rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Pseudokarst topography in a humid environment caused by contaminant-induced colloidal dispersion
  name:
    name part: Sassen, Douglas Spencer
    name part: 1977-
    role:
      role term: creator
  name:
    name part: Mathewson, Christopher C.
    role:
      role term: thesis advisor.
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: txu
    date issued: 2004
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: remote
    extent: 1 online resource.
  abstract: Over fifty small sinkholes (~1 meter in depth and width) were found in conjunction with structural damage to homes in an area south of Cleveland, TX. The local geology lacks carbonate and evaporite deposits associated with normal sinkhole development through dissolution. The morphology and distribution of sinkholes, and the geologic setting of the site are consistent with piping erosion. However, the site lacked the significant hydraulic gradient or exit points for sediment associated with traditional piping erosion. In areas of sinkholes, geophysical measurements of apparent electrical conductivity delineated anomalously high conductivity levels that are interpreted as a brine release from a nearby oil-field waste injection well. The contaminated areas have sodium adsorption ratios (SAR) as high as 19, compared to background levels of 3. Sodium has been shown to cause dispersion of soil colloids, allowing for sediment transport at very low velocities. Thus, subsurface erosion of dispersed sediment could be possible without significant hydraulic gradients. This hypothesis is backed by the observation of the depletion of colloidal particles within the E-horizon of sinkholes. However, there is a lack of precedence of waste brines initiating colloid dispersion. Also, sodium dispersion is not thought to be an important process in piping erosion in humid settings such as this one. Therefore, laboratory experiments on samples from the site area, designed to simulate field conditions, were conducted to measure dispersion verses pH, SAR and electrical conductivity (EC). Analysis of the experimental data with neural networks showed that an increase in SAR did increase dispersion. A dispersion prediction map, constructed with the trained neural network and calibrated geophysical data, showed correlation between sinkhole locations and increased predicted dispersion. This research indicates that a contaminant high in sodium content has caused colloidal dispersion, which may hav…
  note: by Douglas Spencer Sassen.
  note: Vita.
  note: Abstract.
  note: "Major Subject: Geology"
  note: Title from author supplied metadata (automated record created on Apr. 30, 2004.)
  note: Electronic resource.
  note: System requirements: Adobe Acrobat Reader.
  note: M.S. Texas A & M University 2003.
  note: Includes bibliographical references.
  note: Text (Thesis).
  subject:
    topic: Major geology
  subject:
    topic: sodium adsorption ratio
  subject:
    topic: neural networks
  subject:
    topic: oil-field brine
  subject:
    topic: colloidal dispersion
  subject:
    topic: piping erosion
  subject:
    topic: electromagnetic induction
  subject:
    topic: pseudokarst
  identifier: http://hdl.handle.net/1969.1/455
  record info:
    record content source: TXA
    record creation date: 040618
    record change date: 20151026065646.0
    record identifier: in00001839759