Isotopic evidence of nitrate sources and denitrification in the Mississippi River, Illinois

Journal of Environmental Quality
By: , and 

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Abstract

Anthropogenic nitrate (NO3-) within the Mississippi-Atchafalaya River basin and discharge to the Gulf of Mexico has been linked to serious environmental problems. The sources of this NO 3- have been estimated by others using mass balance methods; however, there is considerable uncertainty in these estimates. Part of the uncertainty is the degree of denitrification that the NO3- has undergone. The isotopic composition of NO3- in the Mississippi River adjacent to Illinois and tile drain (subsurface drain) discharge in agricultural areas of east-central Illinois was examined using N and O isotopes to help identify the major sources of NO 3- and assess the degree of denitrification in the samples. The isotopic evidence suggests that most of the NO3- in the river is primarily derived from synthetic fertilizers and soil organic N, which is consistent with published estimates of N inputs to the Mississippi River. The 1:2 relationship between ??18O and ??15N also indicate that, depending on sample location and season, NO3- in the river and tile drains lias undergone significant denitrification, ranging from about 0 to 55%. The majority of the denitrification appears to have occurred before discharge into the Mississippi River. ?? ASA, CSSA, SSSA.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Isotopic evidence of nitrate sources and denitrification in the Mississippi River, Illinois
Series title Journal of Environmental Quality
DOI 10.2134/jeq2005.0012
Volume 35
Issue 2
Year Published 2006
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Journal of Environmental Quality
First page 495
Last page 504