Chlorinated structures in high molecular weight organic matter isolated from fresh and decaying plant material and soil

During the past few years, surveys of AOX (adsorbable organic halogens) in water and TOX (total amount of organic halogens) in soil have demonstrated that natural halogenation of organic macromolecules is responsible for the widespread occurrence of organohalogens in seemingly unpolluted environments. This study revealed the presence of several chlorinated aromatic structures in organic matter derived from different types of decaying plant material and soil. In samples derived from fresh plant matter, however, there was normally no evidence of such structures. Two types of samples were analyzed: (i) lignin materials isolated by acidic solvolysis of fresh and decaying spruce wood, birch leaves, peat moss (Sphagnum), and meadow grass and (ii) high molecular weight organic matter leached with base from spruce forest soil and meadow grass soil. An oxidative degradation technique was used to render the studied structures amenable to gas chromatography with atomic emission detection (GC-AED) and mass spectrometric detection (GC-MS). The identified degradation products were methyl esters of 3-chloro- and 3,5-dichloro-4-ethoxybenzoic acid, 5-chloro-4-ethoxy-3-methoxybenzoic acid, dichloro-and trichlorobenzoic acids, and 3,5-dichloro-4-methoxybenzoic acid.