Mechanisms of Gaseous Elemental Mercury (Hg) Formation in Fresh and Marine WatersEPA Grant Number: GF9500514
Title: Mechanisms of Gaseous Elemental Mercury (Hg) Formation in Fresh and Marine Waters
Investigators: Rolfhus, Kristofer R.
Institution: University of Connecticut
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 1995 through
Project Amount: $30,828
RFA: STAR Graduate Fellowships (1995) Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Earth
This research project is process-oriented and will focus on the mechanisms governing the production of mercury (Hg) under varying environmental conditions such as temperature, light, chemistry, and biology. The research will be organized into three basic investigations: Hg production in laboratory simulations, fresh, and marine waters. Each of these categories will be examined for possible biotic and abiotic mechanisms such as bacteria, phytoplankton, and dissolved organic carbon (DOC).
Initial laboratory experiments will be performed to determine the effects of abiotic processes, including thermal reduction by humic acids, photochemical reduction in dilute DOC solutions, and the effects of organic/inorganic Hg complexation (using metal buffers) at varying pH. These initial studies will set the stage for the experimental design of further work. Bacterial mechanisms will be examined through the use of metabolic inhibitors, filtration, and autoclaving of water samples. Specific inhibition will indicate whether bacteria are involved qualitatively, as well as give insight to responsible metabolic processes. Dominant species of marine phytoplankton will be cultured axenically in order to investigate the effects of light, temperature, and solution chemistry on Hg production in a systematic manner. Emphasis will be placed on the examination of reduction caused by exuded metabolic DOC. Fresh and marine waters will be utilized in similar laboratory experiments related to naturally-occurring processes. Environmental samples will be collected directly from Long Island Sound, while lake water will be obtained from Connecticut and Wisconsin lakes.