- Associated Press - Friday, December 26, 2014

BILLINGS, Mont. (AP) - With a little mathematics and some scientific wizardry, Joseph Shaw and two of his colleagues have put the glory back in Yellowstone National Park’s Morning Glory Pool.

“What we did is something driven by curiosity,” Shaw said.

Named for the blue trumpet-shaped flower, Morning Glory Pool was once called “a perfectly symmetrical and exquisite chalice, which is filled with water of the loveliest, clearest, robin’s egg blue,” according to park literature.

Now, the colors of the hot pool range from orange on the outer edge to yellow then green at its deepest part. Park researchers have blamed the pool’s color change on things thrown into the pool by tourists.

“By the 1950s, people had thrown so much trash, rocks, logs and coins into the spring that Morning Glory Pool became known informally as the ‘garbage can,’” according to the Park Service. What’s more, the garbage reduces the flow of hot water into the pool, lowering its temperature about 50 degrees and allowing bacteria to bloom. The bacteria is the source of the colors visitors to the pool now see.

When Shaw’s colleague from Germany visited the Montana State University researcher in Bozeman in the summer of 2012, they did what about 2 million other folks do each summer - they journeyed south to see Yellowstone National Park.

With interests in optical science, though, Shaw and Michael Vollmer, of the Brandenburg University of Applied Sciences, were not content just to see Old Faithful Geyser erupt or to photograph bison along the road. Instead, they utilized their backgrounds to do a little scientific sleuthing.

“We were just looking for things to do with education and outreach,” Shaw said.

With a shared interest in thermal imaging, they packed along cameras, a thermal imaging camera and a spectrometer and “ended up getting quite a few ideas.”

A paper the duo published this month, along with grad student Paul Nugent, in the journal Applied Optics explains how the three managed to recreate what Morning Glory Pool looked like before it was polluted.

“No mathematical model existed that showed empirically how the physical and chemical variables of a pool relate to their optical factors and coalesce in the unique, stunning fashion that they do,” said a press release on the study.

The colors currently seen in the pool are the result of bacteria that grow in the hot water. What Shaw and his colleague’s showed is that after measuring the reflection of the pool’s rocks and bacterial mats, they could correct for water temperature and water reflectivity to produce an image of what Morning Glory Pool looked like from about 1880 to 1940, before it was trashed.

“Sure enough, it produced this picture of a radiant blue pattern,” Shaw said.

“My understanding is that’s how most of the thermal pools are in Iceland, because they are so hot they don’t have the bacterial mats,” Shaw said.

Based on the depth of the pool, they could also show how the water absorbs color as it gets deeper. Orange, red and yellow colors are absorbed by the deeper water leaving only the blue light to scatter.

“It’s very much like when you’re out in the open ocean, why it looks so blue,” Shaw explained. “That’s what’s driving the color of Grand Prismatic Spring. Only on the outer edge are you seeing the true color of the bacterial mat.”

Grand Prismatic Spring, what Shaw called the granddaddy of them all, is Yellowstone’s largest hot spring - more than 370 feet in diameter and 121 feet deep.

Although some people may question what’s so important about reproducing the color of a hot pool from decades ago, Shaw said fellow MSU biologists and chemists who study Yellowstone’s hot pools have already talked to him about using similar technology to remotely monitor pools for biology changes by analyzing a pool’s color.

But for Shaw there’s a much simpler satisfaction from the research work.

“So now I can go to the park and smile because I know what’s causing the colors,” he said.

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