Chris McConnell’s MESc thesis defense on Isotope Mass Balance of Lakes – 7 Mar 2017, 1pm.

All, please join us for Chris McConnell’s MESc thesis defense:


Isotope Mass Balance in Seasonally Stratified Lakes of South Central Ontario

Tuesday 7th March at 1:00 pm

Room R226, Nipissing University, North Bay


This study explores the simplified Isotope Mass Balance (IMB) of a lake as a tool capable of

revealing evaporation/inflow (E/I) ratios in south‐central Ontario lakes. The IMB has been

used to approximate E/I in annual lake water balance in Northwest Canada and more recently in northern Ontario. This study added stable water isotopes sampling to an extensive long‐term dataset that goes back to 1976 in an effort to constrain the assumptions and uncertainties connected with the method. With minor violations of the underlying assumptions and the lack of a clear evaporation trend line, the simplified IMB proved to be a robust method. The degree of offset from the isotopic composition of precipitation reflected proportionate evaporation loss (+/‐ 20%) and was always able to describe the relative rank of the lakes. Seasonal stratification did not prove to be an issue in applying the method, but sampling of stratified systems did require the whole lake to be characterized. The sampling approach suggested by Gibson (at 1m depth and close to the bottom) did seem to be sufficient.