Utvärdering av geotextildukar för tillfällig sedimentkontroll : Avseende suspenderat material, PAH samt kvicksilver

Geotextildukar används idag som tillfällig kontroll av sedimentgrumling vid vattenarbeten. Syftet med examensarbetet är att ge ökad kunskap kring olika geotextildukars genomsläpplighet med avseende på suspenderat material, PAH (Polycykliska aromatiska kolväten) och kvicksilver vid suspension av sediment från Karlbergskanalen. Detta har gjorts genom en laboration. Resultaten visar att det inom några minuter bildas en filterkaka på de tre undersökta dukarna. Dukarna blir täta då de utsätts för finpartikulärt suspenderat sediment med koncentrationen 57 g/l hämtat från Karlbergskanalen. Under de 2,5 timmar långa försöken har dukarnas permeabilitet kraftigt reducerats. Under laborationen var PAHtot och mängden PAH i den filtrerade fraktionen störst vid turbiditetsmaximum. Den filtrerade fraktionen PAH följde turbiditeten och reducerades med 21 % samtidigt som turbiditeten reducerades med 24 % under försöket. Även den totala kvicksilvermängden var störst vid turbiditetsmaximum, resultaten är dock inte statistiskt säkerställda. Under laborationen gav en högre halt suspenderat material en lägre andel PAH i den filtrerade fraktionen, troligtvis beroende på re-adsorption. För att utvärdera hur stor andel av PAH, kvicksilver, kadmium och koppar som befinner sig i den filtrerade fasen har det genomförts försök där sediment och vatten skakats 3x10 timmar. Av den totala PAH koncentrationen var 0,07 % i den lösta fasen. Endast en låg andel av koppar, kadmium och kvicksilver återfanns i den lösta fasen (< 1 %). Trots den låga andelen i den filtrerade fraktionen skulle motsvarande haltökningar i Karlbergskanalen innebära halter långt över aktuella gränsvärden[1]i dukbassängen. Innan filterkakan bildats sker ingen reduktion av turbiditeten för två av de tre undersökta dukarna. Geotextilskärmarna förhindrar således ingen spridning av miljögifter utan bildningen av en filterkaka. Om filterkakan bildas och består i fält går inte att fastställa utifrån laborationen. [1]MKN MAC för löst Hg och Cd, Naturvårdsverkets föreslagna GV för löst Cu MKN MAC för den totala PAH koncentrationenGeotextiles are used as temporary sediment controls in water during construction work. The aim of this project is to give background information to a cost effective control program and to increase the knowledge about geotextiles and their permeability for suspended sediment, PAH and Hg for a site specific sediment. Laboratory studies have been conducted in order to evaluate three geotextiles with regard to their ability to separate suspended sediment, PAH and Hg. The results show that a filter cake is formed. The textiles became clogged within a time period of 15 minutes and no sediment passed the textiles after this. A sediment concentration of 57 g/l was used. The separation of suspended particulate matter is 28-78 % and the textile with the greatest reduction capacity was the thinnest one. The separation of PAHtot was 79 %, meanwhile the average separation of suspended sediments was 78 %. The geotextile did not reduce the dissolved fraction of PAH. This fraction was larger on the outside suggesting that the concentration of suspended material was too low to re-adsorb the dissolved PAH. The turbidity decreased with 24 % during the experiment due to sedimentation, the dissolved fraction of PAH was reduced with 21 % during the same time period. The amount of Hgtot was largest at turbidity maximum. Laboratory experiments where sediment was shaken 3x10 hours with distilled water have also been conducted in order to evaluate the amounts of PAH, Hg, Cu and Cd that partition in the dissolved phase. 0, 07 % of the total amount of PAH was found in the filtered phase and only small fractions of Cu, Cd and Hg (< 1 %). Despite the small percentage in the filtered fractions the corresponding increase in Karlbergskanalen would result in concentrations well above maximum allowed concentrations[1]in the geotextile encircled area. There is no reduction of the turbidity before the filter cake is formed. It is not possible to draw any conclusions about the formation of a filter cake in field and if a formed filter cake would be broken by hydraulic forces or not. [1]MKN MAC for dissolved Hg and Cd, Swedish Environmental Protection Agency’s suggested limit value for dissolved Cu, MKN MAC for the total PAH concentratio

