Copper and associated toxins are leeching up faster than sediments can accumulate
By Dan Roblee
The Daily Mining Gazette (Houghton)
HOUGHTON, Mich. (AP) - Nothing can live in the stamp sands that cover the bottom of Torch Lake, Michigan Technological University Environmental Engineering Professor Noel Urban told a group of young plant technicians from the Keweenaw Bay Indian Community Natural Resources Department.
The technicians, who'd joined Urban for a cruise designed to teach the effects of historical mining on the lake, next learned that natural sediments that could cover the sands and begin to restore the lake's health are accumulating, but so slowly that copper and associated toxins are leeching up from the stamp sand, actually tailings from mines long closed, to the top of the new sediment faster than the sediments can accumulate.
The excursion, on Tech's research vessel Agassiz, was part of the General Motors-sponsored Ride the Waves education initiative, according to The Daily Mining Gazette of Houghton.
Then the technicians got a chance to do some scientific research themselves, using sonar soundings and a computer to create a transect that would show just how deep the stamps sands were at the bottom of the lake. The result: about 15 meters of stamp sand at the bottom of Torch Lake's south basin.
"The stamp sands are going to be here much longer than we're here," concluded Sierra Ayres, a student at the University of Michigan when she's not planting native vegetation Sand Point, a stamp sand site in the process of remediation in Baraga County. "It's kind of disheartening."
Other onboard experiments, which included measuring the clarity of the water by sight and taking samples of the water check the density of algae, microorganisms and other organic content, showed the lake's water to be much healthier than its bottom.
"Right now the water quality is good," Urban said. "It's kind of surprising considering the stamp sands. ... The algae in the water is good."
Urban said that's partly because small organisms in Torch Lake have evolved quickly, and partly because organic matter flowing into the lake from the Trap Rock River bonds with copper particles and keeps them from becoming toxic.
Other problems in Torch Lake include high mercury levels - the state of Michigan recommends limiting the amount of fish one eats from the lake due to mercury concentrations - and high concentrations of PCBs.
PCBs are chemicals that can cause cancer in high concentrations that had been widely used in electrical equipment at one time, Urban said. He said PCB remediation efforts hadn't moved past the research stage, in contrast to efforts cleaning up the shores of the lake, a difference he characterized as an "out of sight, out of mind" situation.
The KBIC technicians got a chance to see some of those efforts as well, exploring and doing experiments at the Amheek Stamp Mill, also known as the Tamarack City Stamp Mill, where the Environmental Protection Agency had just finished an asbestos cleanup the day before, as well as the Torch Lake shoreline and the Lake Linden Campground.
"We have them collecting scientific data, like do we have good (plant) ground coverage" in areas above stamp sand beaches that have had remediation," said Joan Chadde, education program coordinator at Michigan Tech.
That formula, two hours ashore and two at sea, both heavy in hands-on science, is standard for the Ride the Waves program, said Chadde. The program is generally targeted at somewhat younger students - grades 4 to 12 is the norm - and offers hands-on, aquatically focused environmental education.
Other groups who took part in the Torch Lake activities included a 4-H group and one from BHK Child Development Calumet Great Explorations.
"I learned that the fish can't live on the bottom, because there's not enough oxygen and not much food," said Great Explorations student Sierra Krock, while classmate Trent Tabor added a bit of weird science - that the mud on top of the stamp sands has turned pink and purple from oxidized metals underneath.
Chadde said there will be two more Ride the Waves programs this summer and fall, one that will explore underwater realms using one of Tech's ROVs, or remotely operated underwater vehicles, and one exploring the "Ring of Fire" a shelf on the bottom of Lake Superior that supports an unusually abundant variety of aquatic life.
Published: Thu, Aug 14, 2014
