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Browsing by master's degree program "Nordic Master Programme in Environmental Changes at Higher Latitudes"

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  • Fisher, Ellie (2023)
    Atmospheric aerosols are solid or liquid phase particles which are suspended in ambient air. These particles have an impact on the climate through direct and indirect radiative forcing, and their measurement presents challenges in high latitude environments where concentrations may fall under the detection limit of the responsible instruments. In order to both qualify and quantify the contribution of aerosol particles to environmental change at higher latitudes, it is important to understand their microphysical and optical properties, which control their interaction with visible wavelength radiation. This thesis focuses on the characterisation of the aforementioned aerosol properties in a High Arctic environment, Villum Research Station (Northeast Greenland), during two six-month observation periods in 2020 and 2021. The parameters presented in the analysis are particle total number concentration and size distribution in the 0.3 - 10 μm size range, particle scattering coefficients σsp, particle absorption coefficients σap, and Ångström exponents describing the wavelength dependence of both optical coefficients. The seasonal variability and distribution of these properties was analysed, and case studies of exceptional particle number concentration identified as particle transport events to evaluate the contribution of local and long-distance source regions to the overall aerosol population at the station. The results of the analysis show that there is a notable seasonality to both number concentration and optical characteristics of aerosol particles at Villum Research Station, with median values for these parameters at their highest in the winter, followed by the autumn and then the summer. The dominant species during episodes of exceptional particle number concentrations were found to be dust, Elemental Carbon/Organic Carbon (EC/OC) and mixed aerosols, with source regions across continental Greenland, the Canadian Archipelago and Arctic Ocean.
  • Folestad, Magdalena (2022)
    The study is sought to study how and if the environment has changed in eastern Finnish Lapland in a long-term perspective. Variables related to the current state of the environment, are atmospheric composition and aerosols, meteorology, and biology. The study is based on measurements from Värriö Subarctic Research station for the years 1973 to 2021. Included in atmospheric composition, are the atmospheric anthropogenic gas concentrations of CO, NOx, O3 and SO2. SO2 is also used in a proxy to estimate H2SO4 concentrations. Decreasing long-term trends are found for CO, NOx, SO2 and H2SO4. The decreasing emissions from Kola peninsula, is the cause for long-term decrease of SO2, which result in decreasing H2SO4 concentrations. Results of particle size distribution show an increasing concentration of small particles and decrease of large particles. Decline of particles leads to less NPF, CCN and will resultingly influence cloud properties. Air temperature has increased 2.38 °C and snow cover days have decreased by three weeks, between 1975 and 2021. Snow depth and precipitation show less significant changes. Heat sum have from 1981 to 2021 increased with 247 °C days, indicating more active and growing trees. Birch leave development show indications of leave burst and developed leaves to occur at earlier date, over the years 1981-2021. Grouses, shorebirds, and cavity-nesters show large inter-annual variations. Some of the bird species appears to benefit from environmental changes while others appear to have difficulty adapting.
