Testing the Waters
The Environmental Contaminants Lab helps solve toxic mysteries.
By Larry D. Hodge
Janet Nelson, a member of the golden alga sampling team, bursts through the back door of the Texas Parks and Wildlife Department's Environmental Contaminants Laboratory in San Marcos laden with water samples. The samples Nelson bears are for organic chemist Pamela Hamlett. A tiny organism commonly known as golden alga is killing fish in a Texas lake, and part of Hamlett's job is to measure the toxin in the sample.
"It's a very complex situation in that golden alga produces a toxin, and somewhere in its life cycle, as fish are exposed to it, it affects their gills," Hamlett says. "I get water samples from water bodies around the state weekly when golden alga is active. It's been very difficult to get a handle on this. Lots of times we see toxins at high levels, but no fish die. Then we have a rain event, and the toxin level may be half what it was before, but fish start dying. We're still trying to understand why. Perhaps the rain washes something into the system, like calcium or magnesium, that causes the toxin to become lethal."
Measuring toxin levels is just one part of the lab's work. "Any time fisheries biologists encounter an unusual problem in fish hatcheries or in water bodies that seems to be related to chemistry, we try to get information to help solve their problem," Hamlett says. "Sometimes a game warden will bring in some dead birds and say, 'I think these birds were poisoned.' We extract a crop sample and see if we can find traces of any poison. We are generally looking for between 70 and 100 compounds of interest that may have an impact on animal or fish health."
Hamlett uses a gas chromatograph and a liquid chromatograph, both of which are attached to a mass spectrometer and controlled by a computer. "These are the same instruments used in forensic labs and pharmaceutical development labs," Hamlett explains. "As big fish eat little fish, compounds bioaccumulate and biomagnify. The bigger the fish, the bigger the chance the compound will be found, because there will be more of it."
"More of it" is a relative term. Hamlett and inorganic chemist Gary Steinmetz work with miniscule amounts of material. They start with 2- to 20-gram samples – about the size of 2 to 20 raisins – from the same jar of fish tissue ground in an industrial-strength blender to the consistency of cat food. They reduce the sample through chemical wizardry to just 1 gram. This is still huge compared to the amounts of substances they are looking for, which are measured in parts per million and parts per billion. "A part per million is one gram in a metric ton, or one package of artificial sweetener in a ton," Steinmetz says. "A part per billion is one package of sweetener in 1,000 tons – 25 semi-trailer loads."
And yet the instruments they use must first separate the compounds into still smaller particles. Steinmetz uses graphite furnace atomic absorption – GFAA – or an inductively coupled plasma optical emission spectrometer, ICP-OES for short, to look for heavy metals such as lead, cadmium, arsenic or selenium. Mercury has its own dedicated instrument, a CVAFS (cold-vapor atomic fluorescence spectrometer). "Everything is based on fire and heat," Steinmetz says. "The ICP-OES uses a radio-frequency generator, like a micro-wave oven, to indirectly heat the sample to between 4,000 and 6,000 degrees centigrade. Everything in the sample is ripped down to the elements, which become excited. As they cool, they give off light characteristic of the element, and the intensity of the light tells the amount. That information is fed into a computer, which compares it to a known concentration and calculates the amount in the sample."
Hamlett's machines do a similar thing, breaking complex organic molecules into pieces to look for organic compounds like PCBs, DDT and other pesticides or herbicides. "We bombard the compounds so they fall apart, kind of like a car that goes off a cliff," Hamlett says. "Then we look at the pieces, and we can say 'This is a wheel, this is a bumper – put it all together, this was a Volkswagen Jetta.' The instrument is so sophisticated I can look at just one part, like a wheel, and separate it into lug nuts, wheel cover, tire, and so on. Out of all that, we learn if a particular compound was present in the sample."
Once the compounds in a sample are identified, the lab's job is basically over, though staff members may be called on to testify in court about what they found. TPWD has no regulatory authority over what can be discharged into water, nor does it set standards for water quality and safety. Those tasks fall to the Texas Department of State Health Services and the Texas Commission on Environmental Quality. Yet TPWD's Environmental Contaminants Lab provides information those agencies can use to do their jobs.
"The lab is unusual in that it is set up to look for low levels of contaminants in fish tissues," lab manager Loraine Fries says. "We focus on the environment and fisheries, though our data may be used by DSHS or TCEQ to determine if additional samples are required to evaluate potential effects on human health."
