Boundary-layers around bladed aquatic macrophytes

This paper describes a model of the diffusive boundary-layer around an aquatic macrophyte blade. Nutrient uptake at the base of the modelled boundary-layerwas examined using previously published laboratory data. The analysis showed that, over the outer velocity range 0.01–0.16 ms^-1, nutrient uptake varied between that predicted by flatplate boundary-layer theory and that expected with no mean advection. A ratio of theoretical and actual nutrient uptake rates was defined as a means of categorising the transition between the two transportmodels. The modelling was extended to show how fluctuating boundary conditions may enhance nutrient uptake by the macrophyte; the scenario examined here suggested that at otherwise low outer velocities, periodic stripping of the boundary-layer by passing waves increased nutrient uptake by a factor of 10.