  • Gunnlaugsdóttir, Eyrún Gyða (2022)
    Biological soil crust, biocrust, is a significant contributor to biogeochemical cycles through nitrogen and carbon cycling. Further, it stabilizes soil, facilitates water infiltration, and mitigates soil erosion. The global biocrust cover is believed to decrease by about 25-40% in the next 60 years due to climate change and intensification in land use. Research on biocrust in arctic and subarctic regions is limited, much of the knowledge comes from lower latitudes in arid and semiarid ecosystems. Cold-adapted biocrust might respond differently to increasing temperatures when compared with warm-adapted biocrust. Therefore, it is fundamental to research biocrust in arctic and subarctic regions when looking at how fast the climate is changing in the Northern hemisphere. Temporal variations of soil respiration in subarctic biocrust have not been studied systematically before. This research project focuses on the effects of warming on soil respiration in biocrust, on a diurnal and a seasonal scale. It also focuses on species composition changes of vascular plants in the warming experiment where warming was induced with open-top chambers (OTCs). Soil respiration, temperature, soil water content, as well as plant species composition changes were measured during three field trips that each lasted four days during the growing season of 2021. The results show that soil respiration was lower in September when compared with measurements done in June and July. The highest values of soil respiration were observed during mid-day and the lowest during evenings and nights. The temperatures of OTC plots were, on average, 1.16 °C higher than control plots, and OTC plots had significantly lower soil water content than control plots. During this research, the soil respiration increased with higher temperature but was not different between control and OTC plots during any time of day or month measured. Soil water content did not affect soil respiration significantly, while temperature did. These findings might be explained by less soil water content within warmer plots, but warmth and moisture have been shown to increase soil respiration. In other words, less soil water content might countereffect the increase of soil respiration due to warming. Some vascular plant species were more likely to be found within or outside the warming plots. Dwarf willow, Salix herbacea, decreased in cover within OTC plots. Previous research has shown that warming significantly reduces pollen shed and time of pollen shedding for S. herbacea, which might decrease its abundance within OTC plots. Alpine bistort, Bistorta vivipara, increased in cover within OTC plots compared to control plots. Warming experiments on B. vivipara have shown positive effects on reproductive parameters, which might increase its abundance within warmed OTC plots. Sheep also prefer grazing on B. vivipara. Therefore, it might have less cover in control plots, given that OTCs exclude grazing and that many sheep roam the studied site during the growing season. Vascular plant cover was greater within control plots when compared with warmed plots. Previous results at the same site after one year of warming, from summer 2019, showed more vascular plant cover within the OTC plots when compared with control plots. The results of this research might indicate that vascular plants are gradually affected by the warming and are transitioning towards a new equilibrium. The results of this research are ground for further studies on subarctic ecosystems dominated by biocrust. Many biotic and abiotic factors affect carbon cycles. For future modelling of predicted effects of climate change, having better knowledge on how subarctic ecosystems respond to warming is essential for a better understanding of the functions and feedbacks in a global context.
  • Demeslay, Lise (2023)
    The plastic pollution has become a massive problem in the Arctic, affecting aquatic, and terrestrial ecosystems, the cryosphere, and the atmosphere. One of the solutions proposed by the Arctic Council is to improve waste management by using renewable and sustainable materials. This is where bioplastics reveal their importance. They can be bio-produced by microorganisms from organic waste, they are biodegradable and can be reused. Their production relies on a circular economy system making it sustainable. Here lies the relevance of developing the bioplastic bioproduction and technology. The present research focused on the development of a specific production of polyhydroxyalkanoates (PHAs) from organic waste, in collaboration with the start-up Dionymer (Bordeaux, France). First, the purpose of the study was to up scale the process from the fermentation of chemical volatile fatty acids in flasks (400 mL culture medium) to 2 L bioreactors (BR) by characterizing the main differences in the two processes. Secondly, the research consisted in implementing and testing different set-up for the BR to enhance and improve bioplastic and biomass yields, including aeration and agitation. The characterization of the culture parameters differences between BR and flask pointed out; a higher viscosity of the medium at the end of the process, a darker PHA product and a lower final optical density (OD) (8 versus 12) respectively. Secondly, the focus was on the increase of the OD in BR and finding the origin of the stress, to do so, the following parameters were tested; - three aerations strategies; pO2<10%, <20% and >20%; - two agitations blades; marine and Rushton with baffles; - two aerations spargers; circular and micro. The results revealed that; the pO2 needs to be higher to 20% and it may be linked with the reduction of stress induced to the cells; the marine blades increased the OD and reduced the medium viscosity; the impact of the micro sparger seemed to improve aeration and tent to be very sensitive to antifoam agent that reduced the aeration of the medium. So far, the optimum BR set-up seemed to include the use of marine blades and a pO2 above 20%. More experiments of optimization still need to be performed to unsure a stable and higher production performance.
