Spatial variability in stable isotope values of surface waters of Eastern Canada and New England Sandra Timsic ⇑ , William P. Patterson Saskatchewan Isotope Laboratory, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada article info Article history: Received 2 June 2013 Received in revised form 11 January 2014 Accepted 4 February 2014 Available online 12 February 2014 This manuscript was handled by Laurent Charlet, Editor-in-Chief, with the assistance of Eddy Y. Zeng, Associate Editor Keywords: Stable isotopes Oxygen Deuterium Deuterium excess Eastern Canada Paleoclimate summary 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 d 18 O and dD values to investigate climatic controls on hydrology and to test whether isotope values of surface waters can provide a suitable calibration for eval- uation 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 d 18 O and dD values range from 2.8‰ to 16.0‰, and from 23.8‰ to 118.5‰, respectively. Regression of all d 18 O and dD values yields a surface water line (SWL) (dD = 7.53(±0.11)d 18 O + 3.81(±1.12); r 2 = 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, d 18 O and dD values of lakes and rivers show a more uniform distribution, thus reflecting the prevalence of regional over local hydrological effects. Contour maps of surface water d 18 O and dD values exhibit more detail than existing global precipitation models and suggest (a) a progressive decrease in d 18 O H2O and dD H2O values towards higher latitudes via Rayleigh distillation and (b) generally higher d 18 O H2O and dD H2O values in Western Newfoundland likely due to its proximity to the ocean. Contour maps predict the average annual-amount weighted d 18 O and dD values of precipitation provided by GNIP/CNIP networks fairly well. It was also determined that recy- cled moisture supplies a significant proportion of precipitation in the southern/western parts of our study area, while evaporation could be a more dominant factor for interior Labrador. In addition, a strong agree- ment is observed between temperature and precipitation/surface water d 18 O and dD values, suggesting that d 18 O and dD values of surface waters can provide a suitable template and aid for ongoing paleoen- vironmental research in this region. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Stable isotope values of meteoric waters are commonly used as environmental tracers to track the hydrological cycle, water use, and spatial distribution of precipitation and thus have abundant applications and significant importance for hydrological (e.g. Gat et al., 1994; Gibson and Edwards, 2002; Telmer and Veizer, 2000; Welker, 2000; Yonge et al., 1989), atmospheric (e.g. Gedzelman and Lawrence, 1982; Hoffmann et al., 2000; Jouzel et al., 1997; Lawrence et al., 1982), and climate studies (e.g. Edwards et al., 1996; Kirby et al., 2002; Lachniet et al., 2009; Vuille and Werner, 2005). Owing to the intricate connection between hydrology and climate, stable isotope values of meteoric waters are also often directly and/or indirectly linked to interpretations of data retrieved from proxy climate archives (e.g. ice cores, lake/ocean sediment, plant material, and speleothems). Therefore, gaining a better understanding of stable oxygen (d 18 O H2O ) and hydrogen (dD H2O ) isotope variability through space and time is useful for tracing variability in atmospheric circulation, regional precipitation, and latent heat transport (e.g. Diefendorf and Patterson, 2005; Johnson and Ingram, 2004), thus providing invaluable paleoclimatic evi- dence on a wide range of timescales. d 18 O H2O and dD H2O values of precipitation (here referred to as d 18 O pt and dD pt ) generally display well defined spatial and tempo- ral variability that reflects geographical factors (i.e. latitude, altitude, and continentality) and climatic processes, such as the isotope values of the original water source, rainout mechanisms, temperature, air mass mixing, along with kinetic and equilibrium http://dx.doi.org/10.1016/j.jhydrol.2014.02.017 0022-1694/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +1 306 966 5712. E-mail addresses: sandra.timsic@usask.ca (S. Timsic), bill.patterson@usask.ca (W.P. Patterson). Journal of Hydrology 511 (2014) 594–604 Contents lists available at ScienceDirect Journal of Hydrology journal homepage: www.elsevier.com/locate/jhydrol