatsenatt belysa den typen av föremål ur flera perspektiv som går att sammanfatta ur bevarande och förmedlande.Kanonerna som undersöks är "Brisundskanonen" på Gotlands museum, en kanon från örlogsfartyget Mars ochlavetter bärgade från Gribshunden på Blekinge museum. Undersökningen är gjord genom platsbesök,intervjuer, och litteraturstudier. Målet med undersökningen är att skapa kunskap om marinarkeologiskaföremål, dess egenskaper, värden och processer. / Marine archaeological objects are an under-researched subcategory in museum collections. They differ fromother types of objects in collections as they are more demanding due to their former location. It is also worthestablishing what the object's value is after excavation. As part of value and mediation, the conservation andexcavation of the objects is also addressed.By examining three guns recovered from three wrecks from the period 1480 to 1580 AD. The essay tries to shedlight on the type of object from several perspectives that can be summarized from preservation and mediation.The cannons being examined are the "Brisund cannon" at Gotland's museum, a cannon from Mars, and lavettessalvaged from Gribshunden at Blekinge museum. The investigation is done through site visits, interviews, andliterature studies. The goal of the survey is to create knowledge of how museums best manage this type ofobject.
97

Sonar Sea : The acoustic experience of the Baltic Sea dynamics

Stampe, Elin January 2021 (has links)
This thesis project aims to discuss the conditions and importance of water as a dynamic body in our environment, as water is affecting life on Earth on all levels. By focusing on the Baltic Sea, a sensitive body of water, I am exploring the acoustic characters of the sea dynamics through sound recordings at three bays in the Stockholm Archipelago. How can an acoustic exploration of the Baltic Sea dynamics mediate a sensitive relationship to our marine environments? Sound defines environments and gives indications of their current state. In this project, I intertwine an artistic approach involving our senses with scientific research of measuring to further an understanding of the relationship between humans and nature. The project explores water and sound in two parts, first as a method for listening to the sea, second as a spatial composition created for a sensory experience of the sea’s endless motion. It is my hope that my installation can stir emotions and create an understanding for the environmental challenges facing the Baltic Sea and inspire action towards prosperous natural environments where we live with and not apart from nature.
98

I bronsålderns gränsland : Uppland och frågan om östliga kontakter

Ojala, Karin January 2016 (has links)
In archaeological research, the province of Uppland has often been viewed as the northern ‘periphery’ of the Nordic Bronze Age region. At the same time, many researchers have also emphasized the distinctive and ‘independent’ regional character of Uppland and northern Mälardalen. Throughout the twentieth century, Late Bronze Age contacts between Uppland and areas to the east – especially Finland, the Baltic countries and Russia – were much discussed and played an important role in the creation of Mälardalen as a distinctive Bronze Age region. This dissertation examines how images of the Late Bronze Age in the Mälardalen region, more specifically Uppland, have been formed from the late nineteenth century until today, and how views on eastern contacts have affected interpretations of Bronze Age Uppland. The study consists of three parts: 1) A critical discussion on political dimensions of archaeology and archaeological concepts of contact, interaction, similarity and difference, with a special focus on Bronze Age research. 2) A historical examination of representations of the Late Bronze Age in Mälardalen and Uppland, including a discussion about contacts with northern Sweden and a case study of Broby, a Late Bronze Age site near Uppsala. 3) An analysis of debates on contacts between Mälardalen and areas further to the east, through case studies of bronze axes, so-called Mälar celts and Ananino celts, ceramics and inhumation burials. In the analysis, special focus is placed on the Volga-Kama region in Russia and archaeological research in Russia and the Soviet Union. The study shows that discussions on contacts and interaction between ‘East’ and ‘West’ have, in many ways, been affected by the changing political situation during the twentieth and early twenty-first centuries. Knowledge about archaeological research in Russia and the Soviet Union has been very limited among archaeologists in Sweden. In order to further investigate the character and importance of eastern contacts during the Late Bronze Age, more collaboration and exchange between researchers in the different countries is needed. Furthermore, in order to better understand eastern contacts, it is also necessary to investigate in greater depth the relations between Mälardalen and northern Sweden.

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