The functional hydrological components of the ombrotrophic mire water balance are, considered in terms of their ecological relevance. It is proposed that numerical models provide a suitable framework for mire hydro-systems and their potential as quantitative tools for mire restoration and conservation management is demonstrated. Existing models previously applied to mires are reviewed. The USGS 3-D groundwater model MODFLOW is selected and a new shallow surface and groundwater model GSHAW5 is developed for application to mires. Extensive ecohydrological case studies are undertaken at two mire sites and the models are tested using data collected at the sites. Field studies at Wedholme Flow, Cumbria, extended over four years and the data collected were combined with historical records to form a 10-year hydrological data set. Studies at Trough End Bog, Northumbria, extended over a 3-year period. Topographic, soil and vegetation surveys were carried out at both sites. Watertable fluctuation was recorded manually on a weekly basis and electronically at a 20-minute interval along with automatic meteorological records. New hydrometric techniques were developed in the Surface Water Monitoring Plot, SWaMP, constructed at Trough End to record hydrological exchanges within the hummock-hollow complex of the mire acrotelm. The models operate on very different spatial and temporal scales. GSHAW5 is applied to reproduce ground and surface exchanges in the acrotel. MODFLOW is used to simulate large-scale exchanges in undisturbed areas and between regenerating and active peat cutting areas. Predictive MODFLOW simulations are used to examine the impact of different peat cutting regimes on mire hydrology and potential regeneration. Both models produce simulations strongly correlated to observed hydrological exchanges. The usefulness of numerical models as tools for mire management is considered in light of the model test results from both case studies. It is concluded that both models provide insight and quantitative estimates of hydrological exchanges not possible by other means. MODFLOW simulations reveal considerable water loss from the Wedholme Flow mire reserve to an active peat cutting area. Simulations of Trough End bog reveal hydrological acrotelm processes strongly related to vegetation assemblages. An extensified GSHAW5 acrotelm model is recommended for the simulation of intact ombrotrophic mires.

Anthropogenic disruptions in the form of hydrological alterations, such as dam construction and the associated water diversions are a cause of much upheaval to local and regional ecosystems. Lake 626 within the Experimental Lakes Area of north-west Ontario, along with its downstream wetlands, 626A and 626B are one such system. Construction of a dam at the L626 inflow has completely restricted water flow, reducing and reshaping the watershed, increasing water retention time, and decreasing outflow into the wetlands. This study investigates the state of each wetland through physical and geochemical characterization during the first year following the diversion. Previous studies have found that hydrological diversions in wetlands can lower water table levels, altering soil chemistry and producing a shift in floral and faunal communities. Ultimate consequences involve significant loss of wetland area through conversion to upland habitat. This provides a model for climatic warming scenarios, wherein sustained drought conditions can produce the same result. Boreal wetlands are surprising fragile ecosystems that store massive quantities of carbon and are at risk of releasing it in such situations. One study showed that an extended summer drought in an otherwise average year with above average precipitation produced losses of 90 g C/m2 over the course of the year. Maintenance of reduced-flow in wetlands 626A and 626B is expected to convert the system into a carbon source and reduce overall wetland area. Radiocarbon dating has revealed that following deglaciation, both 626A and 626B basins were open water wetlands, depositing limnic peat for about 3200 and 1300 years respectively. Each site then transitioned into open sedge dominated fen – 626B to the present and 626A until about 2.5 ka BP when Sphagnum began to develop. Wetland 626B is decidedly an open shrub/sedge fen, supporting Myrica gale, Chamaedaphne calyculata and Carex rostrata / lasiocarpa communities. Wetland 626A is a bog/fen complex, sharing similar communities in the fen areas, but housing a large, centrally located bog of shrub species overlying Sphagnum hummocks. Tritium values in 626A were similar to cosmic background levels, indicating that recharge of basal pore water has not occurred in at least 60 years. Tritium in 626B was much higher, suggesting a substantial difference in hydrology or peat hydraulic conductivity between the basins. Measurement of DOC profiles showed high concentrations in near-surface water, reaching over 80 mg/L, and dropping to about 20 mg/L at maximum depths. An opposite trend was seen for DIC and CH4 profiles which increased concentration with depth (25 – 70 mg/L DIC; 75 – 700 μmol/L CH4). Isotopically however, 13C signatures from basal DIC were more positive while signatures from CH4 were typically more negative (-6 ‰ to +4 ‰ DIC; -57 ‰ to -73 ‰ CH4). Breakdown of DOC by LC-OCD showed high concentrations of humic substances and low molecular weight neutrals. The origin of humic substances in surface water became more pedogenic with increasing distance from the L626 outflow, indicating the influence of decaying wetland vegetation on the DOC of adjacent water. A comparison between contemporary and future characterization of boreal peatlands under drought-like conditions will provide a better understanding of the impacts suffered by wetlands during hydrological alterations. The high sensitivity of wetlands to changing hydrology should also provide a measure for gauging the effects of long term climate warming. This will assist in the development of environmental policies to better govern both the establishment of water diversions and the multitude of other practices leading to climate change.

