Document Type
Thesis
Abstract
Mercury, a potent neurotoxin, has been entering the atmosphere in ever-increasing quantities due to anthropogenic activity, particularly the operation of coal-fired power plants; global mercury contamination has resulted. Lake Matoaka is an ideal place to study the sources and pathways of this mercury contamination; its age of 290 years and well-known history ensure that it captures a sufficient record of anthropogenic activity. Two sediment cores were taken from the middle of each branch of the lake so that past mercury inputs to the lake could be deduced. These cores were sectioned and analyzed for mercury concentrations along their lengths. Also, in order to find present mercury inputs three tributaries to the lake were sampled during a storm event to capture overland flow. Mercury concentrations were measured in particulate matter filtered from these surface water samples. Pre-lake sediments from the cores exhibited fairly constant mercury concentrations that matched accepted background sediment values; mercury concentrations for pre-lake sediments averaged 0.040 ppm for both cores. Early lake sediments showed similar mercury levels; however, at a depth of 45 cm mercury concentrations began to rise above the pre-lake sediment peak concentration of 0.061 ppm. This upward trend culminated in mercury concentrations as high as 0.162 ppm in modern lake sediments, confirming that mercury contamination exists in the lake and has increased with time. In addition, Analysis of the particulate matter revealed that the tributary originating from the forested part of the Lake Matoaka watershed possessed the greatest mercury concentration, 0.66 ppm. The other tributaries, which emanated from urbanized areas, each displayed mercury concentrations of only 0.26 ppm. This supports recent findings that forested areas act as concentrators of atmospheric mercury and are the most significant contributors of mercury to inland water bodies.
Date Awarded
2010
Department
Geology
Advisor 1
James M. Kaste
Recommended Citation
Dronfield, Caitlin, "Mercury in Lake Matoaka: An Investigation of Contamination Sources and Pathways" (2010). Geology Senior Theses. William & Mary. Paper 227.
https://scholarworks.wm.edu/geologyseniors/227
