Grantee Research Project Results
Chemical Interactions in Basaltic AquifersEPA Grant Number: U915137
Title: Chemical Interactions in Basaltic Aquifers
Investigators: Neuhoff, Philip S.
Institution: Stanford University
EPA Project Officer: Manty, Dale
Project Period: January 1, 1997 through January 1, 2000
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1997)
Research Category: Fellowship - Geology , Academic Fellowships , Ecological Indicators/Assessment/Restoration
The objective of this research project is to develop a heuristic model of the physical and chemical processes controlling the stability of secondary minerals in basaltic aquifers.Approach:
This research project is a combined theoretical and field-based study of mineral distribution and stability in basaltic aquifers. The field-based portion of the studythis project capitalizes on regional-scale geological experiments preserved in fossil basaltic aquifers in Iceland and Greenland that are now exposed by glacial unroofing. Samples of high permeability, altered lava flow tops were collected throughout the aquifers. Chemical and mineralogical analysis of the samples is beinghas been conducted to determine the distribution and chemical variation of clay and zeolite minerals in the aquifers. In addition, digital analysis of porosity reduction by secondary mineral precipitation is being conducted to determine the variation of porosity in space and time within the aquifers. The theoretical component of this projectstudy study involves thermodynamic modeling of the stability of zeolites in basaltic aquifers. Phase relations observed in the aquifers is being used, in conjunction with experimental observations of zeolite stability and measurements of the thermodynamic properties of zeolites, to assess zeolite stability as a function of temperature, pressure, and solution chemistry.Supplemental Keywords:
fellowship, basaltic aquifers, secondary minerals, mineral distribution, Iceland, Greenland, aquifer, heuristic model.