While streams and rivers emit large quantities of CO2 to the atmosphere, both the mechanisms controlling CO2 evasion as well as the sources of CO2 are still uncertain. One potential source of stream CO2 is in-stream degradation of dissolved organic matter (DOM). Streams and rivers transport, stores and transform large quantities of DOM, which can be more or less biologically reactive (bioreactive) meaning how easily accessible the organic material is for biological degradation. Little is known about the dynamics controlling DOM bioreactvity in agricultural stream water. This project investigated potential physico-chemical and land-use controls of DOM bioreactivity and its link to CO2 evasion in ten Swedish agricultural streams by correlating estimated values of DOM bioreactivity as well as CO2 evasion rates with different parameters for physico-chemical and land-use controls measured during eleven field excursions. A direct positive correlation was found between DOM bioreactivity and CO2 evasion rates during spatial correlation but not when all measurements were used. DOM bioreactivity was found to correlate to parameters for DOM quality and quantity, concentrations of dissolved oxygen (D.O.) and total dissolved solids (TDS) as well as stream width, water depth, specific discharge, temperature and electric conductivity. Nutrients, fraction land-use, catchment size, vegetation cover and turbulence were not found to be potential controls of either DOM bioreactivity or CO2 evasion. CO2 evasion was found to have fewer significant correlations with parameters for DOM quality compared to DOM bioreactivity, indicating a weaker link between CO2 emissions and DOM quality in the stream water, and was not tied to variables affected by increased discharge. Spatial and temporal analysis indicated that while CO2 evasion rates were more site specific, bioreactivity was more influenced by temporal variations where periods of increased bioreactivity and increased variability between sites occurred during periods of increased specific discharge, supporting existence of a hydrological influence on DOM bioreactivity.

Natural hazards, paired with affected communities’ exposure and vulnerability, have caused numerousfatalities and great economic losses worldwide in recent decades. Floods represent about one-third ofall natural hazards, and together with storms they comprise 77% of economic losses caused byextreme weather events from 1980 to 2006 in Europe and have been the main natural hazards inEurope for more than a century. Survey data of public risk perception were collected in Sweden andItaly through online surveys several times during the COVID-19 pandemic, and the respondents wereasked questions about risk perception regarding nine threats: epidemics, floods, droughts, earthquakes,wildfires, terror attacks, domestic violence, economic crises, and climate change. The survey explorespublic perception on five factors: experience, likelihood, potential impact, as well as preparedness andknowledge of the phenomenon. The survey data were analysed by using ordinal logistic regression,were the variable of previous flood experience along with socioeconomic factors were used to explorehow/if previous experience has any statistical significance and potentially affects risk perception. Inaddition, this thesis also presents a spatial analysis of respondents’ previous flood experience andprevious flood events in Sweden, to explore whether this is reflected in the survey data. The resultsshow that the effect of experience on likelihood, knowledge and preparedness is high, and womenhave a higher perceived risk in all variables except preparedness. The results of the spatial analysisshow that the majority of respondents with experience live in North Middle Sweden which correlateswell with the analysis of past flood events during the recent decade. These findings could potentiallybe used in continuous research regarding disaster risk reduction and developing frameworks,specifically how impacts and perception influence other variables such as vulnerability, behaviour, andgovernance.

<p>The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2.</p><p>This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments. </p><p>The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (<1 year) had low carbon retentions, whereas in catchments with long residence times (>3 years) a majority of the imported TOC was removed in the lake systems. </p><p>The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.</p>

The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2. This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments. The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (&lt;1 year) had low carbon retentions, whereas in catchments with long residence times (&gt;3 years) a majority of the imported TOC was removed in the lake systems. The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.

