Dynamics of nitrate concentration-discharge patterns in an urban watershed

Jonathan Duncan, Claire Welty, John T. Kemper, Peter M. Groffman, Lawrence E. Band

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Concentration-discharge (c-Q) relations have been used to infer watershed-scale processes governing solute fluxes. Prior studies have documented inconsistent concentration-discharge patterns at the storm-event scale driven by changes in end-member concentrations. Other studies have evaluated c-Q data from all periods in a composite fashion to quantify chemostasis (relatively invariant changes in concentration over several orders of magnitude variation in streamflow). Here we examine 3 years of high-frequency nitrate and discharge data (49,861 data points) to complement 14 years of weekly data (699 data points) for an urban stream in Baltimore, MD, U.S. to quantify c-Q relationships. We show that these relationships are variable through time and depend on the temporal scale at which they are investigated. On a storm-event scale, the sensor data exhibit a watershed-specific dQ/Q threshold when storms switch from counter-clockwise to clockwise c-Q behavior. On a seasonal scale, we show the influence of hydrologic variability and in-stream metabolism as controls on stream nitrate concentrations and fluxes. On a composite scale, we evaluate the c-Q data for chemostasis using analysis of both c-Q slopes and CVc/CVQ, as a function of time. The slopes of c-Q data for both long-term weekly and high-frequency data sets are in close agreement on an annual basis and vary between dry and wet years; the CVc/CVQ analysis is less sensitive to hydroclimate variability. This work highlights the value of both long-term and high-frequency c-Q data collection for calculating and analyzing solute fluxes.

Original languageEnglish (US)
Pages (from-to)7349-7365
Number of pages17
JournalWater Resources Research
Volume53
Issue number8
DOIs
StatePublished - Aug 1 2017

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watershed
nitrate
solute
streamflow
metabolism
sensor

All Science Journal Classification (ASJC) codes

  • Water Science and Technology

Cite this

Duncan, Jonathan ; Welty, Claire ; Kemper, John T. ; Groffman, Peter M. ; Band, Lawrence E. / Dynamics of nitrate concentration-discharge patterns in an urban watershed. In: Water Resources Research. 2017 ; Vol. 53, No. 8. pp. 7349-7365.
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Dynamics of nitrate concentration-discharge patterns in an urban watershed. / Duncan, Jonathan; Welty, Claire; Kemper, John T.; Groffman, Peter M.; Band, Lawrence E.

In: Water Resources Research, Vol. 53, No. 8, 01.08.2017, p. 7349-7365.

Research output: Contribution to journalArticle

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