Date of Award
Fall 2024
Project Type
Thesis
Program or Major
Earth Sciences
Degree Name
Master of Science
First Advisor
Julia G Bryce
Second Advisor
Stephen Jones
Third Advisor
Ruth Varner
Abstract
Mercury (Hg), and its subsequent transformation to the highly toxic compound methylmercury (MeHg) by microorganisms possessing the recently discovered hgcAB gene complex is of great concern on a global scale. In the Oyster River (OR) system in Durham, New Hampshire, where the historic head-of-tide Mill Pond Dam (MPD) is set to be removed in the near future, this issue is especially pertinent, as Hg is commonly found at alarmingly high concentrations in waterways and dams and will be released downstream upon the extraction of the impoundment. Aquatic sediment samples were collected across a time series throughout the OR system and assessed for total Hg (THg) and microbial community composition, along with several relevant water quality parameters, in order to identify locations of high contamination and estimate the potential for MeHg formation. Several extreme THg concentrations were observed, with a maximum of 1221 ppb, along with the constant presence of Hg methylating organisms, indicating potential MeHg production. No significant patterns were observed between the relative abundance of these organisms and any other factors, suggesting an inability to predict subsequent methylation potential with microbial community composition and environmental factors alone due to the high diversity within methylating organisms and the sporadic distribution of the hgcAB gene complex. However, due to the observations made of extremely high Hg distribution, together with the ubiquitous presence of mercury methylating microbes, sediment remediation prior to the removal of MPD could reduce the risk of releasing Hg into the environment as this ecosystem undergoes change with the planned upcoming MPD removal.
Recommended Citation
Carson, Sophia, "MERCURY DISTRIBUTION AND MICROBIALLY MEDIATED MERCURY METHYLATION POTENTIAL ABOVE AND BELOW THE HEAD-OF-TIDE MILL POND DAM, DURHAM, NH" (2024). Master's Theses and Capstones. 1877.
https://scholars.unh.edu/thesis/1877
