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Wetland management reduces sediment and nutrient loading to the upper Mississippi River

Journal of Environmental Quality

By:
, , , , ,
DOI: 10.2134/jeq2012.0248

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Abstract

Restored riparian wetlands in the Upper Mississippi River basin have potential to remove sediment and nutrients from tributaries before they flow into the Mississippi River. For 3 yr we calculated retention efficiencies of a marsh complex, which consisted of a restored marsh and an adjacent natural marsh that were connected to Halfway Creek, a small tributary of the Mississippi. We measured sediment, N, and P removal through a mass balance budget approach, N removal through denitrification, and N and P removal through mechanical soil excavation. The marsh complex had average retention rates of approximately 30 Mg sediment ha−1 yr−1, 26 kg total N ha−1 yr−1, and 20 kg total P ha−1 yr−1. Water flowed into the restored marsh only during high-discharge events. Although the majority of retention occurred in the natural marsh, portions of the natural marsh were hydrologically disconnected at low discharge due to historical over-bank sedimentation. The natural marsh removed >60% of sediment, >10% of P, and >5% of N loads (except the first year, when it was a N source). The marsh complex was a source of NH4+ and soluble reactive P. The average denitrification rate for the marsh complex was 2.88 mg N m−2 h−1. Soil excavation removed 3600 Mg of sediment, 5.6 Mg of N, and 2.7 Mg of P from the restored marsh. The marsh complex was effective in removing sediment and nutrients from storm flows; however, retention could be increased if more water was diverted into both restored and natural marshes before entering the river.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Wetland management reduces sediment and nutrient loading to the upper Mississippi River
Series title:
Journal of Environmental Quality
DOI:
10.2134/jeq2012.0248
Volume
42
Issue:
2
Year Published:
2013
Language:
English
Publisher:
American Society of Agronomy
Publisher location:
Madison, WI
Contributing office(s):
Upper Midwest Environmental Sciences Center
Description:
11 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
573
Last page:
583
Country:
United States
Other Geospatial:
Mississippi