01975nas a2200217   4500008004100000245010800041210006900149300001300218490000700231520124600238653001001484653002001494653001401514653001801528653002101546653001201567653002201579100001501601700001801616856012301634       2001                        eng d00aCentimeter-scale patterns of oxygen concentrations related to nitrification in prairie stream substrate0 aCentimeterscale patterns of oxygen concentrations related to nit  a347 -3570 v203 aDissolved oxygen (O2) was measured with microelectrodes in shallow subsurface microsites in a prairie stream and related to rates of nitrification determined in the laboratory using the nitrapyrin method. Substrata sampled included diatom mats, leaves and wood (coarse benthic organic matter, CBOM), filamentous green algae, bryophytes, and fine benthic organic matter (FBOM). Significant differences in O2 concentrations were found among the substrata, with anoxic zones occurring primarily in FBOM from deep pool sediments and CBOM from litter accumulations. Filamentous green algae and bryophytes had average O2 concentrations near saturation and intermediate rates of nitrification. Diatom mats had the highest concentrations of O2 (up to several times saturation) and the highest rates of nitrification. In the summer, O2 concentrations were above saturation in epilithon and filamentous green algal mats. Nitrification rates were highest in epilithon and filamentous green algae samples taken in the spring and autumn. A significant positive relationship between nitrification rates and O2 concentration was observed in all seasons except summer. These data suggest that O2 concentration could control nitrification in prairie streams.10aAlgae10amicroelectrodes10aN cycling10anitrification10aO2 concentration10astreams10atallgrass prairie1 aKemp, M.J.1 aDodds, W., K.  uhttp://lter.konza.ksu.edu/content/centimeter-scale-patterns-oxygen-concentrations-related-nitrification-prairie-stream