A spatial analysis of phosphorus in the Mississippi river basin

J Environ Qual. May-Jun 2011;40(3):931-41. doi: 10.2134/jeq2010.0386.

Abstract

Phosphorus (P) in rivers in the Mississippi River basin (MRB) contributes to hypoxia in the Gulf of Mexico and impairs local water quality. We analyzed the spatial pattern of P in the MRB to determine the counties with the greatest January to June P riverine yields and the most critical factors related to this P loss. Using a database of P inputs and landscape characteristics from 1997 through 2006 for each county in the MRB, we created regression models relating riverine total P (TP), dissolved reactive P (DRP), and particulate P (PP) yields for watersheds within the MRB to these factors. Riverine yields of P were estimated from the average concentration of each form of P during January to June for the 10-yr period, multiplied by the average daily flow, and then summed for the 6-mo period. The fraction of land planted in crops, human consumption of P, and precipitation were found to best predict TP yields with a spatial error regression model ( = 0.48, = 101). Dissolved reactive P yields were predicted by fertilizer P inputs, human consumption of P, and precipitation in a multiple regression model ( = 0.42, = 73), whereas PP yields were explained by crop fraction, human consumption of P, and soil bulk density in a spatial error regression model ( = 0.49, = 61). Overall, the Upper Midwest's Cornbelt region and lower Mississippi basin had the counties with the greatest P yields. These results help to point out specific areas where agricultural conservation practices that reduce losses to streams and rivers and point source P removal might limit the intensity or spatial occurrence of Gulf of Mexico hypoxia and improve local water quality.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Agriculture*
  • Conservation of Natural Resources
  • Environmental Monitoring
  • Fertilizers
  • Human Activities
  • Humans
  • Models, Theoretical
  • Phosphorus / analysis*
  • Rain
  • Rivers
  • Soil
  • United States
  • Water Movements*
  • Water Pollutants, Chemical / analysis*

Substances

  • Fertilizers
  • Soil
  • Water Pollutants, Chemical
  • Phosphorus