  • Escanciano Gomez, Alfredo (2022)
    The Baltic Sea is undergoing changes due to climate change, including an increase in its temperature. This may in turn lead to changes in the traits of the species that inhabit it, including non-endemic, invasive species. Palaemon elegans is a species native to the Atlantic Ocean that has been present in the Baltic Sea since the beginning of this century. Abilities such as high thermal tolerance make it successful in colonising new ecosystems like the brackish waters of this sea. However, less is known about the behavioural traits’ adaptions to these changes. This study aims then to find out how climate change may affect the behaviour of this species. To do so, five behaviours expressed by this species were observed and analysed to see how temperature change, seabed composition and body size influence their expression. The behaviours analysed were aggressiveness, movement frequency, reaction to food stimulus, number of feeding interactions and shelter-seeking. Analyses were conducted using ten-minute videos with ten specimens of P. elegans placed in water tanks and interacting in ecosystems representations with elements typical of the seabed where this species lives, both vegetation and rocks. Student's t-tests in R were then performed to test the significance of possible differences between the behaviours studied and the three parameters that may influence their expression. The results obtained show that the increase in water temperature might indeed lead to an increase in the frequency of the five behaviours studied except in aggressiveness. On the other hand, it was found that the composition of the ecosystem does not have a significant influence overall, while body size has a major influence on feeding related behaviours. Therefore,knowing more about changes in the behavior of species susceptible to climate change can be helpful to understand how biodiversity and its distribution will vary in the not so distant and changing future and what consequences it may generate at the ecosystem level.
  • Thrandardottir, Maria Run (2022)
    The aim of this thesis is to tie the knot of art and science, searching for ways to explain and explore complex atmospheric phenomena through art. Primary methods of research are poetry, video and performance art practice. The results of this thesis are five video performance art works as well as five related poems: Listening Again, Coffee Filter, Repetition, Reflection and Snow Angel created in Iceland and Finland from August 2021 until April 2022, focused on atmospheric science. The results are divided into six sections, addressing six aspects of the traditional scientific method to explain my art works. At the same time, I ask the reader to think about the scientific methods in a different way and how can they be expanded? I connect Listening Again to hypothesis, Coffee Filter is related to field work, Repetition is about laboratory work, Reflection about data analysis and Snow Angel about interpreting the results. Finally I compile how the art works were presented at the IBA-Permafrost Snow Seminar, April 1st 2022 at the Finnish Meteorological Institute as the exhibition “Particles of Sensing”. The performances are all influenced by science in addition to their connection to scientific methods. Listening Again is sparked by mineral dust research in Iceland. Coffee Filter is derived from research of Saharan Dust in Finland and the coffee filter sampling method. Repetition deals with dedication to the laboratory, invigorated by transmittance research of black carbon and Reflection spurs from ice nucleation research. Snow Angel was an emotional life performance, a farewell ceremony of the changing cryosphere. Rather than using my art to explain the science, as in scientific communication, the artworks in this artistic research are on one hand inspired by the scientific research and methods and on the other hand they approach atmospheric science with different research questions, with different methods, gaining different results. The artistic background of this thesis will be written through chosen works by several relevant artists. I will dive into the research and repetitional element in my works and compare them to works by Anna Líndal’s, explain the use of the wedding gown as a symbol in the works by Zaituna Kala and Kong Ning and discuss performance and devotion in works by artist Marina Abromović. Furthermore, the thesis as a whole can be thought of as an art piece: a hypothetical marriage contract or manifesto of my commitment and devotion to the lab. This is a journey of becoming completely devoted to what you love, using the phrase “being married to the lab” from various angles, as an inspiration I play on and think about both during the creation of the art works and thesis. Future prospects for this artistic research is to continue exploring atmospheric science through art, expanding it in more arctic countries and contexts and exhibiting to a wider audience. So far I have created two new works and direct products of this thesis. A love relationship with Science was shown at the Arctic Festival, Iðnó Reykjavík, 17/09/22. I created the video performance Red Thread in Greenland in August 2022, a tribute to the effects of the changing ocean and oceanic folk stories. Red thread will be presented alongside the works in this thesis at the Oodi public library, Helsinki on the 7th-9th of October, 2022. Who knows where this research will take me after that.
