<p>Nitrate is one of the most common groundwater contaminants, with levels
commonly exceeding established drinking water limits. In areas of high agricultural or
industrial nitrate use, nitrate contaminated groundwater poses a potential health risk. In situ
denitrification is the microbially mediated reduction of nitrate to innocuous nitrogen gas
compounds and is the principal process for nitrate removal in contaminated aquifers. This
process is becoming increasingly recognized for its ability to reduce or eliminate nitrate
concentrations in groundwater with minimal site disturbance and cost. Predicting the extent
to which denitrification occurs in aquifers as well as the rate, therefore, has become the
focus of numerous mathematical models. However, the predictive capabilities of numerical
models are constrained because knowledge of the biological processes implicated in
denitrification is limited.</p>
<p>This report examines the microbial processes involved in <i>in situ</i> denitrification, and
then applies this knowledge to assess the capability of a two-dimensional numerical model,
NBI02D. NBI02D is a variation of a code, SEAM2D, developed by Widdowson
(1988,1992).</p>
<p>Model development and model application are presented. The model development
overview provides insight to the mathematical methods used to simulate the microbial
processes. The model application compares model predictions with data received from
a USGS research site on Cape Cod, Massachusetts. Data are derived from a natural gradient
experiment in which formate was injected into a carbon-limited aquifer in order
to stimulate and accelerate denitrification. NBI02D simulations for the Cape Cod site are
developed for model verification and model applicability.</p> / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/40718 |
| Date | 20 January 2010 |
| Creators | Killingstad, Marc W. |
| Contributors | Civil Engineering, Widdowson, Mark A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Master's project |
| Format | BTD, application/pdf |
| Relation | LD5655.V851_1996.K555.pdf |
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