Modeling of the nitrogen cycling in the sediments of the Baltic Sea is the major objective of thepresent study. A model of the nitrogen cycling in the sediment of the Western Gotland Basinwas developed. The model simulates the sedimentary biogeochemical processes such asdecomposition of the organic detritus and transformation of nitrogen species in the sediment.The development of the model is based on the methods and approaches implemented in themodel of the freshwater Haringvliet Lake, Netherland. The sediments of Haringvliet and the Baltic Sea were examined in terms of the interactions andcontrols of biogeochemistry. Both systems are eutrophied. This results in a high sedimentationrate of organic matter and creates the same chemical and physical conditions to theirsediments. However, the sedimentation rate and decomposition of organic detritus is higherand nitrification and denitrification is lower in Haringvliet lake system compared to the BalticSea. The results of the model tests show that profiles of the chemical compounds and rates of theprocesses are in good agreement with the observations made in different areas of the BalticSea. The model can be used for simulation of the sediment processes when there is a constantinput of organic matter. The model can also reproduce the behavior of the sediment whensome of the process parameters and conditions are changed. A comparison of the rates of the biogeochemical processes predicted by model and thosemeasured in the different basins of the Baltic Sea was performed. The rates of decompositionof organic detritus, denitrification and nitrification were in agreement with the field data. Basedon the results of the model the nitrogen removal in the sediment was calculated and it wasfound that 26-32% of total nitrogen entering the sediment is removed by denitrification. / <p>www.ima.kth.se</p>

In einem hydronumerischen Modell zur Prognose des Strömungs- und Wasserstandsfeldes flacher Gewässer wird eine auf der Turbulenztheorie basierende Tiefenkorrektur für den Bodenreibungsbeiwertwert eingeführt und auf der Basis von Berechnungen für die DarßZingster Boddenkette überprüft. Für einen ausgewählten Meßpunkt der Darß-Zingster Boddenkette wurde der Reibungsbeiwert sowohl am Boden als auch unter einer Eisschicht experimentell bestimmt. Die Auswirkungen einer Tiefenkorrektur des Reibungsbeiwertes wurden in einem vertikal integrierten hydronumerischen Modell untersucht. Dabei wurden die experimentell bestimmten Reibungsbeiwerte, sowohl für die Reibung am Boden, als auch für die Reibung unter einer Eisschicht im Modell benutzt. Das verwendete Modell zeigt mit den gemessenen Reibungsbeiwerten nach Einführung der Tiefenkorrektur eine bessere Übereinstimmung zwischen Modelldaten und amtlichen Pegelregistrierungen. / For simulation of the flow and water level field in shallow water is introduced a depth correction of the bottom drag coefficient based on the theory of turbulence in a hydronumerical model and tested on calculations for the 'Darß-Zingster Boddenkette'. The drag coefficient was determined experimentally on the bottom and under ice for a selected measurement point in the 'Darß-Zingster Boddenkette'. The result of the depth correction was tested with a depth integrated hydronumerical model. The experimentally deterrnined drag coefficient on the bottom and under ice was introduced in the model. The used model shows with the measured drag coefficient after using the depth correction better agreement between the numerically simulated and measured water level.