  • Bettineschi, Manuel (2023)
    This thesis investigates the impact of the energy crisis on air quality in the Po Valley, Italy, with a focus on the effect of changes in methane consumption over the potential changes in wood burning consumption. The study employs the WRF-CHIMERE model to simulate the consequences of varying wood burning consumption on air quality. Observational data of benzo[a]pyrene and PM2.5 concentrations in the Po Valley are also analyzed. The results indicate that meteorological conditions have a significant influence on air quality, overshadowing the potential effects of emission changes resulting from the energy crisis. However, we observed a model’s bias correlated to the planetary boundary layer height, which could have influenced this result. Further investigation is necessary to correct this bias and comprehensively understand the relationship between energy consumption, air quality, and meteorology in the Po Valley.
  • Särkelä, Karoliina (2023)
    Non-growing season carbon fluxes can contribute to a significant amount of the full-year ecosystem carbon balance. Year-round net ecosystem exchange (NEE) data from 17 years was used to analyse the non-growing season carbon dioxide (CO2) fluxes together with environmental and meteorological variables at Siikaneva fen in Southern Finland. Generally, the fen acted as a sink of CO2 with a mean annual carbon balance of -50.9 (± 39.4) g C m-2. On average, the CO2 emissions during non-growing seasons offset 57% of the following growing seasons CO2 uptake. Two years from the 17-year dataset were a consistent net source of CO2, 2018 and 2016. In 2016, a strong respiration release during the winter-spring transition period turned the annual balance of CO2 to positive, resulting in the highest emission of CO2 during the entire study period. The period of anomalous respiration alone offset 38% of the following growing seasons CO2 uptake. Since the biological activity during non-growing season is low, the CO2 fluxes likely composed mainly of heterotrophic respiration, and thus were likely driven by soil temperature. The relative importance of air and soil temperature, vapor pressure deficit, water table depth, and photosynthetically active radiation (PAR) on NEE of CO2 was analyzed with a random forest algorithm. PAR and soil temperature were the most important drivers during non-growing season, growing season and year-round periods. PAR had the highest importance during growing season while during non-growing seasons, PAR and soil temperature had an equal relative importance. A wavelet coherence analysis further revealed that the mean annual cycles of NEE and soil temperature were coherent during the summer months across the diurnal scale. For instance, NEE correlated positively (decreasing the net carbon sink) with soil temperature and lagged the response to temperature by 4-6 hours. There was no coherence between the annual cycles of soil temperature and NEE during winter. The results emerging from this thesis stress the importance of studying what controls the interannual variation in soil temperature and the possible accumulation of CO2 in soil during non-growing season, but also how they contribute to spring-time CO2 releases like the one observed in spring 2016.
  • King, Maximilian (2023)
    Boreal peatlands are major constituents of the global carbon (C) and water cycles and therefore important climate regulators. These cycle dynamics are strongly determined by plant phenology (e.g., vascular plant photosynthesis and seasonality) and evapotranspiration (ET), next to other abiotic factors. While it is evident that climate change affects these networks of interactions, it is only poorly understood to what extent, as site-specific empirical evidence over multiple decades is lacking. This study investigates the role of phenology (leaf area index: LAI) for peatland C (net ecosystem exchange: NEE) and water fluxes (ET and water table: WT) by combining inter-annual and seasonal observations at the ecosystem level, in Siikaneva fen, Finland (2005-2007, 2014-2022). Interactions with temperature (T), vapor pressure deficit (VPD), photosynthetically active radiation (PAR) and rain were included and tested with various statistical methods (trend- and correlation-analysis, commonality analysis, time lag testing, stepwise multiple-regression, and structural equation modelling). Significant trends were found for LAI (increasing) and WT (decreasing), suggesting ongoing changes in the ecosystem (climate change signal). Within this system LAI provided substantial effects on NEE, less so on ET. These relationships differed seasonally: the greenup season showed the strongest effects of LAI on NEE and ET (and other interactions). However, e.g., PAR and VPD became more relevant for NEE and ET in the later seasons. A time lag analysis suggested that effects (e.g., LAI on NEE) can be delayed at the scale of weeks. Inconclusive evidence was found for the LAI effect on ET and WT (via ET). It is assumed that ET is a limited measure to differentiate between evaporation (E) and transpiration (T) by leaves or the ground, as they might cancel each other out. A shading of increasing LAI over the season might shade moss-ET (and photosynthesis). The applied methods provided complementary information with differing suitability to reveal certain parts of complex network dynamics. A consistent, while seasonally changing, importance of plant phenology for peatland NEE can be concluded. Phenology showed clear correlation with ET, however, the effect size could not be quantified conclusively. Future studies should partition E and T or incorporate the contribution of mosses to both ET and NEE for a more comprehensive understanding. Collectively, this study highlights the role of phenology for peatland C and water fluxes and provides evidence for climate change induced alterations of biotic-abiotic interactions at the ecosystem scale.
