|Mercury in their Midst|
|Natural Match: Mercury in the Everglades|
For more information on this article, contact:
Dr. William Landing:
850-644-6037; e-mail: firstname.lastname@example.org
When state officials were called to the Florida Panhandle to investigate a car-battery recycling plant near Marianna in 1977, they gazed upon a textbook case of human contempt for the environment.
On the banks of a swamp that drains into the nearby Chipola River, easily one of the states most scenic rivers, was a manmade moonscape--an acid-soaked scar of blighted earth, littered with the corpses of trees and the guts of countless cast-off batteries.
The Sapp Battery Salvage Site, a name that soon burned a permanent place in the annals of Floridas storied environmental catastrophes, quickly became a prime candidate for the Superfund, massive federal aid earmarked for cleaning up the nations most vile environmental messes. Despite nearly $2 million spent on clean-up, (and at least another $5 million projected) the site still sits heavily polluted after two decades.
As it turns out, aside from the obvious environmental fall-out--including soil practically sterilized by low pH and groundwater laced with lead and other toxins--the Sapp legacy lives on in a multimillion-dollar statewide hunt to solve one of the more frustrating mysteries ever to confront state environmental officials.
In sampling Chipola River fish for an assortment of heavy metals and other poisons in 1983, state analysts made a curious find. The fish showed low levels of lead, arsenic and cadmium in their flesh, but fairly high amounts of methylmercury--the potentially deadly, organic form of the familiar, silvery metal. The real shocker: The mercury levels were just as high in fish collected miles above the Sapp site as miles below it.
We really didnt know what to make of it, recalls Dr. Tom Atkeson, who, as a state environmental epidemiologist, helped with the early testing. Little did Atkeson know at the time what impact the finding would have on Floridas environmental consciousness, much less his career.
Today, Atkeson heads the Department of Environmental Protections Mercury Program, which since its launch in 1992 has seen, all told, about $12 million poured into a search for answers to Floridas troubling mercury dilemma. The issue goes beyond the oft-told story of mankinds insults to nature and touches on the physical and chemical characteristics of a dangerous environmental contaminant thats in a class of its own.
The Chipola River mercury finding in 1983 is an example of what scientists like to call counterintuitive, that is, the facts dont seem to add up the way common sense might dictate they should. Although mercury is a natural element and as such is ubiquitous in the environment, whenever its found in any elevated levels in fish or other wildlife its usually associated with pollution. Most of that is tied to mercurys use in a number of heavy industrial processes--from the burning of coal in power plants to the smelting of iron and other ores. The peaceful Chipola lay many leagues away from any such operations, and except for the vestiges of the Sapp assault, flows in seagreen coils through near-pristine wilderness even today.
So in the early 80s, where was the Chipolas mercury coming from? Tests on fish throughout the rivers 50-mile length were showing an average methylmercury load of around 0.25 parts per million (ppm)--not high enough to cause public alarm but certainly unusual when contrasted with the trace amounts of other Sapp pollutants, the uniformity of the mercurys distribution in the river and the total lack of any other sources of pollution. State officials looked at what they had and passed the only rational judgment they could.
We concluded that the Sapp battery site couldnt possibly be the principle source of the mercury we were finding in the Chipola, said Atkeson. Of course, that only added to our consternation.
To their credit, state health officials didnt let the matter die. Over the next six years, despite budgets not geared for such, they orchestrated hundreds of mercury tests of lakes, rivers and streams throughout the state, beginning in the north and moving south. Almost wherever they looked, they found levels of mercury in fish higher than what normally could be expected from proximity to suspected sources of pollution, yet still within range of federal health guidelines.
Then in 1988, the first results came back from tests run on largemouth bass and warmouth collected in the Everglades. It was a revelation: The fish showed mercury levels as high as 3.4 ppm, nearly seven times higher than the federal safety limit. Subsequent tests confirmed the findings, and in March 1989, Dr. Charles Mahan, the states chief health officer, issued Floridas first health advisory on the eating of fish caught in the Everglades, declaring them unsafe for human consumption.
Just four months later, wildlife biologists radio-tracking a small group of Florida panthers fighting extinction in the southern Everglades noticed that No. 27, a four-year-old female, hadnt moved in a long while. They soon found her body on the banks of the Shark River Slough near the Everglades National Park. A necropsy revealed that the panthers liver contained 110 ppm of mercury, high enough to kill a human. The big cat had been stuffing herself on raccoons.
