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Spatial and temporal variability of prairie lake hydrology as revealed using stable isotopes of hydrogen and oxygen
Author(s) -
Pham Samantha V.,
Leavitt Peter R.,
McGowan Suzanne,
Wissel Björn,
Wassenaar Leonard I.
Publication year - 2009
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2009.54.1.0101
Subject(s) - hydrology (agriculture) , precipitation , groundwater , environmental science , δ18o , salinity , surface water , stable isotope ratio , oceanography , geology , geography , physics , geotechnical engineering , quantum mechanics , environmental engineering , meteorology
Evaporation and groundwater fluxes are thought to regulate hydrologic variability in lakes of the northern Great Plains, but little is known of how the relative importance of these processes may vary in time or space. To address this issue, we measured the isotopic composition of water (δ 18 O, δ2H) from 70 closed‐basin lakes in southern Saskatchewan, Canada. All lakes occupied endorheic basins along a long gradient of salinity (0.2–115 g total dissolved solids L −1 ). Lakes exhibited synchronous seasonal changes in salinity (synchrony, S = 0.78) and δ 18 O ( S = 0.84) during the dry summer of 2003 (~195 mm rain), whereas coherence was reduced to 0.56 and 0.22, respectively, during the wet summer of 2004 (~295 mm rain). However, despite evaporative enrichment of isotopic ratios during dry summers, hydrologic balances were regulated mainly by changes in water inflow (I) rather than evaporation (E) in both wet and dry years, with particularly strong influence of inflow (lowest E : I ratio) in dry southwestern regions. Analysis of isotopic composition also identified winter precipitation or groundwater as the most influential source of water to most lakes, despite only ~30% of annual precipitation being delivered during winter. Therefore, although seasonal variability in lake chemistry was influenced by evaporation during summer, long‐term mean chemical characteristics of prairie lakes were regulated mainly by changes in winter precipitation or groundwater influx.