Swimmers Hoppers and Fliers

There is no sunrise or sunset. It is December 2007, nearly 350 miles north of the Arctic Circle. What light there is comes as a kind of twilight beginning as a deep cobalt blue shortly before noon and heightening to a liquid lilac before sinking back to darkness above a prism-edged horizon by 3:00 PM. Temperatures have been hovering all week around 0° F with wind chill down to almost -30 degrees. We are surrounded by ice in every direction as far as the eye can see. Our ship is the only one now at sea in the Arctic.

I took these notes while on board the CCGS Amundsen, the Canadian Coast Guard icebreaker and scientific research vessel on the first expedition ever to spend the winter moving through sea ice north of the Arctic Circle. The expedition had begun the previous July and was the largest of the 2007-2008 International Polar Year projects, involving more than 200 scientists from fifteen countries. Called the Circumpolar Flaw Lead System Study, the expedition's mission was to hug the lead of open water between the central sea ice pack—the ice that builds up and moves south from the Polar Ice Cap—and the coastal ice, a place particularly sensitive to environmental changes.

For almost a month, between late November and shortly before Christmas my home, shared with an international science crew of twenty and Coast Guard crew of forty-five, was a 300-foot-long floating laboratory capable of slicing through ice 1 meter thick. During those three-and-a-half weeks, we navigated the ice in the Amundsen Gulf, the westernmost reach of the Northwest Passage, some 90 miles south of the Polar Ice Cap. Conditions have been changing drastically here, and what happens in the far north, says expedition coleader Gary Stern, a senior scientist with Canada's Department of Fisheries and Oceans and professor at the University of Manitoba, may well be a harbinger of what's to come farther south.

One of the expedition's areas of scientific investigation is contaminants, and that's the primary reason I'm along. Even here, hundreds of miles from the nearest industrial or agricultural activity, the sea ice, ocean, and Arctic biota—the scientific term that takes in both flora and fauna—regularly yield evidence of elemental and synthetic chemical contamination. This contamination includes not only herbicides, fungicides, and pesticides—chemicals that are used in open air or that may have washed directly into rivers or released from factories as industrial effluent—but also metals, among them mercury (from both industrial and natural sources). It also includes flame retardants and water repel-lants, among other substances that are, at least in theory, incorporated into the materials of the products they're designed to enhance. Among the errant compounds now found regularly in the Arctic, for example, are brominated flame retardants, including those known as PBDEs (poly-brominated diphenyl ethers) used widely in upholstery foam, textiles, and plastics.1 Also routinely recorded in the far north—some at remarkably high levels—are perfluorinated compounds (PFCs) used as stain repel-lants, waterproofing agents, and industrial surfactants (think Scotch-guard, Teflon, Gore-Tex, and the slick coating on paper used in food packaging such as pizza boxes, candy wrappers, and microwave popcorn bags).

These same compounds are now being detected in animals and people all over the world. A network of more than forty sampling sites on seven continents has found evidence of these environmentally persistent pollutants (synthetic chemicals that tend not to biodegrade or break down into nontoxic components)—a mix of pesticides, fossil fuel emissions, and industrial compounds—virtually everywhere it looked, from Antarctica, North America, Australia, and Africa to Iceland.2 A recent five-year study conducted in U.S. national parks across the American West and Alaska found these same contaminants in the majority of its snow, soil, water, plant, and fish samples.3 That pesticides or the contaminant associated with tailpipe and power-plant emissions are being found in the backcountry of Glacier, Olympic, and Denali national parks, while disconcerting, is not too difficult to understand. There are roads through and around the parks and, at least outside of Alaska, agriculture, weed, pest control, and commercial development are not that far away. But that the same sites, let alone the Arctic, would be contaminated with flame retardants or perfluorinated chemicals—associated primarily with products used indoors—or with PCBs and DDT, which have been out of use in the United States for about thirty years, is more perplexing.

"Anything released in the mid-latitudes travels rapidly north," Gary Stern, who leads the expedition science team dedicated to contaminants study, tells me one morning in his office aboard the Amundsen. Stern is chief scientist for Leg 4B, as this segment of the expedition is called, and he clearly relishes sharing his knowledge. Chief scientist is a position of serious responsibility on a research cruise—"cruise" being the scientific lingo for these voyages. The chief scientist coordinates the ship's route with the captain, decides when environmental sampling instruments can be deployed, and makes sure the expedition's science program stays on track and the science crew stays safe. On an international project like this one, there's the added challenge for everyone of working with different languages—we had five languages on this leg: English, French, Chinese, Spanish, and Catalan—and with scientists of varying experience. Stern's bespectacled gaze is generally intent and serious but he has a subtly impish grin. For the Coast Guard's dress-for-dinner Sundays, Gary wears a Northwest Territories sealskin vest that rather matches his walrus mustache. And he's happy to pose for photos wearing the enviable pair of huge, long-haired white Arctic wolf fur mittens and matching hat made for him by the mother of the Leg 4B wildlife monitor from the Inuvialuit village of Sachs Harbour. The admirable fur handwork and the two computers, one showing a map of current sea ice conditions, on Stern's shipboard desk form a tableau nicely indicative of early twenty-first-century Arctic culture. This is Stern's eighth trip to the Arctic since his first in 1997. An analytical chemist by training, Stern has worked on developing methods to analyze a persistent pesticide called toxaphene. Looking at the mechanisms of transport and trying to understand what happens to such pollutants as environmental conditions change, says Stern, "is what got me interested in the ecosystem aspects of climate change."

