BIOTURBATION EFFECTS OF TANYPUS CHINENSIS AND LIMNODRILUS HOFFMEISTERI ON PENETRATION AND DISTRIBUTION OF SEDIMENT OXYGEN

Bioturbation effects of Tanypus chinensis and Limnodrilus hoffmeisteri, on sediment oxygen penetrationdepth and distribution, were investigated in this research. Surface sediments were collected from Meiliang Bay, in LakeTaihu. Oxygen penetration depth and distribution in sediment were measured by the use of microelectrodes, and thenTanypus chinensis and Limnodrilus hoffmeisteri were added into the sediment. Oxygen exchange rates across the sediment-water interface were calculated by two different methods: oxygen concentration decreased in the flow-throughsystem and oxygen profiles obtained by the microelectrode. Results showed that Tanypus chinensis and Limnodrilushoffmeisteri could enhance the oxygen exchange rates between sediment-water interface, while the second method couldunderestimated the exchange rates.The oxygen penetration depth could be inferred directly from the microprofiles, which demonstrated that oxygenpenetration into sediment were greatly enhanced by Tanypus chinensis. Sediment oxygen penetration depth increasedfrom 6 mm to 10 mm, while Limnodrilus hoffmeisteri showed no significantly effects on sediment oxygen penetrationdepth and distribution. Results of oxygen exchange rates demonstrated that oxygen exchange rates calculated with thesecond method could be underestimated, because the activity of Bottom fauna in sediment could consumed oxygen thusdecreased calculation accuracy.