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Deconstructing the Effects of Flow on DOC, Nitrate, and Major Ion Interactions Using a High‐Frequency Aquatic Sensor Network
Author(s) -
Koenig L. E.,
Shattuck M. D.,
Snyder L. E.,
Potter J. D.,
McDowell W. H.
Publication year - 2017
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2017wr020739
Subject(s) - environmental science , dissolved organic carbon , streams , hydrology (agriculture) , watershed , storm , biogeochemical cycle , drainage basin , antecedent moisture , nitrate , streamflow , ecology , geology , geography , oceanography , computer network , geotechnical engineering , cartography , runoff curve number , machine learning , computer science , biology
Abstract Streams provide a physical linkage between land and downstream river networks, delivering solutes derived from multiple catchment sources. We analyzed high‐frequency time series of stream solutes to characterize the timing and magnitude of major ion, nutrient, and organic matter transport over event, seasonal, and annual timescales as well as to assess whether nitrate ( NO 3 − ) and dissolved organic carbon (DOC) transport are coupled in catchments, which would be expected if they are subject to similar biogeochemical controls throughout the watershed. Our data set includes in situ observations ofNO 3 − , fluorescent dissolved organic matter (DOC proxy), and specific conductance spanning 2–4 years in 10 streams and rivers across New Hampshire, including observations of nearly 700 individual hydrologic events. We found a positive response ofNO 3 −and DOC to flow in forested streams, but watershed development led to a negative relationship betweenNO 3 −and discharge, and thus a decoupling of the overallNO 3 −and DOC responses to flow. On event and seasonal timescales,NO 3 −and DOC consistently displayed different behaviors. For example, in several streams, FDOM yield was greatest during summer storms whileNO 3 −yield was greatest during winter storms. Most streams had generalizable stormNO 3 −and DOC responses, but differences in the timing ofNO 3 −and DOC transport suggest different catchment sources. Further, certain events, including rain‐on‐snow and summer storms following dry antecedent conditions, yielded disproportionateNO 3 −responses. High‐frequency data allow for increased understanding of the processes controlling solute variability and will help reveal their responses to changing climatic regimes.