Talking to scientists on the Amundsen, I quickly learn that what makes understanding atmospheric and ocean circulation key to understanding the impacts of global warming is also essential to understanding the environmental fate of contaminants. Being in the Arctic, especially in winter when ice, light, and open water contrast so dramatically, it's easy to understand how important a role temperature plays in the physical, chemical, and biological fate of everything in the air and ocean. From our extreme northerly location it also became clear what a literally pivotal role the Arctic plays in determining global air and water quality.

Thanks to patterns of atmospheric and ocean circulation, pollutants washed into the sea or released into the air in the Northern Hemisphere—where the bulk of the world's population and industry are located—generally go north, moving from warmer to colder climates. Persistent pollutants also move through the Southern Hemisphere and are accumulating in Antarctic ice, but because there's less industry and human population there, there's been less intensive study in that part of the world. And it was the northern trajectory that brought this phenomenon to light.

It's not known when the first persistent synthetic chemical contaminants arrived in the Arctic, but this kind of pollution has been detected there on a regular basis since the 1960s. Beginning in the 1980s, studies have consistently found what are considered to be high levels of hazardous chemicals in both the Canadian and the European Arctic. "Everyone thought the Arctic was pristine, so we were taken aback to find such high contaminant levels in top predators," says Stern. These substances include pesticides, herbicides, and industrial compounds that are not used locally and that were clearly coming from someplace far away. There are some local sources of persistent pollutants in the Arctic—I visited one in Alaska, a site where U.S. military waste was abandoned—but, says Eric Dewailly, a professor of social and preventative medicine at Laval University who works with the International Network for Circumpolar Health Research, most synthetic chemicals of this type found here come "100 percent from the outside."4

To distinguish these substances from other pollutants cruising the world's air- and waterways—metals such as mercury or greenhouse gases, for example—these long-lasting synthetic chemicals are often referred to as "persistent organic pollutants," or POPs for short. Used in this way, "organic" means that the chemical compound contains one or more carbon atoms. Not all organic compounds are toxic or persistent. These characteristics are determined by the molecule's overall chemical composition and its structure. And not all of the synthetic chemicals that are escaping from consumer products and causing biological anomalies that can lead to health problems are persistent. For example, the constituents of some plastics now under intense scrutiny for their adverse health impacts—bisphenol A, which makes up polycarbonate plastics (clear re-fillable beverage and baby bottles, dishware, appliances, bike helmets, eyeglass lenses, food can liners, and dental sealants among countless other products) and the phthalates (pronounced "thalates") that make polyvinyl chloride (PVC) plastics flexible (shower curtains, toys, medical tubing, packaging, fabric coatings, to name but a very few)—are organic and potentially toxic, but do not last long enough in the environment to be considered persistent or to travel long distances.

Public awareness of POPs such as DDT, PCBs, and dioxins has been growing, but when not part of a calamitous tainted product incident, industrial accident, or alarming health discovery, they have rarely been the stuff of headline news. Yet by 2001 concern about the environmental and health impacts of POPs had risen sufficiently to prompt the United Nation's Environment Programme to have formulated a treaty called the

Stockholm Convention aimed at curtailing the use and release of these chemicals. "Exposure to Persistent Organic Pollutants (POPs) can lead serious health effects," writes the organization that administers the Stockholm Convention, "including certain cancers, birth defects, dysfunctional immune and reproductive systems, greater susceptibility to disease, and even diminished intelligence."5 (The United States has signed, but as of May 2009 had not yet ratified, the Stockholm Convention—so it has not been a full participant in its meetings and decision making, and its use of chemicals is not yet formally bound by the Convention's regulations.)

Until now, the Stockholm Convention has covered only a dozen of the more than 80,000 chemicals that are sold commercially—PCBs, dioxins (which are a chemical byproduct rather than a substance formulated deliberately as a product ingredient), and ten pesticides. In May 2009, nine additional POPs were listed under the treaty.6 Among these new substances are several brominated flame retardants and a perfluorinated compound and its breakdown products—substances known to enter the environment from finished products as well as industrial sites. Before these additions, none of the chemicals regulated by this international agreement were synthetics that emerge from consumer products. Still, what's currently regulated by the Stockholm Convention is but a fraction of the synthetic chemicals that persist in the environment, are bioaccu-mulative, and pose risks to human health.

