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203 Uppsatser om Nitrogen - Sida 11 av 14

Betydelsen av kolkälla och mikrobiell fysiologisk status för temperaturresponsen (Q10) vid nedbrytning av organiskt material :

The increasing threat of climate change has led to a increased need for models to predict future climat. In these models the changes in the soil carbon pools due to changes in microbiel degradation of the organic matter can lead to both positive and negative feedback-effects. There is however a lack of consensues on the temperature respons on degradation soil organic matter. This paper aim to give a better understanding on the factors controlling the temperature respons. The factors studied were the carbon substrate qualitity and the physiological status of the microorganisms.

Increased growth in Norway spruce (Picea abies (L.) Karst.) through small annual additions of nitrogen (N) fertilizer

This project investigated how elevation and vegetation type influences variation in plant litter phenolic content and protein precipitation capacity among and within common plant species for two different vegetation types, heath and meadow, in a subarctic ecosystem in the Abisko region of northern Sweden. As nutrient availability generally decreases with increasing elevation as a result of decreasing temperature, I hypothesised that phenolic content would increase with elevation and be higher on the heath than the meadow. To test this, the total phenolic content and protein precipitation capacity was estimated in leaf litter from 13 species in both heath and meadow vegetation across an elevational gradient ranging from 500 to 1000 meters above sea level (m.a.s.l.) in the study region. The results showed that elevation and vegetation type both had a strong impact on both variables. Total phenolic concentrations decreased with elevation for the meadow, and were greater for the heath than the meadow.

Reingsresultat, drifterfarenheter och kostnadseffektivitet i svenska våtmarker för spillvattenrening

I denna studie har funktionen hos sju anlagda våtmarker för behandling av avloppsvatten i Sverige jämförts över tid med avseende på avskiljning av kväve, fosfor och BOD. Syftet var att undersöka våtmarkernas långsiktiga funktion, skötselåtgärder och relaterade kostnader. Våtmarkerna (1,6 - 28 ha stora) har varit i drift olika länge, mellan 7 och 17 år, och befintliga övervakningsdata samt intervjuer med ansvariga för respektive våtmark användes som grund för studien. Resultaten visade att våtmarkernas reningsfunktion generellt sett varit god utan någon tendens till en försämrad funktion över tid. Våtmarkerna belastades med 1100 - 9900 kg N/ (ha·år) och avskiljde mellan 420 och 2400 kg N/ (ha·år), beräknat som ett medelvärde per anläggning.

Uthållig odling med fokus på kväveutlakning

Kväve är en viktig byggsten i allt levande på jorden, och ingår i bland annat aminosyror,proteiner och DNA. Eftersom kväve återfinns i alla växtens celler har det en avgörande roll ivåra odlingssysystem för att få skördar med bra kvalitet. Kväve utgör också en av de storamiljöbovarna inom lantbruket. Överskott av kväve i odlingar medför risk för kväveförluster.Ett stort problem är kväveutlakning, som menas det kväve som följer regnvatten ner i undrejordlager och vidare till grundvatten, vattenströmmar och hav. Kväveutlakning kan ge storakonsekvenser på miljön, och reslutera i övergödning, döda havsbottnar och oballans i våraekologiska system.

Vallört som växtnäringskälla : växtnäringsförsök och litteraturstudie

Russian comfrey, Symphytum x uplandicum, was tested as a plant nutrient source in a trial with tomatoes. Comfrey liquid was produced by Stiftelsen Holma i Höör. Tomato plants of the cultivar Aromata planted in a medium of soil:peat (1:1) enriched with organic nutrients and lime, were fed with comfrey liquid plus Biofer, in three different concentrations. Two different concentrations of BioRika were used as comparison, along with an unfertilized control group. In the comfrey treatment I a total amont of 1g N, 0,23 g P, 0,84 g K, was given to the tomatoes.

Påverkar jordbruk flödet av akvatiska insekter till land? : Effekter av jordbruk på akvatiskt tillflöde till land vid norrländska bäckar

Streams and riparian zone are closely linked by reciprocal flows of energy and nutrients. A large part of the transportation from water to land is in form of emerged aquatic insects. Conversion of land from forest to agriculture can greatly affect aquatic ecosystems, and due to the close link, also affect the adjacent terrestral zone. Investigating how the presence of agriculture in the surrounding area affects amounts of emergent aquatic insects gives an indication on how agriculture, in turn, may affect the terrestral enviroment. The study was preformed alongside ten streams in northern Sweden; five in landscape transformed by agriculture and five in undisturbed forest areas.

