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A Synoptic Survey of Nitrogen and Phosphorus in Tributary Streams and Great Rivers of the Upper Mississippi River Basin
Citation:
HILL, B. H., D. W. BOLGRIEN, T. M. JICHA, T. R. ANGRADI, AND A. T. HERLIHY. A Synoptic Survey of Nitrogen and Phosphorus in Tributary Streams and Great Rivers of the Upper Mississippi River Basin. WATER, AIR, AND SOIL POLLUTION. Springer, New York, NY, 216(1-4):605-619, (2011).
Impact/Purpose:
Our study empirically links catchment land use and stream chemistry, and demonstrates using monitoring data for estimating nutrient yields at a large regional scale.
Description:
We combined stream chemistry and hydrology data from surveys of 467 tributary stream sites and 447 great river sites in the Upper Mississippi River basin to provide a regional snapshot of baseflow total nitrogen (TN) and total phosphorus (TP) concentrations, and to investigate the relationships between land use and stream chemistry. Catchments in the Mississippi River sub-basin had more land in agricultural uses (51%) than the Missouri or Ohio River sub-basin catchments (25% and 29%, respectively). The difference in agriculture is reflected in the TN concentrations in tributary streams and the great rivers: 5431 and 2112 mg L-1 for the Upper Mississippi; 1751 and 978 mg L-1 for the Missouri; 1074 and 1152 mg L-1 for the Ohio. This agricultural effect was not as evident for tributary stream or great river TP concentrations: 165 and 181 mg L-1 in the Upper Mississippi; 177 and 171 mg L?? in the Missouri; 67 and 53 mg L-1 in the Ohio. We set reference thresholds based on the 75th percentile TN and TP concentrations at our least disturbed sites. The TN threshold was exceeded for 50-63% of the tributary stream and 16-55% of great river lengths, with the greatest proportion in the Mississippi River sub-basin. The TP threshold was exceeded in 32-48% of tributary stream and 12-41% of lengths. Tributary stream N:P ranged from 67:1 (Ohio) to 210:1 (Mississippi); river N:P ranged from 20:1 (Missouri) to 60:1 (Ohio). N:P indicated that N-limitation occurred in 10-21% of total tributary stream length and in 0-46% of great river length; P-limitation ranged from 60-83% of cumulative tributary stream length and from 21-98% of cumulative great river length. Total N flux (concentration x discharge) was highest in the Mississippi sub-basin; TP flux was lowest in the Ohio sub-basin. River TN yield and TP yields for both tributary streams and great rivers were not significantly different between the sub-basins. Our study empirically links catchment land use and stream chemistry, and demonstrates using monitoring data for estimating nutrient yields at a large regional scale.
URLs/Downloads:
A Synoptic Survey of Nitrogen and Phosphorus in Tributary Streams and Great Rivers of the Upper Mississippi River Basin