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Colloquium | Chemical Sciences and Engineering

From The Stratosphere to the Rhizosphere: A Case Study in Isotope Forensics

CSE Colloquium

Abstract: Among the many hazardous anthropogenic contaminants present in our environment, some also have natural sources.  One such contaminant is perchlorate, an oxyanion of chlorine that has many practical uses and has recently been found as an abundant component of Martian soils.  Following recognition of the widespread occurrence of perchlorate in drinking water supplies across the US during the late 1990s, efforts were made to identify its sources by measuring chlorine and oxygen isotope compositions.  Three principal sources (one synthetic and two natural) were clearly discriminated isotopically.  This attracted the attention of the environmental legal community as a potential forensic tool by which to apportion liability for contamination, leading to the introduction of perchlorate isotope data in the federal court system as a key line of evidence.