En ?terinventering och analys av den svenska populationen av svart nervmossa (Campylopus atrovirens)

Bristly swan-neck moss (Campylopus atrovirens) is in Sweden a very rare moss that only grows on a few blocks and cliffs around Gothenburg. The species can globally only be found in areas with high precipitation. Rain fall in Gothenburg has increased with a stronger greenhouse effect. Air pollution in Gothenburg has also improved. Mosses generally benefit from these conditions and this papers hypothesis is that the population of the species has grown because of these more beneficial conditions.

Analys och förbättring av en mätenhet för laddning av elfordon

Reducing the CO2-pollution, resulting from the combustion of fossil coal for energyproduction, is important to affect environmental changes. One way to achieve a reductionis to use the oxy-fuel technology. The technology uses O2 and re-circulated flue gasduring the combustion which results in a flue gas mainly consisting of CO2. The flue gascould then be compressed and stored without environmental effects. A problem thatfollows from the compression is the risk of acidification in sensitive parts of the process.Acidification can occur because of reactions following from the contact of condensedwater and sulphur- and Nitrogen-oxides which are also present in the flue gas.This report compiles and evaluates the basis of a scientific unit with the purpose ofexploring the possibilities of extracting impurities of SOx and NOx from the flue gases.The dimensions of the unit are based on basic conditions, defined for an existing oxy-fuelprocess at Chalmers, and on the results of computer modelling.

Återvinning av näringsämnen från hushållsspillvatten med omvänd osmos

Hammarby Sjöstad is a new district in Stockholm with high environmental standard. Stockholm Water Company evaluates a local wastewater treatment plant with cutting edge technology. The first step is an experimental treatment plant (Sjöstadsverket) with four parallel lines of treatment, each with a capacity to treat wastewater from 150 persons. Within the membrane technology subproject the possibility of using reverse osmosis (usually called RO) to regain nutrients is examined.Reverse osmosis separates the incoming water in a clean permeate and a concentrate that, as the name indicates, is a more concentrated version of the incoming water. Using this method in wastewater treatment, a solution high in nutrients can be obtained without the use of chemical precipitation agent and with no production of sludge.

Design av försöksanläggning för trycksatt rökgasrening vid oxy-fuelförbränning

Reducing the CO2-pollution, resulting from the combustion of fossil coal for energyproduction, is important to affect environmental changes. One way to achieve a reductionis to use the oxy-fuel technology. The technology uses O2 and re-circulated flue gasduring the combustion which results in a flue gas mainly consisting of CO2. The flue gascould then be compressed and stored without environmental effects. A problem thatfollows from the compression is the risk of acidification in sensitive parts of the process.Acidification can occur because of reactions following from the contact of condensedwater and sulphur- and Nitrogen-oxides which are also present in the flue gas.This report compiles and evaluates the basis of a scientific unit with the purpose ofexploring the possibilities of extracting impurities of SOx and NOx from the flue gases.The dimensions of the unit are based on basic conditions, defined for an existing oxy-fuelprocess at Chalmers, and on the results of computer modelling.

Ett hållbart kretslopp? : Förutsättningar för återföring av näringsämnen i humanavlopp till odlad mark; Norrköpings kommun som exempel

Studien undersöker om återföring av näringsämnen, huvudsakligen makronäringsämnena kväve och fosfor, från humanavlopp i Norrköpings kommun kan komma att ske på ett sätt som är i linje med naturvetenskapliga kretsloppsprinciper.Frågan om återföring av näringsämnen och dess problembild är av stor vikt då dagens flöden leder till både resursslöseri och miljöproblem som övergödning. Anledningen till att näringsämnen inte recirkuleras måste bero på någon form av oförmåga hos aktörerna att ta i tu med problematiken.Studien analyserar olika aktörers perspektiv. Aktörerna beskrivs dels i ett nationellt perspektiv men den huvudsakliga fokuseringen ligger på kommunal nivå. Detta på grund av att kommuners roll inom området innebär att de är ytterst ansvariga för utformningen av avloppssystem. Aktörer som agerar i förhållande till kommunen har därför undersökts närmare genom intervjuer med olika representanter för aktörerna.

