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Data Series 703

The δ2H and δ18O of Tap Water from 349 Sites in the United States and Selected Territories

By Tyler B. Coplen, Jurate M. Landwehr, Haiping Qi, and Jennifer M. Lorenz

Thumbnail of and link to report PDF (1.54 MB)Abstract

Because the stable isotopic compositions of hydrogen (δ2H) and oxygen (δ18O) of animal (including human) tissues, such as hair, nail, and urine, reflect the δ2H and δ18O of water and food ingested by an animal or a human and because the δ2H and δ18O of environmental waters vary geographically, δ2H and δ18O values of tap water samples collected in 2007–2008 from 349 sites in the United States and three selected U.S. territories have been measured in support of forensic science applications, creating one of the largest databases of tap water δ2H and δ18O values to date. The results of replicate isotopic measurements for these tap water samples confirm that the expanded uncertainties (U = 2μc) obtained over a period of years by the Reston Stable Isotope Laboratory from δ2H and δ18O dual-inlet mass spectrometric measurements are conservative, at ±2 ‰ and ±0.2 ‰, respectively. These uncertainties are important because U.S. Geological Survey data may be needed for forensic science applications, including providing evidence in court cases.

Half way through the investigation (December 2007), an isotope-laser spectrometer was acquired, enabling comparison of dual-inlet isotope-ratio mass spectrometric results with isotope-laser spectrometric results. The uncertainty of the laser-based δ2H measurement results for these tap water samples is comparable to the uncertainty of the dual-inlet isotope-ratio mass spectrometer, with the laser-based instrument measurements having a slightly lower uncertainty. However, the δ18O uncertainty of this laser-based instrument is about a factor of ten higher than that of the dual-inlet isotope-ratio mass spectrometer.

Revised November 8, 2013

First posted September 12, 2013

For additional information contact:
Director, Reston Stable Isotope Laboratory
U.S. Geological Survey
12201 Sunrise Valley Drive, MS 431
Reston, VA 20192

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Suggested citation:

Coplen, T.B., Landwehr, J.M., Qi, Haiping, and Lorenz, J.M., 2013, The δ2H and δ18O of tap water from 349 sites in the United States and selected territories: U.S. Geological Survey Data Series 703, 113 p., at





Tap Water δ2H and δ18O Measurement Results

Analysis of Uncertainty


References Cited

Appendix A. Site Location Information for Tap Water Samples

Appendix B. Sample Collection Information and Mean Analytical Results Sorted by Site and Date/Time

Appendix C. Measurement Results for VG Micromass Dual-Inlet Isotope-Ratio Mass Spectrometer δ2H Analyses

Appendix D. Measurement Results for Los Gatos Research Isotope-Laser Spectrometry δ2H Analyses

Appendix E. The δ2H Measurement Results, including Mean and Standard Deviation, for Two Methods of Hydrogen Isotope Analysis

Appendix F. The δ18O Measurement Results, including Mean and Standard Deviations, for Two Methods of Oxygen Isotope Analysis

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