About 12% of earth’s peatlands have been drained for peat extraction or agriculture and turned peatlands into carbon sources with reduced biodiversity, water retention and downstream water quality. Rewetting is a strategy used to restore peatlands water table and peat forming vegetation, including Sphagnum spp. which are key species in facilitating water retention, peat- and carbon accumulation in bogs. Halmstad University and Sydvatten have been conducting a scientific study, including a one-year-baseline study on a drained bog in Halmstad, scheduled to be rewetted by ditch blocking. The collected data on bog vegetation in this thesis shall be used as baselines for the scientific study. The aim was to understand if rewetting increases the coverage of peat forming vegetation in drained bogs with the hypotheses that Sphagnum moss have higher degree of coverage in wet compared to drained bogs, and that the plant community in wet bogs are dominated by Sphagnum moss while the drained bog is dominated by brown moss. The estimated mean percent coverage of Sphagnum moss, brown moss (other Bryophytes), heather shrubs, sedges, and reeds was compared between the drained bog, scheduled to be rewetted to a wet bog where ditch clearing has not happened for the last 80 years. My result showed that brown mosses of woody species had a greater and dominant mean coverage at the drained bog, indicating a shift to forest vegetation following drainage. Reeds, sedges, and heathers showed no significant difference between sites. Sphagnum moss demonstrated a significantly higher mean coverage in the wet bog, dominating the vegetation. This reflects a typical bog succession, influenced by Sphagnum mosses capacity of outcompeting other plants. These findings support the hypothesis and indicate that within 80 years, there can be a shift to a peat forming-Sphagnum- dominated bog community in previously drained bogs, through ditch blocking.

This study aimed to investigate the influence of historical peat mining on current sedimentation and sediment quality in Håtjärnen, Håsjön and primarily Yttersjön. One sediment sample were collected from Håtjärnen and from Håsjön, along with 23 additional samples from Yttersjön. Sampling sites in Yttersjön were strategically located from upstream to downstream, near an inlet draining the nearest peat mining site, to assess its impact on sediment composition. This study analyzed subaqueous sediments, which consists of three constituents: minerogenic material, organic material (OM), and biogenic silica (Si). The sediment geochemistry was analyzed through loss on ignition, X-ray fluorescence, Near Infrared spectroscopy, Si/Al-ratio and lastly C/N ratio serving as a proxy for the origin of OM. No patterns in variation were observed in OM, Si/Al ratio, chlorophyll content, or C/N ratios between the upstream and downstream samples in Yttersjön, suggesting that the peat drainage inlet has a negligible impact on the sediment composition. In comparison, Håtjärnen and Håsjön displayed similar compositions of the sediment. An earlier study conducted in this area reported high sediment accumulation rates for the lakes investigated, as well as a substantial organic composition that included peat residues. These new findings, which contradict the earlier study, highlights the importance of analyzing all constituents of sediment to obtain a comprehensive understanding of the sediment composition.

Forested peatlands of the Great Dismal Swamp (GDS) have been greatly altered since colonial times, motivating recent restoration efforts. Community structure and function were hydrologically altered by 19th and 20th century ditches installed to lower water levels and enable early timber harvesting. Contemporary forest communities are comprised of maturing remnants from selective timber harvesting that ended in the early 1970s. Red maple (Acer rubrum) has become the dominant species across GDS, encroaching on or replacing the historical mosaic of cypress (Taxodium spp.)