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Sediment Source Assessment in a Lowland Watershed Using Nitrogen Stable Isotopes 1
Author(s) -
Fox James F.,
Davis Charles M.,
Martin Darren K.
Publication year - 2010
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.2010.00485.x
Subject(s) - sediment , watershed , hydrology (agriculture) , environmental science , stable isotope ratio , deposition (geology) , streams , isotopes of nitrogen , nitrogen , provenance , sedimentary budget , biogeochemical cycle , isotope analysis , geology , sediment transport , environmental chemistry , oceanography , geochemistry , chemistry , geomorphology , computer network , physics , geotechnical engineering , organic chemistry , quantum mechanics , machine learning , computer science
Fox, James F., Charles M. Davis, and Darren K. Martin, 2010. Sediment Source Assessment in a Lowland Watershed Using Nitrogen Stable Isotopes. Journal of the American Water Resources Association (JAWRA) 46(6):1192–1204. DOI: 10.1111/j.1752‐1688.2010.00485.x Abstract: Sediment sources and transported sediments were sampled in a lowland watershed with pronounced fine sediment storage in the streambed. Sediments were analyzed for carbon and nitrogen content and stable nitrogen isotopic composition. Analysis of the data shows that temporarily stored streambed sediments dominate the sediment load during moderate‐ and low‐flow hydrologic events. Modeling of sediment transport and nitrogen elemental and isotopic mass balance was performed for the watershed for a 12‐month time period using a continuous, conceptual‐based model. The model results show that during moderate‐ and low‐flow hydrologic events, the streambed is slowly downcutting. During very high‐flow hydrologic events, deposition is pronounced in the streambed and sediment is replenished to the bed. Nitrogen model results show that elemental and isotopic nitrogen of streambed sediments vary substantially over the simulation period. In this manner, the streambed in a lowland watershed functions as a temporary storage zone that, in turn, can impact the nitrogen elemental and isotopic signature of sediments. The variation could significantly impact estimates of sediment provenance using nitrogen tracer‐based methods. Future work should consider both hydrologic and biogeochemical control on the nitrogen isotopic signature of sediments in small lowland watersheds and streams where a significant portion of deposited fines are temporarily stored.