THE USE OF C-13-LABELED POLYCYCLIC AROMATIC-HYDROCARBONS FOR THE ANALYSIS OF THEIR TRANSFORMATION IN SOIL

The formation of non-extractable residues during biodegradation and hu mification processes in soils and sediments represents a major sink fo r organic contaminants. The mode of incorporation of polycyclic aromat ic hydrocarbons (PAH) and their metabolites into macromolecular organi c matter during microbial degradation was studied applying C-13-labell ed compounds. Mineralisation rates were determined by measuring the (C O2)-C-13 production. An incorporation of C-13-PAH-fragments into humic material could be traced by isotopic analysis of the bulk organic mat ter. Furthermore, selective chemical degradation reactions were perfor med to analyse the precise chemical structure of covalently bound C-13 -labelled PAH fragments in soil humic substances. Structural assignmen ts by GC-MS combined with isotope measurements on the bulk organic car bon and at the molecular level (Isotope Ratio Monitoring-GC-MS) provid ed useful information on the fate of xenobiotics within the soil. (C) 1998 Elsevier Science Ltd. AII rights reserved.