Within a year of the Everglades discovery, state biologists had found mercury-tainted fish in 51 of 80 lakes and streams studied throughout the state, and a spate of new health warnings were issued. None of the mercury findings, however, came close to the scary levels found in the southern Everglades--a baffling find considering that by all accounts the mercury-loaded Glades fish swam in some of the cleanest waters on the planet. And yet bass from nearby Lake Apopka--woefully polluted at the time from agricultural run-offs and other means--showed mercury levels that were barely detectable. How could this be?
For the moment, the riddle was lost in the wake of public outcry over the larger issue: Floridas famous fish and wildlife werent fit to eat anymore, thanks to some inexplicable new environmental menace. Headlines from Pensacola to Key West said as much, and mounting anger and alarm quickly kicked off a frenzy of finger-pointing.
Despite a good deal of science and much official hand-wringing--the finger-pointing continues to this day. Scientists are in agreement only on one thing: Most of the mercury found in Florida waterways comes from the skies, in the form of mercury-laden rain. So where does the rain get it? Heres where consensus stops--and often heated debate takes over.
Prime Suspect: Incinerators
By May 1992, Floridas Department of Environmental Regulation (now the Department of Environmental Protection) thought it had found the answer. A preliminary study, one of the first sanctioned by the states Mercury Task Force hastily formed by Gov. Bob Martinez in late 1989, identified the major manmade source of Floridas mercury woes as the states many garbage incinerators, giant waste-burning furnaces operated by large cities, industries and hospitals, mostly in central and south Florida (and burning an estimated 9,000 tons of waste daily). The finding echoed an independent investigation funded by the Orlando Sentinel right after the Everglades mercury story broke in 89.
But the limited study failed to address substantial evidence that didnt square with its central conclusion. For one thing, most scientists realized there was anything but a tidy link between mercury levels in Floridas fish and how close they were to any incinerators or other local sources of mercury pollution. Bass in some parts of the Everglades, for example, showed moderate to low mercury in their flesh, while bass elsewhere in the same system were loaded. Biologists found largemouth in the Sopchoppy River, isolated from any obvious pollution sources in the eastern Panhandle, for example, with mercury content just as high as some Glades bass.
This phenomenon--of mercury-tainted fish and other wildlife being found considerable distances from any blatant polluter of air or water--had been documented in such states as Wisconsin and Minnesota and in at least one foreign country (Sweden) since the early 1980s. Rain and snow were early suspects, and not just as carriers of regional pollution. In fact, enough was known about the global atmospheric distribution of mercury by 1990 that a U.S. Department of Energy mercury specialist felt confident enough to speculate in the press that Floridas problem could be originating from as far away as South America.
But the official hoopla over incinerators was enough to spawn more headlines, which fueled a rapidly growing environmental protest against waste incineration--and, to a lesser extent, power generation using mercury-bearing coal. Demonstrations organized by Greenpeace drew attention in Miami and Tampa, with protestors scaling incinerator stacks and unfurling banners saying Mercury is Rising and Dont Burn Florida. A number of arrests were made.
After a 31-hour protest at the Pinellas County incinerator in Tampa, Greenpeace regional coordinator Brian Hunt summed it all up for news reporters: "There is no other plausible source for mercury in the Everglades," he said.
A Serious Study Emerges
State agencies--principally DER--responded by calling for tougher emissions standards for incinerators and a moratorium on the building of any new ones. Intensive lobbying by incinerator owners kept most legislative initiatives bottled up early on. At the same time, there was growing awareness among state mercury-watchers that they didnt have enough facts to move aggressively.
Not only did environmental administrators lack solid proof that Floridas own nest-fouling activities were the primary cause of its mercury headache, they had virtually no idea how much mercury--or what kind of mercury, since a lot of the stuff from incinerators is in a form thats basically harmless when it leaves the smokestacks--was raining down on the states waterways in the first place. Even before the 92 report was released, it was obvious that more study--a lot more--was needed if the state was ever going to get a true picture of mercury pollution in the Sunshine State.
