06/06/2010 01:01:00 PM EST
Plastic garbage zones are not just in the Pacific
The plastic garbage patch in the Pacific Ocean has received substantial media attention. However, recent studies have shown that there are a number of such garbage patches, and that unfortunately they are larger than originally believed.
The so-called Great Pacific Garbage Patch is estimated to be 3.5-million-square-kilometer swath (about twice the size of Alaska); sampling suggests it contains more than 20,000 bits of floating plastic per square kilometer. Large swaths of the western North Atlantic also hold significant amounts of plastic debris, according to recently published research. As in the Pacific, the vast majority of the plastic bits scooped from the North Atlantic were tiny; analyses indicate that most of these barely buoyant bits were less than a centimeter across and weighed less than 0.15 grams.
While the stereotype is that this plastic detritus floats on the surface, researchers found that wave action could drive the material to 20-meters below the surface.
Computer simulations indicate that the ideal conditions for the accumulation of these materials are in areas where surface currents converged and flowed at less than two centimeters per second. If correct, then two areas particularly suited to trap flotsam are near South America, one west of central Chile and the other stretching from Argentina across the Atlantic nearly to South Africa. However, little research has occurred in these areas, perhaps because these regions are not biologically productive.
Abstracts of recent papers presented at the February, 2010 Conference of the American Geophysical Union on this issue can be found at http://www.eurekalert.org/pub_releases/2010-02/agu-2os021810.php.