Journal article
Nitrate transport and supply limitations quantified using high frequency stream monitoring and turning point analysis
Journal of hydrology (Amsterdam), Vol.549, pp.581-591
06/2017
DOI: 10.1016/j.jhydrol.2017.04.041
Abstract
Agricultural landscapes often leak inorganic nitrogen to the stream network, usually in the form of nitrate-nitrite (NO (sub x) -N), degrading downstream water quality on both the local and regional scales. While the spatial distribution of nitrate sources has been delineated in many watersheds, less is known about the complicated temporal dynamics that drive stream NO (sub x) -N because traditional methods of stream grab sampling are often conducted at a low frequency. Deployment of accurate real-time, continuous measurement devices that have been developed in recent years enables high-frequency sampling that provides detailed information on the concentration-discharge relation and the timing of NO (sub x) -N delivery to streams. We aggregated 15-min interval NO (sub x) -N and discharge data over a nine-year period into daily averages and then used robust statistical methods to identify how the discharge regime within an artificially-drained agricultural watershed reflected catchment hydrology and NO (sub x) -N delivery pathways. We then quantified how transport and supply limitations varied from year-to-year and how dependence of these limitations varied with climate, especially drought. Our results show NO (sub x) -N concentrations increased linearly with discharge up to an average "turning point" of 1.42 mm of area-normalized discharge, after which concentrations decline with increasing discharge. We estimate transport and supply limitations to govern 57 and 43 percent, respectively, of the NO (sub x) -N flux over the nine-year period. Drought effects on the NO (sub x) -N flux linger for multiple years and this is reflected in a greater tendency toward supply limitations in the three years following drought. How the turning point varies with climate may aid in prediction of NO (sub x) -N loading in future climate regimes.
Details
- Title: Subtitle
- Nitrate transport and supply limitations quantified using high frequency stream monitoring and turning point analysis
- Creators
- Christopher S. Jones - University of IowaBo Wang - University of IowaKeith E. Schilling - Iowa Geological Survey, 334 Trowbridge Hall, Iowa City, IA 52242, United StatesKung-sik Chan - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of hydrology (Amsterdam), Vol.549, pp.581-591
- Publisher
- Elsevier
- DOI
- 10.1016/j.jhydrol.2017.04.041
- ISSN
- 0022-1694
- eISSN
- 1879-2707
- Language
- English
- Date published
- 06/2017
- Academic Unit
- Statistics and Actuarial Science; Radiology; Earth and Environmental Sciences; IIHR--Hydroscience and Engineering
- Record Identifier
- 9984257611302771
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