These persistent synthetic chemical contaminants are now literally everywhere, and detecting, monitoring, and measuring their extent has become a worldwide scientific enterprise. This activity has grown to such a scale that more than a thousand participants from forty-six different countries gathered in Tokyo to share scientific information about these contaminants. On a steamy early September day, those of us attending Dioxin 2007 sat on closely arrayed chairs in a hotel ballroom where we were addressed by Japan's Imperial Highness the Crown Prince Naruhito. "Industry has given us a rich and convenient life," he told us. "But at the same time we're being faced with a new problem: degradation of the environment. Persistent and toxic chemicals that accumulate in the environment and persist on a global scale," he noted, are among our greatest problems. While this was not news to the conference audience, his Imperial Highness's statement seemed remarkable given that the highest levels of the U.S. government had spent much of the preceding decade resisting policies that would begin to deal with the magnitude of this issue.

Over the next three days I listened to a geographic smorgasbord of presentations. Researchers working on virtually every continent, in every ecosystem, shared findings about the presence and behavior of mobile synthetic chemicals with structures and compositions that create an array of environmental and health problems. The magnitude of what these scientists were finding was stunning; the audience was left with no doubt that these substances have permeated the world's environment and are interacting with our most fundamental biochemical mechanisms. ^ ^ ^

It took three days, five plane flights, and one helicopter ride for me to get from my home in Portland, Oregon, to where the Amundsen was stationed in the Arctic Archipelago. Chemical molecules regularly travel farther without the aid of mechanical transport. I wanted to know how this was possible. I also wanted to know why the products of our rich and convenient life are turning up not only in U.S. national parks, but also in polar bears, deep sea squid, newborn babies, Japanese vegetables, eggs laid by hens in Belgian backyards, and packages of American cream cheese, along with most adults who've been tested, not to mention in more obvious sites of pollution like China's Pearl River Delta, the Great Lakes, and San Francisco Bay. I also wanted to get a glimpse of the part of the world on which they are having a significant impact and where environmental changes now underway will determine the effect of contaminants worldwide. So I headed north.

Inside, the ship is warm, dry, and brightly lit. The engines thrum constantly and work goes on twenty-four hours a day. With the loss of daylight, days seem suspended. Outside, beyond the double sets of heavy metal doors, the decks are covered with frost and fine crystalline snow. From my bunk-length berth on the lowest level of the ship, whenever we moved, the sound of breaking ice roared just beyond my porthole. An extraordinary grinding, creaking, and crashing sound, it was like being in the scoop of a giant snowplow.

Labs housing sophisticated analytical equipment are tucked into the corners of the ship, some accessible only from the chilly decks. A cold lab is kept at temperatures down to almost -15° F to preserve ice samples. Labs not much bigger than broom closets hold microscopes to view plankton and other tiny marine organisms, including viruses. There is indoor access to the Arctic Ocean through a kind of trap door in the base of the ship called the Moon Pool, where water sampling bottles and nets are lowered along with an elaborate instrument to measure turbulence. The ice beside the ship also becomes a laboratory. When ice conditions were stable, an "ice cage" could lower scientists and equipment by crane onto the ice about 25 feet below the Amundsen's deck. Arctic research is clearly not for the weak. Heavy boxes holding ice corers—these resemble 4-foot-tall corkscrews that can extract poles of ice about 6 inches in diameter, samples that are an Arctic research staple—and other equipment are hauled out onto the ice. Work goes on in the short Arctic twilight and full dark, illuminated by the ship's powerful spotlights.

Clad in bright orange, insulated one-piece flotation suits, boots warm down to -40° F, big mittens and liner gloves, balaclavas, and hoods, the scientists maneuver their gear onto the ice and begin sampling. "What's the biggest challenge of Arctic winter fieldwork?" I ask. "The cold? The dark?" "Fingers," the scientists all say smiling. Big mittens keep hands warm, but many tasks require dexterity. To ensure I have the full experience, I am given small jobs: recording measurements, sealing sample bags, retrieving ice cores. I quickly agree without hesitation—fingers.

No one is allowed on the ice without a gun-bearer to keep watch for polar bears. Coast Guard crew are all qualified and several scientists have gun licenses but Trevor Lucas, our wildlife monitor for this leg of the expedition, is usually on duty equipped with rifle and two-way radio. A lifelong resident of the tiny Banks Island Inuvialuit community of Sachs Harbour, Trevor is in his thirties and has been hunting for about twenty years. One morning when we were on the ice in the gray blue dark, he turned to me and said, "Seals." Several hundred yards ahead in a spot of open water were several dark specks. Later from the bridge, I watched them through binoculars, as they popped their dark whiskered heads up for air and then dove back in.