  • Helgadóttir, Steinunn (2023)
    Clean snow has the highest albedo of any natural surface, making snow-covered glaciers an important component of the Earth´s energy balance. However, the presence of light absorbing impurities such as mineral dust on glacier surfaces alters their reflective properties leading to a reduction in albedo, consequently increasing absorption of incoming solar radiation which further impacts the glacier surface mass balance (SMB). Icelandic glaciers portray a high annual and inter-annual variability in SMB due to climate variability but deposition of mineral dust originating from glaciofluvial dust hotspots can have large impacts on summer ablation. The frequency of dust storms and deposition is then controlled by high velocity winds and prolonged dry periods. Additionally, Icelandic mineral dust contains high amount of iron and iron oxides which makes it extremely light absorbing. An extensive dust event occurred over the southwest outlets of Vatnajökull ice cap during early July of 2022 causing surface darkening. To investigate the impact of the dust event on the melt season SMB, this study used automatic weather station (AWS) data from three different sites on Tungnaárjökull glacier, a SW-outlet of Vatnajökull ice cap. Daily melt was estimated with a simple snow-melt model and AWS data. To quantify the overall impact of dust on the melt rates, albedo from 2015 melt season for the three AWS sites was used to simulate the surface albedo for a dust-free surface during the 2022 melt season. Essentially, the dust event caused melt enhancement of almost 1.5 m water equivalent (mwe) above 1000 m elevation. As Icelandic glaciers exhibit large spatial variations over the melt season, the SMB sensitivity to dust deposition varied with elevation, being strongest at the uppermost site. Additionally, the sensitivity to timing of dust event were investigated which demonstrated that earlier occurrence increases the melt while later occurrence reduces the melt, compared to the July event. The results of this study reveal the impact of positive radiative forcing on SMB of Tungn
  • Chua, Samuel De Xun (2023)
    The behaviour of Greenland's tidewater glaciers is crucial for the understanding of the Greenland Ice Sheet. The retreat of those marine-terminating glaciers has far-reaching implications, impacting not only the regional hydrography but also the diverse fjord ecosystems. Here, this study investigated the rapid retreat of Narsap Sermia (NS), a tidewater glacier located in Southwest Greenland. Between 1987 and 2022, the volume of ice discharged from NS increased by 45%, a rate more than double the Greenlandic mean. This destabilization led to retreat events occurring in three distinct episodes: 2004-2005, 2010-2012, and 2019-2021. The study identified that changes in subglacial hydrology were pivotal in triggering and sustaining these retreats. Drainage of ice-dammed lakes or increased meltwater resulting from heatwaves over the ice sheet suddenly increased subglacial freshwater discharge, subsequently instigating these retreat events. Once initiated, exposure to elevated ocean temperatures or retreat into a glacial trough further sustained ice loss at the terminus, eventually resulting in a collapse of the glacial front. As of the summer of 2023, Narsap Sermia is still retreating, and the study anticipates that further retreat of approximately 3 kilometers is inevitable. Subsequently, should air and ocean temperatures continue to rise, Narsap Sermia is poised to retreat further for 30 km, dramatically transitioning into a land-terminating glacier. This drastic transformation could occur in as little as 30 years, with profound consequences for local eco-hydrology and nearby communities.