Spatial variability in stable isotope values of surface waters of Eastern Canada and New England

A total of 294 surface water samples were collected in Eastern Canada and the New England states of the USA in 2007, 2009, 2011, and 2013 and analyzed for δ18O and δD values to investigate climatic controls on hydrology and to test whether isotope values of surface waters can provide a suitable calibration for evaluation of paleoenvironmental proxy data in this region. Results demonstrate that surface waters in this region exhibit latitudinal gradients, with some overprinting by regional trends. Surface water δ18O and δD values range from −2.8‰ to −16.0‰, and from −23.8‰ to −118.5‰, respectively. Regression of all δ18O and δD values yields a surface water line (SWL) (δD = 7.53(±0.11)δ18O + 3.81(±1.12); r2 = 0.95; n = 294), similar to slopes of 7.63(±0.06) and 7.96(±0.1) based on monthly and annual precipitation amount-weighted means for GNIP/CNIP stations in this study area. At smaller spatial scales evaporation and greater water residence time generate lake SWL with lower slope (7.50) than river SWL (7.80). At greater spatial scales, δ18O and δD values of lakes and rivers show a more uniform distribution, thus reflecting the prevalence of regional over local hydrological effects.