Nutrient Retention in Restored Streams and Rivers: A Global Review and Synthesis

Water 2016, 8(4), 116; doi:10.3390/w8040116

Author 

Tamara A. Newcomer Johnson ^1,2,* , Sujay S. Kaushal ²

, Paul M. Mayer ³

, Rose M. Smith ²

 and Gwen M. Sivirichi ⁴

¹

US Environmental Protection Agency, Coastal Management Branch, Oceans and Coastal Protection Division, Washington, DC 20460, USA

²

Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 21201, USA

³

US Environmental Protection Agency, National Health and Environmental Effects Research Lab, Western Ecology Division, Corvallis, OR 97333, USA

⁴

AKRF, Inc., Hanover, MD 21076, USA

^*

Author to whom correspondence should be addressed. 

Academic Editor: Athanasios Loukas

Received: 27 November 2015 / Revised: 6 February 2016 / Accepted: 29 February 2016 / Published: 25 March 2016

(This article belongs to the Special Issue Land Use, Climate, and Water Resources)

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Abstract 

Excess nitrogen (N) and phosphorus (P) from human activities have contributed to degradation of coastal waters globally. A growing body of work suggests that hydrologically restoring streams and rivers in agricultural and urban watersheds has potential to increase N and P retention, but rates and mechanisms have not yet been analyzed and compared across studies. We conducted a review of nutrient retention within hydrologically reconnected streams and rivers, including 79 studies. We developed a typology characterizing different forms of stream and river restoration, and we also analyzed nutrient retention across this typology. The studies we reviewed used a variety of methods to analyze nutrient cycling. We performed a further intensive meta-analysis on nutrient spiraling studies because this method was the most consistent and comparable between studies. A meta-analysis of 240 experimental additions of ammonium (NH₄⁺), nitrate (NO₃⁻), and soluble reactive phosphorus (SRP) was synthesized from 15 nutrient spiraling studies. Our results showed statistically significant relationships between nutrient uptake in restored streams and specific watershed attributes. Nitrate uptake metrics were significantly related to watershed surface area, impervious surface cover, and average reach width (p < 0.05). Ammonium uptake metrics were significantly related to discharge, velocity, and transient storage (p < 0.05). SRP uptake metrics were significantly related to watershed area, discharge, SRP concentrations, and chl a concentrations (p < 0.05). Given that most studies were conducted during baseflow, more research is necessary to characterize nutrient uptake during high flow. Furthermore, long-term studies are needed to understand changes in nutrient dynamics as projects evolve over time. Overall analysis suggests the size of the stream restoration (surface area), hydrologic connectivity, and hydrologic residence time are key drivers influencing nutrient retention at broader watershed scales and along the urban watershed continuum. View Full-Text

Keywords: stream restoration;  floodplain;  green infrastructure;  nutrient spiraling;  nutrient retention;  nitrogen;  phosphorus; denitrification;  buried stream;  sustainability;  urban evolution

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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