GAS-CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF MARINE ORGANIC POLLUTANTS - DISTRIBUTION OF ALPHA-HCH ENANTIOMERS IN THE NORTH-SEA

The enantiomeric ratio of alpha-hexachlorocyclohexane (alpha-HCH) in water samples representing different parts of the North Sea has been determined by means of capillary gas chromatography using heptakis (3-O-butyryl-2,6-di-O-pentyl)-beta-cyclodextrin as chiral stationary phase. The correlation between the enantiomeric ratios and the concentrations of alpha-HCH and gamma-HCH, respectively, allowed a tentative characterization of different microbiological degradation pathways in the North Sea. In the plume of the river Elbe, the Skagerrak and the Norwegian coastal current higher gamma-HCH concentrations correlated with an excess of (-)-alpha-HCH, which in part may indicate a transformation of gamma-HCH to alpha-HCH. Off the east British coast and in the central North Sea an excess of (+)-alpha-HCH correlated with high alpha-HCH and low gamma-HCH concentrations which implies an enantioselective degradation of alpha-HCH. Enantiomeric ratios of (+)-alpha-HCH/(-)-alpha-HCH = 1 in the North Sea areas of the Atlantic inflow suggest the importance of non-enzymatic degradation processes in ocean areas far away from the sources of pollutants.