Pollution’s Long Commute
No matter how high you climb up the mountains or how far north you travel into
the Arctic, no matter how remote you find yourself, you will find some of the
world's most toxic chemicals in concentrations that threaten fish and humans.
"Places that are far removed from human activity, places high in altitude
or high in latitude, were once thought to be pristine," said Carl Schreck. "They
are not; nothing is pristine anymore. Pollution doesn't go away, because there
is no 'away'."
Schreck, a professor in OSU's Department of Fisheries and Wildlife, is part
of a collaboration of university and government scientists who have recently
completed a six-year study of airborne contamination in national parks from
California to Alaska. The National Park Service first became interested in
the issue of airborne transport of contaminants when they found compounds such
as DDT and PCBs in arctic parks, far from any agricultural or industrial source.
The Western Airborne Contaminant Assessment Program (WACAP) was commissioned
to learn more about the pollutants found in these remote areas, where they
came from, and how they impact the plants there.
Far from the usual crowds of national park visitors, the researchers trekked
to isolated wilderness lakes in the high Sierra, Rocky, and Cascade mountains,
and deep into Alaska's backcountry. There, they measured toxic metals and other
contaminants in snow, soil, air, water, fish, and vegetation in places once
thought to be among the most pristine areas in the world.
Some of these contaminants have a very long commute, crossing the Pacific
Ocean on atmospheric currents from as far away as Asia and eastern Europe.
These air masses can carry coal smoke (a major source of mercury) and polychlorinated
biphenyls (PCBs) emitted from industrial sites in Russia, China, and elsewhere.
Some concentrate in cold environments, where they settle on soil, vegetation,
and water. Mercury, PCBs, and pesticide compounds can be rained down into arctic
lakes, bound onto falling snowflakes, or absorbed from the air by vegetation.
Staci Simonich is an expert in tracking airborne pollutants in global air
currents. A professor in OSU's Department of Environmental and Molecular Toxicology,
she leads the project's assessment of persistent organic pollutants. "These
compounds can travel very long distances in the atmosphere," Simonich
explained. When air masses hit the mountains of western North America, some
of the pollutants they carry begin to fall out. As contaminants are deposited,
they warm, volatilize, and rise farther up the mountainside before they settle,
volatilize, and rise again. In this way, persistent organic pollutants hopscotch
their way into the highest elevations and latitudes.
It takes more than hopscotch to get a team of scientists and all their research
gear into these remote areas. They carried the bare essentials: 2,000 pounds
of scientific equipment, inflatable boats, hand pumps, dry ice, shelter, and
food for eight people for three or four days. Where pack animals were allowed,
they used horses to help carry the load. In remote arctic lakes, they relied
on floatplanes to reach their sampling sites.
"A floatplane would drop us off with all our equipment a hundred miles
from the nearest village," said Adam Schwindt, one of the OSU researchers
with the WACAP team who worked in the arctic parks. "We just hoped that
the weather would hold for three or four days so the plane could come back
to get us when we were done."
"Bears were a big concern," said Schreck, who leads the USGS Cooperative
Fish and Wildlife Research Unit in Oregon and led WACAP's fish physiology investigations. "Almost
everywhere we sampled, there were bears. And there we were, dissecting fish,
covered in fish blood, in a camp filled with fish samples."
And there was the fatigue factor. The researchers had to carry everything
in, sometimes on their backs, set up camp at 10,000-foot elevations, then work
very precisely for 16-hour days. They devised hand-powered portable gadgets
to accomplish tasks usually reserved for bigger, heavier, more sophisticated
instrumentation. They rigged a hand-cranked centrifuge resembling an old washing
machine and packed in hundreds of pounds of dry ice to freeze their samples
for later analysis.
Using an inflatable raft, a winch, and some aircraft cable, the researchers
probed layers of lake sediments. The layers could be read like a history book
written through more than 130 years. There were layers of fly ash from early
coal-fired plants, cleaner sediments that marked the passage of the Clean Air
Act, and recent increases in contaminants that likely marked the Asian industrial
boom. Pesticides, both those in current use and those long-banned, showed
up in the high lakes of Rocky Mountain, Glacier, and Sequoia national parks.
Many of the contaminants end up in fatty tissues of fish and can accumulate
as contaminated fish are eaten by other fish in turn. Such bioaccumulation
has caused some fish to exceed the safety threshold for food, a concern for
people who live off those fish in arctic communities, Schreck explained.
The researchers observed endocrine disruptions that feminized male fish, a
trait sometimes found in fish in sewage treatment plants. "We have seen
physiological and pathological changes in fish in these lakes and an accumulation
of toxic chemicals in the environment that could only have come by air," said
Michael Kent, director of the center for salmon disease research at OSU and head of
the WACAP fish pathology investigation.
Airborne contaminants are absorbed by some kinds of vegetation, and the researchers
found contaminants accumulated in lichen and in the needles of trees. When
the needles dropped they carried an application of chemicals to the ground
with them. In this way, and in many other ways, toxic metals and organic compounds
persist long after being released into the atmosphere.
In the winter, the researchers carried their gear on skis and sleds to sample
the snowpack. They tunneled down as much as 15 feet into the snow to measure
its temperature, density, and other characteristics. They packed samples of
snow into dozens of containers the size of basketballs and hauled them back
to camp on sleds and in backpacks. Then they shipped the frozen samples to
Simonich's lab at OSU, where her team tested for the presence of 89 different
organic compounds and 49 toxic metals.
"We had to keep the snow frozen until we were ready for the analysis,
because snow chemistry can change as it melts," Simonich explained. Some
of the targeted compounds can turn to gas and escape as the snow melts, so
it took Simonich's team about six days to melt and filter each snow sample
and test it for hazardous compounds.
It took them even longer to develop the laboratory procedures they would use
to test the samples, tests that they would be the first to develop and use. "The
students in my lab were working 24/7, each specializing in one type of test," she
said "The results were phenomenal: two PhD's and two master's degrees
based on new procedures developed during this project."
The strength of the study comes in part from the collaboration among agencies
and across disciplines, according to Dixon Landers, the project's scientific
director and a senior research scientist at U.S. Environmental Protection Agency.
"We had no idea what suite of contaminants we would find or where we'd
find them," Landers said. "We were investigating the presence of
more than 100 compounds across a very large area, essentially from the Arctic
to Mexico." Some sources of pollution were nearby and obvious: smelters,
industrial agriculture, population centers. Others were much more distant.
Still others were the result of chemicals long banned but still making their
presence known. For example, DDT is so persistent, soils are still exhaling
it from applications made 40 years ago.
Jennifer Ramsay, a student researcher with the WACAP team, recalled a moment
working at a site above the Arctic Circle. "A herd of caribou came up
and just stared at us; they probably had never seen a human before," she
said. "It's hard to imagine that you can be so far away from the industrial
world and still measure its impact."