Thesis (M.Sc. Biology)--University of Waikato, 2009. / Title from PDF cover (viewed Apr. 22, 2010). Includes bibliographical references (p. 35-47, 104-120)

Northern peatlands are a globally important soil carbon (C) store, and aquatic systems draining peatland catchments receive a high loading of dissolved and particulate forms of C from the surrounding terrestrial environment. Once incorporated into the aquatic environment, internal processes occur to modify the C pool. Of these, photo-processing preferentially targets terrestrially derived C and therefore might have a significant effect on the C budget of peatland draining aquatic systems. The overarching aim of this study was to investigate photochemical processing of C in Scottish peatland draining aquatic systems in order to determine the importance of this pathway in aquatic biogeochemical cycles. For initial laboratory experiments, water samples from a peatland headwater stream (Auchencorth Moss, SE Scotland) were collected. Laboratory based irradiation experiments were conducted at a range of temperatures, and different filtration treatments, including unfiltered samples, were employed to understand the fraction of C most susceptible to photo-processing. UV irradiation and temperature had a significant effect on DOC and gas headspace concentrations, with Q10 values of ~1.42 and ~1.65 derived for CO2 and CO photoproduction in unfiltered samples, respectively. However, filtration treatment did not induce significant changes in gaseous C production between light and dark samples, indicating that the experimental conditions favoured breakdown of DOC rather than POC to CO2 and CO. In all light treatments a small but significant increase in CH4 concentration was detected. These data were compared to results from experiments conducted in ambient light and temperature conditions. DOC normalised CO2 photoproduction was an order of magnitude lower than in laboratory conditions, although relative abundances of C species within overall budgets were similar and these experiments demonstrated that ambient exposure is sufficient to generate photo-processing of aquatic peatland C. Overall these data show that peatland C, particularly the < 0.2 μm fraction, is highly photoreactive and that this process is temperature sensitive. Further laboratory irradiation experiments were conducted on filtered water samples collected over a 13-month period from two contrasting aquatic systems. The first was the headwater stream draining Auchencorth Moss peatland with high DOC concentrations. The second was a low DOC reservoir (Loch Katrine, C Scotland) situated in a catchment with a high percentage peat cover. Samples were collected monthly from May 2014 to May 2015 and from the stream system during two rainfall events. Significant variation was seen in the photochemical reactivity of DOC between the two systems, with total irradiation induced change typically two orders of magnitude greater and DOC normalised CO2 production a factor of two higher in the headwater stream samples. This is attributed to longer water residence times in the reservoir rendering a higher proportion of the DOC recalcitrant to photo-processing. Overall the magnitude of photo-induced C losses was significantly positively correlated with DOC concentration in the headwater stream, which varied seasonally with highest concentrations detected in late autumn and winter. Rainfall events were identified as important in replenishing the stream system with photoreactive material, with lignin phenol data indicating mobilisation of fresh DOC from woody vegetation in the upper catchment during a winter rainfall event. Whilst these data clearly demonstrate that peatland catchments generate significant volumes of photoreactive DOC, the degree to which it is processed in the aquatic environment is unclear. Field investigations were undertaken to address this uncertainty. In-situ experiments with unfiltered water samples in light and dark conditions were conducted in two contrasting open water peatland pool systems. At the high DOC site (Red Moss of Balerno, SE Scotland), DOC concentrations in surface light exposed samples decreased by 18% compared to dark controls over 9 days and light treatments were enriched in CO2 and CH4. Photochemical processing was evident in δ13C-DOC and δ13C-DIC signatures of light exposed samples, which were enriched and depleted, respectively, relative to dark controls (+0.23 ‰ and -0.38 ‰) after 9 days of surface exposure. At the low DOC site (Cross Lochs, Forsinard, N Scotland) net production of DOC occurred in both light