<p>The objective of the thesis was to explore the potential of diatoms (<i>Bacillariophyceae</i>) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49'E). A modern surface-sediment calibration set including 100 lakes was developed and lake-water pH, sedimentary organic content (assessed by loss-on-ignition) and temperature were identified as most powerful environmental variables explaining the variance within the diatom assemblages. Transfer functions based on unimodal species response models (WA-PLS) were developed for lake-water pH and mean July air temperature (July T), yielding coefficients of determination of 0.77 and 0.70, and prediction errors based on leave-one-out cross-validation of 0.19 pH units and 0.96 °C for lake-water pH and July T, respectively. The transfer functions were validated with monitoring data covering two open-water seasons (lake-water pH) and meteorological records covering the 20th century (July T). The good agreement between diatom-based inferences and measured monitoring data confirmed the prediction ability of the developed transfer functions. </p><p>Analysing a Holocene sediment core from a lake nearby Abisko (Vuoskkujávri), diatoms infer a linearly decreasing July T trend (1.5 °C) since 6,000 cal. BP, which compares well with inferences based on chironomids and pollen from the same sediment core. The lake-water pH inference shows a pattern of moderate natural acidification (c. 0.5 pH units) since the early Holocene, reaching present-day pH values at c. 5,000 cal. BP. By fitting fossil diatom samples to the modern calibration set by means of residual distance assessment within canonical correspondence analysis (CCA), the early Holocene (between 10,600 and 6,000 cal. BP) was identified as a problematic time-period for diatom-based inferences and, consequently, reconstructions during this period are tentative. Pollen-based inferences also show 'poor' fit between 10,600 and 7,500 cal. BP and chironomids probably provide the most reliable July T reconstruction at Vuoskkujávri, with 'poor' fit only during the initial part of the Holocene (between 10,600 and 10,250 cal. BP). </p><p>Possible factors confounding diatom-based July T inferences were investigated. Using detrended CCA (DCCA), Holocene sediment sequences from five lakes indicate that during the early Holocene, mainly physical factors such as high minerogenic erosion rates, high temperature and low light availability may have regulated diatom assemblages, favouring <i>Fragilaria</i> species. In all five lakes, diatom assemblages developed in a directional manner, but timing and scale of development differed substantially between lakes. The differences are attributed primarily to the geological properties of the lake catchments (with strong effects on lake-water pH), but other factors such as climatic change, vegetation, hydrologic setting and in-lake processes appear to regulate diatom communities in each lake differently. The influence of long-term natural acidification on diatom assemblages progressively declined during the Holocene with corresponding increase of the influence of climatic factors.</p>

<p>This thesis contributes to the understanding of glacier response to climate change by ice dynamical studies on Storglaciären, Sweden, and Bonnevie-Svendsenbreen, Kibergbreen and Plogbreen in Dronning Maud Land, Antarctica. Ice surface velocities, ice geometry and temperature information is fed through a force budget model to calculate ice mass outflux of these glacial systems via three-dimensional stress distributions for a flux-gate. </p><p>Field data were collected through repeated DGPS and GPR observations on Storglaciären between July 2000 to September 2001 and on Kibergbreen and Plobreen during the SWEDARP 2002/03 expedition to Antarctica. The work was strongly supported by remotely-sensed information.</p><p>The results from Storglaciären show a strength in the force budget model to discern both spatial and temporal variability in ice dynamical patterns. It highlights the influence of seasonality and bedrock topography upon glacier flow. A modeling experiment on Bonnevie-Svendsenbreen suggested that ice temperature increases substantially under conditions of high stress (≥0.4 MPa) due to strain-heating. This provides a positive feedback loop, increasing ice deformation, as long as it overcomes the advection of cool ice from the surface. These results explain, to some extent, the mechanism behind fast flowing ice streams. Mass flux caclulations from Bonnevie-Svendsenbreen suggest that the outflux given from force budget calculations can be used as a gauge for influx assuming steady state conditions. Plogbreen receives an influx of 0.48±0.1 km³ a^-1 and expedites a discharge volume of 0.55±0.05 km³ a^-1. This indicative negative mass balance is explained by a falling trend in upstream accumulation and the recent rise in global sea level, as it is likely to induce glacier acceleration due to a reduction in resistive forces at the site of the gate. This result is comparable with other Antarctic studies reporting negative mass balances, e.g. from WAIS, as caused by changes in the global atmospheric circulation pattern.</p>

