Thermophilic Bacteria of Yellowstone National Park
CEE:5154 Environmental Microbiology
University of Iowa Department of Civil and Environmental Engineering
December 14, 2015
Amid the vast, sparsely populated regions of Northwest Wyoming, lies one of the most diverse and extraordinary ecosystems in the world, Yellowstone National Park. Yellowstone is one of the world's foremost sites for the study and appreciation of the evolutionary history of the earth. The park has a globally unparalleled assemblage of surficial geothermal activity, thousands of hot springs, mudpots, fumaroles, and more than half of the world’s active geysers (NPS, 2013). ...view middle of the document...
Yellowstone’s hydrothermal system is a direct expression of the immense caldera or “super volcano” located underneath the park. The tremendous amount of energy released from the underlying molten body of magma, heats groundwater and run off from melting snow and mountain streams that percolates through permeable rocks (NPS, 2014). As cooler surface water infiltrates the surface, it meets hot brine heated by the magma in the park’s subsurface. The surface water is heated well above the sea-level boiling point, but remains in a liquid state due to the great pressure of overlying water and rock. This creates super-heated water in the subsurface with temperatures exceeding 200oC (NPS, 2013). This superheated water is less dense than the cooler, heavier water that infiltrates and sinks around it, forming convection currents that allow the buoyant superheated water to migrate back toward the earth’s surface. As superheated water rises, it dissolves silica in the rhyolite and transports silica out of the subsurface (NPS, 2014). The water continues to move upward and begins to cool, causing the dissolved silica to precipitate out of the water. Precipitated silica is then deposited in cracks present in the overlying rock, creating an immense amount of pressure due and preventing superheated water from continuing its upward migration. Pressure builds in the subsurface until the silica deposits are overcome by the force of the rising water. This extreme amount of pressure causes mineral rich, superheated water to violently erupt through fissures in the rock and project out of the park’s surface (NPS, 2014).
This geological phenomenon creates the thousands of geysers located throughout the natural wonder that is Yellowstone National Park. The upwelling of mineral rich superheated water is continually happening in the subsurface of the park, but it is not always as obvious and violent as the magnificent geysers. Hydrothermal features like hot springs, mudpots, fumaroles, and limestone terraces are also formed by the subsurface migration of thermal water. Hot springs are the most common hydrothermal features in the park, and are created by the convection of infiltrating precipitates and super-heated water similar to the geological process that forms geysers. Unlike in the case of geysers, however, convection currents constantly circulate water from the surface to the subsurface in these locations, preventing water from reaching a temperature that would trigger an eruption (NPS, 2013).
Mudpots are formed much like hot springs, but occur in areas of the park where surface water cannot infiltrate the subsurface due to an impermeable depression of clay (NPS, 2013). Thermal water beneath this depression causes steam to rise and heat the surface water that is collected or absorbed by the impermeable clay lining. This causes the clay and water mixture in the depression to boil from the release of hydrogen sulfide gas out of the clay; this phenomenon gives...