The nature and distribution of massive ground ice is one of the most unpredictable and problematic geological variables in near-surface deposits characterized by continuous permafrost. Occurrences of massive ground ice are widely reported in the Yukon Coastal Plain and Mackenzie Delta areas of the Western Canadian Arctic (Pollard and Dallimore, 1988). Mapping its distribution is an enormous challenge facing land management and resource development related to oil and gas in the Mackenzie Delta, Northwest Territories. The melting of ice within permafrost destabilizes the ground, leading to extensive thaw subsidence called thermokarst, which could result in the destruction of ecosystems and infrastructure (Williams and Smith, 1989).

Traditional methods for identifying ground ice involve the drilling of holes to directly measure ice content (Moorman et al., 2003). This technique, however, is expensive, destructive, and only provides point samples. Furthermore, lateral interpolation between holes is unreliable in areas of high variability. Non-destructive geophysical techniques like capacitively-coupled resistivity (CCR) and ground-penetrating radar (GPR) are effective for quantifying the electrical properties of near-surface materials in permafrost environments (Kneisel et al., 2008). The success of geophysical tools in permafrost environments depends on the variations in physical properties between unfrozen/frozen materials and ice-rich sediments/ice-poor sediments (Kneisel et al., 2008). GPR is effective for imaging the near-surface thermal structure and stratigraphy of permafrost (Moorman et al., 2003), so it is a useful compliment to electrical methods. Each of these geophysical tools has been used successfully to map various aspects of permafrost, but only a few studies have incorporated two or more systems in a complimentary fashion (De Pascale et al., 2008).

Although previous studies like Calvert (2002) have shown that CCR is able to delineate relative changes in ice content across the Mackenzie Delta, the primary objective of this thesis is to evaluate how well CCR and GPR work in combination to measure absolute ice contents at Parsons Lake, a potential hydrocarbon development site. More specifically, under what environmental conditions and with what level of confidence are the tools successful? Extensive ice content, ground temperature, and stratigraphic data available at fine depth intervals for 25 boreholes will be correlated with geophysical responses. This project is significant for two reasons: (1) - Using geophysics, land use planners can estimate the subsidence susceptibility of an area using a cheaper, faster, and more environmentally friendly approach. (2) - Conclusions drawn can be used for potential Mars exploration programs focused on studying subsurface ice. Landforms indicative of ground ice in permafrost on Mars have been identified since the early flyby and orbiter missions of the late sixties and early seventies. A geophysical subsurface instrument package, including GPR and CCR would provide a comprehensive 3D representation of the subsurface structures. This data could be directly used for the validation of orbital data interpretation. As well, this package could be used as in conjunction with shallow surface drilling activity. The subsurface characterization produced by the proposed instruments should reduce the risk associated with any drilling operation and provide insight into lateral variations of periglacial features within the subsurface.

Dr. Pollard will supervise the overall progress of the project and guide my understanding of permafrost science. Dr. Kalacska will act as an advisor for the geophysical aspect of the project, especially signal processing of GPR and CCR data.

Sulfate reducing bacteria are important actors in the sulfur, carbon, and oxygen cycles. Their highly tuned metabolism produces characteristic isotopic fractionations evident in waste products (e.g., H2S) and in the metabolic substrates they utilize (e.g., SO42-). These sulfur isotopic signatures are then preserved in the rock record (eg., in grains of pyrite) as the fingerprint of microbial activity. They are used today by biogeochemists to infer the environmental characteristics of the early biosphere as well as to identify evidence for early microbial activity. These biogeochemical studies, however, rely on the assumption that the metabolism of sulfate reducers today and in the past has been the same. Experimental evolution can address this question by revealing the rate of change of microbial metabolism under specific stressors and its impact on sulfur isotopic fractionation. In order to experimentally determine the effects of changes in microbial metabolism on isotopic fractionation, it is essential to understand the experimental subject: Desulfuvibrio vulgaris. This sulfate reducer was chosen as guinea pig as it is well-studied and ubiquitous in anoxic environments worldwide.

