Why Yellowstone Smells Like Rotten Eggs And Why That Is A Good Thing
If you have ever visited Yellowstone National Park and caught a strong rotten egg smell, you were likely smelling hydrogen sulfide.
USGS Yellowstone Volcanic Observatory Scientist-in-Charge Mike Poland recently explained the science behind Yellowstone’s distinctive odor in a video update. According to Poland, hydrogen sulfide is very common in geothermal systems like those found throughout Yellowstone.
The gas is known by its chemical formula H2S and can originate from gases associated with the magma chamber deep beneath Yellowstone. Poland compared magma to a soda, with gases dissolved inside that are trying to escape.
One of those gases is sulfur dioxide, or SO2. As sulfur dioxide rises away from the magma chamber and encounters water, a chemical reaction can transform the sulfur dioxide into hydrogen sulfide.
Poland explained that this process is one reason scientists monitor volcanic gas emissions. The presence of sulfur dioxide can provide different information than hydrogen sulfide because sulfur dioxide may indicate that magma is rising or that there is a pathway from magma to the surface without water interfering.
Yellowstone’s Smell Is A Useful Signal
While hydrogen sulfide is responsible for the familiar rotten egg odor, Poland said being able to detect the gas so readily is actually useful. Human noses are highly sensitive to hydrogen sulfide, making them surprisingly effective monitors for the gas around Yellowstone’s geothermal features.
“So yes, as some people have said, Yellowstone literally stinks, but in our case, for volcanic activity, that’s a really good thing.” – Mike POland
The distinctive smell is therefore more than an unpleasant part of visiting Yellowstone. It reflects the complex geothermal processes occurring beneath the surface and provides an easily detectable sign of hydrogen sulfide in the environment.
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