Project Director

Spratt, Henry

Department Examiner

Van Horn, Gene; Keller, Robert; Wigal, Cecelia


Dept. of Biological and Environmental Sciences


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


Wetlands are an interface between terrestrial and aquatic environments. As anthropogenic impacts on the environment increase it puts these sensitive areas at the forefront of change. Farming on William's Island has not occurred since 2001 but before that it was farmed to provide cost-free upkeep of the island. Simazine is a triazine herbicide, the most commonly used group of herbicides in modem agricultural practices. The fields on William's Island were most likely exposed because they were farmed for numerous years prior to 2001. Because of this the wetland that drains the fields, separating them from the Tennessee River, may have been previously exposed and if this is true the wetland would be able to function as an improved degrader of herbicides. Three sites across the wetland were examined, and three cores taken at each site. Microcosms of the soil were created and inoculated with both C14 Simazine and C12 Simazine. The NaOH, which captured radiolabeled CO2, was sampled from the microcosm set-ups first after roughly 24 hours and subsequently every three days until five samplings were taken, with a sixth sampling a month after the start of the incubations. The radiolabeled CO2 was then counted in a scintillation counter. From the data a mean maximum rate of degradation for each site was calculated. Site A had a rate of 8.91 +/- 0.96 ng Simazine/g wet soil/hour at 25° C incubation; site B had a rate of 8.14 +/- 0.28 ng Simazine/g wet soil/hour at 25°C incubation; site Chad a rate of 9.07 +/- 1.38 ng Simazine/g wet soil/hour at 25° C incubation. There was no statistical difference between the mean maximum rates of the three sites according to the AN OVA test run on Mini tab.Site A had a rate of 2.61+/- 1.07 ng Simazine/g wet soil/hour at 8° C incubation; site B had a rate of 2.61 +/-1.07 ng Simazine/g wet soil/hour at 8° C incubation; site C had a rate of 1.86 +/- 0.41ng Simazine/g wet soil/hour at 8° C incubation. Again, there was no statistical difference between the three sites according to the ANOV A test on Minitab. Although, there was no statistical difference between the three sites within the same temperature incubations, there was obvious difference between the rates at the two temperature incubations. These rates indicate that the wetland does filter Simazine before it contacts the Tennessee River. This happens at a greater rate at higher temperatures, which occur during the season when application takes place and the wetland would have larger amounts of herbicides. Comparison between the rates of degradation in this study and those done on a pristine site indicate substantially increased rates at sites of prior exposure (between 13 and 65 percent higher),corroborating past findings of other research. Although not statistically different there was slightly higher rate of degradation at site B, most likely because it has the most stable saturation throughout the year. More importantly, these rates of degradation indicate that the turnover time of these herbicides in cooler temperatures is slow, meaning that applications of Simazine during seasonal cold periods will have a greater effect on the environment because their degradation takes much longer than during seasonally warm periods.


I would like to thank all the individuals that helped me with this paper. I appreciate Dr. Spratt's guidance through out all of the data collection and his work with me in the field; my parents for all of their support, and all of the faculty in the honors program that guided me through this process. Thanks to Don Curtis we were able to access the island for sampling very easily from the Baylor School's boat ramp. Dr. Wigal was very giving of her time and instructon on the use and interpretation of 16 the statistical analysis with Minitab software. I would also like to thank the interlibrary loan department for all of the resources that they made available. Finally, I would like to thank the Tennessee River Gorge for allowing me to sample in William's Island wetland, and their encouragement of this study.


B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.




Wetland ecology--Tennessee; Herbicides--Environmental aspects


Water Resource Management

Document Type



ii, 29 leaves





Call Number

LB2369.5 .C426 2003