Science Results : Daily Update

Daily Update | Current SEA Research

June 14, 2010

By Giora Proskurowski

One of the hypotheses that we're testing is that the amount of plastic we sample at the surface (using a neuston net or similar device) is an underestimation of the total plastic distributed throughout the upper water column.

While sailing as chief scientist with a SEA Semester last summer in the North Pacific subtropical gyre, I observed that under calm conditions (the surface of the ocean being either glassy or only slightly rippled) I could actually clearly see the fragmented plastic debris. Furthermore, when the wind picked up just a bit, the fragments became much more difficult to see. This could be because the uneven surface makes it hard to actually see the small pieces, or it could be that as the wind picks up it begins to stir the upper ocean, effectively mixing plastic down away from the surface where it cannot be easily seen.

For several hours this morning we had exceptionally calm, glassy, conditions. Sure enough, when the water was still, all of a sudden you could look from the deck of the ship and pick out small white specks in the water. Certainly, some of the specks were bubbles, or jellyfish, but for the most part these white specks were the same types of plastic fragments we are collecting in our nets.

One of our main objectives on this trip is to link how the wind, the sea state, and the weather conditions affect the distribution of plastic on the surface of the ocean. To do this we need many carefully measured data points, and thanks to the diligent work of the ship's company we are up to nine tows, with almost 1400 pieces of plastic carefully separated from Sargassum and biomass.