A gas-fluidized bed bioreactor was developed in this research as a new method for treating polluted air. The fluidization characteristics of selected packing materials were investigated. Then, bioremediation was tested using two types of packing in a fluidized bioreactor, as well as in a comparable packed bed. Microorganisms on the particles biodegrade contaminants in the polluted air, which flows up through the bed. At high flowrates, the polluted air fluidizes the particles, while at low velocities the operation is in packed bed mode.<p>Initially, sawdust was selected for use as a packing material. Due to the poor fluidization properties of sawdust, glass spheres were added. A mixture of sawdust and glass spheres remained well mixed during fluidization. In the mixture, interparticle forces increased with increasing moisture in the sawdust, eventually causing defluidization of the bed. In the absence of bioremediation, mass transfer was studied between ethanol-contaminated air and sawdust/glass sphere packing, and found to be higher in the fluidized versus packed mode. In bioremediation experiments, ethanol removal efficiencies were as high as 95% in both operating modes. The maximum elimination capacities (EC) of ethanol were 75 and 225 g m^-3 sawdust h^-1 in the fluidized and packed beds respectively.<p>The packing of the fluidized bed bioreactor was optimized in order to boost bioremediation rates. Experiments showed that peat granules fluidized well in a bubbling regime, likely due to their relatively high density and sphericity. In peat bioremediation trials, the fluidized mode outperformed the packed bed; the maximum ECs were 1520 and 530 g m^-3 peat h^-1, respectively. Removal efficiency in the fluidized mode decreased with velocity, because the size and amount of large bubbles increased.<p>A steady-state model of the fluidized bioreactor was developed. By taking account of bubble properties during fluidization, the model helps to explain how bubble size, microbial properties and bioreactor residence time affect removal efficiency and elimination capacity of the bioreactor.<p>A peat gas-fluidized bioreactor shows promise as an efficient, low-cost technology for air treatment. Particle mixing in the fluidized bed may prevent operating problems associated with the packed bed bioreactor. Fluidized bioreactors are ideal for the treatment of high volume, low concentration air emissions.

The boreal landscape is complex mosaic of vast forests, lakes and wetlands. Through the landscape flows a fine network of streams and rivers, carrying dissolved and suspended material from atmospheric deposition and weathering of soils and bedrock to downstream recipients. This thesis investigates the transport of U, Th and other metals in the boreal landscape by comparing a set of catchments with contrasting characteristics, ranging from 0.12-68 km2 in area. Using uranium (234U/238U) and oxygen isotopes (δ18O) it was demonstrated that catchment size has a strong impact on the hydrological pathways and on the mobilisation of uranium. Both tracers also displayed a consistent shift towards more superficial sources and more superficial flow pathways when going from winter baseflow conditions to the spring flood. Large spatiotemporal variability was observed with U fluxes ranging from 1.7 -30 g km-2 a-1. Using a wide set of hydrochemical parameters and landscape characteristics it was demonstrated that wetlands play a decisive role for the biogeochemical cycling of many metals. Comparing normalised fluxes of 13 different elements (Al, Ba, Ca, Cr, Cu, La, Mg, Na, Ni, Si, Sr, U and Y) 73% of the spatial variance could be explained based on the wetland coverage and the affinity for organic matter, the latter of which was quantified using thermodynamic modelling. Hence, it was possible to link the large-scale transport patterns of a wide range of metals to fundamental biogeochemical properties. When restraining the analysis to the smaller streams (&lt;10 km2), the explanatory power increased to 88%. For elements such as Na and Si with low affinity for organic matter the decrease in wetland-dominated catchments corresponded closely to the area of mineral soils that had been replaced by peat, indicating that reduced weathering was the main cause of the decrease. For organophilic metals the decrease in wetland-dominated catchments was even greater, suggesting that there also was an accumulation of these metals in the peat. This was confirmed by investigating the distribution of radionuclides in local mire, which revealed considerable accumulation of uranium and thorium along the edges of the mire. Based on the inventories of uranium and thorium and their distribution in the peat it was concluded that the mire historically had been a sink for these metals and that it most likely will continue to be so for a long time to come. All and all, wetlands were estimated to decrease the fluxes of metals from the boreal forests to downstream lakes and oceans by 20-40%, depending on how strongly they bind to organic matter.