The Canadian government issues a fact sheet detailing the contaminants regularly detected in ringed seals from this part of the Arctic. These seals, which are an important traditional food for residents of the Arctic, are known to contain pesticides, PCBs, and mercury along with PBDEs, PFCs, and other relatively new contaminants. On this dark season's leg of the expedition when wildlife is scarce and generally dormant, however, scientists focus on ice, water, and air samples, all of which will be tested for a suite of contaminants.

Ice cores are drilled, sawed into lengths, and put into coolers while we're on the ice. Some of the analysis will be done on the ship. Other samples will be sent to home labs where even more sophisticated equipment awaits. Each of these samples is a kind of snapshot in time, as researcher Jesse Carrie put it, and will provide data that help form one piece of the giant jigsaw puzzle from which a particular picture of the environment will emerge. Spending time with scientists doing this kind of field work, I came to think of their work as a pointillist painting in which each dot on the canvas represented a study that might be years in the planning and execution. It takes many such dots to create a panorama—a picture large enough to give a significant sense of what's happening over time, like the Intergovernmental Panel on Climate Change reports, for example.

The wintertime Arctic offers a vivid picture of the relationship between air and water that's key to both atmospheric circulation and the transport of contaminants. From where we were on the Amundsen, north of 70 degrees north, at the time of year when daylight wanes most dramatically and ice builds, it became abundantly clear how sensitive that environment is to changes in temperature, sunlight, and wind, and how open water can change everything. There were times when it was possible to see heat steaming out of the water—water that was -1° C into air that was about -20° C. The stark contrast between the dusky white expanse of snow-covered ice and intense indigo water illustrated how ice acts like a blanket, regulating heat transfer between ocean and atmosphere. As expedition leader Dave Barber, who directs the Centre of Earth Observation Science at the University of Manitoba, puts it, "The ice is like a little 2-meter cap on top of 500 to 1500 meters of water. Take off the cap and the ocean is able to talk to the atmosphere."

What happens then can prompt a chain of cyclic events cascading across the hemisphere that can affect everything on the planet, from weather circling the globe to the tiniest organisms on Earth. Molecules of contaminants get swept up in this process as well. And some of these molecules, I'll learn later, borne aloft as aerosol particulates—very, very small solids—can influence cloud formation and precipitation, and thus contribute to the processes that set weather cycles in motion. Where a chemical ends up and how it travels depends on its molecular design and structure. This may sound obvious but these are behaviors that, historically, have been examined almost entirely after the fact—long after the horse has left the barn. Developing a systematic understanding of synthetic chemicals' mobility—a primary aim of green chemistry— can help us decide which materials we want populating our lives and landscapes.

By taking samples at numerous study sites over extended periods of time, scientists have discovered that some contaminants travel entirely by air—these are what Frank Wania of the University of Toronto calls fliers. Some—the swimmers—stay in the water, circulating with ocean currents. Most are hoppers, though; they make their way north in what's been dubbed the grasshopper effect, a series of air- and waterborne hops, moving toward the Arctic with cyclical and seasonal patterns of evaporation and condensation.

"Chemicals have several ways to be present in the atmosphere," explains Wania, speaking on the phone from his office. Depending on temperature and weather conditions, as well as the size, shape, and the elements that make up the molecule, the same substance can be found dissolved in water, as a gas, or as a particle. The smaller the molecule, the more volatile it typically is, and therefore the more likely to be swept along with atmospheric currents as a gas. These gas phase molecules— the fliers—can move in meters per second (spend time with scientists and even Americans end up speaking metric), making the trip from their points of origin to remote locations like the Arctic in days or weeks.7 At the opposite extreme, the water-borne swimmers can take years to reach the same destination.

The hoppers, intermediate-sized molecules that can move between gas, liquid, and particle phase, may take days, weeks, or even years to reach the Arctic after their initial release somewhere in the Northern Hemisphere. These hoppers may be present in liquid water, but as temperatures warm they will evaporate to gas phase but then condense and return to join water when temperatures cool. They'll repeat this cycle over and over again, rising and falling—or hopping—with daily and seasonal patterns of warming and cooling. It's in this way that many persistent chemicals move with clouds and precipitation as storm systems and ocean currents circle the globe, and why temperature so strongly influence how and where pollutants travel.

Being able to estimate how fast a contaminant travels has made it possible for Wania and his colleagues to create models that predict contaminant behavior. These scenarios can be used to calculate where and when a mobile and persistent pollutant may end up and when to expect a contaminant's measurable decline once it's taken out of commercial use. Such measures also help scientists track the comparative health impacts of various chemicals both close to and far from their sources.

"Persistence and mobility is what makes something troublesome," says Wania. "It's a very difficult, laborious, and time-consuming process to prove toxicity, and by the time you have evidence it may be too late." If a substance is "persistent, highly mobile, and can't be contained, you have a problem you can't rectify," he tells me.

