Biosensor determination of the microscale distribution of nitrate, nitrate assimilation, nitrification, and denitrification in a diatom-inhabited freshwater sediment

Research was conducted to examine the vertical and temporal distribution of NO3- in diatom-covered sediment during light-dark cycles using a novel microscale NO3- biosensor characterized by absence of interference from chemical species other than NO2- and N2O. Vertical distribution of NO3- assimilation, nitrification and denitrification was measured from the calculated steady-state NO3- profiles by diffusion reaction models. Results show that the stimulatory effect on nitrification by illumination was caused by algal production of O2.NH4+.