As winter descends on Chicago, the PCBs left behind are trapped there, hibernating in a blanket of snow. But come spring, when temperatures warm again, they are set free, and they start globetrotting. Earth's atmosphere is like a giant beer distillery, with continuous cycles of heating and cooling and condensing, and chemicals like PCBs are constantly seeking equilibrium in the environment, seeking out cold climates. They move from the air to the soil and the air to the ocean, and back again, in a phenomenon called the "grasshopper effect." When temperatures rise, the compounds evaporate in the heat, and drift along slowly in the atmosphere at a height of perhaps 1,000 feet. When temperatures cool, they condenselike drops of dew that form on grassand fall to the ground. Some manage to move only a few hundred miles, from Chicago to Michigan, before they drop onto trees or roads or grass or cropland and remain there, slumbering throughout the cold winter. But come spring, when temperatures warm, they evaporate again, moving with northbound winds. Over the coming years, they continually rise and fall like this, hopping across the world, in search of a cold environment where they can eternally rest. Within a few years, they have joined the others that took a faster route to the North Pole. No one knows the precise amount of PCBs that are flowing to the Arctic, but by one estimate sixty-seven tons, mostly in the form of gases, arrive there every year.
Once there, the PCBs that reached northern latitudes via this atmospheric hopscotchthe fastest and most direct route to the Arcticjoin others that took other, slower pathways. Oceans are powerful vectors, their currents slowly carrying masses of contaminants north. In John Donne's "For Whom the Bell Tolls," the poem that proclaims "no man is an island," a clod of dirt from Europe washes out to sea. "We now know where it goes," says Rob Macdonald of Canada's Institute of Ocean Sciences in Sidney, British Columbia. "It goes to the Arctic."
It might take years or decades for a drop of PCBs that originated in Chicago and fell into the Atlantic to flow to the Arctic Ocean, the smallest of the world's oceans, via the small passages between the continents. Some travel the wide, open waters between Greenland and Norway's Svalbard islands, but others squeeze in and out of the Arctic between narrow straits separating Canada from Greenland and Siberia from Alaska. The oceans, like the atmosphere, carry tons of contaminants northbound, largely from the United States and Europe. "The ocean is a big lumbering giant," Macdonald says, "but once it becomes the flywheel, it can become an important source of contaminants." Rivers also empty into the Arctic Ocean, unloading large volumes of chemicals, particularly from Russia. Drifting sea ice stores and transports them, too. There are even biological messengersmigratory birds, fish, and whales that move chemicals from place to place.
Arriving by all these various pathways, the globe-trotting PCBs permeate everything in the Arcticits air, snow, ice, fog, soil, seawater, and ocean sedimentin all regions, no matter how remote, from Siberia to Greenland. Upon their arrival, most of the PCBs stop moving. About two-thirds of the PCBs that find their way to the Arctic stay thereperhaps forty-six of the sixty-seven tons are added to its environment every year, while twenty-one tons continue hopping around the world, according to one scientific estimate. These compounds are slow to break down in frigid temperatures, so they endure in the ice for decades, perhaps centuries. Arctic ice melts and freezes in endless cycles, and the chemicals tend to accumulate along the ice edge. This is where they end their physical voyage and begin a biological one.
Copyright © 2005 by Marla Cone. Reprinted with permission from Grove Atlantic, Inc. All rights reserved.
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