Low transient storage and uptake efficiencies in seven agricultural streams: implications for nutrient demand

Journal of Environmental Quality
By: , and 

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Abstract

We used mass load budgets, transient storage modeling, and nutrient spiraling metrics to characterize nitrate (NO3), ammonium (NH4+), and inorganic phosphorus (SRP) demand in seven agricultural streams across the United States and to identify in-stream services that may control these conditions. Retention of one or all nutrients was observed in all but one stream, but demand for all nutrients was low relative to the mass in transport. Transient storage metrics (As/A, Fmed200, Tstr, and qs) correlated with NO3 retention but not NH4+ or SRP retention, suggesting in-stream services associated with transient storage and stream water residence time could influence reach-scale NO3 demand. However, because the fraction of median reach-scale travel time due to transient storage (Fmed200) was ≤1.2% across the sites, only a relatively small demand for NO3 could be generated by transient storage. In contrast, net uptake of nutrients from the water column calculated from nutrient spiraling metrics were not significant at any site because uptake lengths calculated from background nutrient concentrations were statistically insignificant and therefore much longer than the study reaches. These results suggest that low transient storage coupled with high surface water NO3 inputs have resulted in uptake efficiencies that are not sufficient to offset groundwater inputs of N. Nutrient retention has been linked to physical and hydrogeologic elements that drive flow through transient storage areas where residence time and biotic contact are maximized; however, our findings indicate that similar mechanisms are unable to generate a significant nutrient demand in these streams relative to the loads.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Low transient storage and uptake efficiencies in seven agricultural streams: implications for nutrient demand
Series title Journal of Environmental Quality
DOI 10.2134/jeq2014.01.0034
Volume 43
Issue 6
Year Published 2014
Language English
Publisher American Society of Agronomy, Crop Science Society of America, Soil Science Society of America
Contributing office(s) Washington Water Science Center
Description 11 p.
First page 1980
Last page 1990
Online Only (Y/N) N
Additional Online Files (Y/N) N
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