The fate of resin acids-1. The biotransformation and degradation of deuterium labelled dehydroabietic acid in anaerobic sediments

A lake sediment was collected downstream from the discharge from a bleached kraft pulp and paper mill, spiked with 6-d2-dehydroabietic acid and anaerobically incubated for 264 days. The concentrations of the deuterium label, 6-d2-dehydroabietic acid and resulting biotransformation products were monitored periodically. The 6-d2-dehydroabietic acid transformed to d-tetrahydroretene (62 % conversion), and 6-d2-dehydroabietin (1 % conversion). Towards the end of the study, minor quantities of d-retene and methyl d-tetrahydrophenanthrene were observed. Based on the appearance and disappearance of these and other compounds and mass balances for labelled and unlabelled components, a pathway for the conversion of dehydroabietic acid to several derived base neutrals was proposed. This is the first conclusive study indicating that in resin acid enriched sediments, anaerobic processes form resin acid derived base neutral compounds.