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Evaluation of Sources of Nitrate Beneath Food Processing Wastewater-Application Sites near Umatilla, Oregon

Scientific Investigations Report 2009-5069

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Abstract

Water samples from wells were collected beneath and downgradient of two food-processing wastewater-application sites near Umatilla, Oregon. These samples were analyzed for nitrate stable isotopes, nutrients, major ions, and age-dating constituents to determine if nitrate-stable isotopes can be used to differentiate food-processing waste from other potential sources of nitrate. Major-ion data from each site were used to determine which samples were associated with the recharge of the food-processing wastewater. End-member mixing analysis was used to determine the relative amounts of each identified end member within the samples collected from the Terrace Farm site. The delta nitrogen-15 (delta 15N) of nitrate generally ranged between +2 and +9 parts per thousand and the delta oxygen-18 (delta 18O) of nitrate generally ranged between -2 and -7 parts per thousand. None of the samples that were determined to be associated with the wastewater were different from the samples that were not affected by the wastewater. The nitrate isotope values measured in this study are also characteristic of ammonium fertilizer, animal and human waste, and soil nitrate; therefore, it was not possible to differentiate between food-processing wastewater and the other nitrate sources. Values of delta 15N and delta 18O of nitrate provided no more information about the sources of nitrate in the Umatilla River basin than did a hydrologic and geochemical understanding of the ground-water system derived from interpreting water-level and major-ion chemistry data.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Evaluation of Sources of Nitrate Beneath Food Processing Wastewater-Application Sites near Umatilla, Oregon
Series title:
Scientific Investigations Report
Series number:
2009-5069
Edition:
-
Year Published:
2009
Language:
ENGLISH
Publisher:
U.S. Geological Survey
Contributing office(s):
Washington Water Science Center
Description:
vi, 15 p.
Additional Online Files(Y/N):
Y