Halogenated organic matter in precipitation

Sammanfattning: Deposition in rain and snow plays a crucial role in the regional and global redistribution of a great variety of substances. This thesis is devoted to chemical characterisation and identification of the halogenated organic compounds that are most widespread in rain and snow. The largest amounts of such matter were found in fractions of relatively polar and non-volatile to semivolatile compounds. In particular, a significant part of the organohalogens could be attributed to alkaline-labile organic bases. Moreover, determination of individual organically bound halogens showed that chloroorganics were more abundant than brominated and iodinated organic compounds. Gas chromatographic analysis of specific compounds revealed that the chloroorganics that were found in the largest amounts in the analysed precipitation samples have thus far received little attention from environmental scientists. Dichloronitromethane, which was often present in higher concentrations than any other volatile chloroorganic, has previously not been reported to occur in the ambient environment. A flame retardant, tris(2-chloroethyl)phosphate, was among the most prevalent extractable chloroorganics, and chloroacetic acids were the predominant chloroorganics in the fraction of carboxylic acids. The analytical procedures used included different fractionation methods, (filtration, purging, evaporation and solid phase extraction), pyrolysis, and detection techniques, such as gas chromatography combined with either atomic emission detection (GC-AED) or mass spectrometry (GC-MS). In addition, the group parameters AOX, AOCI, AOBr and AOI (adsorbable organic halogens, chlorine, bromine and iodine, respectively) were determined.