By 1992, Floridas Mercury Task Force, now headed by Atkeson, was faced with a stack of sobering statistics, drawn from dozens of mercury studies from around the nation. Thirty-five of 50 states were reporting findings of methylmercury in freshwater fish--but none had as bad a case as Floridas Everglades. For some unfathomable reason, this near-mythical River of Grass, a 10,000-square-mile marshland, was producing fish, alligators, wading birds and a few fish-loving mammals (i.e. raccoons) with some of the highest levels of mercury ever seen in wildlife.
Fortunately, the phenomenon had become sufficiently politically charged to trigger the release of serious research dollars, mostly from the federal Environmental Protection Agency. The task force eventually marshaled $3 million, which included support from Florida utility companies who were feeling political heat because of their coal-burning generators, to launch one of the most ambitious networks of data collection on atmospheric mercury deposition ever conceived in the U.S.
A relative scientific rarity for its commitment to a long-term (four-year) assessment--the norm for such studies being a year or less--the Florida Atmospheric Mercury Study (FAMS) was the concept of researchers at Texas A&M University and Florida State. The results were analyzed in 1997 and will be released in final form early next year.
Years from now scientists may still be puzzling over the source of the mercury that most assuredly will be wracking Floridas fragile aquatic environment then and well into the next century. But as far as one group of researchers is concerned, the source of Floridas mercury pollution is finally a mystery solved.
An Early, Curious Find
In 1991, FSU oceanographer Dr. Bill Landing (Ph.D. Santa Cruz, http://ocean.fsu.edu/~www/Facultyhome/landing.html) readily accepted an invitation to join the new, state-sanctioned mercury research effort, the most comprehensive yet designed.
An authority in studying low-level trace metals in the environment, Landing got the call from a colleague, Dr. Gary Gill, a marine scientist at Texas A&M. A veteran mercury researcher, Gill sat on a technical advisory committee called to help Floridas Mercury Task Force. A third principle investigator, Dr. Curtis Pollman, a chief scientist with a private, engineering consulting firm in Gainesville, already had joined the group.
From the outset, the FAMS projects primary goal was to find out how much atmospheric mercury was being deposited both annually and seasonally across as much of the state as the budget would permit, but allowing a concentration on the southern Everglades hot spot. The study eventually saw the establishment of nine sampling sites, seven of them south of Lake Okeechobee, and one as far north as Holmes County, near Bonifay, in the Florida Panhandle.
A secondary aim was to try to pinpoint the origins of any elevated levels of mercury found in Everglades rainfall. This dictated that some of the sampling stations be located directly downwind of known sources of mercury emissions, primarily those in the densely populated Gold Coast which crowds the beaches from Palm Beach to Miami. Other sites were selected based on known high levels of mercury contamination in fish, two of which were smack in the middle of the Everglades National Park near where the panther died in 89.
Landing & Co. knew that popular blame for the Glades notorious mercury problem largely lay with the operators of long-running municipal and medical waste incinerators in Broward and Dade counties. Here, finally, was a chance to do the kind of long-term research that could take proper account of seasonal weather variations, something that so-called snapshot studies--those of short duration--could never hope to do.
From the start, the FAMS team suspected that reasonably soon after the data collection began, they would begin to find evidence of a link to the Everglades mercury problem and the many local sources of mercury pollution, the predominant one being incinerators. Researchers still had no such smoking gun, yet all previous studies and speculation pointed to its existence.
Aside from incinerators, one early suspect was the run-offs from the Everglades massive agricultural projects, largely confined to a 1,000-square-mile region near Lake Okeechobee. Big Sugar, slang for the huge sugarcane-growing industry based there, was (and still is) a perennial target of environmentalists. But tests showed that although the cane-producing effluent coursing through Glades drainage canals was loaded with a variety of pollutants, mercury concentrations were uniformly exceedingly low.
Power plants, for the most part, could be ruled out as a major contributor because none of them south of Tampa used coal, burning low-mercury oil and gas instead. Emissions from the one coal-burning plant in Tampa were almost always swept out across the Gulf, thanks to prevailing southeasterly winds. Natural sources--mercury can percolate up from the earth through springs and groundwater seepage--also were dismissed early on as a significant factor.
