Using 15N, 18O, and 17O to Determine Nitrate Sources and Removal Processes from Groundwater, Tucson, Arizona

Persistent Link:
http://hdl.handle.net/10150/193327
Title:
Using 15N, 18O, and 17O to Determine Nitrate Sources and Removal Processes from Groundwater, Tucson, Arizona
Author:
Dejwakh, Navid Rene
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Nitrate is a common groundwater contaminant. Due to adverse health effects, waters above the Maximum Contaminant Level (MCL) of 10 mg NO3-N/L or 0.71 mmols/L, are banned from domestic consumption by the EPA. Studies have measured elevated nitrate concentrations in arid land soils and groundwater around the world. These elevated concentrations could be detrimental to the environment and to human health. Thus, it is important to consider the different sources and processes affecting nitrate concentrations Here, a novel triple isotope system approach was employed, coupling δ17O with δ18O and δ15N of nitrate to determine the sources (atmospheric, terrestrial, fertilizer, wastewater) and removal processes influencing nitrate concentrations in the Tucson basin groundwater system. Results show low groundwater nitrate concentrations (0.2 mmols/L) where wastewater was not a predominant source of water, versus high concentrations (1 mmols/L) above the MCL in groundwaters where wastewater was the dominant water source. Furthermore, groundwater up to 1.6 Km away from the wastewater stream was contaminated with effluent recharge waters. In addition, denitrification was inferred from δ18O and δ15N data with this inference reinforced by δ17O data and δ15N enrichments up to 26. Finally, low atmospheric nitrate was measured in groundwater, representing up to 6% of total nitrate. The triple isotope approach studied here is ideal for determining the proportion of atmospheric nitrate versus other terrestrial nitrate sources and the significance of nitrate removal processes.
Type:
text; Electronic Thesis
Keywords:
Nitrate; Groundwater; Oxygen-17; Wastewater; Atmospheric; Isotopes
Degree Name:
MS
Degree Level:
masters
Degree Program:
Hydrology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Meixner, Thomas
Committee Chair:
Meixner, Thomas

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleUsing 15N, 18O, and 17O to Determine Nitrate Sources and Removal Processes from Groundwater, Tucson, Arizonaen_US
dc.creatorDejwakh, Navid Reneen_US
dc.contributor.authorDejwakh, Navid Reneen_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractNitrate is a common groundwater contaminant. Due to adverse health effects, waters above the Maximum Contaminant Level (MCL) of 10 mg NO3-N/L or 0.71 mmols/L, are banned from domestic consumption by the EPA. Studies have measured elevated nitrate concentrations in arid land soils and groundwater around the world. These elevated concentrations could be detrimental to the environment and to human health. Thus, it is important to consider the different sources and processes affecting nitrate concentrations Here, a novel triple isotope system approach was employed, coupling δ17O with δ18O and δ15N of nitrate to determine the sources (atmospheric, terrestrial, fertilizer, wastewater) and removal processes influencing nitrate concentrations in the Tucson basin groundwater system. Results show low groundwater nitrate concentrations (0.2 mmols/L) where wastewater was not a predominant source of water, versus high concentrations (1 mmols/L) above the MCL in groundwaters where wastewater was the dominant water source. Furthermore, groundwater up to 1.6 Km away from the wastewater stream was contaminated with effluent recharge waters. In addition, denitrification was inferred from δ18O and δ15N data with this inference reinforced by δ17O data and δ15N enrichments up to 26. Finally, low atmospheric nitrate was measured in groundwater, representing up to 6% of total nitrate. The triple isotope approach studied here is ideal for determining the proportion of atmospheric nitrate versus other terrestrial nitrate sources and the significance of nitrate removal processes.en_US
dc.typetexten_US
dc.typeElectronic Thesisen_US
dc.subjectNitrateen_US
dc.subjectGroundwateren_US
dc.subjectOxygen-17en_US
dc.subjectWastewateren_US
dc.subjectAtmosphericen_US
dc.subjectIsotopesen_US
thesis.degree.nameMSen_US
thesis.degree.levelmastersen_US
thesis.degree.disciplineHydrologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMeixner, Thomasen_US
dc.contributor.chairMeixner, Thomasen_US
dc.identifier.proquest2926en_US
dc.identifier.oclc659749573en_US
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