Effects of Biofilm Growth on the Release of Cu from Contaminated Sediment

Biofilm growth widely occurs at the sediment-water interface, which may affect the mass exchange and exhibit biogeochemical impacts. Here, the release of Cu was studied using sediment spiked with CuCl2 in designed T-cell microcosms. Results show that the biomass increased with the cultivation periods under natural lighting, while the growth rate was reduced due to Cu contamination. The Cu (aq) concentration in the porewater was observed to be stratified. Biofilm’s photosynthesis generated O2 and promoted the oxidation of Cu (s) in deeper layers, thus increasing the concentration in porewater. Meanwhile, the higher adsorption capability of biofilm fixed more Cu (aq) from the porewater. These two opposite aspects finally determined the impacts of biofilm growth on Cu release.