Questions Raised About Mercury 'Hot Spots' in the U.S.

Scientists report they've found as many as nine mercury hot spots in the Northeastern United States, places where mercury levels are far above what's considered safe. Where does the mercury come from, and what should be done to regulate it?

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IRA FLATOW, host:

You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.

Up next, a look at mercury in the environment. Coal-fired electric utility plants are spewing toxic mercury into the air that is ending up in potentially dangerous mercury hotspots in lakes and wetlands in New York, New England and Nova Scotia according to two newly released studies. The studies point out that the methods used by the U.S. Environmental Protection Agency to evaluate the amounts of mercury in the environment may grossly underestimate the true levels and the impact of the mercury on fish and local wildlife. And the new study suggests that there may be as many as 14 mercury hotspots in the Northeastern U.S., places where mercury levels are far above what is considered safe.

Joining me now to talk more about it is Charles Driscoll. He's university professor of environmental systems engineering at Syracuse University. He's also a research scientist at the Hubbard Brook Experimental Forest. He joins us by phone. Thanks for talking with us today, Dr. Driscoll.

Dr. CHARLES DRISCOLL (Environmental Engineering, Syracuse University): It's good to be on.

FLATOW: Your study found that fish with mercury levels that were 10 times higher than the EPA Human Health Criteria. Where does this mercury come from?

Dr. DRISCOLL: Well, mercury is a natural occurring element, and it's released by natural processes but also human activities such as combustion processes release it to the atmosphere, and it's found at high concentrations in certain environments.

FLATOW: And where does - the mercury in this case, where does it come from?

Dr. DRISCOLL: Well, it comes from a combination of sources. In the U.S., the largest unregulated source of mercury emissions is coal-fired power plants, but there are other sources as well, such as incinerators in industrial processes. And about a third of the mercury that's released globally comes from natural sources.

FLATOW: There were news reports that there were four, five, six local power companies, power plants in the neighborhood that were accounting for like 60 percent of the mercury.

Dr. DRISCOLL: Well, it - so we found a number of hotspots across this region, from the Adirondacks up to Nova Scotia, and at one of the hotspots in southern New Hampshire, there are some local facilities that appear to be significantly contributing to the mercury problems there.

FLATOW: Now Mercury's pretty heavy so it wouldn't travel very far. Would that be correct?

Dr. DRISCOLL: Well, that's actually not correct. Mercury is a fairly volatile compound when it's released to the atmosphere. And certain forms of mercury fall close to the source, but then other forms of mercury can be transported long distances.

FLATOW: And how long would the mercury remain in the environment?

Dr. DRISCOLL: Well, mercury is a, you know, is a chemical element. It's a - so it's a persistent pollutant. It's not going to be destroyed. So really the only way that it's going to be, you know, eliminated from the system is if it's buried in sediments and soils.

FLATOW: In a press release issued by Hubbard Brook, there is a statement made that people need to know where these highly polluted lakes exist so that they can take appropriate precautions when choosing where to fish and whether or not to consume that fish. Would you agree with that?

Dr. DRISCOLL: Well, yes, I think that there's concern about high concentrations of mercury actually all across the country. Forty-four of the 50 states have some sort of mercury advisory, and your people's exposure to mercury is largely through consumption of fish. So we're not advocating people stop consuming fish. There's lots of good reasons for eating fish. But if you're a sensitive individual, or if you're in a group that's sensitive, or if you consume a lot of fish, I think then you should, you know, take appropriate precautions.

FLATOW: You mean anywhere that you find fish? Or just in the Adirondacks and New England and (unintelligible) or anywhere?

Dr. DRISCOLL: Well, I think - yeah, I think that mercury is mercury, so that if you - if in areas where there are high concentrations of mercury - and as I said, it's pretty widespread - then, you know, people should take note of those advisories and limit their numbers of meals per week or per month from, you know, high-mercury areas.

FLATOW: And is it well-known where these areas are?

Dr. DRISCOLL: Well, I think part of the strength of our study is that we had many, many observations. We compiled data from state agencies and provincial agencies in Canada, so we had a very large database of fish. And so I think for the Northeastern U.S. and southeastern Canada we know a lot of the areas where there are high concentrations of fish - or high - fish that have high concentrations of mercury. But I think in other parts of the country it's not as well known.

FLATOW: Now the administration is working out a cap and trade system for dealing with mercury. I guess it's sort of the same thing that we're dealing with other pollutants in the past. Do you think this will be successful, this kind of system, in cleaning up mercury and making it less dangerous?

