Nitrogen Pollution in the Upper Mississippi River Basin
These sources of nutrients may potentially affect surface- and ground-water quality, so knowledge about the relative importance of each source may assist in the management of surface and ground waters within the study unit.
Croix, and Lower Missis-sippi River Basins because hay comprised a larger part of thetotal acreage of crops grown in these basins. Atmospheric deposi-tion comprised a larger percentage of the nitrogen sources in theSt. Croix River Basin compared to the other three drainage basinsprobably because amounts of the other sources are relatively low.Nitrogen and phosphorus yields in streams were greatest in theLower Mississippi River Basin and the Minnesota River Basin,where amounts of nonpoint sources of these constituents alsowere the greatest per square mile. Land use varies among these four drainage basins. The Minne-sota River Basin (MRB) consists primarily of agricultural land.Soybeans and corn are the principal crops grown, and pigs are thedominant type of livestock raised in this basin. Data obtainedfrom the state agricultural censuses.
Research and modeling indicate that agricultural land use is the primarydeterminant of nutrient loading in the UMR, followed by urban areas. Additionally, both nitrogen andphosphorus loads to the UMR are largely tied to contributions from major tributaries
Cavanaugh, Jennifer C. et al. "Nitrogen Dynamics in Sediment During Water Level Manipulation on theUpper Mississippi River." River Research and Applications, Vol. 22 (2006): 651-666.
Donner, Simon D. et al. "Modeling the impact of hydrological changes on nitrate transport in theMississippi River Basin from 1955 to 1994." Global Biogeochemical Cycles, Vol. 16, No. 3 (2002): 1-19.