The use of dioxin isomer group ratios to identify sources and define background levels of dioxins in the environment.
Abstract Environmental samples containing a mixture of dioxins of which there are seventy‐five isomers, show a characteristic composition indicative of their source and the destruction reactions taking place in the environment. Expressed in terms of isomer group ratios, the study shows that thermochemical reactions rearrange the isomer content to form specific ratios characteristic of the source itself, and upon release to the environment a shift in the ratios to a new and constant set of ratios characteristic of the environment into which they are released. The observed shift is easily modeled, independent of the source, and presumably caused by oxidation reactions in the atmosphere. The reduction/oxidation reactions needed to account for such an observation is demonstrated in a laboratory unit where a single type of dioxin (octachlorodibenzo‐p‐dioxin) is transformed into all isomer group species during incineration