caa a22 4500 445891262 CHVBK 20180317145617.0 cr unu---uuuuu 170323e20110101xx s 000 0 eng 10.1007/s10750-010-0504-4 doi (NATIONALLICENCE)springer-10.1007/s10750-010-0504-4 Net dissolved inorganic nitrogen production in hyporheic mesocosms with contrasting sediment size distributions [Elektronische Daten] [Brett Harvey, Michael Johnson, Joseph Kiernan, Peter Green] The interstitial spaces within streambeds are recognized as an important location of dissolved inorganic nitrogen (DIN) transformations in streams. However, it remains uncertain how physical characteristics of streambeds affect the magnitude and net outcome of subsurface nitrogen transformations. We tested whether the size distribution of streambed sediments, in isolation from the influence of streambed topography and groundwater upwelling, could affect net DIN uptake or production along interstitial flow paths. Mesocosms constructed from PVC pipe (15cm diameter×1m long) were filled with either coarse gravel/cobble or gravel/cobble mixed with finer sediments (5 mesocosms per sediment treatment). Mesocosms were submerged in a stream and oriented, so that surface water flowed through the sediments. After 2months incubation, we measured DIN in interstitial water at 20cm intervals and dissolved oxygen at 10cm intervals along mesocosm flow paths. In both sediment types, DIN concentrations increased longitudinally along mesocosm flow paths in the direction of interstitial flow, indicating net DIN production. Although DIN increased to higher concentrations in mesocosms with fine sediments, greater exchange flow through coarse sediments resulted in similar rates of net DIN production and delivery to surface water. Production of DIN in both sediment types was concentrated within the first 10cm of interstitial flow paths, with no significant production further along the flow paths. Coarse sediments had higher rates of oxygen consumption per unit sediment volume than the coarse-fine sediment mix, suggesting interstitial water velocity may be an important factor affecting hyporheic microbial metabolism. The Author(s), 2010 Hyporheic exchange flow nationallicence Stream nationallicence Sediment size nationallicence Respiration nationallicence Nitrate production nationallicence Harvey Brett Center for Watershed Sciences, University of California, One Shields Avenue, 95616, Davis, CA, USA aut Johnson Michael Center for Watershed Sciences, University of California, One Shields Avenue, 95616, Davis, CA, USA aut Kiernan Joseph Center for Watershed Sciences, University of California, One Shields Avenue, 95616, Davis, CA, USA aut Green Peter Department of Civil and Environmental Engineering, University of California, 95616, Davis, CA, USA aut Hydrobiologia Springer Netherlands 658/1(2011-01-01), 343-352 0018-8158 658:1<343 2011 658 10750 https://doi.org/10.1007/s10750-010-0504-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-010-0504-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Harvey Brett Center for Watershed Sciences, University of California, One Shields Avenue, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Johnson Michael Center for Watershed Sciences, University of California, One Shields Avenue, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Kiernan Joseph Center for Watershed Sciences, University of California, One Shields Avenue, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Green Peter Department of Civil and Environmental Engineering, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 658/1(2011-01-01), 343-352 0018-8158 658:1<343 2011 658 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer