Day 16 S/V Kaisei: Plastic “B-B’s”

19 08 2009

Wednesday, 19 August 2009
Lat: 36° 10’ N Lon: 140° 28’ W

Plastic Pellets

Preproduction Pellet

Preproduction Pellet

Anthony Andrady, PhD, is a Senior Research Scientist in the fields of chemistry and life sciences. He was kind enough to respond to our question about the plastic pellets we are finding.

Around 190 million tons of plastic resin is manufactured annually worldwide. The resin is typically produced as pellets or prils that are a few millimeters in size. Bags of these pre-production, virgin resin pellets are shipped to fabricators who manufacture various plastic products. The fabricator will re-melt the plastic pellets, mix various additives to obtain the desired properties, and process the mix (called a plastic ‘compound’) into the desired shape. These compounded plastics may also be formed into new pellets and transported again, to other processors. The plastic pellets in the ocean originate from large shipping vessels during sea transportation and significant runoff occurs from land-based, plastic-processing operations. How much of virgin resin pellets enter the ocean has not yet been reliably quantified.

However, it is important to note that the team observed only the pellets that float in seawater; likely suspects are: polyethylene, polypropylene, and polystyrene. Other types of pellets, such as nylon or polyester, are denser than seawater and will not be encountered in surface-water collections. Yet, these pellets either remain in mid-water or reach the benthos (sea floor); interacting for incredibly long times with the organisms in such regions. Even, with plastics that initially float in seawater, our work found that surface fouling and incrustation of the plastic material increases the density to a point where they invariably sink in the ocean. Therefore, any semi-quantitative assessments of the pellets the team makes will be serious underestimates of the quantities present at a given location.

Tony L. Andrady PhD of Helix Science LLC is the author of “Plastics and the Environment”. He resides in Research Triangle Park, NC

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