Analytical methods for studying polychlorinated naphtalene congener profiles and levels in the Environment
Abstract: This thesis describes the development, refinement and application of analytical techniques in conjunction with other methods for studying the environmental occurrence, distribution and transformation of polychlorinated naphthalenes (PCNs). The procedures involve selective high-performance liquid chromatographic fractionation on a styrene-divinylbenzene gel permeation column and 2-(1-pyrenyl)ethyldimethylsilylated silica column combined with high resolution gas chromatography and low resolution mass spectrometry. The determination of PCNs on a congener specific basis was investigated and it was concluded that several combinations of liquid and gas chromatographic systems were needed to achieve a complete congener separation. The finally chosen method enabled the separation of 42 of the 49 possible chlorinated naphthalenes (CNs) containing four to seven chlorines.Levels of PCNs were generally found to follow those of PCBs, both geographically and in time trends, thus indicating a common source. Exceptionally high levels of PCNs were found at sites with high levels of PCBs, such as close to some paper mills processing recycled paper, but also at sites with chlorine production industries using graphite electrodes in the chloralkali process.High levels of the persistent 1,2,3,4,6,7- and 1,2,3,5,6,7-hexaCN congeners were found in avian top predators by the Baltic Sea. These levels may contribute to an impaired health and reproduction for these species.Levels of total PCNs in Swedish background sediments were found to be between 0.1 and 1ng/g on a dry weight basis. Several of the 1,3,5,7 and 1,4,6,7 substituted tetra- penta and hexaCN congeners were found to be more abundant in these samples than in source related samples, thus indicating that these congeners are more persistent in the environment. In order to investigate the potential alteration in CN congener profile by sunlight exposure, a photolysis experiment was conducted. Both sunlight and artificial UV exposure resulted in an overall dechlorination. In particular, several of the 1,8-substituted CN congeners were affected. These results may partly explain the differences seen in CN congener profiles between source related samples and background samples.
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