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Area Gold Seekers Discover Mercury Too

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The Science Beat
Area Gold-Seekers Discover Mercury, Too

By Larry Bush

Little beads of "free" mercury permitted the cubic yard of gold-bearing sand concentrate washed out of gravel from pits in Michigan's Washtenaw, Oakland and Clinton counties. 

One geologist who watched the gold extraction process of Au-Min-Co. in a large renovated barn near the outskirts of Ann Arbor termed the high concentration of mercury in the run-off, "fantastic." 

The material from the three gravel pits produced 19 grams of gold and 100 grams of mercury. The thing which puzzles geologists who have been keeping a close watch on Michigan's new gold mining operations is the high concentration of mercury. 

Mercury, that metallic element which is liquid at ordinary temperatures and synonomus with thermometers, is found in connection with gold in northern Canada from where glaciers brought down Michigan's gravel deposits. But it is invariably found in lesser amounts than gold.

Burnell Tindall of Ann Arbor, owner of the local firm which holds mining rights on gravel pits throughout the Power Peninsula, attributes the first collection of quantities of mercury from glacial drift to the "unique" equipment he uses and the method gravel companies use to wash gravel. 

"Nowhere in the United States has anyone collected mercury in one of these devices except right here in Michigan," he said. The devices he speaks of are ladder-like apparatus used to collect gold from sand, and which he has modified and improved on. 

But Au-Min-Co's. discovery of an abundance of mercury in Michigan gravel pits has proved more of a misfortune than a blessing to the firm. 

Gravel pit owners are starting to close the pits to Au-Min-Co. because of the mercury scare generated by reports of high mercury levels in Lake St. Clair fish and Gov. William G. Milliken's prohibition of remaking fish from that lake. 

William Turney of the Michigan Water Resources Commission, who also witnessed the runoff and was long been in contact with firm's operations, told The News, however, the gold mining operation is "doing more good than harm" because it is actually removing mercury from the environment. 

"We are convinced it is not going to be a problem and have given Mr. Tindall a letter in which we offer to talk with gravel pit owners," he said.

Tindall expressed the opinion that fish in the rivers through the state may be picking up methyl-mercury transformed from natural "free" mercury deposits in the glacial drift and could be "loaded" with mercury. 

But even though the analysis of fish from the Huron River las spring has not yet been seen by the press, Turney said levels in fish from the local river are far below those of Lake St. Clair fish. 

Tindall said he observed the first ball of mercury on March 20, 1968, in material from a gravel pit near Ann Arbor. "At that time we still thought it was an oddity," he said. Au-Min-Co. reported it to the U.S. Bureau of Mines Research Station in Salt Lake City, Utah and was informed that "free" mercury had been found in two or three other instances in gravel deposits. 

The firm uses mercury in extracting gold in washings from gravel pits because gold has an affinity (sticks to) it. It was the mining process which convinced Tindall that the earlier finds were something more than an "oddity" and that large amounts of mercury may be found in this state. 

It first became evident when the firm used 150 pounds of mercury at one Michigan gravel pit to collect gold and got back 152 pounds of mercury. Later, in a local gravel pit, Tindall got back 15 additional pounds of mercury and was convinced. 

Tindall, retired president of Ann Arbor's Electric Service Co., said some geologists had told him there couldn't be any free mercury in Michigan's glacial deposits. "We have discovered something people said was impossible," he said. 

Turney said, however, "it only confirms what we have suspected all along -- that mercury is all over the place. The Canadians have found walleyes and pike in isolated lakes where there could be no contamination from industrial or other sources with mercury levels as high as one part per million. It had to come from natural sources."

Dr. John A. Dorr Jr., chairman of the U-M department of geology and mineralogy, said he had seen "free" mercury in alluvial deposits in the west and didn't know why there wouldn't be some in Michigan's glacial deposits even though he hadn't seen any. 

But what puzzles some geologists is not that Tindall has found mercury in local gravel pits, but that he has found such large amounts. One geologist said there should less mercury than gold, but from the Au-Min-Co.'s experience the reverse seems to be true. 

Tindall, like Turney, however, believes natural mercury deposits are no real threat to Michigan fish eaters even though they may be large in scattered areas, because they have been there and available for thousands of years with no serious effects.

Turney said the highest mercury levels in fish from the Huron River were about 0.3 parts per million. Fish from the local river were analyzed for mercury after bottom sediments below the Ann Arbor sewage treatment plant showed 0.75 parts per million of mercury -- highest amount found in any of the state's inland rivers. 

But the mercury levels in Huron River fish are far below the 5 parts per million found in some Lake St. Clair walleyes and lower than the 0.5 parts per million set by the Water Resources Commission as its action level.

Ed Bacon, Michigan Department of Natural Resources biologist, who collected the Huron River fish for the commission, said detectable levels of mercury were found in fish from all parts of the river sampled from Barton Pond to below the sewage plant. He said not all species of fish contained mercury and that higher levels were restricted to certain species such as northern pike. 

Turney said further investigations should be made but a shortage of funds at the state level doesn't permit doing much. 

Be that as it may, the only known human deaths and illness from mercury contamination of waters were the result of large scale industrial pollution in Japan. Bird deaths and effects on their reproduction from mercury in the U.S., Canada and Sweden have been traced to both treatment of seeds with compounds of the metal and consumption of fish from industrial polluted waters by birds. 

In no case has natural mercury like that discovered by the Au-Min-Co. yet been shown to have produced serious consequences. 

