Hot Science coordinator, Monica Brelsford, at the Thermal Biology Institute and Kelly
Hayden of Montana Watercourse visited five 7th grade classrooms at Chief Joseph Middle
School in Bozeman. The students have been studying water quality measurements in
the local stream systems. One measure of water quality is pH. Waterways in the Gallatin
Valley generally have a pH around neutral (pH = 7) and may deviate up or down the
scale (pH = 6-8) depending on underlying soils and pollutants that are introduced
into the system. During this classroom visit, students were introduced to the concept that the concentration
of hydrogen ions (H+) is what determines measured pH. Students used a pH sensitive
solution to determine pH of household substances. The classroom discussion centered on pH levels and microbial growth. High pH (alkaline)
and low pH (acidic) solutions are used as cleaners and food additives which limit
the growth of microorganisms that maybe harmful to humans. For example, we use bleach
(pH = 10) to clean hospital equipment and we use vinegar (pH = 2) to preserve food.
Until recently, it was believed that organisms could not live at extreme pH levels.
Then in the 1960’s a scientist, Thomas Brock, discovered organisms living in the thermal
features of Yellowstone National Park. Many of these thermal features have extreme
water environments that are very acidic (pH= 0) or very alkaline (pH=10) and also
have temperatures near or even above boiling. Researchers have found hundreds of
different kinds of microorganisms that thrive in the thermal waters of Yellowstone.
Echinus geyser in Norris Geyser Basin is a good example of high temperatures (76oC)
and acid pH (3.5) with several microscopic species (both archaea and bacteria) thriving
in its waters. As new species are discovered annually, we realize that our knowledge
of life on earth is far from complete.
Students at Chief Joseph Middle School measure pH levels of common household products to appreciate the naturally occurring pH levels found in the thermal features of Yellowstone National Park.