/tupelo (Nyssa spp.), Atlantic white-cedar (Chamaecyparis thyoides), and pocosin (Pinus spp.). Moreover, peat soil has been exposed to more unsaturated conditions resulting in carbon loss through decomposition and increased peat fire frequency and severity. Installation of ditch control structures aim to control drainage and re-establish historical hydrology, vegetation communities, peat accretion rates, and fire regime. To help inform restoration and management, we conducted two complimentary studies to test hypotheses regarding hydrologic influences on vegetation, peat depths, and peat fire vulnerability. First, we found thicker peat, lower maple importance, and higher species richness at wetter sites (e.g., higher mean water levels). In our second study, we evaluated the integrated effects of peat properties and water level dynamics on peat fire vulnerability. We found decreased burn vulnerability with increased wetness, suggesting that the driest sites were always at risk to burn, whereas the wettest sites never approached fire risk conditions. Together our findings demonstrate strong hydrologic controls on GDS ecosystem structure and function, thereby informing water level management for restoration goals. / Master of Science / Forested wetlands, like the Great Dismal Swamp (GDS) in eastern Virginia, provide valuable ecosystem services, including wildlife habitat, biodiversity, water quality and storage, carbon storage, and many others. Many of these ecosystems have been lost to land conversion, or hydrologically altered. Ditches installed to lower water levels and enable timber harvesting altered GDS ecosystem services. Lowered water levels changed the forest from a historical mosaic of diverse tree species to a more homogeneous forest dominated by one tree species, red maple. Moreover, GDS’s organic soil (peat) has been exposed to drier conditions resulting in carbon loss through decomposition and increased peat fire frequency and severity. To restore GDS ecosystem services, installation of water control structures in the ditches aim to control drainage and re-establish historical water levels (hydrology), forest cover, peat soil development rates, and fire regime. To help guide this hydrology management, we conducted two complimentary studies to test hypotheses regarding hydrology’s influences on vegetation, peat soil, and peat fire vulnerability. First, we found thicker peat soil, lower red maple prevalence, and more vegetation species at wetter sites. In our second study, we evaluated the integrated effects of peat soil properties and water level dynamics on peat fire vulnerability. We found decreased fire vulnerability with increased wetness, suggesting that the driest site was always at risk to burn, whereas the wettest site never approached conditions for fire risk. Together our findings demonstrate hydrology’s strong controls on GDS ecosystem services, thereby informing water level management for restoration goals.

Στην παρούσα διατριβή διερευνώνται οι διεργασίες που λαμβάνουν χώρα στο τυρφογενές στρώμα, έτσι ώστε να ανιχνευθούν οι μεταβολές των φυσικών, πετρογραφικών και χημικών χαρακτηριστικών των οργανικών ιζημάτων συναρτήσει των παραμέτρων τυρφογένεσης, όπως το κλίμα και οι τοπικές γεωλογικές συνθήκες. Απώτερο στόχο συνιστά η μοντελοποίηση παλαιοπεριβαλλόντων γένεσης των γαιανθράκων. Τέλος αξιολογείται η συμπεριφορά των ορυκτών, η γεωχημική συγγένεια και η κινητικότητα των ιχνοστοιχείων σε ενδεχόμενη αξιοποίηση της τύρφης για ενεργειακούς σκοπούς. Η έρευνα εστιάστηκε στους τυρφώνες Φιλίππων (Ν. Καβάλας) και Νησιού (Ν. Πέλλας) στη Βόρεια Ελλάδα και στον παράκτιο τυρφώνα του Κεριού (Ν. Ζακύνθου). Εξετάστηκαν τα ποιοτικά και ποσοτικά χαρακτηριστικά των οργανικών και ανοργάνων ιζημάτων που πληρούν τους τυρφώνες, αλλά και τα αντίστοιχα τυρφογενετικά φυτικά είδη, που αναπτύσσονται στους ενεργούς τυρφώνες Νησιού και Κεριού. Συγκεκριμένα πραγματοποιήθηκαν προσεγγιστική και στοιχειακή ανάλυση, ορυκτολογικοί προσδιορισμοί, εξέταση στιλπνών τομών με ηλεκτρονική μικροσκοπία σάρωσης, αναλύσεις τόσο της ανόργανης χημικής σύστασης (XRF, ICP/OES, ICP/MS), όσο και της οργανικής χημικής σύστασης (13C CP/MAS NMR, FTIR, py-GC/MS), όπως επίσης και ανθρακοπετρογραφικοί προσδιορισμοί. Αναφορικά με τους ορυκτολογικούς προσδιορισμούς εφαρμόστηκε μέθοδος πλήρους ποσοτικοποίησης των ορυκτών φάσεων με εφαρμογή περιθλασιμετρίας ακτίνων Χ σε ξηρό δείγμα, συνυπολογίζοντας την επίδραση του οργανικού υλικού. Αξιολογήθηκε επίσης η εφαρμογή περιθλασιμετρίας ακτίνων Χ σε υπολείμματα οξείδωσης της τύρφης. Οι τυρφώνες Φιλίππων και