The fate of resin acids-2. The fate of resin acids and resin acid derived neutral compounds in anaerobic sediments

A sediment, sampled from a hydroelectric lake receiving a bleached kraft mill effluent discharge, was incubated anaerobically for 264 days. Both recipient and sterilised control sediments were periodically sampled and analysed to monitor the changes in resin acid composition with time. Over 264 days of incubation, the concentration of total resin derived compounds decreased by 50%. The total resin acid concentration was reduced by 50% whereas the concentration of resin derived neutrals decreased by 54%. Relative to an incubated sterile control sediment, the pimaranic acid concentration remained constant, 8-pimarenic and 8-isopimarenic acid concentrations slightly increased and pimaric, isopimaric, abietanic and secodehydroabietic acid concentrations decreased. Dehydroabietic acid was transformed to tetrahydroretene simultaneously with the transformation of labelled dehydroabietic acid to a variety of labelled products. Throughout the incubation period, the concentration of fichtelite remained constant. The concentration of retene slightly increased until the final 50 days of incubation, during which time dehydroabietin and tetrahydroretene concentrations decreased. This is the first study reporting the degradation of a variety of resin acids and derived neutrals in an anaerobic sediment.