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dc.contributor.authorWells, Naomi
dc.contributor.authorEyre, B
dc.date.accessioned2021-11-03T22:50:40Z
dc.date.available2021-05-21
dc.date.issued2021-08-01
dc.date.submitted2021-05-13
dc.identifierhttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000667771200007&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=42fe17854fe8be72a22db98beb5d2208
dc.identifier.issn0016-7037
dc.identifier.otherTB2IX (isidoc)
dc.identifier.urihttps://hdl.handle.net/10182/14359
dc.description.abstractStreams play a critical role in attenuating the excess reactive nitrogen (N) generated from human activities. Consequently, streams can also emit significant amounts of the potent greenhouse gas N₂O. Models and manipulative experiments now suggest that hydrology regulates the balance between N removal and N₂O production, but validating this hypothesis under field conditions has been difficult. We aimed to redress this knowledge gap by measuring changes in the concentration and isotopic composition of NO₃¯ (δ¹⁸O-NO₃¯, δ¹⁵N-NO₃¯) and N₂O (δ¹⁸O-N₂O, δ¹⁵N-N₂O, ¹⁵N-N₂O site preference) in the sediments and surface water of a 30 m stream reach as discharge dropped from 2.7 to 1.8 m3 s−1. Over the eight-day measurement period the changes in conductivity, δ¹⁸O-H₂O, and ²²²Rn indicated that hyporheic mixing decreased and net groundwater inputs increased as discharge declined. This coincided with increases in surface water NO₃¯ (1–3 mg N 1¯¹) and N₂O (700–1000% saturation) that were beyond what could be explained by increased groundwater N inputs. Instead, both N₂O and NO₃¯ isotopic composition indicated that concentration increases were caused by increasing within-stream production (nitrification), rather than decreased reduction (denitrification), as hyporheic exchange decreased. This highlights the importance of oxidising processes in regulating N cycling even under strongly heterotrophic conditions (productivity/respiration: 0.005–0.2). Together these findings provide a first empirical confirmation that relatively short term (daily-weekly) stream flow dynamics directly regulate biological cycling of both NO₃¯ and N₂O.
dc.format.extentpp.124-142
dc.languageen
dc.language.isoen
dc.publisherElsevier
dc.relationThe original publication is available from Elsevier - https://doi.org/10.1016/j.gca.2021.05.026
dc.relation.urihttps://doi.org/10.1016/j.gca.2021.05.026
dc.rights© 2021 Elsevier Ltd. All rights reserved.
dc.subjectstable isotopes
dc.subjectisotopomers
dc.subjecthyporheic zone
dc.subjectsurface water-groundwater interactions
dc.subjecttidal river
dc.subjectsub-tropics
dc.subjectnitrous oxide emission
dc.subjectnitrification
dc.titleFlow regulates biological NO₃¯ and N₂O production in a turbid sub-tropical stream
dc.typeJournal Article
lu.contributor.unitLincoln University
lu.contributor.unitFaculty of Agriculture and Life Sciences
lu.contributor.unitDepartment of Soil and Physical Sciences
dc.identifier.doi10.1016/j.gca.2021.05.026
dc.relation.isPartOfGeochimica et Cosmochimica Acta
pubs.organisational-group|LU
pubs.organisational-group|LU|Agriculture and Life Sciences
pubs.organisational-group|LU|Agriculture and Life Sciences|SOILS
pubs.publication-statusPublished
pubs.volume306
dc.identifier.eissn1872-9533
lu.identifier.orcid0000-0001-9914-5418


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