Νησιού συνιστούν παρόμοια περιβάλλοντα τυρφογένεσης, καθώς και οι δύο αναπτύσσονται σε ενδοηπειρωτικές λεκάνες, των οποίων η βύθιση ελέγχεται κυρίως από τεκτονικούς παράγοντες, με την ανάπτυξη παρόμοιων τυρφογενετικών φυτικών ειδών, όπως Cyperaceae και ειδικότερα το ασβεστόφιλο Cladium mariscus και διάφορα Carex spp., ενώ επηρεάζονται στη σύγχρονη εξέλιξή τους τουλάχιστον και οι δύο από καρστικούς υδροφόρους, συνιστώντας τοπογενείς ποωτυρφώνες, με κύριο μορφολογικό χαρακτηριστικό την παρουσία εξάρσεων (hummocks). Αντίθετα στο Κερί η τυρφογένεση αναπτύχθηκε σε παράκτιο περιβάλλον με τη βύθιση (δηλ. το πλημμύρισμα) να ελέγχεται τόσο από τεκτονικούς παράγοντες, όσο και από τις ευστατικές κινήσεις της θάλασσας, και το πεδίο χαρακτηρίζεται ως υφάλμυρος ποωτυρφώνας. Στο Κερί πέρα από ελόφυτα γλυκών νερών, αναπτύσσονται και είδη υφάλμυρων οικολογικών συνθηκών, όπως Scirpus maritimus και Juncus maritimus, λόγω της υφαλμύρινσης του υδροφόρου ορίζοντα. Με βάση τα χαρακτηριστικά τυρφογένεσης στους τρεις τυρφώνες τροποποιήθηκαν οι δείκτες φάσεων, που χρησιμοποιούνται στη γεωλογία γαιανθράκων, έτσι ώστε να αντανακλούν καλύτερα τις συγγενετικές διεργασίες στο ακρότελμα. Επιπρόσθετα περιγράφονται τόσο ποιοτικά, όσο και ποσοτικά τα χαρακτηριστικά των ιζημάτων στο τελματικό και το λιμνοτελματικό πεδίο, ενώ εκτιμάται επίσης και η πορεία της ενανθράκωσης των υπό μελέτη οργανογενών ιζημάτων, έτσι ώστε να εξαχθούν διαγνωστικές παράμετροι εφαρμογής στα παλαιοπεριβάλλοντα τυρφογένεσης. / The present study focuses on the processes taking place in the peatigenic layer (acrotelma), in order to trace the alteration of physical, chemical and petrographical features of the organic sediments in connection with the peat-forming factors. The ulterior aim is to propose a model for interpreting the coal-forming palaeoenvorinmental conditions. Finally, the mobility of the toxic trace elements is evaluated, in case of peat utilization for power generation in the future. Cores from the peatlands of Philippi (Prefecture of Kavala) and Nissi (Prefecture of Pella) in Northern Greece and of Keri (Zakynthos Island) in Southern Greece, were examined. The objective was to determine the qualitative and quantitative characteristics of the organogenic sediments hosted in the peatlands and additionally, of the peat-forming plants that grow on the surface of the Nissi and Keri mires. A series of laboratory examinations were performed on the collected samples, including proximate and ultimate analyses, mineralogical determinations by applying X-ray diffraction and SEM, inorganic geochemical analyses using XRF, ICP-OES and ICP-MS, organic geochemical analyses using 13C CP/MAS NMR, FTIR and py-GC/MS techniques and organic petrographical examinations on intact samples. Regarding the mineralogical determinations a method for full quantification of the mineral phases has been developed taking into account the pattern of the organic phases. Additionally the application of X-ray diffraction in oxidized peat residues has been evaluated. The Philippi and Nissi peatlands comprise similar peat-forming environments, since: (a) both developed in intermontane basins, the subsidence of which is controlled mainly by the tectonic activity, (b) Cyperaceae, mainly Cladium mariscus and various Carex spp., constitutes the main peat-forming plants, (c) whereas both are affected by karstic waters. They are fens for most of the peat accumulation period. On the contrary, in Keri the peat accumulation developed in a coastal environment due to paludification controlled both by the tectonic activity and the eustatic sea level changes, and the environment is characterized as a brackish mire, where additionally Scirpus maritimus και Juncus maritimus thrive. Taking in consideration the peat-forming features in the three studied peatlands the coal facies indices were modified in order to reflect more precisely the syngenetic processes in the acrotelma. Additionally a model is provided that describes both qualitatively and quantitatively the characteristics of the organogenic sediments deposited in the telmatic and the limnotelmatic fields. Furthermore, the coalification pathways of the studied sediments are interpreted, in order to obtain diagnostic parameters that can be applied to coal palaeoenvironmental studies.

