'Make-a-wish' coins changing the colour of Yellowstone's thermal springs
Friday, February 6, 2015, 6:09 PM - Discovered by geologists in what's now known as Yellowstone National Park in 1871, the Grand Prismatic Spring is the third largest hot spring in the world with a diameter of 90 metres and a depth of 50 metres.
It's arguably the most famous of the area's countless thermal pools, often described as 'liquid rainbows.'
The colourful spectrum in these lakes is the result of pigmented bacteria. The amount of colour the bacteria produces depends on the ratio of chlorophyll to carotenoids and the temperature of the water, which varies with the season.
Now, a new study suggests human activity is having a large impact on the composition of some of the area's springs, as well as their colour.
Researchers at Montana State University have created a mathematical equation to recreate how the colours in the spring appeared before tourists contaminated the spring and their results are startling.
The team visited the site and took a number of measurements and photographs at several pools and used the collected data, combined with available information about the pools, to create their model.
It was discovered that Yellowstone's Morning Glory Pool was once a deep blue -- but years of coins, trash and debris partially covered the pool's underwater vent.
That lowered the overall temperature and turned it hues of orange, yellow and green.
Image of the Morning Glory Pool, taken in August 23, 2012. Crourtesy: Joseph Shaw, Montana State University
Researchers hope the findings can help specialists better monitor the changes taking place in Yellowstone's thermal pools.
A paper on the study has been published in Optics Info Base.
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