A gas-fluidized bed bioreactor was developed in this research as a new method for treating polluted air. The fluidization characteristics of selected packing materials were investigated. Then, bioremediation was tested using two types of packing in a fluidized bioreactor, as well as in a comparable packed bed. Microorganisms on the particles biodegrade contaminants in the polluted air, which flows up through the bed. At high flowrates, the polluted air fluidizes the particles, while at low velocities the operation is in packed bed mode.<p>Initially, sawdust was selected for use as a packing material. Due to the poor fluidization properties of sawdust, glass spheres were added. A mixture of sawdust and glass spheres remained well mixed during fluidization. In the mixture, interparticle forces increased with increasing moisture in the sawdust, eventually causing defluidization of the bed. In the absence of bioremediation, mass transfer was studied between ethanol-contaminated air and sawdust/glass sphere packing, and found to be higher in the fluidized versus packed mode. In bioremediation experiments, ethanol removal efficiencies were as high as 95% in both operating modes. The maximum elimination capacities (EC) of ethanol were 75 and 225 g m^-3 sawdust h^-1 in the fluidized and packed beds respectively.<p>The packing of the fluidized bed bioreactor was optimized in order to boost bioremediation rates. Experiments showed that peat granules fluidized well in a bubbling regime, likely due to their relatively high density and sphericity. In peat bioremediation trials, the fluidized mode outperformed the packed bed; the maximum ECs were 1520 and 530 g m^-3 peat h^-1, respectively. Removal efficiency in the fluidized mode decreased with velocity, because the size and amount of large bubbles increased.<p>A steady-state model of the fluidized bioreactor was developed. By taking account of bubble properties during fluidization, the model helps to explain how bubble size, microbial properties and bioreactor residence time affect removal efficiency and elimination capacity of the bioreactor.<p>A peat gas-fluidized bioreactor shows promise as an efficient, low-cost technology for air treatment. Particle mixing in the fluidized bed may prevent operating problems associated with the packed bed bioreactor. Fluidized bioreactors are ideal for the treatment of high volume, low concentration air emissions.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Restricted until November 2001. Bibliography: leaves 97-104.

Les tourbières nordiques, sont des écosystèmes humides ayant la particularité de produire plus de matière organique qu'elles n'en décomposent. Elles ont ainsi accumulé de formidables quantités de carbone depuis le début de la dernière déglaciation. C'est pour cette raison qu'elles représentent un intérêt particulier pour la modélisation du climat global. En effet, contenant environ un tiers du carbone des sols tout en ne couvrant qu'environ 3% de la surface terrestre, les tourbières émettent également de grandes quantités de méthane, qui a un pouvoir de réchauffement climatique 23 fois plus important que le dioxyde de carbone. Afin de pouvoir intégrer ces différents facteurs dans les modèles globaux du climat et d'estimer leur incidence sur le cycle global du carbone, il est nécessaire de mieux connaitre la dynamique du carbone dans les tourbières elles-mêmes. Les tourbières nordiques ont la capacité d'archiver des informations rapportant les différents changements qu'elles ont subis depuis leur développement. Ces changements incluent les changements climatiques régionaux, qui ont affecté leur végétation et la dynamique du carbone, mais aussi des changements autogènes, c'est-à-dire propres à leur dynamique interne. Il est donc nécessaire de prendre en compte ces différents facteurs en vue de reproduire leur dynamique. Cette thèse a pour objectif d'évaluer la connaissance de la dynamique du carbone dans les tourbières par le biais de l'évaluation du Holocene Peat Model (Frolking et al. 2010). Ce modèle comprend une description des processus d'accumulation, de décomposition, du bilan hydrique et une représentation de la végétation par 12 groupes fonctionnels de plantes ainsi que les boucles de rétroaction entre ces différents processus. Son évaluation a été effectuée en deux étapes. Dans un premier temps, une analyse de sensibilité a permis de déceler les paramètres du modèle ayant une influence sur la quantité totale de carbone dans les simulations, puis les interactions entre les paramètres ont également été analysées. Les résultats montrent que certains paramètres représentent des sources d'incertitude importantes et devraient être l'objet de plus amples recherches (tels que la conductivité hydraulique, le gradient d'anoxie, certains paramètres contrôlant le bilan hydrique et la densité sèche). De plus, parmi les milliers de simulations effectuées, on observe que plusieurs types de développements des tourbières sont possibles, bien que la méthodologie mette l'emphase sur les processus autogènes et contraigne les processus allogènes à un régime de précipitation et une productivité primaire nette (PPN, servant d'indicateur climatique) constants. Par ailleurs, il apparaît que les sphaignes ont une influence sur le type de développement de la tourbière, ce qui affecte par conséquent l'accumulation du carbone. Dans un second temps, le modèle est calibré pour deux sites de la région de la Baie James au Québec. Il s'agit de deux tourbières ombrotrophes ouvertes ayant des caractéristiques écohydrologiques et des taux d'accumulation de carbone différents. Pour chacun de ces sites, deux simulations sont réalisées : la première est basée sur une reconstruction des précipitations et la seconde sur une reconstruction des niveaux de nappe phréatique. Il est notable que les résultats des simulations révèlent des périodes durant lesquelles les tourbières présentent des pertes nettes de carbone. En comparant les résultats des simulations avec les taux d'accumulation de carbone et les résultats des analyses de macrorestes végétaux, on constate que le modèle reproduit, de façon générale, les variations observées dans ces séries de données. De plus, il est conclu que ce modèle peut être utilisé comme outil d'identification des causes de variations de l'assemblage végétal. Bien que de certains processus doivent être étudiés plus avant afin de limiter les incertitudes du modèle, cette thèse a permis d'établir la validité des concepts de dynamique du carbone dans les tourbières en intégrant l'évaluation des dynamiques d'échelle globale et locale. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Tourbière, modélisation, évaluation, analyse de sensibilité, forçage, fonction de transfert.