and dark samples over the experiment duration, in part due to POC breakdown. δ13C-DIC signatures indicated photolysis had occurred in light exposed samples (-1.98 ‰), whilst δ13C-DOC data suggest an absence of photo-processing, as the signatures in both treatments were similar. Accounting for light attenuation through the water column, 46 ± 4.9 and 8.7 ± 0.5 g C-CO2 eq m−2 yr−1 was processed by photochemical and microbial activity in peatland pools within the catchments at the high and low DOC sites, respectively. At both sites, light driven processing was responsible for a considerable percentage (34 and 51%) of gaseous C production when compared to equivalent estimates of microbial C processing and thus should be considered a key driver of peatland pool biogeochemical cycles. It is clear from this study that temperature, seasonal cycles, rainfall events and water residence time provide strong controls on the photoreactivity of aquatic C in Scottish peatland systems. The photo-processing pathway has the potential to alter the C balance of peatland catchments with a high percentage coverage of aquatic systems. Under climate change scenarios where light, temperature and rainfall conditions are expected to change, this process may become increasingly important in aquatic C cycling, particularly if the upward trend in DOC concentrations in northern aquatic systems continues.

Les tourbières sont largement présentes dans les hautes latitudes nord et plus particulièrement dans les régions de pergélisols. Elles contiennent un important stock de carbone et constituent l’une des plus grandes sources naturelles de méthane. Leur représentation dans un modèle de climat estalors primordiale pour améliorer celle du cycle du carbone. De plus, la contribution des émissions de méthane des tourbières reste encore incertaine et de nombreuses incertitudes persistent. Les émissions de méthane des tourbières dépendent fortement du climat et sont influencées principalement par la température et l’humidité du sol. Parallèlement, le réchauffement climatique particulièrement prononcé à ces latitudes conduit au dégel des pergélisols avec une augmentation de la profondeur de la couche active. Ce grand réservoir de carbone peut être partiellement mobilisé et émis sous forme de CO2 ou CH4, en fonction des conditions hydrologiques à la surface.L’objectif de ces travaux de thèse consiste à représenter les tourbières des hautes latitudes dansle modèle de surface ORCHIDEE. Ce développement est effectué dans la version du modèle qui intègreles processus des hautes latitudes tels que le gel des sols. Les tourbières sont représentées parun schéma hydrologique spécifique ce qui améliore les échanges en énergie et en eau. La difficultérepose sur la représentation des processus locaux des tourbières à l’échelle d’un modèle de climatglobal. Certaines propriétés biologiques ont également été prises en compte afin de mieux représenter la végétation de ces milieux. Pour cela, les tourbières sont intégrées comme un nouveau type devégétation et représentées par une fraction de grille, basée sur des observations. Le comportement hydrologique et l’impact de cette intégration sont évalués à échelle des hautes latitudes ainsi qu’à échelle régionale. Ce développement permet d’estimer ensuite l’évolution de l’hydrologie des tourbières suite au réchauffement climatique. Les changements de l’hydrologie des tourbières d’ici la fin du siècle permettent de mieux évaluer les variations futures de leurs émissions de CH4.Ce travail de développement a ensuite été appliqué pour déterminer l’évolution des émissions deméthane. Les tourbières constituent l’une des plus grandes sources naturelles de méthane et contrôlentà plus de 70 % la variabilité interannuelle de la concentration atmosphérique de CH4. Les émissionsde méthane résultent de différents processus physiques et biologiques tels que la méthanogénèse etla méthanotrophie. Pour représenter ces processus, un modèle de densité de flux existant, intégré dans ORCHIDEE, a été adapté pour les tourbières afin d’estimer les émissions de méthane des tourbières des hautes latitudes. L’évolution de ces émissions est étudiée entre le début du 20ème et la fin du 21ème siècles selon différents scénarios climatiques. / Peatlands are widely present in northern latitudes and especiallyin permafrost regions. They contain a high carbon stock and are one ofthe greatest natural sources of methane. Their representation in a climate model is crucial to improve the one of the carbon cycle. Moreover, the contribution of methanepeatland emissions remains uncertain.Methane