Chlorine-36 as a tracer of perchlorate origin

Neil C. Sturchio, Marc Caffee, Abelardo D. Beloso, Linnea J. Heraty, John Karl Böhlke, Paul B. Hatzinger, W. Andrew Jackson, Baohua Gu, Jeffrey M. Heikoop, Michael Dale

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Perchlorate (ClO4-) is ubiquitous in the environment. It is produced naturally by atmospheric photochemical reactions, and also is synthesized in large quantities for military, aerospace, and industrial applications. Nitrate-enriched salt deposits of the Atacama Desert (Chile) contain high concentrations of natural ClO4-, and have been exported worldwide since the mid-1800s for use in agriculture. The widespread introduction of synthetic and agricultural ClO4 - into the environment has contaminated numerous municipal water supplies. Stable isotope ratio measurements of Cl and O have been applied for discrimination of different ClO4- sources in the environment. This study explores the potential of 36Cl measurements for further improving the discrimination of ClO4- sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO4- having high 36Cl abundances (36Cl/Cl = 3100 × 10-15 to 28,800 × 10 -15), compared with those from the Atacama Desert (36Cl/Cl = 0.9 × 10-15 to 590 × 10-15) and synthetic ClO4- reagents and products (36Cl/Cl = 0.0 × 10-15 to 40 × 1015). In conjunction with stable Cl and O isotope ratios, 36Cl data provide a clear distinction among three principal. ClO4- source types in the environment of the southwestern U.S.

Original languageEnglish
Pages (from-to)6934-6938
Number of pages5
JournalEnvironmental Science and Technology
Issue number18
StatePublished - Sep 15 2009


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