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Dan English, DWQ
Dan English leans forward, scalpel in his gloved hand, ready to slice open a brown trout – one of several species now residing in a deep freeze awaiting mercury tests that will help environmental scientists determine the extent of Utah’s mercury contamination among fish.
“We use a Teflon-coated blade,” said English, an environmental scientist with the Division of Water Quality, who along with colleague Benjamin Brown, helped collect the fish samples from various Utah waterways last year. “Teflon versus polypropylene gives us added quality assurance that we are not contaminating the sample.”
He removes a thumb-sized portion of the trout, peels off the skin and mashes the flesh in a crucible. The results are then placed in a sample tube that has been pre-screened to ensure that it is free of mercury or any other contamination that could compromise the results.
“Each fish gets a code that identifies the species and age of the fish, which is based on its length and weight” Brown explains, preparing a label that will identify this particular sample and its source.
English pulls another frozen fish out of the cooler. But before its turn at the scalpel, there is the meticulous cleaning – the cutting board and tools have to first be washed with hexane and carefully rinsed with ultra pure de-ionized water to guard against contaminating this sample with the remains of the previous one.
This process is repeated over and over again, about 50 times a week.The attention to detail is routine when preparing fish for mercury testing at the Utah Public Health Laboratories, located on the University of Utah campus.
The testing is a partnership between the Department of Environmental Quality and the Department of Health that was made possible through the purchase of a $50,000 “direct mercury analyzer” that has greatly accelerated the state’s testing for mercury – mostly in the form of toxic methyl mercury in fish tissues – that has been found in several Utah waterways, prompting consumption advisories for three areas of the state. Before the purchase, Utah environmental scientists had to ship their fish to an Environmental Protection Agency lab in Oregon, where the backlog of samples would result in months of delays.
DEQ just couldn’t wait that long and decided to purchase its own equipment, which arrived about three months ago.
“It’s important that we rely on our own procedures and data,” says Walt Baker, director of the Division of Water Quality. “We can feel confident in the results.”
Dr. Sanwat Chaudhuri, director of the Bureau of Chemical and Environmental Services at the lab, says it is tedious work, making sure the calibrations on the mercury analyzer are accurate and that all of the equipment is sanitized. It also means duplicate testing to ensure accurate results. It is a time-consuming process, but “it is so important that the data is reliable,” she says.
John Whitehead, branch manager for the Division of Water Quality and chairman of the Statewide Mercury Work Group, is a champion of mercury testing, saying the process will help them reach scientifically sound conclusions on the extent of the mercury problem in the state.
“We base our fish advisories on the kinds of results we see here,” Whitehead says. “The faster we can have the results the quicker we can analyze the problem and, if necessary, get the message if consumption of mercury-tainted fish should be limited in certain reservoirs or streams.”
So far, this work has resulted in health alerts issued for three types of fish and two species of duck.
Health Lab Scientists Larry Scanlan (right) and Steven Butala
At the state health laboratory, scientists Steven Butala and Larry Scanlan take the sample tubes prepared by English and Brown and begin another round of preparations for analysis. Dr. Butala removes a sample from the tube and places it on a cutting board that has been sanitized overnight in acid and cleaned with ultra-pure water.
“We take extraordinary precautions,” Butala says. “This is to assure accuracy in the tests.”
The tissue sample is then loaded onto a nickel boat, weighed and then put into a rotator tray inside the mercury analyzer. In about five minutes, a computer detects any presence of mercury. The absence of mercury is reflected on the computer screen by a flat line. But this sample has small amounts of mercury, indicated by a red line spike on a computer screen.
“We have found mercury in fish as low as 0.03 parts per million to as high as .8 parts per million,” Butala says.
“The health advisory screening value is 0.3 parts per million,” Chaudhuri adds. To put that in perspective, it is equivalent to one inch in about 53 miles. The ultra-sensitivity of the analyzer allows detection of even the minute traces of mercury that pose no health risks.
Because the process is painstaking in its detail – only about 25 samples can be processed at one time – there is a backlog of about 500 fish in the freezer waiting for analyses. It should take another two and a half months to process all the fish. But without the analyzer, sending the samples out for analysis would have resulted in much longer delays.
Scientists have yet to draw any conclusions about patterns of mercury contamination, but they have noted that certain fish from certain waterways have elevated levels of mercury.
“We do see a correlation when we analyze fish taken from certain areas,” Scanlan says. “By the time all 500 samples are done, DEQ will have a better idea of what is out there.”
Each week, English and Brown will deliver to Butala and Scanlan samples from another 50 frozen fish, many of them collected last year. On this particular day in mid February, they were processing fish taken from popular fishing holes in southern and northeastern Utah, as well as Strawberry Reservoir and the Weber River.
“We were involved in the collection of the fish, so we know the fish,” English says. “It’s nice to see them through the testing process.”
Chaudhuri says it is exciting to be part of the new mercury analysis effort, which has also forged professional bonds between Health Department chemists and DEQ environmental scientists.
“We are all working together to solve this problem,” she says. “This is a great example of how state agencies can work together.”