The primary objective of my research project is to determine how a number of stress agents (salt –NaCl-, trace metals, low sulfate etc) acts as a selective pressure on D. vulgaris cultures. In order to achieve this objective we need to be able to quantify the growth characteristics of D. vulgaris as evolution proceeds. This will be performed with a high sensitivity protein assay as well as flow cytometry and quantitative tracking of specific genetic markers inserted in different populations of D. vulgaris. An endeavour of my initiative to this project will be to determine growth characteristics of sulfate reducers by using protein-specific tags to differentiate salt-adapted individuals from non-adapted ones. These tests are all being developed with one goal in mind: the determination of fitness (a measure of the growth of a descendant population compared to its ancestors under identical experimental conditions) with the highest accuracy possible. The fitness experiments must be done in order to demonstrate that a significant change in the metabolism of the bacteria, and thus adaptation to the novel conditions, occurred.

From the experiments of Miller and Urey, we know that numerous amino acids may be synthesized through the machinations of Earth’s atmosphere. But the rest remain unaccounted for. Astrophysical processes are the next logical assumption in the discovery of how amino acids and other biomolecules become integrated into planetary systems. Dr. Ralph Pudritz has developed a research program on the origin of biomolecules, specifically amino acids, in planetesimals. This research includes the performing of chemistry simulations designed to discover the origin of amino acids in planetesimals and meteorites. As cited by Emberson and Pudritz (2011, in prep), carbon-rich meteorites contain organic matter such as amino and carboxylic acids. The meteoritic parent bodies are composed of rock and water ice as well as a variety of organic material, which they incorporated from solar nebulae in which they exist. Radionuclides decay in the center of these parent bodies, causing the interior to heat above the melting point of water. With liquid water and organic material now present, a process called aqueous alteration causes the organics to chemically alter their makeup, producing other organic materials, including amino acids. Planetesimals are built up by collisions with smaller bodies, so another consideration is the extreme temperature and pressure change during such impacts. This may produce non-equilibrium conditions affecting amino acid synthesis. Another aspect of amino acid delivery to planets is the encounter between a meteorite and planetary atmospheres and surfaces. Amino acids and other biomolecules would survive such an extreme event, but the intense temperature and pressure changes must be taken into account when considering meteorite impacts as the mode of arrival for planetary biomolecules. This, then, is my research objective: mimic the process of aqueous alteration inside a meteoritic parent body with the intent of predicting amino acid concentrations inside a typical meteorite.

Recent explorations of the Canadian high Arctic led to the discovery of the first and thus far only known subzero (-5°C), hypersaline (24%), perennial spring originating from permafrost methane seeps on Earth (1). The environmental characteristics (cold temperatures, hypersalinity, methane-rich, etc.) of the Lost Hammer (LH) spring make it a potential Mars-analogue site, especially considering the recent discovery of spatial and seasonal variations in Mars atmospheric methane possibly originating from localized “hotspots” or “plumes”(2). Since methane can both serve as energy sources for certain microorganisms or be produced biologically, Mars methane is of important significance for astrobiology. Preliminary analyses of the LH spring and its outflow channels already revealed the presence of methanogens, but mainly of members of the poorly understood anaerobic methane oxidizing Archaea (ANME-1) which make up for the near totality of LH archaeal communities (1). My research project have for primary objective to determine whether or not LH microbial communities are capable of active anaerobic methane oxidation under in-situ conditions (i.e. -5ºC, hypersalinity) via measurements of isotopically labelled methane. Detecting biological methanogenesis and conclusively isolating and characterising subzero halophilic methanogens from saline spring sediments is also a goal of the present research.

I am investigating the biomineralization products generated by acidophilic bacteria that were found in the Rio Tinto river in Spain; a Martian analogue site. Biologically cultured and inorganically synthesized precipitates are being characterized using geochemical methods and molecular techniques in order to assert the presence of biosignatures.

My thesis work involves investigating sulfur isotopes and their implications on atmospheric oxygen and planetary surface environments. I’m looking at four greenstone belts in Northwestern, Ontario to determine if rock type affects the sulfur isotope ratios preserved in the rock record. I’m interested in rocks dated 2.8-3.0 billion years old where sulfur isotopes, especially sulfur 33, have implications for atmospheric oxygen variations. Additionally, I’m working on a Mars analogue site through a Research Assistantship Program with the Canadian Space Agency. Pyrite nodules are present in a cold, dry, buffered environment in the Canadian Arctic and are being oxidized to hematite and jarosite – a mineral generally associated with warm, acidic environments and a prevalent mineralogical component of the Martian surface.

