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TitleDesalination of a sedimentary rock aquifer system invaded by Pleistocene Champlain Sea water and processes controlling groundwater geochemistry
AuthorCloutier, V; Lefebvre, R; Savard, M M; Therrien, R
SourceEnvironmental Earth Sciences vol. 59, no. 5, 2009 p. 977-994, https://doi.org/10.1007/s12665-009-0091-8
Year2009
Alt SeriesEarth Sciences Sector, Contribution Series 20100306
PublisherSpringer Nature
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceQuebec
NTS31G/09; 31G/10; 31G/15; 31G/16; 31H/12; 31H/13; 31H/14; 31I/03; 31I/04; 31J/01; 31J/02
AreaMontreal; St. Lawrence River; St-Jérôme; Joliette
Lat/Long WENS-75.0000 -73.0000 46.2500 45.5000
Subjectssurficial geology/geomorphology; hydrogeology; geochemistry; aquifers; groundwater; groundwater regimes; groundwater geochemistry; sedimentary rocks; salinity; Champlain Sea; Cenozoic; Quaternary
Illustrationslocation maps; plots; cross-sections
Released2009 02 20
AbstractThe objective of this study was to identify geochemical processes and Quaternary geological events responsible for the variations in groundwater geochemistry observed in a sedimentary rock aquifer system, including brackish to saline groundwater. Inorganic constituents and environmental isotopes were analyzed for 146 groundwater samples. Dissolution of carbonates dominates in recharge areas, resulting in Ca-, Mg-HCO3 groundwater. Further along flow paths, under confined conditions, Ca2+–Na+ ion exchange causes groundwater evolution to Na-HCO3 type. Na-Cl groundwater is also found and it falls on a seawater mixing line. Using conservative tracers, Cl- and Br-, the original Champlain Sea water is shown to have been, in the region, a mixture of about 34% seawater and 66% freshwater, a composition still retained by some groundwater. Na-Cl groundwater thus results from mixing with former Champlain Sea water and also from solute diffusion from overlying marine clay. The system is thus found to be at different stages of desalinization, from the original Champlain Sea water still present in hydraulically stagnant areas of the aquifer to fully flushed conditions in parts, where more flow occurs, especially in recharge zones. The geochemical processes are integrated within the hydrogeological context to produce a conceptual geochemical evolution model for groundwater of the aquifer system.
GEOSCAN ID287258