Another major influence on the movement and deposition of persistent pollutants is precipitation. Put simply, the more it rains or snows the more likely these contaminants are to wash out of clouds and be deposited on land, lakes, rivers, and oceans. In a recent paper Wania and colleague Torsten Meyer note, "Real substances affected by changes in rain rate include lindane, aldrin [both highly toxic and persistent pesticides], highly chlorinated PCBs, PBDEs, and some currently used pesticides."8 When it's warmer, more of these substances will tend to evaporate again and join the cloud layer, and from there the cycle of condensation and precipitation begins again. When present as aerosol particulates, the contaminants may accelerate precipitation as water droplets coalesce around the tiny solids.

Increased precipitation caused by global warming will bring contaminants along with the moisture, notes Robie Macdonald, a research scientist with the Canadian Department of Fisheries and Oceans, and his colleagues. "Look at the effects of storms like [Hurricane] Katrina, where archived contaminants were released into a very important estuary," says Macdonald of the pollution that was washed into the Gulf of Mexico. "If there are more frequent and intense storms with climate change, poorly archived contaminants get released. This is what's been set in motion." Raining toxics sounds a bit extreme, but that's what it amounts to.

Whatever affects atmospheric and ocean circulation clearly plays an important role in where environmentally roving persistent pollutants end up. The big hemispheric wind and ocean patterns known as gyres and oscillations all play a part—as do more localized storm systems and currents. "These routes all seem to force contaminants released in Europe to the Arctic," explains Derek Muir, a senior scientist in aquatic ecosystems research with Environment Canada who specializes in contaminants. "Think about Chernobyl," Muir says by way of illustration. "The radioactivity there ended up in western Scandinavia where a lot of reindeer were sacrificed as a result. Other contaminants follow the same pathway north from Russia."9

What happens once pollutants reach the far north is very much influenced by where there is ice. Ice typically stabilizes contaminants and holds them in place until they're released again when temperatures rise high enough for melting to begin. Greenland, which Muir describes as "a big block of ice 3000 meters or more thick," appears to play a big role in fate of contaminants in the Arctic, Muir tells me. With the current accelerated melting of the Greenland Ice Sheet, it's likely that Greenland is now acting as a source of contaminants in the Arctic as well as a sink.

More evidence of glaciers releasing contaminants emerged recently with the discovery that Adelie penguins on the Western Antarctic Peninsula are being contaminated by a current source of DDT.10 Since levels of DDT in the atmosphere have been declining, it would seem logical that amounts in exposed animals would also decline—especially in such a remote location. But levels in these penguins have remained the same, prompting a study that found glacial meltwater to be the source of the continued contamination.

Evidence of PCBs, pesticides, mercury, and other contaminants being released to the atmosphere with Arctic melting and erosion continues to emerge as well. On the east side of Greenland and across the Greenland Sea on the remote Norwegian islands of Svalbard that reach all the way up to 80 degrees north—in the path of air and water currents coming off of Greenland and the European mainland—levels of PCBs, PBDEs, and perfluorinated compounds have been found to be particularly high. Sval-bard's polar bears have contaminant levels higher than bears on the west side of Greenland or in the Canadian Arctic, says Muir.

If global air and ocean currents generally tend to push pollutants released in North America toward the Arctic, when pollutants are released within range of the Atlantic Gulf Stream or get picked up by northerly air currents that also blow east, North American pollutants can be transported across the Atlantic toward Europe. Similarly, air masses may travel a northeasterly path from Asia across the Pacific to North America. The manufacture of chemicals, plastics, metals, cement, and electronics—and waste processing—all sources of persistent and hazardous pollutants, are clustered in southeastern China along with rapidly growing and urbanizing populations. This regional industrial effluent, combined with powerplant, tailpipe, and shipping emissions and dust resulting from construction and desertification, creates a potent maelstrom of contaminants. Thanks to the trans-Pacific air currents, pollutants released in China make tracks across the north Pacific toward the western United States and cause local air pollution health problems in Japan and Korea. Dust from China can reach California in as few as four days and makes a regular contribution to formation of Los Angeles smog.11

"There's definitely evidence that the Chinese mainland is a source of contaminants" that end up in North America, says Muir. NASA satellites are now able to track these transcontinental dust storms and those that are traveling to and from other continents—the phenomenon is worldwide—and concern over the health risks posed by the contaminants they carry has prompted the U.N. World Meteorological Organization to create a tracking and alert system to warn of serious airborne hazards.12

Where the globe-trotting chemicals originating in Asia come down to earth depends both on atmospheric conditions or weather and the molecules themselves. If sufficiently volatile, explains Muir, the persistent pollutants can move swiftly across the Pacific and on up to the Arctic. But the chemistry of some contaminants—those that are heavier and less volatile—causes them to drop out of the atmosphere into the northern Pacific Ocean where they may move slowly through the water or be taken up by fish and marine mammals. Persistent pollutants that include PCBs, brominated flame retardants, and perfluorinated compounds have been consistently found in fish, seals, whales, and fish eating birds along the Pacific coast over the past decade. "Fish can become their own transports of contaminants and fish-eating birds are known to excrete contaminants," says Robie Macdonald. "Migrating animals are not a huge transport mechanism but it's focused," he explains, "because they take the contaminants to where they feed and hatch their young."

