Dahl Rasmussen, A. AR. Roskilde University, adr@virgil.ruc.dk
Banta, G. GB. Roskilde University, banta@ruc.dk
Andersen, O. OA. Roskilde University, andersen@ruc.dk

Effects of bioturbation by the lugworm Arenicola marina on transfer of Cd from water to sediment or from sediment to water, and on the spatial distribution of Cd in sediment were studied using laboratory sediment cores and 109-Cd. The rate of removal of Cd added to overlying water was 3-5 times higher and the irrigation rates calculated from Br flux were about 10 times higher in cores with lugworms than in cores without lugworms. The lugworm irrigation and particle mixing resulted in bimodal sediment distribution patterns of Cd with peaks at the top and at the site of the worms, while all Cd was deposited in the top few mm sediment in cores without worms. When Cd was uniformly mixed with sediment before core setup or added as a thin layer to the top of cores, the net rate of Cd transfer from sediment to water was about 2,5-3,5 times lower when worms were present, indicating that irrigation processes strongly favours sediment binding of Cd. In these experiments, peaks of Cd also occurred at the location of the worms. It is notable that bioturbation increased the fraction of sediment-bound Cd even when Cd was initially not present in the water phase. Bioturbating macroinfauna strongly influences the kinetics of both water-borne and sediment-bound pollutants in near-coastal biotopes, where sediments are important sink for particle-reactive compounds.
Day: Thursday, Feb. 4
Time: 11:45 - 12:00pm
Location: Hilton of Santa Fe
Code: SS30FR1145S