Grand Prismatic Spring In Yellowstone National Park

In 1871, Grand Prismatic Spring was discovered and named by the Hayden Expedition for its striking coloration. Later, many geologists, traveled to the area to confirm the colors described by explorers and trappers. Grand Prismatic Spring is noted for being the largest hot spring in Yellowstone National Park and third largest in the world. The spring is located halfway between the Upper and Lower Geyser Basins. The central location provides dramatic scenery for Yellowstone’s fast visitors. The spring is approximately 90 meters wide and 50 meters deep and expels an estimated 560 gallons of water per minute. A hot spring such as Grand Prismatic Spring, is an area where heated water can easily rise through cracks and fractures in the
earth’s surface. The movement of water is not blocked by mineral deposits. Very hot water cools as it reaches the surface, sinks, and is replaced by hotter water from beneath. This circulation of water is fairly continuous and does not result in geyser eruptions. At Grand Prismatic Springs, siliceous sinter is precipitated from the silica-rich water and is deposited along the edge of the pool. This is represented by the white mineral deposits furthest from the colorful edge of the hot spring. Grand Prismatic Spring sits on a bed of rhyolitic rock located on the west side of the present Yellowstone caldera. Rhyolite is a light colored volcanic rock with high silica content. Water deep in the Earth is warmed by the heat of the magma. This hot water circulates and dissolves some of the silica in the rocks, carrying it in solution to the surface of the hot spring. As the mineral-rich hot water flows over the ground and cools, silica compounds come out of solution and are deposited as a precipitate called siliceous sinter, creating the white-grey landscape around the spring. thermophiles -- microbes that thrive in the high-temperature environments of many hydrothermal sites. These exceptionally hardy single-celled organisms can be found in hot springs and other hydrothermal features, some of which are at near-boiling temperatures and have sulfuric water nearly as acidic as battery acid. There are many kinds of thermophiles in a typical hydrothermal feature, each adapted to local conditions and existing in harmony with other thermophiles and the non-living environment.
The breathtaking colors are attributed to the various species of thermophilic bacteria living in the spring. The blue water in the center is very hot, but it may support chemotrophic life – a chemotroph is an organism that uses chemicals for a source of energy. As you move farther from the heat source of the spring, life begins to flourish. The cyanobacteria – aquatic photosynthesizing bacteria - that live at the edges of Grand Prismatic Spring cover the color spectrum including yellow, green, orange, red, and brown.

The spring has a neutral to alkaline pH (8.4). The temperature of this spring is hottest in the center, reaching a high of 87 degrees Celsius. As water flows outward from the center, it cools and degasses, creating gradients of temperature and changes in the water’s chemistry. The topography of the landscape also can affect temperature. Shallow, dryer areas are cooler than deeper, wetter areas.

Grand Prismatic Spring has a unique combination of chemotrophic and phototrophic life. Although there is overwhelming evidence that most of the life at this hot spring is photosynthetic, we can infer that there is the presence of Aquifex, a chemotrophic bacteria. Due to the lack of a sulphurous smell and because of the presence of Aquifex at Octopus Spring (a smaller hot spring which is geologically and chemically similar to Grand Prismatic Spring), it is plausible that there are at least small amounts of Aquifex at the warmest internal edges of the spring. Aquifex would be using hydrogen gas as its source of both energy and electrons.

The hydrothermal features of Yellowstone are magnificent evidence of Earth’s volcanic activity.
Amazingly, they are also habitats in which microscopic organisms called thermophiles—“thermo” for heat, “phile” for lover—survive and thrive. Grand Prismatic Spring at Midway Geyser Basin (above) is an outstanding example of this dual characteristic. Visitors are awed by its size and admire its brilliant colors. However, the boardwalk they follow (lower right corner of photo) spans a vast habitat for a variety of thermophiles. Drawing on energy and chemical building blocks available in the hot springs, microbes construct substantial communities throughout the
park.

The thermophiles that thrive in these pools and their runoff channels are heat-loving microorganisms (also called microbes), some of which are descendants of the earliest lifeforms on earth.

These lifeforms, called cyanobacteria, began to create an atmosphere that would eventually support human life. Cyanobacteria are found in some of the colorful mats and streamers of Yellowstone’s hot springs.

Planetary Connections By studying extreme environments such as the one found at Grand Prismatic Spring, scientists are able to infer what life could be like on other planets. These extreme environments help identify the criteria for life and establish biomarkers – physical or chemical "signatures" left by organisms. Defining specific biomarkers sets parameters when searching for the presence of life either in the past or present on other planets. Using satellites and other equipment from space, scientists can search for signs of life – or the conditions necessary for life as we know it - using certain criteria.
Methods used include scanning the landscape for areas of elevated heat or indicators of water. NASA has also used reflection of infrared and absorption of blue and red light waves as a biomarker; these wavelengths reflections and absorptions are characteristic of photosynthesizing organisms. On the surface, several methods can be employed to search for presence of organisms. One method would be the use of temperature gradients. Another approach would be a change in color such as those demonstrated in the cyanobacteria of Grand Prismatic Spring. Fossils and stromatolite type remains would be strong indicators of the existence living organisms at some point in time. Finally, terracing such as that demonstrated by the cyanobacteria could imply the existence of living organisms.

1. Janiskee, Bob. "Thermophile Research in Yellowstone Helps Guide the Search for Extraterrestrial Life | National Parks Traveler." Commentary, News, and Life in America's Parks | National Parks Traveler. 10 Jan. 2011. Web. 27 Sept. 2011.
<http://www.nationalparkstraveler.com/2011/01/thermophile-research-yellowstone-helps-guide-search-extraterrestrial-life7446>.

2. Dartnell Dr., Lewis. "Biological Constraints on Habitability." News and Reviews in Astronomy & Geophysics 52.1 (2011): 1.25-.28. Print.

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