ABSTRACT

This chapter discusses the occurrence and magnitude of stable isotope fractionation during biotic and abiotic transformation of common organic contaminants. It provides an overview of isotope enrichment factors (ε), which are necessary for the quantication of contaminant degradation based on stable isotope data from eld sites and can help to characterize degradation mechanisms. This chapter also discusses why the magnitude of isotope fractionation varies between different substances. Because the observed isotope fractionation is caused by isotope effects during the initial irreversible transformation step (see Chapter 3), the reaction

4.1 Introduction .................................................................................................... 79 4.2 Key Factors that Inuence the Magnitude of Isotope Fractionation ..............80