Abstract
Isotopic data can be used for tracing the origin and behavior of ClO4- in the environment. Four independently varying parameters have been measured on individual ClO4- samples for this purpose: delta 37Cl, 18O, 17O, and 36Cl/Cl. At least three distinct types of ClO4- have been identified isotopically, and these distinctions have proven to be useful in forensic applications. Additional data for natural ClO4- are urgently needed, however, to obtain a global picture of its isotopic variations. Improved methods for sample preparation and isotopic analysis with much better sensitivity would be helpful for measuring ClO4- isotopic variations in some sample types such as aerosols and precipitation as well as foodstuffs and bodily fluids, which have been precluded by the impracticality of obtaining the currently-required milligram amounts of ClO4-.. Further experimental and theoretical investigations of atmospheric ClO4- production mechanisms may lead to improved explanations of observed isotopic variations in natural samples.