Sustainability Aspects of Bioenergy and Nutrient Recovery from Marine Biomass : Baltic Sea case studies

Coastal areas around the world are experiencing environmental problems such as climate change and eutrophication. These, in turn, lead to emerging challenges with excessive amounts of biomass that impact coastal communities. Developing utilisation strategies for marine biomass is therefore highly relevant and forms part of the blue growth research field. In response to environmental concerns, as a waste management strategy and as part of blue growth research initiatives, several Baltic Sea coastal projects have been initiated in recent years to study utilisation of maritime biomass. However, the sustainability of these utilisation strategies has not been critically appraised. Therefore, the work presented in this thesis explored some key sustainability aspects of two Baltic Sea case studies utilising common reed (Kalmar, Sweden) and mass-occurring filamentous macroalgae (Trelleborg, Sweden) for biogas and biofertiliser recovery. Energy analyses suggested that both case studies could provide a positive energy balance and have the potential to achieve nutrient recovery. Moreover, a contingent valuation study in Trelleborg demonstrated considerable welfare benefits of biomass utilisation. These findings indicate that marine biomass utilisation strategies highlight potential to contribute to environmental and welfare benefits of these coastal communities.QC 20141126</p

Sustainability Aspects of Bioenergy and Nutrient Recovery from Marine Biomass : Baltic Sea case studies

Coastal areas around the world are experiencing environmental problems such as climate change and eutrophication. These, in turn, lead to emerging challenges with excessive amounts of biomass that impact coastal communities. Developing utilisation strategies for marine biomass is therefore highly relevant and forms part of the blue growth research field. In response to environmental concerns, as a waste management strategy and as part of blue growth research initiatives, several Baltic Sea coastal projects have been initiated in recent years to study utilisation of maritime biomass. However, the sustainability of these utilisation strategies has not been critically appraised. Therefore, the work presented in this thesis explored some key sustainability aspects of two Baltic Sea case studies utilising common reed (Kalmar, Sweden) and mass-occurring filamentous macroalgae (Trelleborg, Sweden) for biogas and biofertiliser recovery. Energy analyses suggested that both case studies could provide a positive energy balance and have the potential to achieve nutrient recovery. Moreover, a contingent valuation study in Trelleborg demonstrated considerable welfare benefits of biomass utilisation. These findings indicate that marine biomass utilisation strategies highlight potential to contribute to environmental and welfare benefits of these coastal communities.QC 20141126</p

Testing tools - Schools Columbus ägg? : A comparision of two tests which can be used for detecting students with reading and writing disabilities.

Det finns många olika typer av tester som används i skolan för att upptäcka läs- och skrivsvårigheter hos elever. Dessa tester saknar vetenskaplig grund men används ändå i skolan. Detta arbete har därför undersökt två tester, ett screeningtest – Läskedjor-2, och ett kartläggningstest – Kartläggaren. Dessa tester valdes specifikt för att de används i Linköpings kommun. Det är två olika typer av tester som undersöks i den här uppsatsen, men en del av förmågorna som testas är desamma för testerna och därför jämförbara. Materialet har analyserats med hjälp av en kritisk hermeneutisk analysmetod. Metoden är baserad på Phillips &amp; Browns fem steg för kritisk hermeneutisk analys. Med hjälp av analysen blev många skillnader tydliga, men den största skiljelinjen mellan testerna är normeringen av testen och testernas höga respektive låga validitet och reliabilitet.