Emissioner i slutna utrymmen Med speciell inriktning på emissioner av formaldehyd och organiska syror

This study aimed to evaluate the levels of formaldehyde and organic acids that can build up within enclosed spaces. Another goal was to compare two types of paints that can be used as coating barriers within showcases and in turn compare them to the modern, and by many highly recommended, material of Marveseal®. A low volatile waterborne alkyd/acrylate paint and a two component polyurethane paint was compared to Marveseal® in two series of experiments. One series measured the level of formaldehyde, and thus the effectiveness of the three chosen barriers, and the other series measured the level of volatile organic acids, both the acids emitted from the paint itself, and that of the wood. One box in each series were not treated at all and was used as a reference.The fact that different types of materials emit volatile organic compounds have long been known.

Nutrient effects on microorganism communities in nutrient poor soils

Better, more efficient fertilizers with great productivity and economic returns are needed, but it is important today to find fertilizers that are also sustainable. It is also important to carefully monitor their impact on the environment, including potential side-effects. In this context, the microbial communities that carry out numerous essential functions contributing to a functional ecosystem are of particular interest. The present study is a complement to a pot experiment that investigated the potential of different waste products for use as fertilizers and how they affect the microbial community. In the pot experiment, the clearest treatment change in microorganism community function was found in the fully fertilized treatment used as a positive control. The question was whether this was indirect, i.e.

Attityder till implementering av precisionsodlingsteknik :

Different techniques for precision agriculture have been available during the last decade. Some of them are more widely used than others. The main purpose of this thesis was to investigate the different attitudes to precision agriculture that exists among farmers and advisors in Sweden. Eight advisors and sixteen farmers were asked for their opinion of a number of specific techniques for precision agriculture, such as yield-mapping, precision liming, the Yara Nitrogen Sensor and site-specific fertilization with phosphorous and potassium. They were also asked to describe the way in which the counselling in Swedish agriculture is used and also about it's importance for the adaptation of new techniques. The high costs are mentioned to be one of the most important reasons why precision agriculture hasn't been more widely spread. Several farmers refer to their farms as too small to bear the costs that come with the techniques. The individual interest for technique among the potential users plays an important role.

Kaliumgödsling på torvmark - effekt på tillväxten hos planterade granar (Picea abies)

Peat  lands  are  a  great  potential  resource  for  increased  forest  growth  in  Sweden, there  are  approximately  6.5  million  hectares  of  peat  lands,  whereof  around  70% produce less wood than one m3sk/ha and year and are therefore classed as forest waste  land.  There  are  over  200  000  hectares  of  peat  land  that  is  already  drained and  wooded,  and  that may  be  suitable  for  fertilization.  Forest  production  on  peat soils  usually  requires  drainage  and  fertilization.  Dewatering  requires  ditching  the area, so that the roots can have access to oxygen. Nitrogen is often abundant in the peat but other nutrients; especially potassium is in short supply. The  purpose  of  this  work  was  to examine  the effects  of  potassium  fertilization  on the  growth  of  spruces  that  were  planted  on  drained  peat  land  and  how  different amount of fertilizers affects the growth. Potassium deficiency is strongly growth inhibiting, since potassium is important for substance  transport  in  the  tree.  Potassium  is  also  important  for  the  carbohydrate formation, and because increasing the sugar content of the cells constitutes a lower freezing temperature does potassium availability in the soil play a major role in the winter  resistance  of  many  species.  Potassium  is  not  found  in  any  organic compounds in the tree, but is present in cell and tissue fluids. A fertilization trial was started in 1978 in Siljansfors Experimental Forest. The plots in the experiment were fertilized with different amounts of potassium and one plot was  left  without  fertilization.  All  plots  that  were  fertilized  with  potassium  grew considerably better than the unfertilized plot. The difference in production between the unfertilized plot and the plot that received the most potassium was 7.2 m3sk/ha and year. The unfertilized plot can still be classified as waste land. The theoretical production capacity was estimated using a Swedish system for site quality  estimation  of  wetlands  after  ditching  (dikningsbonitering).  The  plot  with most  potassium  produced  after  fertilizationaproximately  in  level  with  theoretical estimations.  Key  words:  Peat  land,  Fertilization,  Ditching,  Growth,  site  quality..

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