The effects of mineral reactions on trace metal characteristics of groundwater in desert basins of southern Arizona

Persistent Link:
http://hdl.handle.net/10150/191127
Title:
The effects of mineral reactions on trace metal characteristics of groundwater in desert basins of southern Arizona
Author:
Marozas, Dianne Catherine
Issue Date:
1987
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:
The geochemistry, of groundwater collected from deep wells in the western section of the lower Santa Cruz basin of southeastern Arizona, was studied in order to determine the extent to which geochemica] analysis can be used to assess fluid flow and major and trace element migration patterns along hydrologic flowpaths in desert basins. Interaction between groundwater and enclosing sediments, and mixing between chemically distinct basin groundwater is found to exert a significant control on the chemical patterns that have evolved in the system. Activity-activity diagrams of the Na-Si-O-H system show that groundwater throughout the basin clusters near the three phase boundary between fluid, kaolinite, and montmorillonite and trends along the boundary to higher log (aNa⁺/aH⁺) values. A reaction model generated with computer program PHREEQE, that combines silicate weathering, kaolinite-Na-beidellite equilibrium, calcite equilibrium, and solution mixing, can simulate trends in groundwater composition along flowpaths in the basin. Trace metals introduced into the basin by the weathering of a buried porphyry copper deposit become spatially separated upon migration. Metal concentrations are found to be correlated to major cation concentrations. Cu is associated with high Na concentrations and a high ratio of Carbonate:Ca, whereas Zn is associated with high Ca concentration and a low ratio of Carbonate:Ca. Behavior of Cu and Zn during low-temperature transport can be controlled by the effects of mineral alteration on groundwater composition. Computer analysis of early basin diagenesis shows that changes in major solute composition that accompany weathering, constrained by equilibrium with clays and calcite, can produce the metal segregation pattern observed in the basin. Because the aquifer is strongly influenced by silicate and carbonate mineral equilibrium, the introduction of Central Arizona Project recharge, which is not in equilibrium with alluvial minerals, into the basin, requires a response by mineral reactions that attempt to restore the system to a state of equilibrium with kaolinite, montmorillonite, and calcite. A reaction model is developed to predict the consequent effects of outside recharge on groundwater quality.
Type:
Dissertation-Reproduction (electronic); text
Keywords:
Hydrology.; Groundwater -- Quality -- Arizona -- Pinal County.; Trace elements in water -- Arizona -- Pinal County.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Titley, Spencer R.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleThe effects of mineral reactions on trace metal characteristics of groundwater in desert basins of southern Arizonaen_US
dc.creatorMarozas, Dianne Catherineen_US
dc.contributor.authorMarozas, Dianne Catherineen_US
dc.date.issued1987en_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.abstractThe geochemistry, of groundwater collected from deep wells in the western section of the lower Santa Cruz basin of southeastern Arizona, was studied in order to determine the extent to which geochemica] analysis can be used to assess fluid flow and major and trace element migration patterns along hydrologic flowpaths in desert basins. Interaction between groundwater and enclosing sediments, and mixing between chemically distinct basin groundwater is found to exert a significant control on the chemical patterns that have evolved in the system. Activity-activity diagrams of the Na-Si-O-H system show that groundwater throughout the basin clusters near the three phase boundary between fluid, kaolinite, and montmorillonite and trends along the boundary to higher log (aNa⁺/aH⁺) values. A reaction model generated with computer program PHREEQE, that combines silicate weathering, kaolinite-Na-beidellite equilibrium, calcite equilibrium, and solution mixing, can simulate trends in groundwater composition along flowpaths in the basin. Trace metals introduced into the basin by the weathering of a buried porphyry copper deposit become spatially separated upon migration. Metal concentrations are found to be correlated to major cation concentrations. Cu is associated with high Na concentrations and a high ratio of Carbonate:Ca, whereas Zn is associated with high Ca concentration and a low ratio of Carbonate:Ca. Behavior of Cu and Zn during low-temperature transport can be controlled by the effects of mineral alteration on groundwater composition. Computer analysis of early basin diagenesis shows that changes in major solute composition that accompany weathering, constrained by equilibrium with clays and calcite, can produce the metal segregation pattern observed in the basin. Because the aquifer is strongly influenced by silicate and carbonate mineral equilibrium, the introduction of Central Arizona Project recharge, which is not in equilibrium with alluvial minerals, into the basin, requires a response by mineral reactions that attempt to restore the system to a state of equilibrium with kaolinite, montmorillonite, and calcite. A reaction model is developed to predict the consequent effects of outside recharge on groundwater quality.en_US
dc.description.notehydrology collectionen_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.typetexten_US
dc.subjectHydrology.en_US
dc.subjectGroundwater -- Quality -- Arizona -- Pinal County.en_US
dc.subjectTrace elements in water -- Arizona -- Pinal County.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairTitley, Spencer R.en_US
dc.contributor.committeememberNorton, Denisen_US
dc.contributor.committeememberLong, Austinen_US
dc.contributor.committeememberSchreiber, Joseph, Jr.en_US
dc.contributor.committeememberAnthony, John W.en_US
dc.identifier.oclc213339944en_US
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