Uptake of dissolved nickel by Elodea canadensis and epiphytes influenced by fluid flow conditions

Using a laboratory mesocosm consisting of live plants and epiphytes grown in a re-circulating flume, dissolved nickel uptake by Elodea canadensis Michaux is compared with nickel uptake by the associated epiphytic community under a range of flow conditions. A flux model was developed and applied to the measured tissue nickel concentration data and generated three parameters descriptive of nickel uptake: uptake rate, equilibrium concentration, and time to equilibrium. The relationship of these parameters to flow conditions, represented by the dimensionless variable Reynolds number, was compared between epiphytes and plants. Water flow was shown to have a stronger effect on the uptake performance of epiphytes than that of plants, implying that water-side mass transfer plays a more important role in epiphytic nickel uptake than it does in plant nickel uptake. Although nickel concentrations were much higher in the epiphyte community than in E. canadensis, more total nickel was sequestered in E. canadensis. This research indicates that fluid flow conditions alter nickel uptake by E. canadensis and the epiphytic community and that the two have different preferential flow regimes. It also suggests the promising bioremediation potential of both in moving fluids in aquatic environments.