emissions from peatlands strongly depend on the climate and are influenced primarily by temperature and soil moisture. Meanwhile, climate change is particularlysevere at these latitudes and leads to thawing permafrost with increasing the active layer depth. This large carbon reservoir may be partially mobilized and emitted asCO2 or CH4, depending on hydrological conditions at the surface.The aim of this PhD thesis is to represent northern peatlands in the ORCHIDEE land surface model. This development is carried out in the version of the model that incorporatesprocesses in high latitudes such as the soil freezing. Peatlands are represented by a specific hydrological scheme which improves the exchange of energy and water. The difficulty isbased on the representation of local peatlands processes across a global climate model. Some biological properties were also considered to represent bettervegetation of these environments. To do so, peatlands are integrated as a new type ofvegetation and represented by a fraction of a grid, based on observations. Thehydrological behaviour and the impact of this integration are estimated at the boreal scale as well asregionally. This development then allows estimate changes in the hydrology of peatlands due to global warming. Studying the changes in hydrology of peatlands by the end of th 21st century will improve the prediction of future changes in their CH4 emissions.This development work was then applied to determine the evolution of methane emissions. Peatlands are one of the largest natural sources of methane and control more than 70% interannual variability of atmospheric concentration of CH4. Methane emissions result from various physical and biological processes such as methanogenesis and the methanotrophy. To represent these processes, a flux density model, integratedin ORCHIDEE, was adapted for peatlands to estimate their methane emissions. The evolution of these emissions is studied between the early 20th and late 21st centuries under different climate scenarios.

The aim of this thesis was to assess the effect of root exudates on the biodegradability of dissolved organic matter. The experiment was done in laboratory conditions, using the dissolved organic matter sampled in a spruce swamp forest located in Šumava National Park and an artificial mixture of root exudates prepared according to known composition of root exudates released by peatland plants. Main hypothesis was that the input of root exudates into the peatland pore water will affect decomposition of less-degradable dissolved organic matter, with the resulting effect dependent on the quantity and quality (C:N ratio) of the input.

Large areas of northern peatlands have been drained and afforested in the second half of the 20th century with significant impacts on important ecosystem services, including loss of biodiversity and potential changes in C storage. A considerable effort is currently invested into restoring original peatland function and ecosystem services, with an increasing area of newly restored peatland areas over recent years. However, the effect of restoration on the greenhouse gas (GHG) budget is unknown. This study is the first quantification of CO2, CH4 and N2O fluxes from forest-to-bog restoration sites spanning 0 to 17 years in age. Further, the impact of afforestation on peat decomposition is measured in situ, and the impact of afforestation on the biochemical composition of the peat in relation to CO2 and CH4 fluxes is investigated. Results show that forest-to-bog restoration is successful from a GHG perspective, since all three major GHG fluxes of the restoration sites are changing along the chronosequence towards the fluxes from near pristine bog sites. The peat decomposition rate under the forest plantations is a big part of the total soil respiration at 126.8 ± 14.7 g C m-2 y-1 (44% of total soil CO2 efflux) and our results indicate a slowing down of peat decomposition towards the near pristine bog. CH4 fluxes increase with restoration age, whilst all sites remain a small sink for N2O. I observed changes in peat quality and nutrient availability in the pore water under forests. Different CO2 fluxes between vegetation-free peat cores from different sites for the same temperature and water level show that these differences in peat quality and nutrient availability shape the biogeochemical processes in the peatlands. However only small differences in CH4 fluxes between sites were evident, suggesting that on its own (and in absence of biotic interactions under field conditions), forestry effects on CH4 flux are limited.

