Peatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal peat soils described the effect of pore dilation as a result of increased salinity in peat soils, while recent studies in Everglades peat soils showed specific salinity thresholds that may represent a permanent loss of the structural integrity of the peat matrix that may represent early stages of peat collapse. While most of these previous efforts have focused on drivers, recent work has also explored conceptual models to better understand the mechanisms inducing peat collapse. However, few datasets exists that consistently compare differences in physical properties under different in‐situ salinity conditions. In this study differences in the physical properties of peat soils across a salinity gradient along the western edge of Big Cypress National Preserve are investigated to test how differences in salinity may induce physical changes in the soil matrix. The physical properties targeted for this study include porosity, hydraulic conductivity, and carbon content. Measurements are conducted at the laboratory scale using peat cores and monoliths collected at selected locations to investigate: 1) how overall soil physical properties change spatially over a salinity gradient at the km scale moving from permanently saline to freshwater conditions; and 2) how physical properties change spatially at specific sites as dependant on vegetation boundaries and proximity to collapsed soils. This study has implications for better understanding the potential relation between physical changes of the soil matrix and the phenomena of peat collapse in the Everglades as saltwater intrusion progresses inward and alters freshwater ecosystems. Furthermore, a better mechanistic understanding of the peat collapse phenomenon can potentially help mitigate its occurrence. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Lipidy v půdě vykazují poměrně vysokou resistenci k biodegradaci, mohou proto tak zajistit informace o zdrojích organické hmoty a diagenetických procesech. Půdní organická hmota je vysoce heterogenní a vyskytují se v ní různé dynamické systémy. Vztahy mezi těmito systémy a molekulární strukturou ještě nejsou úplně známy. Analýza lipidů a bitumenu byla provedena u dvou vzroků (rašelina a lignit). Množství skupin sloučenin (volné uhlovodíky a volné ketony, vázané alkoholy, vázané mastné kyseliny, vázané -hydroxy kyseliny, volné dikyseliny a polycyklické sloučeniny) bylo idetifikováno pro oba vzorky a jejich distribuce byly určeny. GC/MS analýza volných a vázaných lipidů zjistila jejich různé zdroje během chemické degradace. Některé podobné znaky mohou být znakem uchovávání části vosků a suberinu z vyšších rostlin (dlouhé řetězce vázaných mastných kyselin). Velké rozdíly v molekulárním složení lipidů byly pozorovány mezi vzorky, dokládající význam studia lipidů z mladého sedimentu (rašelina) a starého (lignit).

The increased human impact on the environment and climate after the retreat of the Last Glacial has strengthened its importance in the region of Västernorrland where Mesolithic sites are evident. This study focuses on a multiproxy analysis, where archaeological and natural science methods are combined to test several techniques in a peat sample. The origin of the peat sample is coming from the formation of a postglacial kettle hole situated near to Mesolithic sites. The aim of this thesis is twofold. Firstly, to estimate the value and the weakness of each method as also the combination of multiple results. Secondly, to reconstruct the palaeoenvironment including the detection of possible indications from past cultures. To begin with, the peat sample was collected from a kettle hole near Lillsjön lake, see (fig. 1) in 2010. The total depth of the peat sample was 80 cm and after its sampling, it was placed in a cold storage room until the spring of 2019, when analysis was conducted. Initially, a theoretical background will be presented as well as information for the area of study in the section of Scientific background. Moreover, a short theory is going to be given for the formation of the landscapes in cold environments as also the validity of beetle fossils with examples from previous case studies. After the theory part, all the methods are specified with results and appropriate diagrams and tables. After the analysis, the discussion will follow by combining all the methods and give potential theories for the reconstruction of the palaeoenvironment. The discussion part is divided into smaller chapters and after the conclusion an appendix is given with fossil photographs that were taken during the identification, see (fig.15,16,17).

Large areas of northern Sweden have been ditched to promote forest growth by draining wet soils and peatlands. These ditches have greatly added to length of Sweden’s stream and river network, but the ecological properties of these man-made aquatic environments is poorly understood. The aim of this thesis was to evaluate the extent to which forest ditches support benthic macroinvertebrate communities, test the factors might influence variation in these communities across ditches, and evaluate how these communities differ from those observed in more natural headwater streams. To do this, I analysed macroinvertebrate family richness and community composition from 16 sampling sites distributed across two ditch networks in northern Boreal Sweden. At each site, I also compiled information related to channel structure, water depth, and the upstream distance from more typical headwater streams. I then tested whether variation in community metrics among ditch sites was related to differences in local habitat properties as well in the spatial position of sites within the ditch network.  Finally, I used existing data from four headwater streams within the same broader catchment to evaluate how these communities compare with those observed in forest drainage ditches. Results showed that macroinvertebrate family richness and community composition varied among ditch sampling sites, but that these systems supported a range of aquatic taxa that are typically found in headwater streams.  Overall, family richness tended to increase among ditch sampling locations that had greater water depth at the time of sampling and that were located further downstream in the ditch network. In addition, sampling locations with mineral substrate tended to support communities with a greater representation of more sensitive aquatic orders when compared to sites dominated by peat sediments. Finally, while family richness was not significantly different between ditches and headwater streams, benthic communities in streams were dominated by different set of taxa that reflect greater flow velocity and better overall water quality conditions.  Overall, my results suggest ditches in the boreal forest landscape can support benthic communities that closely resemble what is observed in headwater streams. However, ditch habitats were also highly variable, with several sites indicating poor local habitat conditions for many benthic organisms.  Hydrological patterns, including water depth, but also unmeasured variables like flow velocity and the potential for seasonal drying likely play a key role in influencing the ecological properties of ditches in these landscapes.

