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763 Uppsatser om Soil carbon - Sida 25 av 51
Näringsretention i återskapad våtmark på betesmark : studier av en mad vid Bornsjön
It is important to construct or recreate different types of wetlands and study their retention of nutrients, since knowledge of their effectiveness in this matter is poor. In 2003 a wetland was constructed on an old meadow on the western shore of Lake Bornsjön in central Sweden. The main purpose of the wetland was to reduce the amount of phosphorus entering the lake, which is the back-up water supply for Stockholm when the city cannot obtain water from Lake Mälaren. Large areas around Lake Bornsjön consist of agricultural land and the nutrient concentrations in the inflows to the lake are usually relatively high (approx. 1 mg/l total nitrogen and 0.05-0.1 mg/l total phosphorus).
Val av tidpunkt för markberedning vid naturlig föryngring under skärm av Pinus sylvestris i Svealand : Timing of scarification when using natural regeneration in seed tree stands of Pinus sylvestris in Central Sweden
This thesis is built on a field study that was carried out in two seed-tree stands near by Götbrunna in Uppland, Sweden. The aim was to examine if scarification carried out in spring time could generate a more dense seedling establishment when using natural generation, than scarification carried out in autumn. It was also investigated whether there were differences in mortality the first season between the two plot-types. Plots were established block-wise with 50 blocks (pairs) on each site. The spring scarification was made with a hoe during 22-23 of April.
Närsaltsdosering till luftad damm : en åtgärd för ökad TOC-reduktion hos Skoghalls Bruk luftade damm
In the process of making carton boards into Skoghall Mill, are great quantities of water being contaminated. This water has to be treated before it is possible to release into the recipient, Kattfjorden. One of the contaminations that is important to extract from the wastewater, is organic carbon (measured as TOC-total organic carbon) because microbiological breakdown can lead to the bottom becomig free of oxygen.The wastewater treatment at Skoghall Mill is done through an external wastewater treatment that is located at the factory. The biological treatment (aerated lagoon) is a 140 000 m3 water pool with surface aerator, which is give oxygen to the water. In the lagoon live microorganisms who performs the biggest part of the TOC-reduction.One problem with the lagoon is that the treatment of TOC is considerably worse during wintertime than during summertime.
Småskalig vattenkraft :
Small hydropower plants have been an important source for electricity for many years.
During the 70?s the general thought was that nuclear was the future. Around 2000 small
waterpower plants were shut down. It wasn?t profitable to invest in.
Termomekanisk utmattning av Sanicro 25 : Materialmodellering med finita elementmetoden
The report aims to describe the austenitic stainless steel Sanicro 25 from a thermomechanical point of view. The thermal and mechanical properties of the material make it suitable for use in coal ? and thermal power plants. By the use of Sanicro 25 it would be possible to bring the efficiency of these plants up while bringing the carbon emissions down.A material model is created from material testing and validated through simulation in the finite element software Abaqus. The model that has been derived describes the material behavior during loading and stress relaxation for the first cycle in a thermomechanical fatigue test well.
Kalkning och vitaliseringsgödsling : synpunkter från organisationer och myndigheter samtprivata markägare i Kronobergs län
The background for this thesis is that at the beginnings of 1980´s the National Board of Forest started an experiment of lime dressing to reduce acidification in forest soil and in ground water. The purposes of this report are to explain organization?s, government?s and private landowners viewpoint on lime dressing and vitalization fertilization, some socio-economic aspects are presented. The general conclusions are that the majority of the interested party?s are positive to vitalization fertilization but the forests owner?s in generally need much more information about this topic..
Metodik för bestämning av åkerdikens status : fallstudie av ett dike i Munktorps socken
Agricultural drainage ditches are links between fields, lakes and oceans, having the potential to transport e.g. sediment and nutrients. When in a good condition, drainage ditches can act as sinks for e.g. phosphorus and sediments and prevent eutrophication downstream.
The aim of this study was to determine the condition of one agricultural drainage ditch and to come up with suggestions for appropriate measures. The aim was also to determine
which of the ditch?s properties that were possible to evaluate visually, which processes they represented as well as which properties required complementary physical analysis.
This in order to contribute to the work of developing a method for determining the status/condition of agricultural drainage ditches.
Inneklimatet på ett kontor : Undersökning av inneklimatet vån. G4 stadshuset samt kontor på Ånghammargatan
This report describes an investigation of the indoor climate in two different workspaces. Since we a big part of our lives are staying indoors in artificial environments, and more particularly in our workplaces, we think it would be interesting to do this investigation. The technical solutions for air treatment systems began with simple natural systems without fans and where the thermal rise of the air applied. In modern time is technical air treating systems used to take care of the fresh air supply. This type of units can supply filtered air with the right temperature to the building. Well-functioning ventilation is essential to bring clean fresh air to the room and effectively remove impurities without sound- or draught problems. The indoor climate is relevant for the output capacity.