Just as size and structure help determine how a chemical travels, molecular structure and composition also determine whether or not that substance will bind with soil, remobilize with groundwater or, when temperatures warm sufficiently, if it will be released again as a vapor. Molecular composition and structure also determine if a substance will be taken up by plants and animals, and if so how and to what effect. Understanding these pathways—and their environmental influences—is key to figuring out how a chemical will behave in the environment, how it will interact with the food web, and how people may be exposed.

The chemicals most likely to accumulate in plant and animal tissue and thus climb the food web are those that are fat-soluble. Lipophilic chemicals, as they're called scientifically, are working their way up the food web anywhere flora and fauna—including people—are exposed to such pollutants. Lipophilic literally means "fat loving," and this term is used to describe chemicals that have an affinity for and are soluble in fat. Materials with this property are also often persistent—that they are fat- rather than water-soluble makes them resist environmental degradation. And they are "bioaccumulative"—when they lodge in fat cells they can accumulate in plant or animal tissue as part of the fat reserves being stored for energy. When an animal burns fat for energy—this happens in people as well as in birds and fish—the fat cells release their contaminants, thus fat is both a source and sink of persistent pollutants

There are multiple ways people may absorb a particular lipophilic chemical, however, which is one reason figuring out sources of human exposure to these contaminants is tricky. For example, people are exposed to brominated flame retardants through household dust but also through food they eat that has accumulated these chemicals in its fat. In the Arctic—where contaminants are aggregating and animals that are staples of the traditional Northern diet have large stores of fat—the potential for exposure is magnified. The region's top predators, polar bears and humans, have some of the world's highest exposures to these pollutants.

Conditions in the Arctic are now changing in ways that make the region more vulnerable to contaminants' effects and are increasing the potential for exposure elsewhere as well. Global warming is prompting changes that are increasing the load of contaminants in the Arctic and exacerbating their impacts—among them the effects of the Greenland Ice Sheet melt. When persistent chemicals reach the Arctic, they are typically held in place for long periods of time by permafrost and ice. As rising temperatures melt the ice and permafrost, the contaminants are released.

"Climate change has brought earlier spring and summer is lasting longer," Stern tells me one dark winter day. "There's also more precipitation and it's lasting longer." More rain and snow along with greater and faster snowmelt cause erosion along riverbanks, lakes, and coastlines. All of this is likely to wash soil-bound contaminant particulates into lakes, rivers, and the oceans along with whatever pollutants come with the precipitation. This is already being seen in the Arctic Archipelago along the Amundsens route. "The permafrost has been melting really badly on Banks Island, especially near the inland lakes and along the coast," Trevor Lucas tells me.

"The system is complex," says Robie Macdonald, describing the processes at work in the arctic that contribute to the distribution of persistent pollutants. "A major concern," he explains, "is whether you have water as a liquid or water as a solid: ice." This sounds simple, but in the Arctic it makes, almost literally, a world of difference. In addition to the extent of Arctic ice and rate of melting, age of ice also matters. For the physical properties of sea ice change as it ages and these dynamics can affect the surrounding ecology profoundly.

The first few days I was on the Amundsen we moved swiftly through newly forming ice. When we moved through the same stretch of Beaufort Sea several weeks later, we were nearly trapped by blocks of ice almost 3 feet thick. To make headway we had to advance, retreat, and advance again. This was all what's called first-year ice—ice that has formed during the immediate winter. What scientists are watching warily is the ratio between first-year and multiyear ice—ice that has lasted through at least one summer melt season and is, on average, thirteen years old. Multiyear ice is mostly water and dense like an ice cube from the fridge. New ice is laced with brine crystals—little pockets that can harbor life and possibly contaminants. The porous new ice melts faster than the old, further pushing the Arctic system from light to dark.

"Twenty years ago, multiyear ice made up about 60 percent of the Arctic Sea ice cover. There is only now half that much," Jinping Zhao of Ocean University in Quindao, China, explained to me on the Amundsen.13 This sounds dramatic in the abstract, but it's even more impressive encountered firsthand. Multiyear ice is arguably the old growth of ice. Massive, hummocked, and imposing, it is—like an ancient forest—an ecosystem anchor. What's happening now as temperatures warm is roughly analogous to what happens when an ancient forest becomes riddled with clear-cuts.