Northern Iceland is a place of great interest for climatic studies. The land was fairly untouched by human activity until the Landnám period (870-930 AD), when humans first started to colonize the island. The study site is situated in the valley of Hjaltadalur close to the village Hólar, which after the settlement of humans became the religious and culture center of northern Iceland. Peat sediment cores were drilled to gain knowledge of the climatic fluctuations and environmental development in the area. Peat is a perfect archive of climatic and environmental changes due to its ability to preserve material like pollen, tephra and insect fossils which can be identified and analyzed to gain a better understanding of the past climate. Out of four possible drilling sites in the valley of Hjaltadalur, northern Iceland, Viðvik peat land was chosen for climatic analyses. Pollen, loss on ignition, tephra and radiocarbon dating analyses were performed on the peat material and samples for future macrofossil analyses were collected. The analyses provided useful information and insights into temperature fluctuations during the late Holocene, which could be correlated with other palaeoclimate research made in the past decades in the northern regions of Iceland. The pollen diagrams presented in this thesis show a transition from a warm and dry forestlike landscape to a cooler, more humid, open landscape during the last 5000 years. This visible transition, which contributed to a reduction of the birch population, started before the european settlement and thus implies that humans were not solely responsible for the birch decline in Iceland after the Landnám period (870-930 AD).

Atmospheric mineral dust plays a dynamic role in the climate system acting both as a forcing and a feedback mechanism. To date, the majority of paleodust studies have been conducted on marine sediments or polar ice cores, while terrestrial deposition has been less studied. As such, it is important to produce new terrestrial Holocene paleo–dust records and fill existing regional gaps. Ombrotrophic (atmospherically–fed) peat bogs can be used to reconstruct dust deposition through elemental chemistry analysis. Multi–elemental data sets are commonly used infer net dust deposition rates, source changes, grain size, and mineral composition. Mineralogical identification of dust particles is particularly important because it allows both provenance tracing and increased understanding in climate and ecosystem feedbacks. Establishing mineralogy from elemental data of mixed mineral matrixes can however be challenging. X–ray diffraction analysis (XRD) is a standard technique for mineral identification which ideally requires removal of organic matter (OM). Therefore, a test procedure was undertaken where common OM removal methods were evaluated on bulk peat samples was therefore undertaken. The results showed that combustion at 500°C was most efficient in removing OM, while leaving the majority of minerals intact, but not all. In this Licenciate thesis, early result of a paleodust study from Draftinge Mosse, southern Sweden, are also outlined. Here, the method development mentioned above was applied, enabling a combination of elemental data with mineralogy. Future work includes minor and trace element analysis by ICP–AES and ICP–MS, evaluation of the reproducibility of single core reconstructions, tests of some of the methodological assumptions used in previous paleodust studies, source tracing and paleodust reconstruction from a second site (Gällsered Mosse). / Atmosfäriskt mineraldamm, mineralpartiklar som lyfts upp i atmosfären och avsätts via eoliska processer, spelar en komplex roll i klimatsystemet då partiklarna påverkar klimatet, samtidigt som rådande klimat också påverkar partikelmängden. De flesta hittills genomförda mineraldamms- studier har utförts på marina sediment eller iskärnor trots att mineraldammspartiklar i störst utsträckning deponeras på kontinenterna. Ombrotrofa mossar (högmossar) kan användas för att rekonstruera avsättning av mineraldamm över tid genom geokemiska analyser på olika djup i torvkärnor. Den kemiska sammansättningen ger information som kan användas för att härleda variationer i partikelmängd, källområden, kornstorlek, samt mineralogisk sammansättning. Bestämning av mineralen är av särskild vikt då det möjliggör identifikation av partiklarnas källområden samt ger kunskap om partiklarnas del i klimat- och ekosystem processer. Att via geokemiska data identifiera mineral prover av blandad sammansättning är dock utmanande, särskilt då många mineral har en liknande kemisk sammansättning. Röntgen diffraktions analys (XRD) är en standardmetod inom berggrundsgeologi för att identifiera mineral, som här används på torvprover. Metoden är icke-destruktiv, men kräver att provet är relativt rent från amorfa faser, så som organiskt material. Då torv innehåller stora mängder organiskt material (>98 %), som dessutom karaktäriseras av att vara svårnedbrutet, utformades ett testprotokoll för att studera vilken metod som är bäst lämpad för att ta bort organiskt material från denna specifika jordtyp. Resultaten från genomförda tester visade att förbränning (500°C) är mest effektivt och även lämnade en majoritet av mineralen intakta, dock inte alla. I denna licenciatavhandling beskrivs även de övergripande målen med min forskning samt tidiga resultat från en mineraldammstudie från Draftinge mosse (Småland), där resultaten från metodstudien ovan applicerats och kombinerats med andra geokemiska data. Vidare arbete inom detta doktorandprojekt kommer innefatta ytterligare geokemiska analyser (spårämnesanalys med ICP-MS och ICP-AES) samt identifiering av källområden. Dessutom kommer ytterligare en mosse (Gällsered mossse) att studeras för förändringar i avsättning av mineraldamm under de senaste 7000 åren.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 95-96. / by William Kensett Nuttle. / M.S.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21312号 / 農博第2297号 / 新制||農||1065(附属図書館) / 学位論文||H30||N5146(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 舟川 晋也, 教授 縄田 栄治, 教授 北山 兼弘 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

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