Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1994. / Includes bibliographical references (leaves 133-135).

The stable isotopes of the conservative element boron, 11B and 1°B, have been employed as co- migrating isotopic tracers to determine the origin of nitrate observed in groundwater from a large capacity (2500 gpm) irrigation well in the Avra Valley of southeastern Arizona. The isotopic ratios of the conservative element, boron, provided an identifying signature for various nitrate rich source waters. Additional chemical parameters were also examined to corroborate the isotopic indications. Findings of this investigation indicate that most of the nitrate observed in groundwater from well CMID 18 at the beginning of the 1993 irrigation season was due to municipal wastewater contamination. As the irrigation season progressed, an increasing proportion of nitrate was contributed by irrigation return flow from neighboring agricultural fields.

Thesis (M. S. - Geosciences)--University of Arizona, 1992. / Some pages are not numbered. Includes bibliographical references (leaves 36-37).

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Thesis (M.S. - Soil, Water and Environmental Sciences)--University of Arizona. / Includes bibliographical references (leaves 107-111)