By midway of the FAMS project, 1994-95, the team was drawing a bead on its primary mission--putting a number on just how much of this rainfall mercury gets dumped annually across south Florida. The stats were showing a yearly average of roughly 900 pounds of the stuff raining down on the region each year. But there were few clues that tied the bulk of this deposition to any specific source.
In compiling the deposition numbers, Jane Guentzel--Landings doctoral student who led the field collection and data analysis for the project--made a surprising find. She saw a striking relationship between the amount of mercury collected and the amount of rainfall recorded at any given site. The stats clearly showed that the more it rained, not only did the mercury deposition go up--which made sense--but the concentration of mercury in the rain went up as well. Only in extreme rainfall did the mercury concentration show a leveling off or decline, a sign perhaps of being finally washed out of the stormy skies.
It was another counterintuitive moment, flying in the face of a widely held dictum borne of the rising environmental consciousness in the Sixties, the admonition about dilution being the answer to pollution. Here was an example of just the opposite--up to a certain point, the more the dilution the more the pollution.
Of a dozen or more atmospheric pollutants tested for--including lead, zinc, copper, cadmium, aluminum, manganese, iron, sulphate, nitrate and others--only mercury, and to a lesser extent aluminum and iron, showed the phenomenon. During the rainy months, always in the summertime, concentration per volume of rainwater dropped dramatically for all the other adulterants--just as the dilution theory would predict. Conversely, in the drier months of December, January and February, rainfall concentration of most of the pollutants shot upwards, while the mercury load fell by as much as four times the concentration found in summer rain. What was going on here?
Overall, we were seeing five to eight times as much (total) mercury falling during the wet-weather months as we saw in winter, Guentzel said. Initially, our reaction was one of disbelief. We just couldnt figure out what process could possibly cause this to occur.
Mercury from Afar
It would take another year-and-a-half of tedious collecting (all instruments used in the field had to be prepared in a special clean room at FSU to guard against contamination) and data analysis before the FAMS team had a theory that fit all the evidence.
What Landing and his colleagues were left with was a conviction that Florida was a victim of mercury pollution primarily coming from somewhere else.
We knew this was plausible from what had been observed in Sweden in the early 1980s, said Landing. They set up the largest network of air monitoring stations ever built and showed that industrial pollution coming from great distances was responsible for the mercury found in fish in a number of remote lakes.
Environmental scientists also were becoming increasingly aware of a global cycle at work in the long-range atmospheric transport of elemental mercury, the vaporized form of the silvery metal found in nature, he said. By the early 90s, scientists were speculating that once introduced into the atmosphere from the smokestacks of a variety of industries, a substantial amount of this gaseous elemental mercury could drift for as long as a year in the upper atmosphere before falling back to earth. When it does so, the substance is no longer elemental mercury but an oxidized (rusted) version of it, an inorganic form that, unlike the raw metal itself, easily dissolves in rainwater. Once returned to the Earths surface, bacteria and sunglight can change the substance back into its elemental form which can then evaporate, starting the whole process all over again.
Most of the mercury were getting here in Florida is coming from overseas, says Landing flatly. And theres just not much we can do here in the state to stop it.
Landing says the study shows that when it comes to mercury pollution from the skies, Florida stands in harms way like no other state in the union. Through a collusion of latitude and a luxuriant Atlantic shoreline constantly swept by warm, easterly tradewinds, on a state-by-state basis Florida gets the lions share of airborne mercury dumped by rainfall on the North American continent.
This is how the FAMS researchers see it: All sorts of heavy industries--primarily in the northern hemisphere both in this country and abroad--throw vaporized, elemental mercury skyward, where it builds up in air layers high above the earth. In the U.S., this loaded airstream routinely travels westward across the Atlantic Ocean, where it collides and mixes with air off the European coast and then turns south. This foreign air may very well contain its own mercury load picked up from across Northern Europe, even Russia and China. The blended air mass then continues all the way down past North Africa before catching a ride on the great tradewind highway that carries it back west, across the ocean directly into Florida.
By the time this mercury-laden air reaches Miami (in as short a time as 30 days), ozone and ultraviolet radiation have chemically altered a comparatively small proportion of the non-soluble elemental mercury and turned it into a highly reactive, gaseous form that readily mixes with water molecules.
