Date of Award

2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

S.F. Korom

Abstract

To simplify the in situ mesocosm (ISM) design given in Schlag (1999), a modified ISM was designed and built in which a 6-inch long sand point replaces three 16-inch diameter screens. The modified design also includes an optional submersible pump mounted on top of the ISM chamber, making it capable of applications at depths greater than those attainable using a peristaltic pump from the ground surface. Two ISMs, one the original design (0-ISM) and the other the modified design (M-ISM) with an optional submersible pump, were installed in the Karlsruhe aquifer, near Minot, ND, in late June, 2003. Tracer tests were initiated in both ISMs to monitor denitrification rates at the two sites. The analytical results of water samples collected from the two ISMs showed no evidence of denitrification in the 0-ISM. However, the analytical results showed that the M ISM had a first-order denitrification rate constant (r2 = 0.99) of 0.0031/day with organic carbon, ferrous iron, and sulfide as the apparent electron donors. The submersible pump experienced a minor electrical problem, but showed promise as a means to make the modified ISM appropriate for deep installations.

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