Concentrations of Dioxins and Dibenzofurans in the Atmosphere

Abstract

Polychlorinated dibenzo-p-dioxins and dibenzofurans have been found in environmental sinks such as lake sediments and human fat. We have previously shown that the most likely source of these compounds is municipal or chemical incineration of chloroaromatic compounds and that there is a transformation of the congener class profile for these compounds as they move from source to sink. This report examines the transportation and depositional media of these compounds by analyzing ambient air and rain samples. Air was sampled with a high volume sampler and split into operationally defined particulate and vapor phases with a glass fiber filter and a polyurethane foam plug. Rain was sampled with a one square meter wet-only collector. The analytical methodology is based on a two step chromatographic cleanup followed by negative ion gas chromatographic mass spectrometry. Concentrations of the different congeners in the samples were 1 to 750 femtograms per cubic meter of ambient air for the vapor and particulate samples. Concentrations of the rain samples were in the picogram per liter range. These are the first measurements of these compounds in ambient air and rain samples. The concentrations in these samples were used to determine vapor/particulate ratios and to compare vapor and particulate scavenging by rain.