ABSTRACT
Linkages between δ18O–δ2H and hydrological processes have been investigated from isotopic time series recorded in the St. Lawrence River basin. Three stations were monitored from 1997 to 2008. They include the Ottawa River, the St. Lawrence River main channel at Montreal and the fluvial estuary. All sites depict seasonal isotopic cycles characterized by heavy isotope depletions during the snowmelt period and heavy isotope enrichments throughout the ice-free period. The data define δ2H–δ18O regression lines falling below the meteoric water line. In the Ottawa River, calculations suggest that approximately 8 % of the total inflow to the basin is lost through evaporation. In the St. Lawrence River main channel, seasonal isotopic fluctuations most likely reflect hydrological processes occurring within the Great Lakes and mixing with tributaries located downstream. In the St. Lawrence River fluvial estuary, isotopic data allow partitioning streamflow components and suggest that the recorded seasonal variations mainly respond to mixing processes.
Acknowledgements
The authors thank Hydro-Quebec for in kind support and access to data. Environment Canada provided discharge data for the St. Lawrence River fluvial estuary. This project was possible due to the implication of numerous researchers, professionals, technicians and students over the years, their contribution is acknowledged. The helpful comments from two reviewers and the editor are acknowledged.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
† Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria.