1. Use of slow filtration columns to assess oxygen respiration, consumption of dissolved organic carbon, nitrogen transformations, and microbial parameters in hyporheic sediments
- Author
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L. Mauclaire, Florian Mermillod-Blondin, Bernard Montuelle, Laboratoire d'Ecologie des Hydrosystèmes Fluviaux (EHF), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Geological Institute [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Qualité des eaux et prévention des pollutions (UR QELY), and Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF)
- Subjects
0106 biological sciences ,Geologic Sediments ,Biogeochemical cycle ,Hyporheic sediments ,Environmental Engineering ,Denitrification ,Nitrogen ,Tetrazolium Salts ,slow filtration columns ,010501 environmental sciences ,01 natural sciences ,Bacteria, Anaerobic ,chemistry.chemical_compound ,Rivers ,Nitrate ,microbial activities ,Dissolved organic carbon ,biogeochemical processes ,Hyporheic zone ,Biomass ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Water Science and Technology ,Civil and Structural Engineering ,Formazans ,Chemistry ,Hydrolysis ,010604 marine biology & hydrobiology ,Ecological Modeling ,Environmental engineering ,Proteins ,Sediment ,Fluoresceins ,Pollution ,Carbon ,6. Clean water ,Bacteria, Aerobic ,Oxygen ,respirations ,13. Climate action ,Environmental chemistry ,Aerobie ,Surface water ,Filtration - Abstract
Biogeochemical processes mediated by microorganisms in river sediments (hyporheic sediments) play a key role in river metabolism. Because biogeochemical reactions in the hyporheic zone are often limited to the top few decimetres of sediments below the water–sediment interface, slow filtration columns were used in the present study to quantify biogeochemical processes (uptakes of O 2 , DOC, and nitrate) and the associated microbial compartment (biomass, respiratory activity, and hydrolytic activity) at a centimetre scale in heterogeneous (gravel and sand) sediments. The results indicated that slow filtration columns recreated properly the aerobic-anaerobic gradient classically observed in the hyporheic zone. O 2 and NO 3 − consumptions (256±13 μg of O 2 per hour and 14.6±6.1 μg of N–NO 3 − per hour) measured in columns were in the range of values measured in different river sediments. Slow filtration columns also reproduced the high heterogeneity of the hyporheic zone with the presence of anaerobic pockets in sediments where denitrification and fermentation processes occurred. The respiratory and hydrolytic activities of bacteria were strongly linked with the O 2 consumption in the experimental system, highlighting the dominance of aerobic processes in our river sediments. In comparison with these activities, the bacterial biomass (protein content) integrated both aerobic and anaerobic processes and could be used as a global microbial indicator in our system. Finally, slow filtration columns are an appropriate tool to quantify in situ rates of biogeochemical processes and to determine the relationship between the microbial compartment and the physico-chemical environment in coarse river sediments.
- Published
- 2005