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Nitrogen Removal by Streams and Rivers of the Upper Mississippi River Basin
Citation:
HILL, B. H. AND D. W. BOLGRIEN. Nitrogen Removal by Streams and Rivers of the Upper Mississippi River Basin. BIOGEOCHEMISTRY. Springer, New York, NY, 102(1-3):183-194, (2011).
Impact/Purpose:
To demonstrate the interaction of stream chemistry, stream size, and NO3-N uptake metrics across a range of stream sizes and across regional scales.
Description:
Our study, based on chemistry and channel dimensions data collected at 893 randomly-selected stream and river sites in the Mississippi River basin, demonstrated the interaction of stream chemistry, stream size, and NO3-N uptake metrics across a range of stream sizes and across regional scales. Our findings suggest that NO3-N removal from streams is equally dependent on NO3-N availability and factors that increase the contact of NO3-N rich waters with benthic sediments. This interplay of chemistry, biology, and hydrology is demonstrated by the apparent NRpct thresholds, NO3-N (> 500 mg L-1), z (>1 m), Q (> 10 m3 s-1), and A (> 10000 km2), presented by our data (Fig. 3). While many researchers have focused on the importance of headwater streams (Alexander et al. 2007; 2008; Craig et al. 2008), we found that the large rivers, due mostly to a greater width to depth ratio than smaller streams, were also significant vectors for NO3-N removal. This single factor overcame the inefficiency of NO3-N removal in larger rivers and their shorter length with the drainage network, with the net result being that large rivers are significant N sinks on the landscape.
