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Full-Text Articles in Physical Sciences and Mathematics
Impact Melt Emplacement On Mercury, Jeffrey Daniels
Impact Melt Emplacement On Mercury, Jeffrey Daniels
Electronic Thesis and Dissertation Repository
Impact cratering is an abrupt, spectacular process that occurs on any world with a solid surface. On Earth, these craters are easily eroded or destroyed through endogenic processes. The Moon and Mercury, however, lack a significant atmosphere, meaning craters on these worlds remain intact longer, geologically. In this thesis, remote-sensing techniques were used to investigate impact melt emplacement about Mercury’s fresh, complex craters. For complex lunar craters, impact melt is preferentially ejected from the lowest rim elevation, implying topographic control. On Venus, impact melt is preferentially ejected downrange from the impact site, implying impactor-direction control. Mercury, despite its heavily-cratered surface, …
Linking Mining Wastewater Discharge To Methylmercury Production In A Sub-Arctic Peatland, Lauren E. Twible
Linking Mining Wastewater Discharge To Methylmercury Production In A Sub-Arctic Peatland, Lauren E. Twible
Electronic Thesis and Dissertation Repository
It is well established that the addition of sulphate (SO42-) to peatlands increases methylmercury (MeHg) concentrations in pore waters via microbial methylation. Less information exists about the effects of different concentrations and sources of SO42- loading on MeHg production in remote, non- SO42- impacted regions like Canada’s north, where increased SO42- loadings come not from the atmosphere, but often from mining waste water and rock tailings. A three year field study (two years of loading; one year of recovery) examined the effects of simulated wastewater (containing 27.2 mg/L SO42- …
Dissolved Organic Matter In Subarctic Streams And Rivers: Direct And Proxy Measures Of Quantity, Quality, And Mercury, Tara M. Despault
Dissolved Organic Matter In Subarctic Streams And Rivers: Direct And Proxy Measures Of Quantity, Quality, And Mercury, Tara M. Despault
Electronic Thesis and Dissertation Repository
The drainage network of the Hudson Bay Lowlands (HBL) peatland complex regulates the transport of freshwater and solutes, including dissolved organic matter (DOM) and mercury, to Hudson Bay. Due to the remoteness and areal extent of the HBL, traditional, campaign-based sampling programs are unable to fully elucidate the region’s hydrology and biogeochemistry. This study investigated seasonal variability of DOM quantity and quality in two distinct stream orders to explore DOM sources to surface waters in the region, and assessed optical measurements as proxies for riverine DOM and mercury. In-stream primary production and enhanced microbial processing influenced DOM characteristics during base …
Bioaccumulation And Concentration Of Mercury In Rivers And Streams Of The Hudson Bay Lowland, Ashley Warnock
Bioaccumulation And Concentration Of Mercury In Rivers And Streams Of The Hudson Bay Lowland, Ashley Warnock
Electronic Thesis and Dissertation Repository
Methylmercury (MeHg) is a neurotoxin that biomagnifies in northern aquatic food webs to high enough concentrations to cause concern for human consumption. The Hudson Bay Lowland of Canada is projected to experience climate and land-use impact in the immediate future, and these environmental stressors may affect the exposure to and subsequent bioaccumulation of MeHg in subarctic fish populations. The focus of this research is to evaluate the spatial variability in total and MeHg in water, sediment, and biota within and across a range of subarctic streams and river reaches of the Hudson Bay Lowland. This data was then used to …
Peatland-Stream Hydrological And Biogeochemical Connectivity In The James Bay Lowland, Ontario, Meghan Kline
Peatland-Stream Hydrological And Biogeochemical Connectivity In The James Bay Lowland, Ontario, Meghan Kline
Electronic Thesis and Dissertation Repository
The Hudson-James Bay Lowlands are the second largest peatland dominated area on the planet, and are expected to be particularly vulnerable to future climate change. Changes in climate will affect peatland hydrology and biogeochemistry, impacting the aquatic ecosystems this region supports, however there is limited information about the hydrology and biogeochemistry of this landscape under current conditions. This thesis focuses on assessing the nature of hydrological and biogeochemical connectivity between a fen and 2nd order channel in the Central James Bay Lowland, Ontario. Specifically the study focuses on the role of preferential hydrological flowpaths in the riparian area, such …
Peat As An Archive Of Remote Mercury Deposition In The Hudson Bay Lowlands, Ontario, Canada, William James Goacher
Peat As An Archive Of Remote Mercury Deposition In The Hudson Bay Lowlands, Ontario, Canada, William James Goacher
Electronic Thesis and Dissertation Repository
Peat from the Hudson Bay Lowlands (HBL) in Northern Ontario, Canada was used to reconstruct historical accumulation of mercury (Hg) over more than 7000 years before present. Nine cores, many with previously published paleoclimate studies, were analyzed for Hg and accumulation rates were calculated. Anthropogenic Hg enrichment factors were calculated based on accumulation rates. A more exclusive calculation of the anthropogenic enrichment factor corroborates modelling efforts that have suggested re-cycling legacy Hg is a much greater contributor to present day deposition than previously thought, but not prior to ~500 cal yrs BP. An older pre-industrial record provides a better background …
Hydrology And Biogeochemistry Of A Bog-Fen-Tributary Complex In The Hudson Bay Lowlands, Ontario, Canada, Thomas A. Ulanowski
Hydrology And Biogeochemistry Of A Bog-Fen-Tributary Complex In The Hudson Bay Lowlands, Ontario, Canada, Thomas A. Ulanowski
Electronic Thesis and Dissertation Repository
The Hudson Bay Lowlands (HBL) contains 26 Gt C sequestered in a 2 meter thick layer of peat which blankets a quarter of Ontario, Canada. The hydrological and chemical influence of the HBL peatlands to surface waters is recognized, but information on peatland runoff processes and the evolution of groundwater through this vast, carbon-rich landscape remain scant. This study focused on elucidating the groundwater flow patterns of a bog-fen-tributary complex in the central region of the HBL, and estimating exports of groundwater, dissolved organic carbon (DOC), total (THg), and methyl (MeHg) mercury during the 2011 ice-free season. Hydrometric data, combined …