Low-level jets (LLJs) are local wind speed maximums in the atmospheric boundary layer. In the Baltic Sea, LLJs are frequently occurring in spring and summer. It is an important phenomena to consider for wind energy parks, and changes in turbulence during the jets can effect the efficiency of said parks. In this study, the effect that offshore LLJs have on turbulence intensity (TI) is analysed and the goal is tounderstand if TI significantly changes as the jets form, and if the changes aredifferent above and below the core. The theory of shear sheltering predicts that turbulence decreases below the core of a LLJ, and it has been experimentally tested previously with various results. However, turbulence characteristics above the core ofa LLJ has not been studied before. LiDAR measurements of wind speed and TI profiles, up to 300 m, from the island of Östergarnsholm in the Baltic Sea are used. The measurements are from the period 2016-2020 and are limited to a sector with unobstructed line-of-sight to the ocean. Complete LLJ-events, which includes non-LLJ profiles before and after the actual jets, are analysed. The LLJs are found to appear in low TI conditions related to stable stratification. Mean TI increases with 38 - 47% above the core as the jets appear, and then returns to approximately the initial values after the jets disappear. Below the core, mean TI instead decreases with 14 - 19% during the jets, which is compatible with the theory of shear sheltering. For future studies it is recommend to choose a location with larger unobstructed line-of-sight to the ocean, further optimise the LLJ-finding algorithm and also analyse other turbulent quantities. / Vindmaxima på låg höj (LLJ, för eng. Low-level jets) är lokala vindhastighetsmaximum i det atmosfäriska gränsskiktet. I Östersjön är LLJs vanliga, framförallt på våren och sommaren. Det är ett viktigt fenomen att beakta för vindkraftsparker, och turbulensförändringar i samband med LLJs kan påverka effektiviteten av vindkraftverk. I denna studie analyseras effekten som LLJs över havet har på turbulensintensiteten (TI) och målet är att förstå om TI förändras närströmmarna bildas, och om förändringarna är olika ovan och under kärnan. En teori förutspår att turbulens minskar under kärnan i en LLJ, s.k. skjuvningsblockering (eng. Shear sheltering), och den har testats tidigare med varierande resultat. Turbulens ovanför kärnan i en LLJ har dock inte studerats tidigare. LiDAR-mätningar av vindhastighets och TI-profiler, upp till 300 m, vid ön Östergarnsholm i Östersjön används. Mätningarna är från perioden 2016-2020 och är begränsade till en sektor med fri siktlinje mot havet. Kompletta LLJ-event, vilket inkluderar icke-LLJ-profiler före och efter själva strömmen, analyseras. Resultatet visar att LLJs förekommer vid låga TI-förhållanden relaterade till stabil skiktning. Medel TI ökar med 38 - 47% överkärnan när strömmarna dyker upp och återgår sedan till ungefär de ursprungligavärdena efter att strömmarna försvunnit. Under kärnan minskar medel TI istället med 14 - 19% i samband med strömmarna, vilket är förenligt med skjuvningsblockerings-teorin. För framtida studier är det rekommenderat att välja en plats med större fri siktlinje till havet, ytterligare optimera identifikationen av kompletta LLJ-event och även analysera andra variabler för att karakterisera turbulensen.

Östersjön omfattas av en stor mångfald marina ekosystemtjänster som livnär närliggande samhällen. Deras funktion är hotad av en mängd terrestra och akvatiska aktiviteter som har förorenat havet, vilket kräver en långsiktig hållbar förvaltning. Syftet med denna uppsats är att bidra med kunskap om och förstå utmaningar och möjligheter i att uppnå en god ekologisk status i Östersjön. Studien baseras på en granskning av förvaltningsmetoder hos länsstyrelser och kommuner i två områden som är skyddade av den regionala överenskommelsen Helsingforskonventionen; Höga Kusten i Västernorrland och S:t Anna-Missjö i Östergötland. Till grund för det analytiska ramverket ligger Havs- och vattenmyndighetens rapport, som beskriver ekosystemtjänster som Östersjön bidrar med, samt även tjänsternas status, åtgärder och utmaningar som uppstår vid förvaltning. Resultatet baseras på kvalitativa metoder för att samla in data, genom att specifikt studera dokument samt intervjuer med lokala tjänstemän. Den insamlade empirin har blivit kategoriserad och analyserad i linje med Havs- och vattenmyndighetens rapport, därefter har innehållet diskuterats. Resultatet visar att mest fokus lades på hantering av övergödning, ohållbart fiske och reglering av föroreningar, samt deras trade-off- och synergieffekter som påverkar förvaltningen av just dessa ekosystemtjänster. Följaktligen, är det nödvändigt för tjänstemän att samverka med lokalbefolkningen för att uppnå en hållbar förvaltning av de skyddade områdena och deras ekosystemtjänster. Generella utmaningar ansågs vara tid, resurser och kunskap för förvaltning av marina miljöer. Dock genomsyrar myndighetens ramverk om ekosystemtjänster stora delar av länsstyrelserna och kommunernas arbete med marin förvaltning på Höga Kusten och S:t Anna-Missjö. Ekosystemtjänsternas status och funktioner är integrerade i länens och kommunernas förvaltningsmetoder av de skyddade områdena. Ekosystemtjänster som begrepp är däremot frånvarande och inte explicit nämnt i arbetet. / The Baltic Sea offers a diversity of marine ecosystem services which is providing support to nearby human communities. Their functions are jeopardized by terrestrial and aquatic activities which have heavily polluted the sea, necessitating long-term sustainable management. The aim of this bachelor thesis is to provide a scientific contribution to understanding the challenges and opportunities for reaching a good ecological status in the Baltic Sea, as well as insight into the ongoing management practices of Swedish county administrative boards and municipalities. Practices that involve conserving ecosystem services in two different marine protected areas the High Coast and St. Anna-Missjö, both of which have been designated important by a regional convention; the Helsinki Commission. Therefore, the Swedish Agency for Marine and Water Management has adopted a report on which ecosystem services the Baltic Sea provides, and the status of the services in different parts of the sea. This study is based on qualitative methods to gather data by a thorough reading of documents written by the counties and semi-structured interviews of local officials. The data has summarily been categorised and analysed in line with the national agency’s report, then discussed afterwards. The results show that the management practices were heavily emphasised on dealing with activities that lead to eutrophication, unsustainable fishery as well as regulation of polluting substances; where trade-offs and synergy-effects converge that impacts the management of other marine ecosystem services. Hence, it is necessary for officials to network with locals to have sustainable management of the protected areas and their ecosystem services. The officials pointed to the presence of a lack of time, resources and expertise in managing marine environments. Although the agency’s perspective on marine ecosystem services permeates large parts of county administrative boards and municipalities' work with marine management in the High Coast and St. Anna-Missjö. The status and functions of ecosystem services are integrated in their management practices of the protected areas. However, the concepts themselves are more absent and not mentioned explicitly.

