Anomalous concentrations of silica in ground water of the eastern San Joaquin Valley, California.

Persistent Link:
http://hdl.handle.net/10150/191167
Title:
Anomalous concentrations of silica in ground water of the eastern San Joaquin Valley, California.
Author:
Cehrs, David, 1948-
Issue Date:
1991
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:
Anomalous concentrations of silica in ground water of the eastern San Joaquin Valley originate from several diverse sources and are subsequently modified by recharge or diagenesis. Statistics, geochemical models, and column studies identified potential sources of silica in ground water and those parameters most important in influencing its distribution. Principal components analysis indicated inverse time and potassium as the parameters which best relate to silica. Inverse time relates to ground-water recharge while potassium relates to either the rhyolitic Friant Pumice, the hardpans of the eastern San Joaquin Valley, or diagenetic losses. A lumped parameter model suggests that recharge is responsible for the drop in silica concentrations beneath Fresno since 1971. The Madera County model indicates higher silica concentrations associated with the Friant Pumice, older geologic units with hardpans, finer grained sediments, and areas of ground-water discharge. Lower silica concentrations are associated with unweathered sediments, areas receiving recharge, and areas underlain by the Corcoran Clay. Column leaching studies produced silica concentrations from the Friant Pumice of up to 90 mg/1, Turlock Lake and Riverbank Formation hardpans from 40-50 mg/1, and younger Modesto Formation sediments from 10-40 mg/l. Spatially, volcanogenic sediments impart the highest silica concentrations to the ground water, 70-95 mg/1, and occur along the eastern margin of the valley, north of the San Joaquin River, or in San Joaquin River fluvial deposits. Iron-silica hardpans, found at various depths along the east side of the valley, are associated with silica concentrations of 40-70 mg/l. The typical arkosic sediments of the eastern valley have silica concentrations of 20-40 mg/l. Silica concentrations in ground water are modified by recharge and diagenetic processes. Either natural or artificial recharge having 4-16 mg/1 silica may lower ambient silica concentrations in ground water. Recharge occurs beneath some rivers and in transmissive paleochannel deposits; artificial sources include agricultural overirrigation and basin recharge. The down-gradient loss of silica to the sedimentary column, more prevalent at depth, apparently is by the sorption of silica on clays, the formation of clays, or deposition of amorphous silica.
Type:
Dissertation-Reproduction (electronic); text
Keywords:
Hydrology.; Silica -- California.; Groundwater -- Management.
Degree Name:
Ph. D.
Degree Level:
doctoral
Degree Program:
Hydrology and Water Resources; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Davis, Stanley N.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleAnomalous concentrations of silica in ground water of the eastern San Joaquin Valley, California.en_US
dc.creatorCehrs, David, 1948-en_US
dc.contributor.authorCehrs, David, 1948-en_US
dc.date.issued1991en_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.abstractAnomalous concentrations of silica in ground water of the eastern San Joaquin Valley originate from several diverse sources and are subsequently modified by recharge or diagenesis. Statistics, geochemical models, and column studies identified potential sources of silica in ground water and those parameters most important in influencing its distribution. Principal components analysis indicated inverse time and potassium as the parameters which best relate to silica. Inverse time relates to ground-water recharge while potassium relates to either the rhyolitic Friant Pumice, the hardpans of the eastern San Joaquin Valley, or diagenetic losses. A lumped parameter model suggests that recharge is responsible for the drop in silica concentrations beneath Fresno since 1971. The Madera County model indicates higher silica concentrations associated with the Friant Pumice, older geologic units with hardpans, finer grained sediments, and areas of ground-water discharge. Lower silica concentrations are associated with unweathered sediments, areas receiving recharge, and areas underlain by the Corcoran Clay. Column leaching studies produced silica concentrations from the Friant Pumice of up to 90 mg/1, Turlock Lake and Riverbank Formation hardpans from 40-50 mg/1, and younger Modesto Formation sediments from 10-40 mg/l. Spatially, volcanogenic sediments impart the highest silica concentrations to the ground water, 70-95 mg/1, and occur along the eastern margin of the valley, north of the San Joaquin River, or in San Joaquin River fluvial deposits. Iron-silica hardpans, found at various depths along the east side of the valley, are associated with silica concentrations of 40-70 mg/l. The typical arkosic sediments of the eastern valley have silica concentrations of 20-40 mg/l. Silica concentrations in ground water are modified by recharge and diagenetic processes. Either natural or artificial recharge having 4-16 mg/1 silica may lower ambient silica concentrations in ground water. Recharge occurs beneath some rivers and in transmissive paleochannel deposits; artificial sources include agricultural overirrigation and basin recharge. The down-gradient loss of silica to the sedimentary column, more prevalent at depth, apparently is by the sorption of silica on clays, the formation of clays, or deposition of amorphous silica.en_US
dc.description.notehydrology collectionen_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.typetexten_US
dc.subjectHydrology.en_US
dc.subjectSilica -- California.en_US
dc.subjectGroundwater -- Management.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineHydrology and Water Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairDavis, Stanley N.en_US
dc.contributor.committeememberYeh, T.C. Jimen_US
dc.contributor.committeememberLong, Austinen_US
dc.contributor.committeememberWilson, L. Grahamen_US
dc.contributor.committeememberBull, William B.en_US
dc.identifier.oclc221707294en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.