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Thesis Format



Master of Science




Longstaffe, Fred J.


Lockdowns and travel restrictions during the COVID-19 pandemic forced a significant fraction of London, Ontario, Canada residents to remain in one location for long enough to reach isotopic equilibrium with their primary drinking water source(s). This situation created ideal natural conditions for measuring the isotopic fractionation between the stable hydrogen and oxygen isotopes of drinking water and hair or nail tissues, and for determining the magnitude of intra-population variation in tissue δ2H and δ18O. Hair and nail of participants who reported exclusively drinking London municipal tap water spanned much larger δ2H and δ18O ranges than their drinking water. Forensic δ2Hdrinking water and δ18Odrinking water reconstructions presuming a constant tissue-drinking water isotopic fractionation therefore carry high uncertainty. London and southern Ontario values of δ13Chair and δ15Nhair for omnivores vary by < 1 ‰ between COVID-19 and pre-COVID-19 times, suggesting that the overall dietary habits of Londoners were not affected by the pandemic.

Summary for Lay Audience

Stable isotopes are atoms of the same element that differ in their number of neutrons. Stable isotopes of hydrogen and oxygen are of particular interest to archeological and forensic investigations because they reflect the isotopic compositions of drinking water, which in turn typically reflect the isotopic compositions of local fresh water. Stable isotopes in fresh water vary predictably with geography. Hence, it is hoped that stable isotope compositions of drinking water incorporated into hair and nails can be used to reconstruct the region of origin of unknown hair and nail tissues.

Travel restrictions and lockdowns during the COVID-19 pandemic forced residents of London, Ontario, Canada – who consume municipal tap water of near constant isotopic composition – to remain in their local area long enough for the hydrogen and oxygen isotopes within their hair and nails to reflect local tap water. This created a unique opportunity to study the relationship between the stable hydrogen and oxygen isotope compositions of drinking water and hair and nail tissues grown during this period. This study found, however, that the isotopic range London municipal tap water was much smaller than the isotopic range of hair and nail of London residents consuming this water. This finding thus limits the utility of hair and nail isotopic compositions as a tracer of geographic origin in archeological and forensic investigations.

The stable carbon and nitrogen isotope compositions of hair and nails reflect one’s dietary habits. The small range of carbon and nitrogen isotope compositions measured for hair and nails in London residents indicate consumption of diets with generally similar isotopic compositions. Moreover, the stable carbon and nitrogen isotope compositions of hair from London and southern Ontario omnivores collected prior to the start of the COVID-19 pandemic did not differ significantly from those collected in the present study. These similarities suggest the dietary composition of London residents has not changed significantly since the start of the pandemic.

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Available for download on Saturday, April 20, 2024