Hållfasthetsegenskaper i gjutjärn : tensile properties of cast iron
In the last few years people have become more and more aware of how humanity is affecting the climate. In the direction of reducing the greenhouse gases is to design engines with higher tensile properties and reduced weight, in order to achieve lower fuel consumption and cleaner fuel incineration in today's truck engines.In order to achieve these requirements it?s necessary to increase the combustion pressure in the engine. This requires higher tensile properties and high thermal conductivity of the engine material. The department of Component Technology at the University of Jönköping in collaboration with Volvo Powertrain AB, Scania CV AB and DAROS Piston Rings AB has been commissioned to develop this material and to find knowledge of material properties used in truck engines and piston rings used for marine applications.The purpose with this work is to analyze the tensile properties of a series of cast iron, cast under different metallurgical conditions.Four different series of cast irons have been analyzed from four points of view, carbon concentration, nodularity, amount inoculation and cooling rate.After the tensile test all specimen data was analyzed in a mathematic calculation program called Matlab 2006a.
Elevers tankar om klimatförändringar
This work examines the students´ thoughts on climate change with a focus on carbondioxid through photosynthesis and the carbon emissions from cars. The study is based on two subject areas, one with a focus on enhanced greenhouse effect, and the other focusing on photosythesis. The survey was conducted by means of qualitative interviews with students in grades four and six. The results describe that student´s understanding for photosynthesis and the carbondioxids function for photosynthesis doesn´t change significantly from grade four to grade six. I have divided the students inte three levels based on their understandingof the various fields, and their use of adequate concepts.
Hantering av schaktmassor med hänsyn till miljömålen "giftfri miljö" och "begränsad klimatpåverkan"
I Sverige pa?gick under 2013 efterbehandlingsa?tga?rder pa? 1789 fo?rorenade omra?den. Det nationella miljo?ma?let ?giftfri miljo?? har av regeringen angetts som det styrande miljo?- ma?let vid efterbehandling. Efterbehandlingen syftar till att minska risken fo?r fo?rore- ningsspridning i mark fra?n avslutade verksamheter som industrier, va?gar med mera.
Studie av koldioxidgradienter i havets ytskikt
Studie av koldioxidgradienter i havets ytskiktSofia SöderholmDenna studie bygger på ett nyligen utvecklat instrument som har mätt koldioxidkoncentrationer på tre olika djup i vattnet samt en nivå i luften. Då detta instrument var oprövat i vatten har en utvärdering av mätmetodens lämplighet för vattenmätningar utförts. Syftet med mätningarna var att undersöka ytvattnets vertikala koldioxidgradient för att med hjälp av denna kunna beskriva flödet av koldioxid mellan hav och atmosfär bättre. Detta flöde är en viktig del av den globala kolcykeln och en djupare förståelse för koldioxidflödets beteende kan i framtiden bidra till mer noggranna klimatprognoser. Hur de beräknade flödena från profilinstrumentet påverkas av temperaturgradienterna i vattnets ytskikt har även det studerats.
Ärtrev som substrat för biogasproduktion : En litteraturstudie och rötning i labbskala
Until 2020, 49% of Sweden's use of energy must derive from renewable sources. Greenhouse gases must as well decline with 40% compared to 1990 as a part of Sweden's 16 environmental objectives. Biogas is part of the effort to achieve these objectives, but as the demand for biogas increases, more substrates are needed to meet the demand. The purpose is to investigate the conditions for pea residue as substrate by performing lab-scale mesophilic digestion with different fractions and notch lengths and then to summarize pea residue as a substrate for biogas production. During anaerobic digestion, 1000 ml bottles were used as reactors for digestion.
Brand equity in the industrial purchase decision : a case study of the Swedish market for agricultural machinery
High brand equity is a great asset for companies that operate their business in a free and competitive market. Brand equity can arise from both product-related and non-product related attributes and may be viewed from many different perspectives. This study examines which different attributes that contribute to enhance brand equity from customers point of view at the Swedish market for agricultural machinery.
The study have been developed using a comprehensive literature search in order to investigate the field regarding brand equity and brand image. The literature review results in one product specific and one non-product specific approach in order to examine factors that contribute to enhanced brand equity. This takes the form as one survey-based approach regarding the non-product related attributes which is examined by interpreting the extra value added by different attributes.
Dynamiken hos organiskt kol i Mälarens avrinningsområde : flöden, drivande faktorer och modellering
I denna rapport undersöks hur mängden organiskt kol, TOC (Totalt organiskt kol), varierar i tid och rum i Mälarens avrinningsområde, samt vad det är som styr TOC-halten i Mälaren. Det är viktigt att förstå dynamiken hos TOC i Mälaren och i dess avrinningsområde eftersom ökat TOC i vattnet påverkar vattenkvaliteten och orsakar problem vid beredning av dricksvatten. TOC kan bland annat reagera med klor/UV-ljus och bilda cancerframkallande ämnen. Det kan också öka antal mikrober i vattnets distributionssystem.Arbetet omfattar analys av samband mellan elementen, transportberäkningar per ytenhet av elementen till Mälaren och en modelleringsansats för ett av avrinningsområdena. Rapporten innehåller även en jämförelse mellan de olika vattenföringsmodellerna samt uppmätt vattenföring för analys av eventuella systematiska skillnader mellan dessa som påverkar beräkningen av TOC och de andra elementens transport till Mälaren.Analysen av sambanden mellan variablerna TOC (mg/l), kaliumpermanganat förbrukning (KMnO4, mg/l), absorbans_F (F=filtrerad), järn (mg/l), mangan (mg/l) och SO4_IC (sulfat mätt med hjälp av jonkromatografi, mg/l), visade att vissa av dessa variabler är korrelerade med varandra.