Sulfur cycling in a eutrophic lake

Abstract

<p>Sulfur cycling in lakes is affected by factors both without and within the water column. Precipitation and deposition of sulfur compounds, primarily from the burning of fossil fuels, depends upon location, but the changes that can occur in the lake itself can also be attributed to chemical and biological composition. Crystal Lake, in Clark County Ohio, is unique both biologically and chemically. This project focused on the changes in hydrogen sulfide and sulfate over one year, and the relationship with the present chemoautotrophic bacteria. In this lake, anoxygenic photosynthetic purple sulfur bacteria have greatly influenced the concentrations of sulfur compounds at certain depths. These and other microorganisms use the chemical constituents in the water column as well as sunlight and carbon dioxide to make biomass. Specifically, purple sulfur bacteria take up hydrogen sulfide, and then oxidize it to elemental sulfur which is then stored within their cell membrane as globules. The elemental sulfur globules are then oxidized to sulfuric acid. These chemical processes provide energy for the microbes during periods of darkness or low sunlight. In Crystal Lake the purple sulfur bacteria tend to live at certain depths where the combination of sufficient light and anoxic conditions allows for their proliferation. Over time the changes in the inputs of sulfur from deposition and precipitation have decreased due to the enforcement of laws like the IfClean Air Act". This project, combined with past data and future studies would give valuable information about the impact of pollution control legislation on water quality in lakes.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 16, 2010</p>