Alpine Lake Testing
DB: This is Earth and Sky, on an ongoing monitoring program that involves a pair of small mountain lakes nestled high in Wyoming’s Snowy Range.
: We’re doing research at the Glacier Lakes Ecosystem Experiment Site to look at the effects of atmospheric deposition on wilderness-type ecosystems . . . We’re concerned about the effects of air pollutants and what they do to these ecosystems. They’re very sensitive to input from chemicals in the atmosphere.
JB: That’s Bob Musselman. He’s tracking the water quality in these lakes. The researchers use plastic tubing and a pump to suck up water from different depths. Back at the lab, samples are tested for nutrients, such as nitrogen. Nitrogen is important for plant growth – it’s often what ecologists call a “limiting factor” in high-elevation ecosystems in the western U.S. That is, the amount of available nitrogen controls total plant growth, even if plenty of other nutrients and water are available. So far, the lakes and other ecosystems at the Glacier Lakes Ecosystem Experiments Site are clean and unpolluted . . .
DB: They’re being studied as models of wilderness ecosystems – the researchers are gathering baseline data on the functioning of a normal, unpolluted high-elevation lake. Thanks today to our friends at the U.S. Forest Service. We hope you’ll visit our website at earthsky.com. We’re Block and Byrd for Earth and Sky.
Our thanks to the following individual who assisted in the preparation of this script:
Dr. Robert Musselman
Plant physiologist
USDA Forest Service
Rocky Mountain Research Station
Fort Collins, CO
The following articles and websites were used in preparing this script:
Reuss, J.O., F. A. Vertucoi, R.C. Musselman, and R. A. Sommerfield. “Chemical fluxes and sensitivity to acidification of two high-elevation catchments in southern Wyoming.” Journal of Hydrology 173 :165-198; 1995.
Musselman, Robert C., Technical Coordinator. The Glacier Lakes Ecosystem Experiments Site. USDA Forest Service General Technical Report RM-249.
Musselman, Robert C. “Spatial and temporal patterns in water chemistry of two high-elevation lakes in southeast Wyoming.” In: Proceedings of the Interior West Global Change Workshop, April 25 – 27, Fort Collins, Colorado. Richard W. Tinus, Technical Editor. USDA Forest Service General Technical Report RM-GTR-262.
Web site for Glacier Lakes Ecosystem Experiments Site (USDA Forest Service)
Author’s notes:
According to Bob Musselman, “Sampling lakes in the winter is quite challenging – we have high winds, they’re gusty. Often the temperature is below zero, often down to minus 30 or below, which can of course cause a wind chill of (edit) minus 50 or lower.”
“Nitrogen deposition in our area is quite low compared to that in the eastern United States,” he added. The two alpine lakes Musselman is studying – East Glacier Lake and West Glacier Lake in the Snowy Range of southern Wyoming’s Medicine Bow Mountains – are not in an “official” wilderness area, but they are still remote and very clean.
Besides being found in organic matter, nitrogen is present in many kinds of polluting emissions, and it can be carried on the wind and deposited far from its source.
Sampling lakes in winter poses some special challenges for Dr. Musselman’s team. After drilling a hole eight inches in diameter through three-foot-thick ice (a process that take about five minutes), they snake flexible plastic tubing down into the water and use a peristaltic pump to bring water samples up from different depths in the lake. A 12-volt battery powers the pump; to keep pump and battery working in minus-30 temperatures, they are sheltered in a 30-quart picnic cooler. Before heading into the field, the researchers warm some antifreeze in the office microwave oven and add it to the cooler to keep the equipment warm.
“We’ve learned quite a lot in thirteen years of sampling these lakes,” says Dr. Musselman. The lake-water chemistry and the composition of the phytoplankton population differ from winter to summer, “ but not as much as you might expect,” he says. For example, the lakes are cold in winter-but they’re also cold in the summer. The upper layers warm up only a few degrees, while the deepest water remains at an almost constant temperature year round.
Both lakes experience a “spike” of nutrient inputs in spring, when the snow melts, washing a winter’s accumulation of dust and atmospheric fallout into the lakes. And for lakes that are generally low in nutrients, both have surprisingly diverse phytoplankton populations-more than 200 different species, a level of diversity that would be more typical of a more nutrient-rich lake.
