Bedrock Structure Control on Soil-Gas Radon-222 Anomalies in the Toronto Area, Ontario, Canada

Abstract

Research Article| January 01, 1998 Bedrock Structure Control on Soil-Gas Radon-222 Anomalies in the Toronto Area, Ontario, Canada IMSHUN JE; IMSHUN JE Environmental Earth Sciences, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario, M1C 1A4 Canada present address: Handex of Illinois Inc., 1701 West Quincy Avenue, Naperville, IL 60540. Search for other works by this author on: GSW Google Scholar NICHOLAS EYLES NICHOLAS EYLES Environmental Earth Sciences, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario, M1C 1A4 Canada Search for other works by this author on: GSW Google Scholar Author and Article Information IMSHUN JE present address: Handex of Illinois Inc., 1701 West Quincy Avenue, Naperville, IL 60540. Environmental Earth Sciences, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario, M1C 1A4 Canada NICHOLAS EYLES Environmental Earth Sciences, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario, M1C 1A4 Canada Publisher: Association of Environmental & Engineering Geologists First Online: 09 Mar 2017 Online Issn: 1558-9161 Print Issn: 1078-7275 © Association of Engineering Geologists 1998 Environmental & Engineering Geoscience (1998) IV (4): 445–454. https://doi.org/10.2113/gseegeosci.IV.4.445 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation IMSHUN JE, NICHOLAS EYLES; Bedrock Structure Control on Soil-Gas Radon-222 Anomalies in the Toronto Area, Ontario, Canada. Environmental & Engineering Geoscience 1998;; IV (4): 445–454. doi: https://doi.org/10.2113/gseegeosci.IV.4.445 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract Soil-gas radon is a newly recognized environmental hazard that has received much interest in the United States, but few studies have been conducted in Canada, particularly in urban areas. This paper describes the results of a 2-yr study of near-surface in situ radon soil-gas levels in the eastern end of the Greater Toronto Area (GTA: population 5.5 million) of southern Ontario, Canada. Transects up to 550 m in length, cross surface lineaments (stream valleys) associated with a prominent but deeply buried mid-Proterozoic shear zone (Central Metasedimentary Belt Boundary Zone: CMBBZ) that underlies the eastern GTA. Early Paleozoic and Pleistocene glacial strata that overlie the CMBBZ are extensively fractured.Regional background levels of radon identified in this study (100–200 pCi/L) are consistent with results of previous work in southern Ontario but repeat measurements also identified anomalously high radon levels (up to 1000 pCi/L). Anomalies occurred at or closely adjacent to the same locations along each transect over the duration of the study. Strata are extensively fractured and it is likely that fractures provide pathways for radon transport to the surface by carrier gases such as CO2, H2 and CH4 released from black shales. This transport mechanism has been recognized elsewhere in southwestern Ontario in regard to radon migration along faults and used to define hydrocarbon reservoirs.In light of these findings, hazardous or near-hazardous levels of radon may occur elsewhere above fractured strata that underlie the GTA. Mapping of fractures and related structures would appear to provide a useful means of delineating potentially hazardous radon levels across this heavily urbanized area. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.