Food security and eutrophication are two issues proven to have severe impacts on both humanity and the environment. This study suggests improving the local food security by utilizing phosphorus and nitrogen, available in severe eutrophic small lakes, in local food production, thus turning eutrophication from a problem into a resource. The study theoretically experiments the possibility of using eutrophic water in a greenhouse, where hydroponics is used as a cultivation method. The eutrophic water is pumped from the lake into the greenhouse, and then to the hydroponic system, which is expected to remediate the water, returning clean water to the lake. The objective of this process is to phytoremediate eutrophic water and simultaneously, produce edible commercial plants. Finding the best matching lake and plant nitrogen to phosphorus (N:P) ratio, is of key importance to optimize the remediation process. Based on data from a literature review, edible plants N:P ratios are found lower than typical lake N:P ratios, suggesting that, in some cases, edible plants in the hydroponic system would require additional nutrients to grow optimally. Finding the best matching lake and plant N:P ratio is thought to optimize the remediation process. Matching the lake and plant N:P ratio was conducted in Python.

As drivers of biogeochemical cycles and nutrient recycling, such as carbon turnover, the microbial community is essential in sustaining functioning ecosystems. Together with the metazoan community, the microbial community constitute the majority of all life in the benthos. Environmental change in biotic and abiotic factors may influence the dynamics of these communities, for example through a sorting or driving effect on the community structure through assembly processes. Environmental change, e.g. change in dissolved oxygen concentration, salinity and temperature, can directly or indirectly affect community composition. How, in what way, and to what extent, benthic bacterial and meiofaunal community composition in the eutrophied, brackish benthic environments, in the Baltic Sea sub-basin the Baltic Proper, respond to environmental change is understudied, both at local and seascape scale. This thesis aimed to study and understand the effects of environmental variation on the diversity and biogeographic patterns of Baltic Sea sediment bacterial and meiofaunal communities. A further aim was to understand the links between the different community levels by studying the interaction between meiofaunal- and macrofaunal communities in relation to environmental variation. Community diversity was analysed along a latitudinal transect of national environmental monitoring stations in the Baltic Proper using a framework of metapopulation and metacommunity theory. The analyses were based on environmental genomics, with high-throughput sequencing, bioinformatics and statistics. The total community genome was analysed using phylogenetic marker gene fragments as a proxy for taxonomic diversity, to investigate diversity, community structure and dynamics. Salinity and oxygen were found to be the main abiotic environmental drivers of benthic community composition and alpha- and beta-diversity patterns. Furthermore, macrofauna-meiofauna interactions were significantly more complex in higher salinity environments. Results also showed that both enhanced environmental gradients and dispersal following a major inflow of saline and oxygenated water from the Atlantic Ocean, influenced the composition of sediment bacterial communities at the seascape scale of the Baltic Sea, as shown by a reduced beta-diversity and increased alpha-diversity, and the development of a significant distance-decay of community similarity. This study also identified strong metapopulation dynamics of the benthic sediment bacterial communities with many satellite and a few core taxa. The outcomes from this study contribute to the understanding of how environmental variation and environmental change relate to changes in Baltic Sea benthic community diversity and composition, and important factors and processes governing community dynamics.

