Atmospheric transport of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in air masses across the United Kingdom and Ireland:: Evidence of emissions and depletion

A sample extraction/cleanup and high-resolution gas chromatography-high-resolution mass spectrometry procedure is described and used to routinely quantify the full range of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxanes and dibenzofurans (PCDD/Fs) and di- to octahomologue groups in samples of similar to 500-1000 m(3) of remote/rural European air. The relative standard deviations of sum of toxic equivalents (Sigma TEQ) and Sigma PCDD/F concentrations from five concurrent samples each of 700 m(3) air were 10 and 11%, respectively. Air samples for PCDD/Fs were taken simultaneously at three sites in May 1997: (i) on the remote western Irish coast, (ii) on the northwest coast of England, and (iii) at a regional background site in the northeast of England. For three sampling events where the air passed successively over the two English sites, the increase in air concentrations was used to calculate an emission rate for the mainland United Kingdom land mass; this crude approach gave values of similar to 2-12 g Sigma TEQ/day, which is broadly in line with annual primary atmospheric source inventory estimates. For another event, when an air mass moved successively over the north of England to the Irish west coast, atmospheric half-lives were calculated to be similar to 0.3-4 days for different homologues, which is broadly in line with laboratory and theoretical estimates.