The objective of the thesis was to explore the potential of diatoms (Bacillariophyceae) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49'E). A modern surface-sediment calibration set including 100 lakes was developed and lake-water pH, sedimentary organic content (assessed by loss-on-ignition) and temperature were identified as most powerful environmental variables explaining the variance within the diatom assemblages. Transfer functions based on unimodal species response models (WA-PLS) were developed for lake-water pH and mean July air temperature (July T), yielding coefficients of determination of 0.77 and 0.70, and prediction errors based on leave-one-out cross-validation of 0.19 pH units and 0.96 °C for lake-water pH and July T, respectively. The transfer functions were validated with monitoring data covering two open-water seasons (lake-water pH) and meteorological records covering the 20th century (July T). The good agreement between diatom-based inferences and measured monitoring data confirmed the prediction ability of the developed transfer functions. Analysing a Holocene sediment core from a lake nearby Abisko (Vuoskkujávri), diatoms infer a linearly decreasing July T trend (1.5 °C) since 6,000 cal. BP, which compares well with inferences based on chironomids and pollen from the same sediment core. The lake-water pH inference shows a pattern of moderate natural acidification (c. 0.5 pH units) since the early Holocene, reaching present-day pH values at c. 5,000 cal. BP. By fitting fossil diatom samples to the modern calibration set by means of residual distance assessment within canonical correspondence analysis (CCA), the early Holocene (between 10,600 and 6,000 cal. BP) was identified as a problematic time-period for diatom-based inferences and, consequently, reconstructions during this period are tentative. Pollen-based inferences also show 'poor' fit between 10,600 and 7,500 cal. BP and chironomids probably provide the most reliable July T reconstruction at Vuoskkujávri, with 'poor' fit only during the initial part of the Holocene (between 10,600 and 10,250 cal. BP). Possible factors confounding diatom-based July T inferences were investigated. Using detrended CCA (DCCA), Holocene sediment sequences from five lakes indicate that during the early Holocene, mainly physical factors such as high minerogenic erosion rates, high temperature and low light availability may have regulated diatom assemblages, favouring Fragilaria species. In all five lakes, diatom assemblages developed in a directional manner, but timing and scale of development differed substantially between lakes. The differences are attributed primarily to the geological properties of the lake catchments (with strong effects on lake-water pH), but other factors such as climatic change, vegetation, hydrologic setting and in-lake processes appear to regulate diatom communities in each lake differently. The influence of long-term natural acidification on diatom assemblages progressively declined during the Holocene with corresponding increase of the influence of climatic factors.

This thesis contributes to the understanding of glacier response to climate change by ice dynamical studies on Storglaciären, Sweden, and Bonnevie-Svendsenbreen, Kibergbreen and Plogbreen in Dronning Maud Land, Antarctica. Ice surface velocities, ice geometry and temperature information is fed through a force budget model to calculate ice mass outflux of these glacial systems via three-dimensional stress distributions for a flux-gate. Field data were collected through repeated DGPS and GPR observations on Storglaciären between July 2000 to September 2001 and on Kibergbreen and Plobreen during the SWEDARP 2002/03 expedition to Antarctica. The work was strongly supported by remotely-sensed information. The results from Storglaciären show a strength in the force budget model to discern both spatial and temporal variability in ice dynamical patterns. It highlights the influence of seasonality and bedrock topography upon glacier flow. A modeling experiment on Bonnevie-Svendsenbreen suggested that ice temperature increases substantially under conditions of high stress (≥0.4 MPa) due to strain-heating. This provides a positive feedback loop, increasing ice deformation, as long as it overcomes the advection of cool ice from the surface. These results explain, to some extent, the mechanism behind fast flowing ice streams. Mass flux caclulations from Bonnevie-Svendsenbreen suggest that the outflux given from force budget calculations can be used as a gauge for influx assuming steady state conditions. Plogbreen receives an influx of 0.48±0.1 km3 a-1 and expedites a discharge volume of 0.55±0.05 km3 a-1. This indicative negative mass balance is explained by a falling trend in upstream accumulation and the recent rise in global sea level, as it is likely to induce glacier acceleration due to a reduction in resistive forces at the site of the gate. This result is comparable with other Antarctic studies reporting negative mass balances, e.g. from WAIS, as caused by changes in the global atmospheric circulation pattern.