Die Bestimmung von Variationen des Meeresspiegels ist heute wichtiger Gegenstand geodätischer Forschungen. So stellt der mittlere Meeresspiegel eine geometrische Grenzfläche der Erdfigur dar. Seine säkulare Änderung ist darüber hinaus eine wichtige Größe u.a. bei der Planung künftiger Küstenschutzmaßnahmen. Die zuverlässige Schätzung dieser Größen aus den relativ kurzen Zeitreihen aktueller Satellitenaltimeterbeobachtungen wird jedoch durch lang- und kurzzeitig wirkende Meeresspiegelvariationen erschwert. Am Beispiel der Ostsee wurde ein Verfahren entwickelt, diese Variationen in den Beobachtungsdaten mit Hilfe modellierter Oberflächenauslenkungen, die einem hochauflösenden ozeanographischen Modell der Ostsee entnommen wurden, zu reduzieren. Die Streuung der beobachteten Höhen wurde so von ursprünglich etwa 15 bis 25cm auf unter 10cm reduziert. Vor der Nutzung des Modells ergab der Vergleich der modellierten mit beobachteten Variationen des Meeresspiegels eine Genauigkeit der modellierten Meeresspiegelauslenkungen von 5 bis 15cm. Darüber hinaus konnte unter Verwendung von Pegelbeobachtungen eine Modellverbesserung erzielt werden. Die Kombination der Beobachtungen unterschiedlicher Altimetermissionen erforderte des Weiteren eine Homogenisierung der Reihen und die Überprüfung ihrer Langzeitstabilität. Hierzu erfolgte eine absolute Altimetervalidierung durch Vergleich mit Pegelmessungen in der südlichen Ostsee. Relative Biaswerte wurden durch Vergleich der Beobachtungen unterschiedlicher Altimeter im Bereich der gesamten Ostsee ermittelt. Die korrigierten und um die modellierten Meeresspiegelvariationen reduzierten Altimetermeeresspiegelhöhen bildeten im Weiteren die Grundlage zur Bestimmung des mittleren Meeresspiegels der Ostsee und seiner säkularen Änderung. Der lineare Trend des Meeresspiegelanstieges in der Ostsee, bezogen auf das Geoid, ergab sich zu (+1,2+-0,8)mm/Jahr. Die Kombination dieses Wertes mit der an Küstenpegeln beobachteten relativen Meeresspiegeländerung erlaubte weiterhin die Schätzung postglazialer Landhebungsraten im Küstenbereich an den Pegelstationen. Die mittlere Meerestopographie innerhalb der offenen Ostsee wurde, bezogen auf ein regionales Geoidmodell, mit einer Genauigkeit von etwa 3 bis 10cm bestimmt. Das erarbeitete Verfahren zeigt das Potential der Kombination geodätischer Beobachtungsverfahren mit den Ergebnissen einer präzisen Modellierung der beobachteten Größe. Die Arbeit stellt eine regionale Studie dar, die - bei Vorhandensein entsprechender Daten - auch auf andere Regionen übertragbar ist. / The determination of sea level variations is a major topic of present geodetic research. The mean sea surface is a geometric boundary surface to describe the figure of the Earth. Its secular change has, for instance, to be considered in future coastal protection projects. However, the estimation of reliable values for these parameters from the relatively short altimeter observation time series is hampered by long- and short-term sea level variations. For the Baltic Sea, a processing scheme was developed that uses sea surface elevations taken from a high-resolution oceanographic model of the Baltic Sea to reduce these sea level variations in the observations. Thus, the standard deviation of the observed sea level heights was reduced from original values of about 15 to 25cm to final values of less than 10cm. A comparison of the modelled and the observed sea level variations was performed before the model was employed. From this, the accuracy of the modelled sea surface elevations was found to be in the order of 5 to 15cm. Moreover, the oceanographic model could be improved by the assimilation of tide gauge observations. The combination of the observations of different satellite altimeters requires also the homogenisation of the time series and the examination of their temporal stability. The comparison with tide gauge observations at the southern coast of the Baltic Sea allowed the determination of the absolute bias of each altimeter mission. Relative bias values were estimated by comparison of altimetric heights of different missions within the entire Baltic Sea. Finally, the time series of the corrected and reduced altimetric sea level heights formed the basis on which the mean sea surface of the Baltic Sea and its secular change were determined. The linear rate of the sea level rise in the Baltic Sea with respect to the geoid was estimated to (+1,2+-0,8)mm/year. This absolute rate was then combined with the relative sea level change observed at coastal tide gauges, allowing the estimation of the rates of the postglacial rebound in the vicinity of the gauges. The mean sea surface topography in the open Baltic was determined with an accuracy of about 3 to 10cm. A regional geoid model served as the reference surface. The presented procedure shows the potential of combining geodetic observations with the results of a precise model of the observed parameter. It can be regarded as a regional study that can be applied also to other regions where observational and modelled data are available.

