title: Bacterial production and their role in the removal of dissolved organic matter from tributaries of drinking water reservoirs.
abstract: Enhanced concentrations of dissolved organic matter (DOM) in freshwaters are an increasing problem in drinking water reservoirs. In this study we investigated bacterial DOM degradation rates in the tributaries of the reservoirs and tested the hypotheses that (1) DOM degradation is high enough to decrease DOM loads to reservoirs considerably, (2) DOM degradation is affected by stream hydrology, and (3) phosphorus addition may stimulate bacterial DOM degradation. Bacterial biomass production, which was used as a measure of DOM degradation, was highest in summer, and was usually lower at upstream than at downstream sites. An important proportion of bacterial production was realized in epilithic biofilms. Production of planktonic and biofilm bacteria was related to water temperature. Planktonic production weakly correlated to DOM quality and to total phosphorus concentration. Addition of soluble reactive phosphorus did not stimulate bacterial DOM degradation. Overall, DOM was considerably degraded in summer at low discharge levels, whereas degradation was negligible during flood events (when DOM load in reservoirs was high). The ratio of DOM degradation to total DOM release was negatively related to discharge. On annual average, only 0.6-12% of total DOM released by the catchments was degraded within the tributaries.
authors.affiliation: Helmholtz-Centre for Environmental Research UFZ, Dept. River Ecology, Brückstraße 3a, D-39114 Magdeburg, Germany; Helmholtz-Centre for Environmental Research UFZ, Dept. Lake Research, Brückstraße 3a, D-39114 Magdeburg, Germany. Electronic address: norbert.kamjunke@ufz.de.
authors.forename: Norbert
authors.initials: N
authors.lastname: Kamjunke
authors.affiliation: Helmholtz-Centre for Environmental Research UFZ, Dept. Hydrogeology, Permoserstr. 15, D-04318 Leipzig, Germany.
authors.forename: Marieke R
authors.initials: MR
authors.lastname: Oosterwoud
authors.affiliation: Helmholtz-Centre for Environmental Research UFZ, Dept. Lake Research, Brückstraße 3a, D-39114 Magdeburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Herzsprung
authors.affiliation: Helmholtz-Centre for Environmental Research UFZ, Dept. Lake Research, Brückstraße 3a, D-39114 Magdeburg, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Tittel
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D018441:Biofilms; D018533:Biomass; D060766:Drinking Water; D005618:Fresh Water / Q000382:microbiology; D006812:Humic Substances / Q000032:analysis; D010758:Phosphorus / Q000378:metabolism; D010933:Plankton / Q000378:metabolism; D012621:Seasons; D014873:Water Pollutants / Q000032:analysis / Q000378:metabolism*; D014881:Water Supply
chemical_list: D060766:Drinking Water; D006812:Humic Substances; D014873:Water Pollutants; D010758:Phosphorus
keywords: Bacterial production; DOC; Freshness index; Humification index; Phosphorus