title: Role of surface and subsurface processes in scaling N2O emissions along riverine networks.
abstract: Riverine environments, such as streams and rivers, have been reported as sources of the potent greenhouse gas nitrous oxide ([Formula: see text]) to the atmosphere mainly via microbially mediated denitrification. Our limited understanding of the relative roles of the near-surface streambed sediment (hyporheic zone), benthic, and water column zones in controlling [Formula: see text] production precludes predictions of [Formula: see text] emissions along riverine networks. Here, we analyze [Formula: see text] emissions from streams and rivers worldwide of different sizes, morphology, land cover, biomes, and climatic conditions. We show that the primary source of [Formula: see text] emissions varies with stream and river size and shifts from the hyporheic-benthic zone in headwater streams to the benthic-water column zone in rivers. This analysis reveals that [Formula: see text] production is bounded between two [Formula: see text] emission potentials: the upper [Formula: see text] emission potential results from production within the benthic-hyporheic zone, and the lower [Formula: see text] emission potential reflects the production within the benthic-water column zone. By understanding the scaling nature of [Formula: see text] production along riverine networks, our framework facilitates predictions of riverine [Formula: see text] emissions globally using widely accessible chemical and hydromorphological datasets and thus, quantifies the effect of human activity and natural processes on [Formula: see text] production.
authors.affiliation: Center for Ecohydraulics Research, University of Idaho, Boise, ID 83702; amarzadri@uidaho.edu.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Marzadri
authors.affiliation: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Dee
authors.affiliation: Center for Ecohydraulics Research, University of Idaho, Boise, ID 83702.
authors.forename: Daniele
authors.initials: D
authors.lastname: Tonina
authors.affiliation: Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento 38123, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Bellin
authors.affiliation: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Tank
keywords: N2O; N2O emission potentials; emission scaling law; greenhouse gas; riverine networks