As anyone whos lived there can testify, South Florida has no shortage of airborne water molecules, especially in the monsoon months of June through September, when daily rainfalls of an inch or more are commonplace. These set-your-watch (typically afternoon) deluges are triggered when warm air rises from the sun-baked peninsula, cools and then greets warm, moist air arriving via the tradewinds. The collision sets off chains of spectacular thunderstorms unlike anything seen elsewhere on the Eastern Seaboard.
Landing says that such convective thunderheads, which can stand 12 miles high, provide the first opportunity for overseas air masses to drop their burden of soluble mercury. And drop it they do, along with particles of aluminum and iron, major constituents in African dust typically caught up in the imported air. All the FAMS sites showed a consistent pattern of such dust arriving along with the washed-out mercury.
Basically, these huge convective storms serve as mercury scrubbers, using the same fundamental process you see in some emission control devices in industry, he said. These clouds interact with the atmosphere to a height of 60,000 feet or more, and when the (overseas) air mass hits them, they simply scavenge the mercury out.
Florida is in the unenviable geographic position of being the only significant land mass between North Africa and the U.S. mainland capable of creating these super-tall storm systems, he said. Storms out over open ocean water typically are lower in altitude and less frequent than South Floridas famous frog-stranglers. Unfortunately, this keeps the tradewinds loaded with mercury until they make landfall in the Sunshine State.
But what about the finding that, in general, the harder it rains, the higher the mercury content by volume? Rainwater collected on the west coast of the state showed just as much dissolved mercury as that collected where many of the storms begin, on the east side. Why dont the coastal storms near Ft. Lauderdale and Miami wash out most of the mercury beforehand?
This strongly suggests that what were dealing with here is a large reservoir of water-soluble mercury in the upper atmosphere, perhaps larger than whats been estimated before, says Landing.
Apparently, the layer of air lying seven to 10 miles high over Florida gets constantly replenished with mercury-laden air from over the Atlantic. From May to October, this air mass is subject to daily, often violent confrontations with peninsular air, but the resulting thunderstorms--no matter their ferocity--cant keep pace with the volume of water-soluble mercury wafting in on the tradewinds. As the volume of rain goes up, so does the volume of mercury that gets poured into the states wetlands. During the summer months, its literally raining concentrated mercury from a source almost with no end.
doesnt get washed out over South Florida may continue on in a
north-northwesterly direction, says Landing, but the FAMS study wasnt
designed to investigate that possibility. Nevertheless, the idea is
plausible and may help explain how some mercury turns up in the fish of
the Panhandles Chipola and other North Florida water bodies. Regions
further inland figure to fair better, since in more northern latitudes
convective thunderstorms tend to be less frequent and dont reach as
far into the skies.
The FAMS wintertime deposition findings cast the most light on the issue of local-source mercury pollution of any study done so far. Dade, Broward and Palm Beach counties run a phalanx of city, county and industrial waste-burners that include the oldest (which usually means dirtiest) incinerators in the state.
Several localized studies have shown a marked increase in mercury deposition in the immediate vicinity of some incinerators in Broward and Dade counties. What the FAMS project shows, however, is that this localized influence is generally confined to downwind corridors of only a few miles, too short to reach into the most affected parts of the Everglades, says Landing.
For example, seasonal rainfall collected at the FAMS site in Andytown, only 15 miles directly downwind from a major incinerator in Ft. Lauderdale, showed a mercury content essentially the same as samples collected at the Beard Research Center in the Everglades National Park, 55 miles away. The same was found to be true for sites in Fakahatchee Strand (70 miles away) and at a site near Ft. Myers on the west coast, which also sits near a power plant and a new incinerator in Lee County.
Still, wintertime deposits of mercury across the region contrast significantly with rainy season patterns. Since most incinerators remain fairly consistent with their emissions year-round, and many run non-stop, Landing says it stands to reason that their contributions to rainfall mercury would show up best during the dry season. This is when there arent many tall thunderstorms around stripping out the mercury-load of the tradewinds, which swing down into the southern Caribbean beginning in October.
And this may in fact be the case, says Landing. The emission plumes spewing from incinerator stacks greet the southerly moving cold fronts, the regions predominant rainmakers from October to April, and the result is showers that often have elevated concentrations of mercury. Such evidence may be the clearest signal yet found of local sources combined contributions to the regions mercury equation, he said.