No description available.

Carbon (C) biogeochemical cycling studies in northern peatlands, in particular the production, consumption, storage and emission of C gases (CO2 and CH4) over space and time between different peatland landforms can help in understanding their current and future role in the global C cycle. In some peatlands, a distinct surface patterning of vegetation, interspersed with open water pools, controls the spatial and temporal variability in CO 2 and CH4 exchange to atmosphere. These open water pools initially develop from shallow, flooded hollows to deeper water bodies and at some point reach a limit in their depth. Observations link pool size to age and spatial location on the peatland surface and over time the proportional cover of pools increases, playing an important role in the long-term peatland C balance. / The processes responsible for the production of CO2 and CH 4 in pools remain unexplored. In particular, the contribution of pools to the peatland C balance over the timeframe of the development of a pool complex is not explained and pools are not incorporated into current peatland models. A field study was carried out to examine the exchange of CO2 and CH4 from pools to atmosphere and to explore the spatial and temporal dynamics in CO2, CH4 and DOC storage in pools of different size and spatial location. This was undertaken to improve the understanding of the processes responsible for the generation of CO 2 and CH4 over the timescale of pool development. The empirical study was carried out during spring, summer and fall over two years in an ombrotrophic, raised bog, Quebec, Canada. A modelling component was carried out to examine the contribution of pools to the long-term peatland C balance. / Measurements of dissolved concentrations and emissions of CO2 and CH4 from pool surfaces to atmosphere were different among pools of different sizes and spatial location. Shallow pools had consistently higher emissions of both CO2 and CH4 and higher water column dissolved CO2 and DOC concentrations. Deeper pools had greater concentrations of sediment CH4. Dissolved organic carbon in pools was allochthonous, with a greater concentrations and proportion from higher plant materials in shallow pools, likely contributing to the observed water column CO2 concentrations and greater CO2 emissions. / All pools were supersaturated with dissolved CO2 and CH 4 at the time of sampling, with shallow pools up to eight times atmospheric equilibrium concentrations for CO2 and concentrations were up to one hundred times greater than CH4, comparable to findings in other global freshwater systems. Results suggest that greater decomposition is occurring in shallow pools due to warmer water and basal sediment temperatures and increased light penetration and dissolved oxygen (00) and that greater CH4 production and oxidation accounts for some of the differences reaching a limit at 0.7 m deep. Even though this range of pools are not as deep as pools found on other northern peatlands, the results provide evidence for the potential processes responsible for the generation of CO2 and CH4 emissions to atmosphere and demonstrate that pools have a significant role in the short and long-term peatland C balance. Modelling the hypothesised processes responsible for the generation of CO2 and CH4 shows that if sediment decomposition is the major source of these gases then the dynamical link between pool sediments, C gas production and pool growth has been demonstrated. Ultimately their role as source or sink is largely determined by their size (depth), the proportional cover on the landscape and their rates of C storage in sediments versus rates of C uptake and exchange.

