An Andean lake of many colors This image taken by an astronaut on the International Space Station pr

An Andean lake of many colorsThis image taken by an astronaut on the International Space Station presents a view of a fascinating lake known as Laguna Verde, found in the high Andes of Northern Argentina, close to the Chilean border. The source of the lake’s name should be obvious just from the photo; the central portion of the lake almost seems to glow with an eerie greenish-blue tint. It actually took me a few minutes to understand the entire scope of the lake…the turquoise-colored part of the lake is obvious, but that’s not the entire lake. The lake stretches from the deep brown/black colored water on the left side of this image, through the colored portion, through the milky-white portion, and all the way to the deep black segment on the right. The full length of the lake stretches nearly 60 kilometers.The panoply of colors seen in this image occurs due to the lake’s chemistry. The lake is found in a very dry area, sandwiched between the high peaks of the Andes, surrounded by mountains and volcanoes, and sitting at an elevation of 4100 meters. The lake is hypersaline; water flows in carrying salts and sediments from the surrounding hills, but water only leaves by evaporation; the salt is trapped in the lake.Different types of bacteria live in the different portions of the lake depending on the temperature and salinity. The white, milky portion of the lake is very shallow, typically only a few centimeters deep and heavily impacted by solar heating and evaporation. The deeper portions of the lake likely are slightly less saline and also able to maintain more continuous temperatures, leading to the different types of life in each section.This image is oriented so that the up direction faces to the West. The upper portion of this image almost reaches the Chilean border. Following along the trace of the lake due North would lead to the volcano Ojos del Salado, the second highest mountain in the Western Hemisphere. Although not pictured, likely some of the water feeding Laguna Verde does drain down from this high peak.-JBBImage credit:http://earthobservatory.nasa.gov/IOTD/view.php?id=81106&src=twitter-iotdOjos del Saladohttp://en.wikipedia.org/wiki/Ojos_del_Salado -- source link

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