Sea junk.
Objects lost in the ocean can traverse the Subarctic Gyre for years.
Credit: (map) Ebbsmeyer et al., Eos 88, 1 (2007); (flotsam) Dave Ingraham
Shoes, toys, and other flotsam in the North Pacific can float as many as 13,000 kilometers, only to wind up 3 years later exactly where they started. The surprising finding comes thanks to the most realistic simulation to date of the Subarctic Gyre, a current that traces a circular path between North America and Asia. The analysis sheds new light on the complex movements of the ocean, which affect transportation, climate change, and other key environmental issues.
Every ocean hosts one or more gyres, created by Earth's rotation and prevailing winds. Little is known about the exact paths and power of these gyres, so Curtis Ebbesmeyer, a retired oceanographer based in Seattle, Washington, and collaborators created a model of the Subarctic Gyre. As a reality check, the team predicted trajectories of small objects caught in the gyre, such as plastic toys and Nike sandals--the kind of junk that has washed up in droves every so often on coastlines.
Drifting roughly 11 centimeters per second, the hypothetical flotsam took 2 to 4 years to circle the gyre. The team then compared those estimates to real-world observations. In 1992, for example, 29,000 toys on a cargo ship en route from Hong Kong to Washington state fell overboard in the North Pacific. Since then, beachcombers in Sitka, Alaska, have reported finding some of the lost toys at about 3-year intervals.
Ebbesmeyer says that the new model of the Subarctic Gyre will allow oceanographers to better understand the navigation of sealife, such as the migration routes of salmon. In addition, he says, the findings--published 2 January in Eos--show that buoyant junk keeps on drifting and poses a long-term hazard to seabirds and other creatures that might ingest it. "You lose something in the ocean, and it doesn't disappear," Ebbesmeyer says.
The model could also help researchers track oil spills and harmful algal blooms, notes oceanographer Nandita Sarkar of Old Dominion University in Norfolk, Virginia. "A study like this can be really helpful," she says.
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