[Truncated abstract] Relationships between the persistence of organic matter added to soil, the dynamics of soil organic carbon (C) and phosphorus (P) were examined in four experiments on lateritic soils of Western Australia. The main objective was to quantify the release of P following organic matter application in soils which have high P adsorbing capacity. Another objective was to confirm that due to its recalcitrant materials, the effect of peat lasted longer in soil than other sources of organic matter in terms of increasing plant-available P fractions. Three experiments were conducted under glasshouse conditions for various lengths of time, with nine- to twelve-month incubations to investigate these hypotheses. As expected, organic matter with lower C:N ratios than peat (lucerne hay) decomposed more rapidly compared with peat, and the most active mineralisation took place within the first three months of incubation. Soil organic-C (extracted by 0.5 M K2SO4) had a significant positive correlation with P extracted with 0.5 M NaHCO pH 8.53. For a higher application rate (120 ton ha-1), peat was better than wheat straw and lucerne hay in increasing extractable bicarbonate-P concentrations in soil, especially at incubation times up to 12 months. Throughout the experiment, peat was associated with a steady increase in all parameters measured. In contrast to peat, nutrient release from lucerne hay and wheat straw was rapid and diminished over time. There was a tendency for organic-C (either in the form of total extractable organic-C or microbial biomass-C) to steadily increase in soil with added peat throughout the experiment. Unlike wheat straw and lucerne hay, extractable organic-C from peat remained in soil and there was less C loss in the form of respiration. Therefore, peat persisted and sequestered C to the soil system for a longer time than the other source of organic matter. Freshly added organic matter was expected to have a greater influence on P transformation from adsorbed forms in lateritic soils than existing soil organic matter. By removing the existing soil organic matter, the effect of freshly applied organic matter can be determine separately from that of the existing soil organic matter for a similar organic-C content. In order to do this, some soil samples were combusted up to 450° C to eliminate inherent soil organic matter. The release of P was greater when organic-C from fresh organic matter was applied to combusted soils than in uncombusted soils that contained the existing soil organic matter. The exception only applied for parameters related to soil micro-organisms such as biomass-C and phosphatase. For such parameters, new soil organic matter did not create conditions favourable for organisms to increase in activity despite the abundance of organic matter available. More non-extractable-P was formed in combusted soils compared to bicarbonate-P and it contributed to more than 50% of total-P. As for the first experiment, peat also showed a constant effect in increasing bicarbonate extractable-P in the soil

The Matlabas mire, an actively peat accumulating wetland, is located in the headwaters of the Matlabas River, Marakele National Park, Limpopo Province, South Africa. Various seepage zones and artesian peat domes are contained in this peatland that consists of two tributaries of which the western one is partially channelled. The occurrence of decaying peat domes and desiccated areas with terrestrial vegetation, as well as the apparent erosion on the western tributary, have raised concerns on the health of this wetland. A network of piezometers was installed in the mire and results confirm that the system is fed primarily from seepage from the slopes of the catchment. Chemical analysis and temperature recorded indicate an isolated groundwater source of which the water does not mix with surface water. This is linked with isotope analysis of the age of peat in various sections of the mire. Erosion was attributed to anthropogenic changes in the catchment. Management recommendations include rehabilitation and reinstating the driving forces that support the mire. / Environmental Sciences / M. Sc. (Environmental Management)

Skogsbränder utgör ett stort problem både lokalt, regionalt och globalt. De förstör stora värden, frigör stora mängder kol ut i atmosfären och är mycket resurskrävande att bekämpa. Under markytan kan glödbränder fortsätta långt efter att flambranden ovan mark är släckt. Glödbränder brinner mycket långsammare än de öppna flambränderna, men är istället svårare att upptäcka och ställer andra krav vid bekämpning. En typ av glödbrand som kan påträffas i skogsbränder är torvbränder. Det är glödbränder som uppstår i torvmarker som utsatts för torka. Branden äter sig sakta igenom torven och kan gå djupt ner i marken. Svårigheter med att lokalisera bränderna och att få ner tillräckligt med vatten i de djupare torvlagerna gör dem svåra att släcka. Idag används ofta dimspikar, även kallade jordspett, för att släcka bränder som gått ner under markytan. På vissa ställen har även skärsläckaren börjat användas. Detta arbete syftar till att ge en bättre förståelse för de två verktygens funktion och effektivitet vid släckarbete av torvbränder. För att göra det har två tester genomförts på