My time on the Amundsen, and in April 2008 on the USS Knorr—a Woods Hole Oceanographic Institution research vessel at sea for another International Polar Year expedition called ICEALOT, investigating air chemistry in the European Arctic—gave me a whole new respect for weather maps. What these charts revealed would determine both the ship's course—hence our safe passage—and each day's scientific activity.

On the Knorr, every morning began with a meeting at which the day's chart of storm systems—air currents, pressure systems, and temperature—were discussed. The cloud ceiling, the height of the planetary boundary layer, and the prevailing winds would all help the scientists decide how to deploy sampling instruments and figure out what streams of pollutants might be detected. Along with the data that make their way into civilian weather reports—plots of cold fronts and pressure ridges— ICEALOT scientists also had access to information from satellites that track anthropogenic pollutants. These data appeared schematically as variously colored plumes tracing carbon emissions, sulfur, and nitrogen compounds. It's with these pulses of greenhouse gases and smog-producing compounds that persistent pollutants also travel.

The chemical constituents of Arctic air masses influence both weather patterns and air quality, I learned from scientists on the ICEALOT expedition. It also had become evident that pollutants themselves, as they influence cloud formation and whether surfaces absorb or reflect light, are contributing to warming trends. Looking at the weather maps and listening to the scientists explain pollutants' behavior, I began to picture little footprint tracks of these chemicals streaming across open waters, the undulating coastlines, and mountain ranges, gathering in clouds, melting snow, and being absorbed by plants and animals along the way. But how were these substances getting into the atmosphere and oceans in the first place?

Industrial smokestacks, drainpipes, open air or water applications of substances designed to kill certain forms of life, along with leaks, spills, and waste emissions are, collectively, one dimension of the answer. But what about those traces of what amounts to bits of what my computer is made of, or my neighbors' carpet, or our car upholstery, and the material lining the insides of the local pizzeria's delivery boxes—how are they getting to the clouds and ocean?

Monica Danon-Schaffer is a chemical engineer at the University of British Columbia who is investigating how and why these kinds of chemicals are ending up in landfill leachate and water in the Canadian Arctic including north of the Arctic Circle. One of the great things about writing about science is its endless opportunities to inflict one's curiosity on people who are professionally curious. If you're lucky—as I have been—you find scientists who are as enthusiastic about explaining as you are eager to ask. Monica is one of those people.

We were in the Austin, Texas, airport waiting for early morning flights home after a conference. Though it's not even 7:00 AM and she's loaded down with backpack, hiking boots, and computer bag—luggage from an extended research trip up north—she whips a notebook out of her pack.

"Let me show you something," she says. In seconds Monica has sketched out of series of molecules—PCBs, PBDEs, a couple of perfluo-rinated compounds, and another kind of chemical called a short-chain chlorinated paraffin (used as industrial lubricants and coatings, among other applications). The PCBs and PBDEs are markedly similar: strongly bound carbon ring structures with either chlorine or bromine atoms attached. The chlorinated paraffin and PFCs also bear a striking resemblance: Both are made up of long, branching chains. Both of these shapes—the rings and these kinds of long interlocking chemical branches—are very sturdy and stable, Monica tells me. The very structure that makes these substances effective in squelching fire, effectively flexible, or adept at resisting moisture, for example, Monica explains, is what makes them so persistent. These molecules are strong and don't easily give up either their structure or its linked chemical activity. And as it turns out, this is also what them makes them incompatible with, or toxic to, some vital biological systems.

While these substances resist degradation persistently in the environment, because they are added to—mixed in—rather than chemically bound to the materials they're used to modify, eventually they become separated and leave the finished product. This is partly what makes it so difficult to keep track of and trace these chemicals environmentally. For one, exactly how much of each substance is produced is not precisely known. Nor is it known exactly how much goes into each product, let alone how much can be expected to separate out and when or where this happens. As I later learn, the mixtures of these chemicals used commercially are typically not 100-percent pure and so may contain other synthetics that finished products may also shed. Then there's the fact that, in the environment, many of these problematic synthetics break down into smaller molecules that may be more persistent or more toxic than their larger cousins.

Finally it dawns on me that what in one dimension is a design success—a new material that prevents upholstered furniture from bursting into flame or another that makes it possible to etch semiconductor circuits and prevent fabric from soaking up stains—may under other circumstances be a design flaw. ^ ^ ^

An important thing to know about the scientific detective work of monitoring and measuring pollutants is that generally you will only find what you set out to look for. The methods for detecting particular chemicals in any form—gas, liquid or particulate—are very specific. While the same sample of ice, water, or air may yield an entire suite of contaminants, how one kind is detected may not be compatible with measuring another. As Tom Harner, a senior scientist with Environment Canada who specializes in hazardous air pollutants, explained to me, "Every persistent organic pollutant is different and unique. Every chemical is a different story. Because each chemical is unique, we can't investigate for a range of chemicals—we really have to do one at a time and look at each chemical's diversity of properties."

