Effects of instream processes, discharge, and land cover on nitrogen export from southern Appalachian Mountain catchments

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dc.contributor.authorWebster, Jackson R.en
dc.contributor.authorStewart, Rebecca M.en
dc.contributor.authorKnoepp, Jennifer D.en
dc.contributor.authorJackson, C. Rhetten
dc.contributor.departmentBiological Sciencesen
dc.date.accessioned2020-03-06T13:58:09Zen
dc.date.available2020-03-06T13:58:09Zen
dc.date.issued2019-01-15en
dc.description.abstractCatchments with minimal disturbance usually have low dissolved inorganic nitrogen (DIN) export, but disturbances and anthropogenic inputs result in elevated DIN concentration and export and eutrophication of downstream ecosystems. We studied streams in the southern Appalachian Mountains, USA, an area dominated by hardwood deciduous forest but with areas of valley agriculture and increasing residential development. We collected weekly grab samples and storm samples from nine small catchments and three river sites. Most discharge occurred at baseflow, with baseflow indices ranging from 69% to 95%. We identified three seasonal patterns of baseflow DIN concentration. Streams in mostly forested catchments had low DIN with bimodal peaks, and summer peaks were greater than winter peaks. Streams with more agriculture and development also had bimodal peaks; however, winter peaks were the highest. In streams draining catchments with more residential development, DIN concentration had a single peak, greatest in winter and lowest in summer. Three methods for estimating DIN export produced consistent results. Annual DIN export ranged from less than 200 g ha(-1) year(-1) for the less disturbed catchments to over 2,000 g ha(-1) year(-1) in the catchments with the least forest area. Land cover was a strong predictor of DIN concentration but less significant for predicting DIN export. The two forested reference catchments appeared supply limited, the most residential catchment appeared transport limited, and export for the other catchments was significantly related to discharge. In all streams, baseflow DIN export exceeded stormflow export. Morphological and climatological variation among watersheds created complexities unexplainable by land cover. Nevertheless, regression models developed using land cover data from the small catchments reasonably predicted concentration and export for receiving rivers. Our results illustrate the complexity of mechanisms involved in DIN export in a region with a mosaic of climate, geology, topography, soils, vegetation, and past and present land use.en
dc.description.adminPublic domain – authored by a U.S. government employeeen
dc.description.notesU.S. Forest Service; National Science Foundation, Grant/Award Number: DEB0823293en
dc.description.sponsorshipU.S. Forest ServiceUnited States Department of Agriculture (USDA)United States Forest Service; National Science FoundationNational Science Foundation (NSF) [DEB0823293]en
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1002/hyp.13325en
dc.identifier.eissn1099-1085en
dc.identifier.issn0885-6087en
dc.identifier.issue2en
dc.identifier.urihttp://hdl.handle.net/10919/97224en
dc.identifier.volume33en
dc.language.isoenen
dc.rightsCreative Commons CC0 1.0 Universal Public Domain Dedicationen
dc.rights.urihttp://creativecommons.org/publicdomain/zero/1.0/en
dc.subjectbaseflowen
dc.subjectcatchmenten
dc.subjectdischargeen
dc.subjectland coveren
dc.subjectNitrogenen
dc.subjectnonpoint sourcesen
dc.subjectstormsen
dc.subjectstream exporten
dc.titleEffects of instream processes, discharge, and land cover on nitrogen export from southern Appalachian Mountain catchmentsen
dc.title.serialHydrological Processesen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.dcmitypeStillImageen

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