A Bacia hidrográfica do Rio Sorocá-Mirim encontra-se no Planalto de Ibiúna, que faz parte de um conjunto de blocos falhados formando grábens e meio grábens, que compõem um sistema de bloqueio estrutural onde a água é aprisionada em sub superfície criando as condições ideais para a formação de turfeiras. Características como a geometria dos interflúvios, a assimetria das vertentes e das planícies de inundação e também a disposição da rede de drenagem, denotam a grande influência das estruturas geológicas nesta bacia hidrográfica. As zonas de acumulação de matéria orgânica encontradas na Bacia do Sorocá-Mirim estão vinculadas à ambientes fluviais particulares, relacionados ao controle estrutural, que é característica marcante da área. O presente trabalho teve como objetivo estudar turfeiras, em dois ambientes fluviais diferentes (terraço e anfiteatro) em relação às suas características físicas, químicas, orgânicas e sua distribuição areolar para entender como a formação destas turfeiras foi influenciada por esses ambientes. O levantamento topográfico das duas áreas, assim como uma série de ensaios e análises laboratoriais demonstraram que as turfeiras dos dois ambientes apresentam idades diferentes em aproximadamente 1000 anos (turfeira da área 2, terraço, mais antiga do que a turfeira da área 1, anfiteatro), mesmo tipo de plantas acumuladas ao longo destes anos e diferenças principalmente no que se refere à posição preferencial ao acúmulo da matéria orgânica e à variações, no sentido das maiores profundidades, de diversos parâmetros observados. Verificou-se que a área 1 sofreu maiores alterações do modelado, e consequentemente nas suas condições hidrológicas ao longo dos tempos, passando a ser um ambiente mais drenado, mais oxigenado, com uma turfeira que apresentou resultados laboratoriais mais heterogêneos, com concentrações de matéria orgânica e dos elementos vinculados a ela, variando bastante ao longo da feição. A área 2 não sofreu grandes alterações no modelado, mantendo-se mais úmida ao longo do tempo o que acarretou em uma turfeira mais homogênea com valores mais constantes de matéria orgânica e dos elementos vinculados a ela, ao longo da feição. Essas diferenças são reflexo da influência do modelado nos processos de acumulação da matéria orgânica, onde em cada feição (terraço, ou anfiteatro) a matéria orgânica é acumulada em posições específicas, sofrendo maior ou menor interferência de materiais minerais adjacentes; e principalmente o modelado controla as condições hidrológicas, diferentes, em cada uma das feições, fazendo com o que o ambiente seja mais ou menos úmido e desta forma sendo o elemento principal de controle dos processos de evolução da matéria orgânica. / The Sorocá-Mirim River basin is located on the Ibiúna Plateau, wich is part of a set of failed blocks forming grabens and half grabens, which makes up a structural block system where water is trapped in sub-surface creating the ideal conditions for the formation of peatlands. Characteristics such as the geometry of interfluves, the asymmetry of slopes and flood plains and also the layout of the drainage network, denote the great influence of the geological structures in this basin. The areas of accumulation of organic matter found in the Sorocá-Mirim Basin are linked to particular fluvial environments, related to structural control, which is a characteristic feature of the area. The present study aimed to study peatlands in two different fluvial environments (terrace and amphitheater) in relation to their physical, chemical, and organic characteristics and their areolar distribution to understand how the formation of these peatlands was influenced by these environments. The topographic survey of the two areas, as well as a series of laboratory tests and analyzes showed that the peatlands of the two environments present different ages in approximately 1000 years (peatland of area 2 older than the peatland of area 1), same type of plants, accumulated along these years and differences mainly with respect to the preferential position to the accumulation of the organic matter and the variations, in the direction of the greater depths, of several observed parameters. It was verified that area 1 underwent major alterations in the landform, and consequently in its hydrological conditions over time, becoming a more drained, more oxygenated environment, with a peatland that presented more heterogenous laboratory results, with concentrations of organic matter and the elements attached to it, varying greatly throughout the feature. Area 2 did not undergo major alterations in the landform, remaining wetter over time which resulted in a more homogeneous peat with more constant values of organic matter and the elements bound to it, along the feature. These differences reflect the influence of landform on the processes of organic matter accumulation, where in each feature (terrace or amphitheater) the organic matter is accumulated in specific positions, suffering more or less interference of adjacent mineral materials; and mainly the landform controls the different hydrological conditions in each of the features, making the environment more or less moist and thus being the main element of control of the evolution processes of organic matter. The work showed that landform is the main conditioning element of the humidity of the environments and consequently of the processes of evolution and the characteristics of the peatlands.

