Danielle Finlayson

Radon is a radioactive daughter product of uranium that is naturally occurring in sedimentary sequences and granitic intrusions throughout Nova Scotia.  Occurrences can be found in Southern Nova Scotia in such outcrops as the South Mountain Batholith and the Horton Group.  Health Canada has recently lowered the national regulated radon guideline for indoor air to 200Bq/m³ due to evidence that radon is the second leading cause of lung cancer.

This study was undertaken in order to establish whether rocks with variable uranium content from weathered outcrops of known uranium concentration, contributed significant amounts of radon to waters and soils associated with these rocks. Through a series of experiments it was determined that radon is readily leached from weathered rocks both of high uranium concentrations of 212 ppm and low uranium concentrations of 4 ppm. The uranium concentration of the source rock is not the sole indicator in identifying a radon problem in water and soil gas. Source rocks with low or high uranium concentrations yielded elevated radon levels in water  of >1,000,000 Bq/m³. This research has found that radon is not only being leached from the uranium in the rock but also from radium which is the direct parent rock of radon.  Further analysis of the leached water identified that uranium is being leached into the water with results as high as 22µg/L dissolved in the water, which exceeds the recommended guideline for Canadian drinking water. The main concern for the leaching of the radon from the source rock is the potential for the radon and radium to be redistributed through surface and groundwater.  This study also confirmed that radon outgases more rapidly from warm water than from cold water, and although there is no current Canadian guideline for radon in water, radon in hot water outgases readily and so can contribute to the level of radon in indoor air, particularly in bathrooms of homes.

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Pages: 91
Supervisor: Anne-Marie Ryan