title: Hydrologic Controls on Nitrogen Cycling Processes and Functional Gene Abundance in Sediments of a Groundwater Flow-Through Lake.
abstract: The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.
authors.affiliation: U.S. Geological Survey , Menlo Park, California, 94025 United States.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Stoliker
authors.affiliation: U.S. Geological Survey , Boulder, Colorado, 80303 United States.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Repert
authors.affiliation: U.S. Geological Survey , Boulder, Colorado, 80303 United States.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Smith
authors.affiliation: Virginia Institute of Marine Science , Gloucester Point, Virginia, 23062 United States.
authors.forename: Bongkeun
authors.initials: B
authors.lastname: Song
authors.affiliation: U.S. Geological Survey , Northborough, Massachusetts, 01532 United States.
authors.forename: Denis R
authors.initials: DR
authors.lastname: LeBlanc
authors.affiliation: U.S. Geological Survey , Northborough, Massachusetts, 01532 United States.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: McCobb
authors.affiliation: U.S. Geological Survey , Menlo Park, California, 94025 United States.
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Conaway
authors.affiliation: Korea Institute of Geoscience and Mineral Resources , Daejeon, 34132 Republic of Korea.
authors.forename: Sung Pil
authors.initials: SP
authors.lastname: Hyun
authors.affiliation: Korea Institute of Geoscience and Mineral Resources , Daejeon, 34132 Republic of Korea.
authors.forename: Dong-Chan
authors.initials: DC
authors.lastname: Koh
authors.affiliation: Korea Institute of Geoscience and Mineral Resources , Daejeon, 34132 Republic of Korea.
authors.forename: Hee Sun
authors.initials: HS
authors.lastname: Moon
authors.affiliation: U.S. Geological Survey , Menlo Park, California, 94025 United States.
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Kent
mesh_terms: D058440:Denitrification; D019015:Geologic Sediments / Q000382:microbiology*; D060587:Groundwater; D062070:Hydrology / Q000379:methods; D060106:Lakes / Q000737:chemistry; D008404:Massachusetts; D059013:Microbial Consortia / Q000235:genetics*; D058465:Nitrification; D058458:Nitrogen Cycle