Atmospheric chemistry is painstaking work. Scientists spend most of the day staring at computer screens, logging in and analyzing data. It's quiet and not particularly visual or dramatic work. What it all means comes not in the collection of raw data but in later analysis, typically using other sets of data to provide context and perspective. The more observations and data there are, the richer the picture of what's happening environmentally. So we are here, cruising the Greenland, Norwegian, and Barents Sea during spring ice melt—which this year allows the Knorr to go farther north than she's ever been, just shy of the mid-April ice edge above Svalbard, a couple of degrees beyond 80 degrees north. "No one has been in this part of the Arctic at this time of year to take these kinds of measurements before," Tim Bates and Patricia Quinn, chief scientists for the ICEALOT cruise, tell me. The data gathered on board will help the researchers understand if and how short-lived pollutants—particu-larly ozone, aerosols, and methane—are contributing to accelerated rates of Arctic warming. These changes influence global weather patterns, and hence the trajectory and impacts of these and other pollutants.

These contaminants reflect and absorb light and influence cloud formation and air chemistry in ways that can increase both atmospheric and surface temperatures. Understanding how these pollutants behave and contribute to warming in the Arctic—particularly in the spring, when sea ice is decreasing and open water increasing—should help guide strategies for reducing these impacts by curtailing the emissions that set these processes in motion.

While the scientists are logging data, I have plenty of time to explore the ship. The library has a set of Patrick O'Brian novels, some thrillers, and more highbrow fare ranging from John McPhee's books to Jared Diamond's and Bruce Chatwin's. There are field guides to marine life, to birds of the Southwest Pacific, the West Indies, and the Galapagos. There are music dictionaries and books on geology. There is also a volume entitled How to Abandon Ship. "Do not hurry," it says. "A toothbrush will help alleviate thirst, and carefully rationed whiskey or brandy is good for morale."

The berth that Lynn Russell, a professor of atmospheric chemistry at the Scripps Institution of Oceanography, and I have been assigned is below decks, across from the engine room. We sleep in shallow, narrow metal bunks near a wall of heavy metal lockers and drawers. On top of the lockers are orange life preservers, tubular sacks that contain survival suits, and boxes that hold smoke hoods. At night the metal vibrates in a symphony that John Cage might have entitled Work for Bandsaw, Electric Cello, and Cement Mixer. For a couple of days we have heavy seas, with winds up at 35 knots and whitecaps that wash across the deck-level portholes. At one dinner, the usually boisterous and hungry science crew stares quietly and palely at bowls of spaghetti and meatballs.

After a couple of days along the north coast of Svalbard, where we can see the craggy, snow-covered fjords of Ny Alesund—where some of the longest-running, high-latitude records of persistent pollutants have been logged—we turn south toward Iceland along the east coast of Greenland. About 340 miles north of Iceland we pass Jan Mayen Island, the world's northernmost volcano, where by 1638 Dutch whalers had hunted the last of the local Greenland right whales to extinction. According to seafaring lore, an Irish monk named Brendan sailed close to the island in the sixth century, saw the fiery mountain surrounded by glaciers and freezing seas, and reported that he'd found the entrance to hell. When we sail by it's a snow-covered Mount Fuji rising from the sea against a clear blue sky. Gannets, gulls, skuas, and fulmars ride the turquoise-lit swells, likely carrying with them invisible loads of pollutants, some of which may be decades old.14

"We are seeing these chemicals in people and in biota where they shouldn't be," says Tom Harner. "With the newer generation of chemicals we're going at things a bit more quickly than we did with what we're now calling the 'legacy POPs,'" says Harner. "We're now trying to extrapolate from our existing knowledge base. Some models apply fairly well. For example, with PCBs and PBDEs, there's pretty good agreement on how these chemicals behave in the environment," he explains. I think of the molecules Monica Danon-Schaffer sketched out for me and how the PBDEs so strikingly resemble PCBs.

"But some of these compounds almost have two personalities," Harner continues. "In one phase they can be hydrophobic—resist water and prefer to partition or attach to fat—and so accumulate in fat tissue, soil, and plant cuticles. In other phases they can be hydrophilic—be water-soluble—and be transported that way." In other words, some compounds can hop, swim, and fly—behavior that is influenced both by the chemicals' structure and the physical landscape and atmospheric conditions that surround them.

Asking questions about how a chemical's structure will determine its behavior under various environmental conditions is a prerequisite of green chemistry. Had such questions been asked about PCBs or PBDEs— or had more attention been paid to the answers and their implications— they might not be turning up in birds cruising the northernmost fjords of Norway, for example. Similarly, had such questions been asked of some everyday plastics, their molecules might not be making less lengthy but no less significant journeys from products made from those materials to our bodies.

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