M. Caffee Abelardo D. Beloso Jr. L.J. Heraty J.K. Böhlke P.B. Hatzinger W.A. Jackson B. Gu J.M. Heikoop M. Dale N.C. Sturchio 2009 <div class="hlFld-Abstract"><div id="abstractBox"><p class="articleBody_abstractText">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⁻<span>&nbsp;</span>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⁻<span>&nbsp;</span>sources in the environment. This study explores the potential of<span>&nbsp;</span>³⁶Cl measurements for further improving the discrimination of ClO₄⁻<span>&nbsp;</span>sources. Groundwater and desert soil samples from the southwestern United States (U.S.) contain ClO₄⁻<span>&nbsp;</span>having high<span>&nbsp;</span>³⁶Cl abundances (³⁶Cl/Cl = 3100 × 10⁻¹⁵<span>&nbsp;</span>to 28,800 × 10⁻¹⁵), compared with those from the Atacama Desert (³⁶Cl/Cl = 0.9 × 10⁻¹⁵<span>&nbsp;</span>to 590 × 10⁻¹⁵) and synthetic ClO₄⁻reagents and products (³⁶Cl/Cl = 0.0 × 10⁻¹⁵<span>&nbsp;</span>to 40 × 10⁻¹⁵). In conjunction with stable Cl and O isotope ratios,<span>&nbsp;</span>³⁶Cl data provide a clear distinction among three principal ClO₄⁻<span>&nbsp;</span>source types in the environment of the southwestern U.S.</p></div></div><div class="hlFld-Fulltext"><br data-mce-bogus="1"></div> application/pdf 10.1021/es9012195 en ACS Chlorine-36 as a tracer of perchlorate origin article