Science Results : Daily Update

Daily Update | Current SEA Research

July 6, 2010

By Giora Proskurowski

Today we passed the century mark for neuston tows. Just before noon today we put our 100th neuston net in the water. That means that on this trip we've towed a 3-foot swath through the ocean that is about 200 nautical miles (230 statute miles) long.

During this time we've captured, counted, and archived almost 46,000 pieces of plastic. The vast majority of these pieces are very small, about half the size of a pencil eraser or smaller. If we assume that the average mass of this plastic is about a one-tenth the mass of a paper clip (0.02 g), then the sum total of our collection is approximately 3 pounds (this mass does not include the larger plastic pieces, greater than 5 cm, that we've caught in our tows).

While the mass of this amount of plastic seems somewhat underwhelming, it is critical to remember that this number both excludes the larger pieces that we've collected in the nets, that plastic is not just in the surface but distributed throughout the mixed layer, and that this is from just a single meter swath of the ocean.

In my mind, the most difficult part of explaining oceanography to students and the public is trying to convey the enormous size of the ocean. When you spend four weeks at sea without seeing land, and leave from a remote island, the appreciation for the size of the ocean deepens. However it is still hard to grasp that the seemingly endless horizon surrounding this ship is a circle with a radius of only four or five miles – not even a tiny pixel on a satellite image.

Thus the values for plastic concentration that we measure with our nets is rapidly scaled up when we start extrapolating to larger areas. The ounce of plastic we collect in a neuston tow can represent several thousand pounds of plastic in the radius of the Cramer's horizon (say around 20 pounds per square mile), and many millions of pounds in this region of the Atlantic.

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For more from sea, listen to an interview with Chief Scientist Giora Proskurowski on the July 2, 2010 Science Update podcast, produced by AAAS.