The Canadian Council of Ministers of the Environment (CCME) endorsed the Reference Method for the Canada-Wide Standard (CWS) for Petroleum Hydrocarbons (PHC) in Soil – Tier 1 Method in 2001. The purpose of the CWS is to provide laboratories with analytical methods for producing accurate and reproducible PHC soil chemistry analysis results. CWS PHC concentrations are reported according to the following carbon ranges/fractions: F1 (C6-C10), F2 (C10-C16), F3 (C16-C34) and F4 (>C34). The Canada-wide Standards for Petroleum Hydrocarbons (PHC) in Soil provide generic soil quality guidelines for the each of the four PHC fractions. The CWS PHC extraction solvents inadvertently co-extract natural biogenic organic compounds (BOC) from organic soils. BOCs, such as waxes and fatty acids, are produced by living organisms such as plants, animals and microbes. PHC analysis of highly organic clean soils and manure compost can cause false exceedences of the F3 soil quality guidelines. This thesis presents a new mathematical Tier 2 approach to resolving biogenic interferences through the use of biogenic versus petrogenic Gas Chromatography - Flame Ionization Detector (GC-FID) chromatogram patterns produced by the CWS PHC Tier 1 method. This approach is based on the results of four studies: i) 300-day crude oil contaminated peat and sand microcosm experiment; ii) 300-day diesel drilling waste contaminated manure compost and sand microcosm experiment; iii) PHC analysis of 14 light to heavy crude oils and iv) Canadian background PHC soil field survey. These studies determined that the clean soils and compost had F3 ranges that were dominated by the F3b sub-fraction range (C22-C34). In contrast, the F3a (C16-C22) and F3b sub-fraction ranges were evenly distributed in the 14 fresh light to heavy crude oils. The diesel drilling waste was strongly dominated by the F3a sub-fraction range. The second important trend was that F2 concentrations were either non-detectable or slightly detectable in all of the clean soils and compost samples. In contrast, F2 concentrations were strongly prevalent in all of the crude oils and in the diesel drilling waste. F2 and F3b concentrations were applied to the F2:F3b ratio, which identified PHC absence in the clean materials (<0.10 ratio) and PHC presence (>0.10 ratio) in the contaminated materials. The %F3a:%F3b distributions were applied to the BOC-adjusted PHC F3 calculation, which estimated true PHC F3 concentrations in the clean and contaminated soils and manure compost. The combination of these two approaches provided an accurate and efficient solution to resolving false detections of crude oil and diesel PHCs and false exceedences of F3 soil toxicity guidelines by in clean soils and compost.