Detta arbete ämnar diskutera och analysera mediamaterial i form av video och film från Sveriges Utbildningsradios mediaplattform UrPlay. Materialet analyseras via hur det förhåller sig till Skolverkets kursplan i geografi. Syftet med detta är att se hur väl materialet förhåller sig till de riktlinjer som finns för undervisning. Det syftar även till att undersöka vilken variation av material det finns i geografi och vad det säger om geografin som skolämne. Då både Sveriges Utbildningsradio och Skolverket är statliga organisationer bör det finnas samband mellan innehåll och läroplan. Hur mediaplattformar och användandet av film i skolundervisning redovisas med tidigare forskning om generellt filmanvändande som ej är specifikt för geografi. Forskningen är därför bredare än specifikt för geografiämnet och tar in en allmän synvinkel på film i undervisning. Senare redovisas även forskning och bakgrund om själva läroplanen samt dess kursplan för geografi. Metoden som använts i arbetet är en kvalitativ datainsamling och består av analys samt genomgång av fem videor som finnes under geografikategorin på UrPlays hemsida. Resultatet redovisar de kopplingar som finns mellan mediamaterialets innehåll och det centrala innehållet i kursplanen för geografi. Resultatet består av genomgångar av det utvalda materialet samt vilka delar av det centrala innehållet som de uppfyller. Analysen i arbetet ämnar för att kritiskt materialet i förhållande till läroplanen. Variationen samt utbudet jämförs även med andra tillgängliga ämnen på hemsidan. Här blir det tydligt att majoriteten av videor är ämnesöverskridande och till viss del fyller större delar av centrala innehåll i andra kursplaner än geografi. I arbetets slutsats redovisas att det tillgängliga materialet förhåller sig till kursplanen dock endast till en viss mån. Sedan presenteras en generell diskussion samt vilka brister detta arbete har. / This text aims to discuss and analyse media material in video form produced by The Swedish educational radio. The material is available to find on their website UrPlay and can be viewed by whomever. The material is analysed in relation to the Swedish curriculum and its course specific syllabus in geography. The aim is to get an understanding of how well the material produced meets the expectations of said curriculum. It also aims to see what variation there is to the material found under the geography category on UrPlay and what its variation says about geography as a school subject. Both The Swedish educational radio and The Swedish School board are organisations owned by the Swedish government hence there should be a connection between material and curriculum. The usage of media platforms and film in educational purposes have been researched and a broader perspective than just geography have been taken into consideration. Choice of methodology for collection data is a qualitative analysis and consists of analysis and general review of five videos found under the geography category on UrPlay. In the result part of this project, the connections between material and geography syllabus are demonstrated. The result is demonstrated by thorough briefings of chosen videos. It is then viewed in relation to the syllabus and what parts of the syllabus that are covered in said videos. In the analyse section of this text that aims to critically analyse the material in relation to the syllabus it becomes evident that the majority of videos are not subject specific to geography. It rather shares the content with other subjects and to some part fill more criteria of other syllabuses. However, it does fulfil some parts of the geography syllabus. In the conclusion the results are discussed and shows that the material fills the criteria of the syllabus to some extent. Thereafter a general discussion and flaws within the project are presented.

<p>The main aim of this thesis was to contribute with detailed information of regional environmental change during the Holocene through studies of speleothems and their growth environments from two caves, Korallgrottan and Labyrintgrottan in northwestern Sweden, and a cellar vault in Uppsala. This was done through studies of stable isotopes and luminescence properties in the speleothems in combination with a detailed monitoring study in Korallgrottan.</p><p>The monitoring study suggests that stalagmites fed by stalactites with slow and stable drip rates from deep inside the cave may be suitable as palaeoclimate archives. Similarities between oxygen isotope signals of contemporary samples from Labyrintgrottan and Korallgrottan emphasize the potential of speleothems from Labyrintgrottan to also provide high resolution regional palaeoclimate information.</p><p>Except for a number of cold events stalagmite δ¹⁸O records from northern Scandinavia indicate that temperatures were warmer than today between 9500 and 6000 years ago. During this period the interval between 7800 and 6000 years ago seems to have been the warmest. The area above Labyrintgrottan was most likely covered by much denser vegetation than today at the time of stalagmite growth (9500-7500 years ago) and was, unlike today, probably situated below the local tree-limit between 9000 and 8000 years ago. The δ¹⁸O record of a stalagmite from Korallgrottan covering the last 4000 years agrees with the concept of a warmer period, the so called Medieval Warm Period, centred around AD1000 and a colder period, the so called Little Ice Age, somewhere between AD1000 and today.</p><p>Studies of luminescence properties in fast growing speleothems from Uppsala indicate that the variations in luminescence intensity are annual and that the annual lamiae of the luminescent record represent a flush of organic material.</p>