Science Results : Daily Update

Daily Update | Current SEA Research

June 28, 2010

By Giora Proskurowski

I'm turning over today's report to our third assistant scientist, Skye Morét-Ferguson. Skye has been intimately involved with the plastics research at SEA since she first started sailing as an SEA scientist in 2005. Skye has been at the front lines of this research for the last couple of years, doing most of the quality control on the data and sample sets going back to 1986. Her many SEA voyages, combined with keen attention to the details and patterns of the ocean have given her an intuitive grasp of ocean life that many oceanographers do not possess.

By Skye Morét-Ferguson

There is a certain kind of plastic particle making its way to beaches and the open ocean that has been receiving considerable amounts of media attention lately – the plastic pellet, also known as a "nurdle" or "nib". Think of a plastic pellet as an early and vital step in the industrial plastic process. Like grain, virgin plastic can be shipped in bulk and then melted down to make different consumer plastic items. Therefore many times pellets have not yet acquired the chemical additives that change their color and malleability.

The pellets that we collect in our nets often look translucent white to light brown (and on a rare occasion, black). Their shape is much like the top of two hamburger buns face-to-face and sized down to approximately 3 to 4 millimeters in diameter and about 2 millimeters high, and thus quite recognizable.

SEA students and professional scientists have been distinguishing between pellets and "user" plastics such as fragments and line for the last 30 years. This protocol was established to quantify open ocean pellet concentrations over time, and to possibly discern point-source pollution, as other coastal studies had accomplished in the 1970s and 1980s.

In 1991, parts of the plastics industry voluntarily instituted a Pellet Retention Environmental Code – a "commitment to total containment of plastic pellets," outlining ways to prevent spillage and to recapture spilled material. SEA scientists who have sailed for the last few decades will tell you that they have seen the results – they see fewer pellets now than they have in the last couple of decades.

Out of the 67 neuston tows on our trip so far, pellets have made up an average of 0.6 percent of plastic collected in each tow, or 6 pellets for every 1000 degraded "user" plastics (fragments, thin sheets, line, foam, etc.). The highest percentage of pellets in any tow made up 4.4 percent of all plastic particles. For perspective, that number signifies 1400 pellets per square kilometer, as opposed to the 30,500 "user" plastics also in that same square kilometer.

The take home message is that pellets in the open ocean are not the greatest threat when it comes to marine plastic pollution. We all need to make a concerted effort to keep the plastic items that we use on a daily basis from entering our waterways.