Subsurface peat decomposition, through CO2 production, was analyzed in laboratory and field experiments in a bog, poor fen, and beaver pond margin at Mer Bleue, Ottawa. Intact core samples in 10 cm depth intervals from 5--45 cm below the surface of each site were incubated in the laboratory. Treatments involved aerobic and anaerobic conditions at 4 and 14°C. Field measurements of CO2 flux were made by a static chamber technique. / Incubation results indicate modelled CO2 surface fluxes differ amongst wetlands. Aerobic CO2 modelled surface fluxes at 4°C were 2.3, 3.1 and 4.2 g CO2 m-2 d-1 for the bog, the beaver pond margin, and the poor fen, respectively. On average, aerobic production rates from peat cores with field moisture conditions were 11.7 times larger than anaerobic production rates. A mean Q10 of 2.3 defined the role of temperature. Differences among the peat samples were related to degree of decomposition, and differences among the sites were related to trophic status and nutrient availability. / A model of CO2 production was constructed and validated against field fluxes of CO2. The model provides a good prediction (r 2 = 0.72) of subsurface peat decomposition. The results suggest that warmer peat temperatures and lowered water tables, as predicted by climate change scenarios, will increase surface CO2 fluxes due to peat decomposition.

This study uses life cycle analysis to examine the net greenhouse gas (GHG) emissions from the activities of the peat industry in Canada for the period 1990 to 2000. GHG accounting is undertaken for (1) land use change, (2) peat extraction and processing, (3) the transport of peat to market by truck, train and ship, and (4) the in situ decomposition of extracted peat. The emission estimates were based on results from GHG accounting models using data derived from scientific literature, government and industry statistics, and the responses to a questionnaire sent to Canada's peat establishments. The questionnaire, designed to obtain information on peat extraction methods, land and fuel use, as well as the transportation of peat, had a response rate representing 69% of Canada's total peat production in the year 2000. Results indicate that 540 600 tonnes of greenhouse gases were emitted in 1990 and 893 300 tonnes were emitted in the year 2000 (emission figures are measured in CO2 equivalents using a 100-year time horizon). Peat decomposition was by far the largest source of GHG emissions, averaging 70.6% of total emissions during the eleven-year period from 1990 to 2000. Greenhouse gases from land use change averaged 14.7%. An average of 10.4% of total emissions resulted from the transport of peat to market, while GHGs from extraction and processing averaged 4.3%. Predictions of the annual GHG emissions from the peat industry, assuming a "business as usual" context, were produced for the years 2001 to 2012. These figures were compared with those resulting from various greenhouse gas reduction scenarios.

The reconstruction of past environmental conditions is a fascinating research area that attracts the interest of many individuals in various geological disciplines. Paleoenvironmental reconstruction studies can shed light on the understanding of past climates and are a key to the prediction of future climate changes and their consequences. These studies take on special significance when focused on areas sensitive to climate change. The Arctic region, which is experiencing dramatic changes today in its peatlands and in its ocean, is prime example. The entire region plays a major role in global climate changes and has recently received considerable interest because of the potential feedbacks to climate change and its importance in the global carbon cycle. For a better understanding of the role of Arctic peatlands and the Arctic Ocean to global climate changes, more records of past conditions and changes in the region are needed. This work applies different geochemical proxies, with special emphasis on lipid biomarkers, to the study of a permafrost peat deposit collected from the Eastern European Russian Arctic and a marine core retrieved from the Lomonosov Ridge in the central Arctic Ocean. The results reported of this study show that molecular stratigraphy obtained from the analysis of lipid biomarkers in both peat and marine profiles, combined with other environmental proxies, can contribute significantly to the study of Arctic ecosystems of the past. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>

The quantitative effects of increasing the organic matter contents of three soils upon their susceptibility to compaction, the recovery of tilth after compaction and the fertility of the soils were investigated. These effects were further studied on the production of bush bean (Phaseolus vulgaris). / Soil consistency limits, soil water status, applied pressure and organic matter contents were used to predict shear strength, penetration resistance and water retention characteristics of compacted soils, with the aim of meeting the widespread demand for possible techniques of soil compaction prediction. / Soil compaction increased the ability of the soils to retain moisture, increased penetration resistance, shear strength and decreased the available water capacity of soils. On the other hand, organic matter increased the ability of the soils to retain moisture, expanded the available water capacity and decreased the penetration resistance and shear strength of compacted soils. / Although soil compaction increased the stem diameter of bush bean; the height, yields and root dry matter of the crop decreased with higher compaction levels. On the contrary, higher organic matter levels increased the plant and yield parameters of the crop.