Radon Gas Detection via Vegetation Spectra Responses Using Space-borne Remote Sensing: A Tool for Uranium Exploration
Date
2019-08-29
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0003-4684-8050
Type
Thesis
Degree Level
Masters
Abstract
This research aims to determine if there is a discernable satellite-derived spectral signature within vegetation communities that can be linked to elevated occurrences of radon gas. Radon surveys, where the gas is measured directly on the ground, are a tool used in uranium exploration as statistically significant elevated radon values are known to occur in proximity to uranium mineralization. To-date, there has been little to no research into the use of optical remote sensing to quantify radon gas in uranium exploration. Through digitizing and geo-referencing historic survey data from Cluff Lake, Saskatchewan, the radon values were first explored along environmental gradients to understand its spatial distribution. The data were then linked with satellite imagery (Sentinel-2A) to explore spectral patterns and evaluate the potential of characterizing a spectral response that can highlight areas containing above background gas concentrations. Results show that there is strong potential for mapping radon gas via changing spectral characteristics within vegetation, interpreted to be attributed to the effects of radiogenic stress and metal contamination within plants coinciding with anomalous radon gas occurrences and/or elevated amounts of its progeny. It is shown that there are differences in spectral curves of natural-logarithmically transformed radon point-values that have been grouped based on standard deviation between what is considered background, moderate, and high values of radon. Furthermore, vegetation indices using Sentinel-2A bands, focusing in the red-edge and NIR portion of the electromagnetic spectrum, show a significant variation of means between grouped radon values allowing for trend detection and radon pseudo-survey map generation. Investigation into radon distribution at Cluff Lake has also shown a potentially significant relationship between radon gas and vegetation communities, specifically black spruce (Picea mariana), which was not hypothesized. The potential species specific relationship between radon gas and vegetation, along with the variation in spectral curves differentiating what is considered background and elevated occurrences of the gas, show strong potential for further refining radon pseudo-survey maps based on spectral characteristics of the tree-canopy. This research was designed as a tool in uranium exploration, to compliment geological, geophysical, and geochemical exploration methods. The research also has trans-disciplinary applications in biogeochemistry, ecology, and the environmental sector as an aid in mapping radiogenic contamination.
Description
Keywords
remote sensing, radon, uranium exploration, radiogenic-stress, vegetation
Citation
Degree
Master of Science (M.Sc.)
Department
Geography and Planning
Program
Geography