title: Control of nitrogen export from watersheds by headwater streams.
abstract: A comparative (15)N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen occurred in the smallest streams. Ammonium entering these streams was removed from the water within a few tens to hundreds of meters. Nitrate was also removed from stream water but traveled a distance 5 to 10 times as long, on average, as ammonium. Despite low ammonium concentration in stream water, nitrification rates were high, indicating that small streams are potentially important sources of atmospheric nitrous oxide. During seasons of high biological activity, the reaches of headwater streams typically export downstream less than half of the input of dissolved inorganic nitrogen from their watersheds.
authors: Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
authors: B J
authors: BJ
authors: Peterson
authors: W M
authors: WM
authors: Wollheim
authors: P J
authors: PJ
authors: Mulholland
authors: J R
authors: JR
authors: Webster
authors: J L
authors: JL
authors: Meyer
authors: J L
authors: JL
authors: Tank
authors: E
authors: E
authors: Marti
authors: W B
authors: WB
authors: Bowden
authors: H M
authors: HM
authors: Valett
authors: A E
authors: AE
authors: Hershey
authors: W H
authors: WH
authors: McDowell
authors: W K
authors: WK
authors: Dodds
authors: S K
authors: SK
authors: Hamilton
authors: S
authors: S
authors: Gregory
authors: D D
authors: DD
authors: Morrall
mesh_terms: D000042:Absorption; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D018441:Biofilms; D017753:Ecosystem; D056890:Eukaryota / Q000378:metabolism; D005618:Fresh Water; D005658:Fungi / Q000378:metabolism; D019015:Geologic Sediments; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D010788:Photosynthesis; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012621:Seasons; D014481:United States
chemical_list: D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen