1. Alaska Stable Isotope Facility Water and Environmental Research Center Institute of Northern Engineering University of Alaska Fairbanks 1764 Tanana Loop Fairbanks AK99775‐5910USA
2. Department of Geosciences University of Alaska Fairbanks 1930 Yukon Drive Fairbanks AK99775‐5780USA
3. U.S. Geological Survey Eastern Mineral and Environmental Resources Science Center 12201 Sunrise Valley Drive, MS954 Reston VA20192USA