Luleå räddningstjänsts övningsfält, ett för dimspik och ett för skärsläckare. En försöksuppställning byggdes upp med en invändig tvärsnittsarea på 80×80 cm och en höjd på 1,1 m. Den fylldes sedan med torv som packades lätt tills torvlagret var 1 m tjockt. Det som undersöktes var verktygens penetreringstid för vattnet att nå 1 m ner i torven samt hur stor spridning vattnet fick över tvärsnittsarean på djupet 1 m. Båda verktygen hade liknande flöden (56 l/min för skärsläckaren och 58 l/min för dimspiken) så de uppmätta skillnaderna i resultat berodde på hur vattnet transporterades, inte på mängden vatten. Skärsläckaren slog igenom på cirka 1 sekund och bildade ett utgångshål på cirka 1 dm2, där det var blött ytterliga någon centimeter runtomkring för en total våt area på cirka 2 dm2. Testet avslutades efter 30 sekunder då ingen förändring kunde ses i storleken på utgångshålet och den våta arean från efter de första få sekunderna. Vattnet sprutade rakt igenom torven. Dimspiken vätte igenom efter 26 sekunder och den våta arean växte kontinuerligt. Inget utgångshål bildades i detta fall. När dimspiken stängdes av efter 1 minut och 45 sekunder, så hade cirka 32 dm2 blivit blött; vilket motsvarar ungefär halva tvärsnittarean hos försöksuppställningen. Spridning fortsatte efter att dimspiken slagits av och nästan hela tvärsnittsarean var blöt efter ytterligare några minuter. Skärsläckaren hade en mycket snabb penetreringstid, men sprutade istället mycket vatten rakt igenom torven, vilket medförde att stora mängder vatten passerade genom torven utan att väta en stor yta eller volym. Dimspiken hade en mycket längre penetreringstid, i gengäld så sköts inte vattnet rakt igenom torven utan spred ut sig och vätte en större yta. Båda verktygen har sina för- och nackdelar. Vilket verktyg som är bäst är väldigt situationsberoende. Skärsläckaren har bland annat snabbare penetreringstid och möjliggör fler snabba ingrepp, medan dimspiken täcker en större area per angreppspunkt och är lättare och säkrare att hantera. / Wildfires are a major problem both locally, regionally and globally. They destroy large values, emit large quantities of carbon into the atmosphere and are very resource intensive to fight. Smoldering fires can continue under the ground surface long after the flaming fire above ground is put out. Smoldering fires burn much slower than the flaming fires, but in turn they are harder to discover and require different means to fight. Peat fire is one type of smoldering fire that can be found in wildfires. It is a smoldering fire that occur in peatlands exposed to drought. The fire slowly eats its way through the peat and can go deep into the ground. Difficulty locating them and getting enough water into the deeper peat layers makes them difficult to extinguish. Today, fognails are often used to extinguish smoldering fires in the ground. The cutting extinguisher is another tool that has been used to fight smoldering fires in the ground in some cases. This bachelor thesis aims to provide a better understanding of the function and efficiency of the two tools in extinguishing peat fires. To do this, two tests have been carried out on the fire department’s training field in Luleå, one with a fognail and one with a cutting extinguisher. A test stand was constructed with an internal cross-sectional area of ​​80×80 cm and a height of 1.1 m. It was then filled with peat which was lightly packed until the peat layer was 1 m thick. What was investigated was the tools’ penetration time for the water to reach 1 m down into the peat and the size of the water spread over the cross-sectional area at the depth of 1 m. Both tools had similar flows (56 l/min for the cutter extinguisher and 58 l/min for the fognail) so the differences arose in how that water was used, not the amount of water. The cutting extinguisher broke through in about 1 second and formed an exit hole of about 1 dm2 with additional wetness of a few centimeters around for a total wet area of ​​about 2 dm2. The test was terminated after 30 seconds when no change could be seen in the size of the output hole or the wet area from after the first few seconds. The water sprayed right through the peat. The water from the fognail got through after 26 seconds and the wet area grew continuously. No exit hole was formed in this case. When the fognail was turned off after 1 minute and 45 seconds, about 32 dm2 had become wet, which corresponds to about half the cross-sectional area of the test stand. However, spreading continued despite the fognail being turned off and almost the entire cross-sectional area was wet after a few more minutes. The cutting extinguisher had a very fast penetration time, but as a result it sprayed a lot of water right through the peat without wetting a large area or volume. The fognail had a much longer penetration time, but in return, the water was not shot straight through the peat, but spread out and wet a larger surface. Both tools have their advantages and disadvantages. Which tool is the best depends a lot on the situation. The cutting extinguisher has, among other things, a faster penetration time and allows for more rapid interventions, while the fog nail covers a larger area per attack point and is easier and safer to handle.

No description available.