[Biodegradation mechanisms of 17beta-estradiol (E2) by lake sediment]

Batch experiments using lake sediment mud liquors spiked with E2 were performed under aerobic and anaerobic conditions. The catabolic mechanisms of E2 were also induced. The results indicate that under aerobic condition, 99% of E2 can be removed from aqueous phase after as short as 24 h. Concentration of estrone (E1) firstly increase and then decrease slowly until to vanish from aqueous phase; Under anaerobic condition, 4% of E2 still be in aqueous phase after 96 h of reaction. Concentration profile of E1 show that E1 firstly increase then decrease, then increase and then decrease to vanish from aqueous phase finally. Analyzing the concentration profiles of E2 and E1, we draw a conclusion that E2 is oxidized to E1 by dehydrogenase and then E1 was oxidized by other enzymes within sediment to mineralization completely under aerobic condition. Under anaerobic condition, there is a mutual translation relation between E2 and E1. E2 was oxidized to E1 by dehydrogenase and synchronously E1 is reduced to E2. During this mutual translation course, E2 and E1 can be degraded gradually to finally mineralization completely by other enzymes within the reaction system. Comparing with E2, E1 can accumulate more easily within biosolid in natural waters.