Biogeochemistry of Carbon and Nitrogen in Aquatic Environments

Research Topics Index                                                                               Project Home

Fate of Nitrogen During Transport Through Agriculturally Impacted Rivers

Field Sites:  Iroquois River and Sugar Creek, Indiana and Illinois 

Photograph of Iroquois River in flood, near Foresman, IN, May 2000.

Iroquois River near Foresman, IN., May 2000.

Photograph looking upstream along Sugar Creek, Benton County, IN, 17 June 2002.

Sugar Creek, Benton County, IN., 17 June 2002.



      Ronald Antweiler, USGS, Boulder, Colo.

      J.K. Böhlke, USGS, Reston, Va.

      Mary A. Voytek, USGS, Reston, Va.

      Judson W. Harvey, USGS, Reston, Va.

      Lesley Smith, University of Colorado, Boulder, Colo.

      Andy Laursen, Notre Dame University,  South Bend, Ind.

Field Assistance:

Upper Illinois NAWQA Project, USGS Illinois District Office

    George Groschen, Project Chief

    Dave Dupre

    Kevin Richards

Project Summary

      Nitrogen contamination of surface waters is an undesirable side effect and a key concern for many agricultural practices in the U.S.  Although transport of nitrogen by the Mississippi River has been suggested to be a contributing factor in the development of a hypoxic zone in the Gulf of Mexico, little is actually known about the net effect of in-stream processes on nitrogen transport in small and medium sized rivers.  The goal of this project is to conduct a detailed, multidisciplinary investigation of denitrification and nitrification in two agriculturally impacted rivers.  The rivers differ in size, flow, and bed sediment characteristics.  The project is designed to conduct Lagrangian (time of travel) sampling to determine the overall effect of denitrification and nitrification on riverine nitrogen loads, nitrogen speciation, nitrogen isotope geochemistry, and trace constituent concentrations.  This approach requires careful characterization of stream hydrology; depth and width integrated discharge, flow, and tributary inputs.  In-stream tracer studies will be used to quantify the extent of hyporheic exchange.  Additionally, nitrification and denitrification will be measured directly using a variety of techniques.  These will include incubation techniques with stream-bed cores using 15N, quantification of within stream nitrogen/argon ratios, and molecular probe characterization of the microbial populations responsible for each activity.  The information obtained from this study will provide one of the first comprehensive examinations of nitrification and denitrification in streams, from the perspective of nitrogen loads, and should facilitate evaluation of the role of these processes in mediating or mitigating transport of nitrogen (regardless of source) to coastal receiving waters.  The results should also greatly improve the reliability of regional transport models that simulate nitrogen discharge in streams and rivers draining agricultural areas.  

Map illustrating the locations of Sugar Creek and Iroquois River in Indiana and Illinois.

Index map of Iroquois River drainage astride Indiana-Illinois border.  

Circles on stream courses are sampling points examined in our study.

Funding Sources

U.S. Dept. of Agriculture, NRICG Program

USGS NRP - Hypoxia Program 


Upper Illinois River Basin NAWQA

USGS Stream gauging stations:  

     Iroquois River 

     Sugar Creek 

USGS Fact sheet: Nitrogen in the Mississippi River Basin - click here

Indiana Real-Time Stream Flow Data- click here.

NOAA Hypoxia Assesment page

Photograph of Sugar Creek, Benton County, IN, June 2003.
Projects Index                                                                     Top of Page 
Return to Biogeochemistry of Carbon and Nitrogen in Aquatic Environments Home Page

USGS Home Page  |  USGS Water Resources  |  USGS Toxics Hydrology Program  |  USGS NRP | 

USGS Search  |  USGS Privacy Policy  |  USGS Disclaimer |