The geothermal features of Yellowstone National Park have awed visitors and scientists for generations. Scientists believe they have only begun to understand the biological and geochemical complexity of hot springs, geysers, mudpots, and fumaroles.
A new academic paper exploring the geochemical and microbiological make up of mudpots, authored by Montana Tech researchers has been published by the American Chemical Society’s Earth and Space Chemistry online on November 28th, 2023 and is the cover of the recent issue, December 21st, 2023. Authors include Gavin (Geogia R.) Dahlquist Selking (M.S. Geosciences: Geochemistry, ’17), Paul Helfrich (M.S. Ecological Restoration, ’21), Jacqueline Timmer (M.S. Geochemistry’ 12), and Dr. Alysia Cox, Associate Professor of Environmental Chemistry. “Mudpot Geochemistry Reveals Subsurface Geologic Activity” has its origins in fieldwork conducted eight years ago as Dahlquist Selking’s MS thesis.
Most of the research on the project was conducted in July of 2016, with Dahlquist Selking and Cox developing the project shortly after Cox began teaching at Montana Tech in August 2015.
Cox typically refrains from assigning projects to graduate students, and instead lets students’ curiosity lead the way.
“Gavin asked about what people know about mudpots, and the answer is almost nothing, because they are kind of a pain to sample,” Cox said.
That question sparked a graduate thesis in which Dahlquist Selking designed a special filter apparatus specifically for mudpot sampling. It is specialized equipment for a very unique experience. In the summers, Cox takes one or two six-person teams to Yellowstone National Park to conduct sampling and experimentation under her Yellowstone research permit. The groups spend two weeks in the field and typically work 12-hour days, where researchers rise early, hike out into the field to the location of mudpots not accessible to the general public, and collect samples.
The geothermal features of the park can be hazardous, and safety of people and the natural resource are top priorities. Teams survey the mudpots from 360 degrees before approaching to ensure the earth appears stable and there aren’t any obvious dangers to the researchers, like an undercut area. Bison hoof prints are usually a good indication that the ground will withstand the weight of a human.
“Hydrothermal areas are off limits, and we have special permission to sample them,” Cox said. “We are allowed to sample because of our authorized research permit, and we are very careful when we sample thermal features. If it is not safe, we do not approach, and we have been in situations where we have not sampled because it was not safe.”
The teams have a 6-foot (2 meter) long scoop, with an extender that can reach an additional 6 feet if need be. The scoop collects a mudpot sample and the team then partitions the material for analysis in the field and back in the lab. Sediment and water samples are analyzed and then frozen for possible future analysis. Students also conduct tests that can only be done in the field, like spectrophotometry measurements of iron, silica, and sulfide. A day’s work usually includes sampling 2-3 mudpots.
Dalquist Selking’s geochemical findings uncovered interesting geochemical information about the mudpots.
“When we looked at the dissolved chemistry of the mudpot, we could tell which rock unit was under the mudpot,” Cox said.
Getting a snapshot of what lies beneath is helpful, because it provides insight that otherwise would be difficult to gather in the park’s protected landscape.
“The only other way you can get to depth besides geophysical imaging is to drill,” Cox said. “When you look at surface expressions like mudpots and hot springs, we can use these features as windows into the deep.”
Learning more about mudpot chemistry gives possible insight into how life formed on Earth. Dahlquist Selking’s research found that some mudpots are more aerobic than previously thought. The earliest life was anaerobic, so the aerobic mudpots are less useful as analogs to early life habitats.
“Mudpots are important because they are a unique subset of hydrothermal features,” Cox said. “I like to think about life and evolution of life. Looking at these mudpots as a possible habitat for early life is of interest to me.”
Cox’s Laboratory Exploring Geobiochemical Engineering and Natural Dynamics (LEGEND) continues to analyze the samples that originated with Dahlquist Selking’s research. Paul Helfrich is an Earth Science and Engineering doctoral student whose work focuses on environmental DNA. Environmental DNA is a method to determine which species are present in an ecosystem by analyzing the DNA shed by the organisms living in the area. Because each species has unique DNA, the samples contain information on a variety of organisms living in the mudpot.
“The microbiology of the mudpots is very complex,” Helfrich said. “The mudpots host immense microbial diversity. We detected more than 630 microbial species in the features but only about 5 or 6 represented more than 1% of the total community. We see that mudpots have incredible diversity but just a few microbes dominate them.”
One of the sampled mudpots had just recently formed, yet the microbial community found mirrored a nearby, older mudpot.
“This is something we will probably never get to see again. Predicting when a new mudpot will spring up is impossible, so this is a unique look into mudpot community evolution. What we saw is that the new mudpot was somewhat similar to a mudpot that is very nearby.”
Based on the data, Helfrich hypothesizes that how mudpots are biologically seeded might be related to geographical location. “I think that mudpot microbial communities might be seeded by subsurface flow from nearby features, but more research is needed to confirm that idea. If that is the case, it could have huge implications for how thermal features biogeochemical signatures form.” Helfrich said.
Future investigations will work to further analyze the genomes of the microbes in the mudpots.
“We’d like to do metagenomic work and look at all the DNA present. That would allow us to do some more complex microbial modeling” Cox said. “Metagenomic characterization will allow us to not only see what microbial communities are present in the mudpots but make connections between their functional potential and mudpot geochemistry” Helfrich added.
To learn more about the work of the LEGEND researchers, read the scholarly article online at https://pubs.acs.org/doi/full/10.1021/acsearthspacechem.3c00214.
Students who are interested in joining Cox’s research team or expeditions can reach out to her at firstname.lastname@example.org.