title: Novel evidence for natural formation of dioxins in ball clay.
abstract: Elevated concentrations of dioxins in ancient ball clay from the Mississippi Embayment suggest natural formation of dioxins in the environment. Evidence for such natural formation in ball clay derives from unique congener profiles in undisturbed ancient clay deposits and from the lack of other anthropogenic contaminants. Here we present novel evidence of natural formation of dioxins based on congener-specific carbon isotopic analysis of octachlorodibenzo-p-dioxin (OCDD) in ball clays from the USA and Japan. The analyses were performed using a combination of double-column high performance liquid chromatography clean-up and two-dimensional gas chromatography-isotope ratio mass spectrometry. Elevated concentrations of OCDD found in ball clays from the USA and Japan were isotopically distinguished from the anthropogenic source materials (fly ash and pentachlorophenol) and environmental samples (sediment and soil). The isotopic signatures and the occurrence of OCDD in ancient ball clays deposited in the Tertiary Era provide evidence for the in situ formation of dioxins.
authors.affiliation: Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, USA.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Horii
authors.forename: Bert
authors.initials: B
authors.lastname: van Bavel
authors.forename: Kurunthachalam
authors.initials: K
authors.lastname: Kannan
authors.forename: Gert
authors.initials: G
authors.lastname: Petrick
authors.forename: Kerstin
authors.initials: K
authors.lastname: Nachtigall
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Yamashita
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry; D000077215:Clay; D004147:Dioxins / Q000737:chemistry*; D007564:Japan; D010416:Pentachlorophenol / Q000737:chemistry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives / Q000737:chemistry; D014481:United States