By using flumes in greenhouse experiments, we created a gradient of flume-scale heterogeneity of patch-scale flow increasing the number of bed-roughness elements and we determined flume- and patch-scale nitrogen-uptake following stable isotope 15N-NO3 tracer injections. This dataset includes the patch scale measurements of 15N-NO3 uptake and biomass by biofilm. Measurement location within the flume corresponds to 18 locations where patch scale flow velocity was measured. These samples were collected at the end of the 9h 15N-NO3 addition in each flume.

Replication at patch scale: 18 per flume for Ubiofilm--This study was supported by the scholarship "DAAD Forschungsstipendien für promovierte Nachwuchswissenschaftler (Postdoc- Programm)" of the German Academic Exchange Service.