Three Michigan doctors who have thoroughly studied the problem of mercury pollution on human health, report in the lead article in the October issue of "Michigan Medicine" that a half pound of fish containing 2 parts per million of methyl-mercury can be eaten per week without danger of illness. 

Drs. Thomas B. Eyl of St. Clair and Kenneth R. Wilcox Jr. and Maurice S. Reizen, both of Lansing, say, however, in their article entitled "Mercury, Fish and Human Health," that "if the fish ingested contain 05 parts per million, the limit of ingestion should not exceed 2 1/2 pounds per week."

They point out that fish from Lake St. Clair might easily average 2 parts per million. However, this is the maximum level reported for western Lake Erie fish and averages, even for the most susceptible species probably would be much lower. 

The hooker is that some people have lower methyl-mercury tolerance levels than others. The doctors also point out that "because of demonstrated potentially catastrophic danger to the fetus, pregnant women should not eat methyl-mercury-contaminated fish, even in small quantities."

They also say "a daily intake of approximately one-half pound of fish containing 4 parts per million, continued for any significant length of time, could easily be fatal."

To be on the safe side, it would seem that the state of Michigan should somehow provide funds to continue and expand monitoring of fish for mercury contamination in the Huron River and other Michigan streams. But as it stands now it appears that as far as this state in concerned, the only threat to human health remains with Lake St. Clair and the St. Clair River. 

The mercury metal itself in the environment is apparently no direct threat to humans. It is only when it is transformed into methyl-mercury by bacterial action under certain conditions that is becomes dangerous. 

"The efficiency of our unit in mercury recovery could lessen the possibility of pollution. If the units were in every gravel pit in Michigan, the possibility of mercury pollution would be substantially minimized," Tindall said. 

Technology Triumphs

Coal mining is a dirty business and a lot of miners end up with what is commonly called "black lung" or pneumoconiosis from breathing in lung-irritating coal dust over the years. 

The government finally decided to do something about this disabling disease of coal miners -- namely close down the dirtiest mines until they are cleaned up -- but how to tell in which mines the miners were breathing in the most coal dust? 

Ann Arbor's Gelman Instrument Co. and modern technology came to the rescue with a sampling device worn by miners which picks up the tiny particles of coal. 

Based on the sequential air sampler invented by Charles Gelman, president of the firm, this was a spectacular achievement in itself. But weighing the particles on a routine basis to the required one-tenth of a milligram from thousands of filters in perhaps even more spectacular. 

"We are measuring to the accuracy of a small flake of dandruff. It represents good technology applied in volume and another first for Gelman," said Bernard Sobin, head of the project. 

A portion of the basement of the Gelman plant at 600 S. Wagner Rd., has been set aside for mass production of 10,000 filter devices a week and 1,800 scale measurements per scale per week on six delicate scales in a specially designed clean air room. The operation involves 12 production workers per shift. 

Such fine measurements are not unusual under laboratory conditions, but it represents a first in terms of mass production, Sobin explained. "It is the highest type of technology in a production situation," he added.

Pat Braden, Gelman information manager, pointed out that while the filters and their plastic cases are produced in the Ann Arbor plant, the portable, battery-operated pump worm by the miners is made by UNICO of Fall River, Mass., and the clean bench used in the production process by Pure Air of California, both Gelman subsidiaries. 

"This package is essentially used as a breathing apparatus," Sobin said of the filter device worn by miners. "The design package has been blessed by the U.S. Bureau of Mines and we are in full production," he said. 

"This device is called a cyclone equivalent to the nose and its membrane filter equivalent to the lund," Braden noted. Governemtn inspectors check the local operation periodically for the quality control. 

"Another necessity -- again in the air sampling line -- has produced another Gelman first: high-volume, high-precision gravimetric sampling. While this first doesn't doesn't involve a new product in the true sense of the word, it does involve the largest, most concerted effort of its kind ever undertaken," he said. 

"It involves pushing the state-of-the-art a step forward. At the accuracy required (in weighing particles of coal dust), changes in the moon's gravity can be noted, and air buoyancy, or the tendency of the capsule to "float" in the air becomes a factor. 

"No one touches the capsules, for the smear of oil or perspiration left on the surface would ruin the measurement -- the operators handle them with tweezers only," Braden said. 

When the weight of dust measured by the Gelman workers is too great, the atmosphere in the mine is considered too dirty and government closing of the mine is possible. The maximum permissible weight of dust collected in eight hours must be less than 3 milligrams according to the new federal law. 

"To achieve the precision required in the contract with the government, two Gelman employees weigh each capsule independently; a third person compares the weights. If they agree, the capsule is passed, if not it is rejected," Braden said.

Sobin said "coal miners are dirt and miserable and suddenly, after all these years, the government decided to do something about it. Coal mine operators are willing to fulfill the letter of the law but if they can find any reason to avoid complying they do. 

"However, the mine operators are dragging their feet and only 10 per cent are equipping miners with the Gelman devices at present. "About a dozen mines have been closed until they clean up as a result of the sampling so far," Sobin said. 


Larry Fahrner (foreground) of 1206 Cambridge Ct., weights fine particles of coal dust no heavier than a small flake of dandruff at Ann Arbor's Gelman Instrument Co. The local firm has a contract with the government to do the first mass weighing of particles that fine in connection with mine safety surveillance. Sandra Schultz (immediately behind Fahrner) and other Gelman workers in the background are performing identical tasks.