Research Summary:

The underlying theme of this project is to use basic scientific information (carbonate petrography, isotope geochemistry) to provide background information about the Snake River Plain aquifer at Test Area North, Idaho National Engineering and Environmental Laboratory (INEEL) so that a remediation strategy for this polluted aquifer can be devised. Calcite is a sink for Strontium-90, a major pollutant, and if calcite precipitation rates in the aquifer can be accelerated this isotope can be sequestered for a long enough period that radiometric decay (half life 29 years) will mitigate the problem.

The image above is a cathodoluminscence photo. Basically, bright luminescence tips of calcite crystals formed recently (within last 50 years) within an anaerobic TCE plume. Pre-existing calcite is nonluminescent and formed during the geologic past.

NOTE THAT THE SMALL AMOUNT OF OBSERVED CALCITE MATCHES (WITHIN AN ORDER OF MAGNITUDE) THE AMOUNT OF CALCITE CALCULATED TO HAVE FORMED BASED ON NETPATH MASS BALANCE MODELING!

Paper:

Tobin, K.J., Colwell, F.S., Onstott, T.C., and Smith R., 2000, The most recent calcite spar at the Test Area North, INEEL (Idaho): a possible example of contamination driven calcite precipitation. Chemical Geology. 169: 449-460.

Abstracts:

Tobin, K.J., Fredrickson, J., Colwell, F.S., Smith, R., and Onstott, T.C., 1999, Recent calcite precipitation in a fractured aquifer waste plume: reconciling laboratory and natural microbial CO2 mineralization. 4th International Symposium on Subsurface Microbiology. p. 47.

Tobin, K.J., Onstott, T.C., and Colwell, F., 1997, Establishing background calcite mineralization as a prelude to an in situ biomediation effort (INEL, Idaho). GSA Abstract, 29(7): 461.