Dr. DRISCOLL: Well, I think that the cap and trade program, as you point out, is that it's been successful for other pollutants. It's been extremely successful for sulfur dioxide. I think we have concerns about it for mercury. I think if the cap is not stringent enough, then there's the potential - and if there's unconstrained trading - then I think there's the potential for hotspots to, you know, to continue on in the future. I think one of the things that we want to try to point out that is if the - if we embark on a cap and trade program, it's critical to have measurements in place, on the ground measurements that track how successful the program has been and to know if it's been effective or additional controls are warranted.

FLATOW: Now the cap and trade - for my listeners who don't know what it is - means that people are able - utilities are able to - if they're not polluting as much, they're able to trade their credits they get for being cleaner and sell them to another utility that might be able to use them because they are polluting more. Would that be generally ballpark?

Dr. DRISCOLL: Yeah, that is correct, yeah.

FLATOW: And you're saying that this system may not work for mercury because it might create hotspots where these people are allowed to pollute greater.

Dr. DRISCOLL: Well, I think the hotspots probably already exist, and I guess we anticipate that the Clean Air Mercury Rule would reduce mercury emissions. But the concern is if you have a sensitive area near a emitting source, then the sensitive areas may not recover very rapidly, depending on, you know, how the trading plays out.

FLATOW: And what would make one area more sensitive than another area?

Dr. DRISCOLL: Well, there's some characteristics that make it sensitive. Generally, forested areas are sensitive because trees, the canopy in trees scavenges mercury out of the atmosphere. So for example I do a lot of work in the Adirondacks, and we find that mercury that's deposited in land, maybe as much as 75 percent of it, comes in from gases that are scavenged out from the forest canopy.

Also if you're in an area where there are a lot of wetlands, wetlands allow for the conversion of inorganic mercury, which is the form that's deposited on the land, to methyl mercury. And methyl mercury is the form that bio-concentrates in the aquatic food chain. So mercury in water, which is found in fairly low concentrations, can concentrate by a factor of a million, maybe up to 10 million, as methyl mercury because methyl mercury has the ability to bio-accumulate. And that's why our exposure to mercury largely occurs through fish.

The last factor is that lakes that are particularly unproductive often show the highest concentrations of mercury in fish. And this is sort of counterintuitive. You think about a pristine lake that's not very productive, that should be low in contaminants. But in the case of mercury, there's a given amount of mercury per lake and that mercury is associates with the organisms, their biomass in that lake. And so a small amount of organisms will concentrate that mercury to a greater extent. Or if you have a large amount of organisms or a large amount of biomass, that mercury will be diluted. So nutrient-poor lakes tend to have higher fish mercury concentrations.

So those types of characteristics that we see in many of these areas in the Northeast, and also in other parts of the country, you know, make these areas particularly sensitive.

FLATOW: You know, just after the decades we've been hearing of acid rain falling on these forests, now we're hearing that there's mercury falling on them.

Dr. DRISCOLL: Well, that's an interesting point because there are interesting sort of linkages and connections between the acid rain problem and the mercury problem. Both are associated with fossil fuel combustion, particularly coal combustion. Also the same types of sensitive areas are impacted. And it appears that the - the bacteria that exist in wetlands and lake sediments that process sulfate, which is a component of acid rain, also are responsible for producing methyl mercury, which is the form of mercury that bio-accumulates.

And then finally when the water is acidified by acid rain, it appears to accumulate more mercury in fish. So I think the problems are closely interconnected.

FLATOW: Now, can you give us an idea of what kind of fish - you know, normal fish that we would catch going out on a lake in the Adirondacks?

Dr. DRISCOLL: Yeah, so it's part of our study. As I mentioned, we compiled, you know, different, you know, data from all sorts of types of fish, over 40 different species. And these are freshwater fish, but of course the problem occurs also for ocean fish. But some of the fish that have highest mercury concentrations include, you know, fish that we think of as the - as prize fish that are really in the upper part of the food chain. Fish like walleye and lake trout and northern pike have the highest mercury concentrations, where the ones with the lowest concentrations are fish that are largely bottom-feeding fish like white sucker and bullhead and fish like that.

FLATOW: Is there any place you could take the fish to have them analyzed, to know - let's say you have a favorite fishing hole and you want to know if the fish in this lake are, you know, I should be eating the fish.