An invisible disability : reading disability and the school´s obligations

Syftet med den här studien var att få en bredare bild av läsproblematik, vad det innebär och hur det kan uppkomma. Detta för att lärare ska kunna arbeta förebyggande i klassrummet. Syftet var även att titta närmare på det ansvar och de möjligheter skolan har i arbetet för att hjälpa elever med läsproblematik. Studien har gjorts i form av en litteraturstudie och resultatet visar på att läsproblematiken är ett komplext begrepp med flertalet olika definitioner. Läsproblematiken kan ha flera olika orsaker, biologiska som sociokulturella. Vissa studier visar på att skillnaden mellan pojkar och flickors läsning beror på motivation, uppmuntran till läsning och läsande förebilder. När det kommer till skolans ansvar och möjligheter att hjälpa elever med läsproblematik visar resultatet att möjligheterna är många, men bristen på tydliga riktlinjer försvårar processen, vilket kan resultera i att elevers läsinlärning blir lidande. En upptäckt rörande tester som används vid utredningar kring elever med läsproblematik visar att de tester som används saknar helt vetenskaplig grund. Det finns alltså ingen forskning kring testernas validitet eller reliabilitet. Man har alltså utgått från praktiska framgångar vid val av tester.

Non-market values of algae beach-cast management - study site Trelleborg, Sweden

Eutrophication is one of the most serious global threats to coastal areas. One effect of eutrophication is seasonal macroalgal blooms. As a consequence, large amounts of beach-cast algae are today reported from coastal areas worldwide. In this study, we analyze nonmarket benefits by capturing local residents' Willingness To Pay (WTP) for an environmental program to regularly remove and utilize beach-cast algae to produce bioenergy and biofertilizer. Results indicate a considerable WTP among local residents in the Baltic Sea study site. This WTP estimate together with a potential increase in non-resident beach tourism amounts to potentially substantial welfare benefits from the environmental program. These benefits could encourage similar environmental programs in the future

Harvesting of drifting filamentous macroalgae in the Baltic Sea: an energy assessment

Eutrophication combined with climate change has caused ephemeral filamentous macroalgae to increase and drifts of seaweed cover large areas of some Baltic Sea sites during summer. In ongoing projects, these mass occurrences of drifting filamentous macroalgae are being harvested to mitigate eutrophication, with preliminary results indicating considerable nutrient reduction potential. In the present study, an energy assessment was made of biogas production from the retrieved biomass for a Baltic Sea pilot case. Use of different indicators revealed a positive energy balance. The energy requirements corresponded to about 30%–40% of the energy content in the end products. The net energy gain was 530–800 MJ primary energy per ton wet weight of algae for small-scale and large-scale scenarios, where 6 000 and 13 000 tonnes dwt were harvested, respectively. However, the exergy efficiency differed from the energy efficiency, emphasising the importance of taking energy quality into consideration when evaluating energy systems. An uncertainty analysis indicated parametric uncertainty of about 25%–40%, which we consider to be acceptable given the generally high sensitivity of the indicators to changes in input data, allocation method, and system design. Overall, our evaluation indicated that biogas production may be a viable handling strategy for retrieved biomass, while harvesting other types of macroalgae than red filamentous species considered here may render a better energy balance due to higher methane yields

The perception of aquaculture on the Swedish West Coast

Efforts are on the way on the Swedish West Coast to develop the capacity for cultivation of marine resources, notably of kelps. Given that this is a region of great natural and national heritage, public opposition to marine developments has been identified as a possible risk factor. This survey thus sought to shed light on awareness levels, perceptions of different types of aquaculture and on reactions to a scenario depicting future aquaculture developments on the West Coast. When asked about their general opinions of aquaculture, respondents tended to be favourable though a majority chose neutral responses. On the whole, respondents were favourable to the depicted scenario. Finally, it was found that the high-awareness group tended to be more supportive than the low or medium-awareness groups, hinting at the benefits of increasing awareness to reduce public aversion and to support a sustainable development of aquaculture on the Swedish West Coast