But even if it is, says Landing, such dry-season concentrations generally arent on the same scale with those seen in the wet season. If all of the mercury the FAMS researchers collected in South Florida during the wintertime were attributable to local sources, it still would amount to only a drop in the bucket when compared to whats coming down year-round, he said.
If the incinerators were a real big factor on an annual basis, since they run at about the same rate all the time youd expect the deposition to be more uniform throughout the year. But were seeing anything but that. Only about 10 percent of the mercury deposited annually in the Everglades gets deposited during the winter months.
The pattern just may dovetail with common sense: Nearly three-fourths of the year, most of the smoke and gases belching from incinerators in Dade and Broward counties get blown generally northwest, bypassing much of the central Everglades. The most contaminated fish in the Glades are found 35 miles southwest of Miami, nearly 90 degrees in the wrong direction of prevailing winds.
Calculations by Guentzel and Landing, which take into account both rainfall mercury and settled-out, mercury-laden dust, put a 30 percent cap on the maximum potential contribution of mercury emission sources in Dade and Broward counties to the Everglades annual mercury outfall. But Landing thinks the real figure may be as low as 15 percent.
The low figure--lower by far than any other study suggests--immediately calls into question the economic wisdom of government regulations on local sources, a big issue in Florida and elsewhere. A 1993 study showed that the cost of mounting mercury control devices on incinerators across the state would range from $2 million to $50 million apiece.
If you take the 30 percent, which I believe is high, and cut it in half, youd still have at least 85 percent of the (mercury) deposition you had to start with, says Landing. Just to take out 10 to 15 percent might not be worth the cost.
This fall, the EPA was busy polishing a long-in-coming comprehensive report to Congress (it was originally due in 1994) on mercury pollution in the U.S. The document is the likely starting point for a move to tighten regulations on mercury-emitting industries. Preliminary suggestions for tighter controls call for a mix of measures, from conventional emission scrubbers to a continued reduction of mercury as a raw material or catalyst. All take into account various cost-benefit analyses, which are an easy bet to raise a ruckus among some environmental groups.
A Once and Future Problem
What the EPA names as the single, number-one source of mercury pollution in the nation is, somewhat surprisingly, medical waste incineration. Of an estimated 243 tons of mercury pumped into American air for the study year 1989, combustion sources of all kind accounted for 85 percent. The burning of medical (hospital) waste was pegged at 27 percent of that, significantly higher than coal-burning power plants (21 percent), which is the source most commonly cited by environmentalists as the chief villain.
At first glance, the findings might seem to conflict with those of the FAMS study. Not so, says Landing. Floridas situation is unique to the continent, and while its industries may be contributing to the national, even global problem, they dont count for much in poisoning the states fish and wildlife. Sources far beyond its balmy shores are responsible for that, he says.
Not everyone whos read (now Dr.) Guentzels final paper--a FAMS summary taken from her dissertation and submitted for publication this summer--agrees. A month-long University of Michigan study conducted in the Glades last year argues in favor of the local-source theory. The FAMS report surprised DEPs Tom Atkeson when he first heard it, but hes anxious to hear more.
If we do find that the majority of the mercury is coming from overseas, then we need to say it and say it loudly, he said.
Meanwhile, work progresses on a $6 million complementary project directed by the U.S. Geological Survey, within the U.S. Department of the Interior. In 1995, the USGS launched the Aquatic Cycling of Mercury in the Everglades (ACME) program. The project largely looks past the source issue and focuses on how the mercury thats already in the system is mucking up its food chain and what can be done about it. DEP scientists are involved, as are mercury specialists within the states Game and Freshwater Fish Commission whove tracked the problem for nearly 20 years.
Slated to be finished in 1999, the ACME study is expected to write the basics of new tools for managing a complex mercury problem that has no peer--one that in all likelihood will be around for many more years to come.
Editors Note: The Florida Atmospheric Mercury Study was underwitten by grants from the U.S. Environmental Protection Agency; the Florida Department of Environmental Protection; The Florida Electric Power Coordinating Group; Florida Power & Light; The Electric Power Research Institute. and The South Florida Water Management District. For more information about this study, visit the FAMS web site at http://126.96.36.199/FAMS2/Fams.htm or direct inquiries to Dr. William Landing at (850) 644-6073, e-mail: email@example.com