... microprofiles of O2, NH4+, NO2-, and NO3- in the autotrophic nitrifying biofilm (B). The distribution and magnitude of the estimated specific rates of net consumption and production of ... localization, and quantification of microbial populations, (2) the determination of physicochemical microenvironment, and (3) the measurement of their in situ activity. Combination of FISH and microsensor ... biofilm. After reaching the steady-state condition, microprofiles of NH4+, NO2-, NO3-, and O2 in the biofilms were measured by use of microsensors, and the spatial distributions of...