Ce travail a porté sur l'étude de la structure et de la dynamique des bio(géo)macromolécules de la tourbière des Sagnes (Limousin, France) à l'aide de méthodes de dégradation chimiques et thermochimiques. La première partie a été consacrée à l'application de méthodes de dégradation chimiques pour apprécier l'impact d'une perturbation argileuse contemporaine sur la tourbière étudiée dans le cadre d'un partenariat entre l'université de Poitiers et AREVA. La tourbière présente un fonctionnement normal : activité microbienne et apport de matière organique en surface (acrotelme et mésotelme) et état du sédiment profond (catotelme) non perturbés. La seule influence notable du dépôt argileux, c'est l'augmentation apparente de l'activité de bactéries sulfato-réductrices sous sa zone de dépôt. Une seconde partie de développement analytique a tout d'abord porté sur l'évaluation de la capacité de la thermochimiolyse préparative en présence de TMAH d'analyser en un temps court et simultanément plusieurs familles de biogéomarqueurs. Pour cela, les résultats obtenus ont été comparés avec ceux obtenus par les méthodes chimiques habituellement utilisées. Compte-tenu des différents mécanismes impliqués, la thermochimiolyse apparait plus comme une méthode complémentaire. Enfin, une nouvelle méthode d'analyse des sucres (utilisation du bromure d'acyle) a été développée. Cette méthode a permis l'analyse sélective des sucres de la fraction lignocellulosique (principalement xylose et arabinose). / The purpose of this work was to study the structural composition, and consequently, dynamics of bio(geo)macromolecules of the Sagnes peatland (Limousin, France) by chemical and thermochemical degradation techniques. The first part constituted a framework between the university of Poitiers and AREVA and aimed to present a molecular inventory of a peat disturbed by a clay deposit. Results show that the clay deposit has no significant impact on the peatland evolution: microbial activity and production in the upper layer (acrotelm and mesotelm) and no apparent modification of the deepest organic sediment in the bottom layer (catotelm). Only phospholipid analysis showed an increase in sulfate-reducing bacteria under the clay deposit zone. The second part consisted of comparative studies between the most used chemical and thermochemical techniques for molecular characterization. Thermochemolysis should be viewed and used as a pertinent and a complementary method for the analysis of complex environmental systems. Finally, a novel technique using acetyl bromide allows the specific analysis of ligno-cellulosic carbohydrates (especially xylose and arabinose).

Abstract Peatland drainage changes catchment conditions and increases the transport of suspended solids (SS) and nutrients. New knowledge and management methods are needed to reduce SS loading from these areas. This thesis examines sediment delivery and erosion processes in a number of peatland drainage areas and catchments in order to determine the effects of drainage on sediment and erosion dynamics and mechanics. Results from studies performed in peat mining, peatland forestry and disturbed headwater catchments in Finland are presented and potential sediment load management methods are discussed for drainage areas and headwater brooks. Particular attention is devoted to erosion of organic peat, sediment transport and methods to reduce the impacts of peatland drainage in boreal headwaters. This thesis consists of six articles. The first and second papers focus on the erosion and sediment transport processes at peat harvesting and peatland forestry drainage networks. The results indicate that in-channel processes are important in drained peatland, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Sediment properties determine the bed sediment erosion sensitivity, as fluffy organic peat sediment consolidates over time. As flashiness and peak runoff control sediment entrainment and transport from drained peatland areas, water quality management should include peak runoff management. The third, fourth and fifth papers studies use and application of peak runoff control (PRC) method to the peat harvesting and peatland forestry conditions for water protection. Results indicate that effective water quality management in drained peatland areas can be achieved using this method. Installation of the PRC structures is a useful and cost-effective way of storing storm runoff waters temporarily in the ditch system and providing a retention time for eroded sediment to settle to the ditch bed and drainage network. The main effect of the PRC is on SS and SS-bound nutrients. The sixth paper is concentrated to test new restoration structure to be used in degraded headwater brooks. The results show that addition of woody restoration structures to the channel is effective and simple sediment management methods in headwater areas. New information provided in this thesis on sediment erosion and transport processes in drained peatland areas can help to improve water quality control in these areas. In-channel processes are important for both peatland uses, since the drainage network often constitutes temporary inter-storm storage for eroding and transporting material. Therefore, controlling these processes is a key to effective water quality management, which can be achieved using the PRC method in drainage areas or by utilisation of natural fluvial processes in natural channels downstream.