Dr. DRISCOLL: Well, yeah, there are laboratories that analyze the fish and - including there are state agencies that analyze fish for mercury. In fact, there are techniques now that have been developed that you could take a biopsy sample of the fish and extract a muscle sample and analyze it for mercury and then release the fish and the fish could continue to survive without, you know, being consumed in the analysis process.

FLATOW: Well, I'm asking because you say that we should be careful about where we're fishing. Shouldn't we be careful about where we're fishing?

FLATOW: Well, I think that that's true. And in this report, we try to indicate common water quality measures that are linked to high concentrations of mercury in fish. So if regions or states, you know, can look at this information and even if they don't have direct measurements of mercury and fish, they can provide some guidance to their, you know, communities, you know, fishermen who might be concerned about areas where the fish are high in mercury.

FLATOW: Talking about mercury and fish this hour on TALK OF THE NATION: SCIENCE FRIDAY from NPR News. Talking with Charles Driscoll, university professor of environmental systems engineering at Syracuse University. Also a research scientist at the Hubbard Brook Experimental Forest.

I think the message that you're saying here, if I'm reading you correctly, is yes, we have found this in the Adirondacks, you know, New England, up into Canada. But don't laugh at us because this could be in your backyard too. Would that be correct?

Dr. DRISCOLL: Yeah, that's correct. Yeah. So if - I think there are more consumption advisories for mercury than any other contaminant, and you know, as I said, virtually every state has some sort of advisory for mercury. So it's clearly a widespread problem. It's just not a northeastern problem.

FLATOW: And we don't normally hear much about it.

Dr. DRISCOLL: Well, yeah. I think that's true. I think that's true. Probably it's, you know, there are other environmental issues that maybe have overshadowed it a little bit.

FLATOW: Let's go the phones. Carl in Buffalo, New York. Hi, Carl.

CARL (Caller): Good afternoon, Ira. Good afternoon, Charles. I'm going to preface my question with a comment, that NPR's one of the most refreshing things on this Earth, man. Keep up the great work, everybody. My question is, I live within 10 miles of the Huntley Station(ph) coal-fired power plant in Buffalo, New York. At what mile am I somewhat safe away from that plant? And everybody have a great weekend.

FLATOW: Thank you.

Dr. DRISCOLL: Okay. Well, I've not done work specifically at that facility and there are a number of issues concerning coal fire power plants, including, you know, inhalation of particles and things like that. But with respect to mercury, there are forms of mercury that are deposited fairly near the source. And by that I'm saying within, say, 50 miles or a hundred miles. So our studies show that there is - there can be elevated inputs of mercury in the area immediately around the facilities, although I'm not specifically familiar with that facility.

FLATOW: But your study is showing that it doesn't have to be transported a hundred miles.

Dr. DRISCOLL: It can be deposited fairly close to the source, yup.

FLATOW: Would it not behoove every community that's, you know, near a coal-fired power plant to see what kind of mercury is going on there?

Dr. DRISCOLL: I think that that would be wise. I think that, you know, one of the recommendations that we make is - particularly if we're going to embark on a cap and trade program is to have a better assessment of what the natural resources are adjacent to these facilities. So if there are a sensitive sites adjacent to emitting sources, mercury-emitting sources, then appropriate action can be taken.

FLATOW: And what kind of reaction have you gotten from organizations or regulatory agencies like the EPA, for example?

Dr. DRISCOLL: We were - last week, we gave briefings to both the House and the Senate, and also to EPA. And I think people were quite interested. And we had good dialogue. I know that there are a number of people on the Hill that are particularly interested in a mercury monitoring program. And we had very good discussions with EPA about our findings and how they are consistent with their findings and issues concerning mercury monitoring. So we were actually surprised at the interest and response from the report. And we've had very good dialogue with, you know, these federal groups, but also state groups as well.

FLATOW: Let's hope, Doctor, that talk is more than cheap. Thank you for taking time to be with us.

Dr. DRISCOLL: Okay. I enjoyed it very much. Thank you.

FLATOW: You're welcome. Charles Driscoll, university professor of environmental systems engineering at Syracuse University in Syracuse, New York. He's also at Hubbard Brook Experimental Forest. Stay with us, we're going to take a short break, change gears. When we come back, we're going to talk about the weighty issue of gravity. That's on the minds of physicists we're going to be meeting in Tucson to talk about it. Stay with us. We'll be back and we'll talk about it with you after this short break.

I'm Ira Flatow. This is TALK OF THE NATION: SCIENCE FRIDAY from NPR News.

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