title: Nitrogen retention in headwater streams: the influence of groundwater-surface water exchange.
abstract: Groundwater-surface water (GW-SW) interaction lengthens hydraulic residence times, increases contact between solutes and biologically active surfaces, and often creates a gradient of redox conditions conducive to an array of biogeochemical processes. As such, the interaction of hydraulic patterns and biogeochemical activity is suspected to be an important determinant of elemental spiraling in streams. Hydrologic interactions may be particularly important in headwater streams, where the extent of the GW-SW mixing environment (i.e., hyporheic zone) is proportionately greater than in larger streams. From our current understanding of stream ecosystem function, we discuss nitrogen (N) spiraling, present a conceptual model of N retention in streams, and use both of these issues to generate specific research questions and testable hypotheses regarding N dynamics in streams.
authors.affiliation: Department of Biology, Virginia Polytechnic Institute, Blacksburg 24060, USA. sathomas@vt.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Thomas
authors.forename: H M
authors.initials: HM
authors.lastname: Valett
authors.forename: P J
authors.initials: PJ
authors.lastname: Mulholland
authors.forename: C S
authors.initials: CS
authors.lastname: Fellows
authors.forename: J R
authors.initials: JR
authors.lastname: Webster
authors.forename: C N
authors.initials: CN
authors.lastname: Dahm
authors.forename: C G
authors.initials: CG
authors.lastname: Peterson
mesh_terms: D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry*; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis* / Q000378:metabolism; D009586:Nitrogen Fixation; D009656:North America; D010084:Oxidation-Reduction; D045483:Rivers / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D014197:Trees
chemical_list: D012997:Solvents; D009584:Nitrogen