I denna uppsats diskuteras jakten och nyttjandet av säl på Gotska Sandön, med utgångspunkt i en osteologisk analys av säl- och människoben från en begravningsplats på öns norra kust. Diskussionen inkluderar dessutom jämförelser med arkeologiska lokaler och etnografiska beskrivningar från öar som Gotland, Stora Karlsö, Fårö och Runö. Människobenen kommer från en individ och har daterats till 1400-talet e.Kr. Resultatet av den osteologiska analysen, jämfört med etnografiska källor, indikerar att individen kan ha varit en säljägare. Sälbenen talar om att gråsäl har jagats, och att jakten har inkluderat gamla sälar och sälhanar. Dessa sälar har jagats för sitt skinn och späck snarare än för sitt kött. Sälbenens förekomst på begravningsplatsen kan bero på en förkristen tradition, att de har misstagits för människoben eller att de har varit avfall från den närliggande medeltida boplatsen på Säludden. / This essay discusses the hunting and use of seals on Gotska Sandön, based on an osteological analysis of seal and human bones from a cemetery on the northern coast of the island. The discussion includes comparisons with archaeological sites and ethnographical descriptions from islands such as Gotland, Stora Karlsö, Fårö and Ruhnu. The human bones come from one individual and has been dated to the 15th century AD. The results of the osteological analysis, compared with ethnographical sources, indicate that the individual may have been a seal hunter. The seal bones indicate that grey seal was hunted, and that the hunt included old seals and male seals. These seals were hunted for their skin and blubber rather than their meat. The seal bones may have been buried in the cemetery because of a pre-Christian tradition, them being mistaken for human bones, or them being waste from the nearby medieval settlement on Säludden.

The Baltic Sea has for a long time had a problem with eutrophication. Historical phosphorus emissions from land, but nowadays the greatest source of eutrophication is the internal leakage of phosphorus from the bottom sediment. Both the European Union and Sweden has identified this problem and stated that the Baltic Sea should be saved, but only counteractive measures have been taken. Upstream work to limit the phosphorus emissions into the Baltic Sea will not solve the problem with eutrophication. The aim of this study has been to develop a business model that contributes to a reduction of the internal leakage of phosphorus in the Baltic Sea and at the same time makes it possible to make use of the resources that reside in the bottom sediment. The study has a deductive approach which consists of a literature review and semistructured interviews with stakeholders to the resources of the bottom sediment. The literature review creates a framework for the business model and the results from the interviews are used to define how the business model should meet the requirements of the stakeholders. The result indicates that there is an interest in circulated materials from the Baltic Sea, but there are challenges within price and politics that need to be faced. Circulated materials are often more expensive to produce than new materials due to the fact that the established methods have existed for a long time and have become cost-effective to stay competitive. Laws and regulations are not adjusted for a circular philosophy, which needs to be revised for the market to target circular solutions. The developed business model has a basis in the concept of the circular economy and focuses on utilising all the substances in the sediment as resources to meet the requirements of the market. / Östersjön har länge haft problem med övergödning. Historiskt sett har det släppts ut mycket näringsämnen från land men idag är den största källan till övergödning ett internläckage av fosfor från bottensedimentet. Både EU och Sverige har identifierat problemet med övergödning och fastställt att Östersjön bör räddas, men endast förebyggande åtgärder har vidtagits. Att bara arbeta uppströms kommer inte att lösa problemet. Uppsatsens syfte har varit att ta fram en affärsmodell som bidrar till minskning av internläckaget av fosfor i Östersjön och samtidigt gör det möjligt att nyttja de resurser som finns i bottensedimentet. Studien har en deduktiv ansats som består av en litteraturstudie och semistrukturerade intervjuer med intressenter till de resurser som finns i bottensedimentet. Litteraturstudien skapar ett ramverk för affärsmodellen och resultatet från intervjuerna används för att definiera hur affärsmodellen bör möta intressenternas behov. Resultatet visar att det finns intresse för cirkulerade råvaror från Östersjön, men att det finns utmaningar inom pris och politik som måste bemötas. Cirkulerade material är ofta dyrare att producera än nya material då de etablerade processerna har funnits länge och blivit kostnadseffektiva för att vara fortsatt konkurrenskraftiga. Lagar och regleringar är inte anpassade efter en cirkulär filosofi vilket behöver revideras för att marknaden ska inriktas på cirkulära lösningar. Den resulterande affärsmodellen har en utgångspunkt i cirkulär ekonomi och fokuserar på att nyttja samtliga ämnen i sedimentet som resurser för att möta marknadens behov.

In collaboration with Under ytan, a company cultivating algae locally on Åland, I have designed tableware made from and for algae-based food. Using the framework of the Set Table, I explore algae in a local context and reflect upon the usage of algae in marine restoration. The Set Table is full of symbols regarding culture, history, life and festivals. By gathering around the table, we share food, stories and create consciousness of the Baltic Sea.