The discovery of biosignatures on other planets may be interpreted as evidence for the existence of extraterrestrial microbial life. Preserved in the geologic record, these signatures can also provide us with information about the timing and sequence of events leading to the origin of life. My focus is on distinguishing between biosignatures and abiosignatures within extreme environments. For my Master’s research project, I am analyzing the concentrations and isotopic compositions of organic compounds, such as volatile fatty acids and lipids, present in deep terrestrial subsurface environments in Ontario and South Africa. By investigating these Martian analogue sites, I hope to gain insight into the potential for life on Mars, as well as the history of life on Earth.

My research utilizes analogue environments, Pavillion and Kelly Lakes (British Columbia; Canada), which reflect the biogeochemical processes active on the primitive Earth and possibly on other planets such as Mars. The objectives are to: 1) identify a possible biosignature associated with photosynthetically-influenced carbonate precipitation within microbialite nodules in Kelly Lake and 2) compare these results to biosignatures formed by photosynthetic influences on isotopic geochemistry discovered within microbialites in the near-by Pavillion Lake. This will be completed through stable isotope analysis (δ13C and δ18O), molecular analysis of the microbial phospholipid fatty acids, and imaging of microbialite-associated microbial communities. The results from these experiments will indicate whether the microbialite formation mechanisms active in Pavillion Lake, along with their associated biosignatures, are found among similar systems such as Kelly Lake. This may have large implications in the understanding of biosignature formation and the use of these markers in the search for extra-terrestrial life.

My project is involved with the geochemistry and biosignatures in Archaean age metasedimentary rocks in the Abitibi greenstone province of the Canadian Shield. In particular the ankerite veins hosted within the Late Archean Tisdale (2707 – 2705 Ma) and Porcupine (2685 – 2673 Ma) assemblages in the Dome Mine, Timmins, Ontario, Canada. The potential sub-seafloor formation of this ankerite vein is of particular interest and by looking at the mineralogy and isotopes, the environmental conditions of the hydrothermal system and biosphere can be constrained and confirm whether it was a sub seafloor deposit. As well, I will be exploring the preservation potential for organic biosignatures in this deposit by looking at the mineralogy, isotopic signatures and organic compounds present.

The aim of my thesis is to determine whether ground penetrating radar (GPR) is an effective tool in characterizing the nature ground ice. I will be collecting high resolution GPR data over ground ice of various origins in the Canadian arctic this summer, and subsequently correlating this data with the chemical and electrical properties of permafrost cores collected at the survey site. Similar studies have been performed on glacial ice and I'm testing whether they are also suitable techniques for ground ice research.

PROJECT COMPLETE

Possible Archean mineral/microbial interactions: laboratory model of microbial growth on serpentinized and non-serpentinized mineral surfaces

Serpentinization reactions in peridotite-hosted systems such as Lost City Hydrothermal Field could have been common in near surface waters during the Archean (2.5-3.8 billion years ago) [1]. These processes would have presumably occurred alongside the early biosphere, containing methanogens and dissimilatory sulfate reducing bacteria. Within photic regions of Archean oceans, cyanobacteria could have produced oxygen oases via oxygenic photosynthesis [2]. Fayalite, enriched from fayalite-magnetite iron ore (Forsythe Iron Mine, Quebec), was reacted with synthetic, anoxic Archean seawater for 6 months at 120oC. This serpentinization model system increased silica concentration in fluid phase and produced secondary minerals (i.e., chrysotile) on fayalite mineral surfaces. Scanning electron microscopy (SEM) revealed Methanococcus voltae and Desulfovibrio spp. preferred colonizing serpentinized versus non-serpentinized mineral surfaces. Colonization by Desulfovibrio spp. was enhanced by the formation of extra-cellular polymeric substances. Using SEM-energy dispersive x-ray analysis, the sulfate reducing bacteria were also found to produce iron sulfides suggesting that dissimilatory sulfate reduction was active on the serpentinized mineral surfaces. In contrast to more selective colonization by Methanococcus and Desulfovibrio, cyanobacteria grew as a mat across the fayalite ‘sediment’ surface. Detection of CH4 and O2 in gas phase indicated growth of methanogens and cyanobacteria in their respective reaction systems. Cyanobacterial growth increased pH of reaction system, catalyzing CaCO3 precipitation on cyanobacterial cell surfaces. Physically ‘tearing’ the mat from the mineral sediment surface during SEM sample preparation resulted in distinctive filamentous molds within an exopolymeric matrix. This is comparable to tidal flows tearing biofilms in natural systems, indicating cyanobacteria possess stronger affinity for the mineral substrate than biofilm. It also created unique casts of the cyanobacteria that if fossilized would produce unique biomarkers.