Designing and conducting TPWD contaminant studies and interpreting the data from the lab's work for possible impacts to fish and wildlife resources falls to Roxie Mills and Mark Luedke, TPWD's Contaminants Assessment Team (CAT). In addition, Mills and Luedke share that information with other state and federal agencies through the Fish Sampling Advisory Subcommittee, part of the interagency Toxic Substances Coordinating Committee. "We have quarterly meetings in which there is an open sharing of data," Mills says. "TPWD's data are used by those agencies to decide if there is a problem and if they need to do something about it. We are a service organization. We provide data that no one else is gathering. TPWD has the ability to go out and do studies that give us good numbers that can be used to make a difference."
One example of making a difference Mills cites involved a factory in Bryan that had made arsenic-based cotton defoliants since the 1940s. After TPWD biologists found numerous deformed fish in a reservoir near the factory and other agencies found elevated arsenic levels in the surface and groundwater downstream of the factory, the company closed the facility and began cleaning up the site.
"Most of the issues we deal with are brought to our attention by other agencies or other TPWD employees," Luedke says. "Because TPWD does not have regulatory authority over water quality, our goal is to say, 'There may be a problem that should be assessed.'"
Luedke cautions that focusing on the occasional problem obscures the big picture. "People are often overly concerned about contaminants, but by and large, things are fine," he says. "TPWD Inland Fisheries biologists are collecting fish for contaminant testing as part of a statewide project to sample Texas reservoirs, and so far the results show that contaminants are generally not a concern to the health of our fisheries," he says.
Mills cites concern over mercury in East Texas reservoirs as one example of a complex contaminants issue. "Mercury is the classic bioaccumulator – once in the water, anything that takes it up passes it on to whatever eats it. It's a biomagnifier, so the top predator gets the most, and fish are the ultimate receptors. Contaminants like mercury and selenium bind in muscle tissue and tend to stay there. What we've found happening in East Texas threw people for a loop, because it's not what was expected."
Mills and Luedke selected 57 counties in East Texas where mercury bioaccumulation seemed likely and sampled 60 reservoirs over three years. "What we found didn't seem to make sense," Mills says. "We had reservoirs high and low in mercury bioaccumulation in close proximity. What seems to be driving this is not sources of mercury or how old the fish are, but very small differences in the watersheds. The good news is we are not finding mercury bioaccumulation everywhere we look. The bad news is we don't appear to have a source we can shut down and make it go away. While the mercury concentrations found indicate little, if any, adverse impacts to the fish communities, DSHS [Department of State Health Services] is doing human health risk assessments on about 20 percent of the reservoirs to determine what, if any, steps need to be taken to protect those who consume fish caught from those reservoirs."
In addition to its work with fresh waters, the Environmental Contaminants Laboratory works with the Environmental Protection Agency's National Coastal Assessment program. "We have a contract with TCEQ to survey Texas lakes and streams and another with EPA to do a survey of coastal sites," Steinmetz says. "We can give individual attention to samples that other labs can't because they have a heavy regulatory workload. They may have to analyze 5,000 samples every three months. Plus lots of labs analyze water and soil, but very few do fish well. We have the ability to use some of the best science out there to produce quality data on fish tissues."
"Few state labs, especially those run by resources agencies, have our capabilities in terms of equipment and staff, and our niche for tissue analysis is unique," Fries points out. "While we used to focus on persistent chemicals like DDT and PCBs, we know their concentrations will be decreasing, because they aren't being used anymore. Our new challenge will be to test for modern transient chemicals which break down quickly but are more toxic to fish than the persistent chemicals used in the past."
While TPWD's ECL lab and CAT focus on the health of the environment and the fish in it, their work contributes to the efforts of TCEQ and DSHS to protect human health. "If it's bad for fish, it may be bad for people, too," Fries says. "With agencies working together to bring different perspectives and expertise to the table, we get a much more complete picture than we ever could working alone."
And that's better for everyone.
While the Environmental Contaminants Lab does not provide services for private parties, it does work closely with TPWD's Kills and Spills team, which responds to reports of fish or wildlife kills or soil and water pollution.
To report a kill or spill, call one of the department's 24-hour communication centers. In the Houston area, you can call (281) 842-8100. In the rest of the state, call (512) 389-4848. Contact information for biologists around the state is available at: www.tpwd.state.tx.us/killsandspills.
For information on fishing advisories and closures, visit the Texas Department of State Health Services Web site: www.tdh.state.tx.us/bfds/ssd/.