Wednesday :: Aug 25, 2010

One word: Plastics

by Turkana

Good science, bad news:

Despite growing awareness of the problem of plastic pollution in the world's oceans, little solid scientific information existed to illustrate the nature and scope of the issue. Now, a team of researchers from Sea Education Association (SEA), Woods Hole Oceanographic Institution (WHOI), and the University of Hawaii (UH) published a study of plastic marine debris based on data collected over 22 years by undergraduate students in the latest issue of the journal Science.

A previously undefined expanse of the western North Atlantic has been found to contain high concentrations of plastic debris, comparable to those observed in the region of the Pacific commonly referred to as the "Great Pacific Garbage Patch."

The greatest concentration of the more than 64,000 pieces of collected plastic was centered at a latitude roughly corresponding to Atlanta, Georgia.

Said SEA scientist Kara Lavender Law, the Science paper's lead author, "Not only does this important data set provide the first rigorous scientific estimate of the extent and amount of floating plastic at an ocean-basin scale, but the data also confirm that basic ocean physics explains why the plastic accumulates in this region so far from shore."

Surprisingly, despite a great increase in the disposal of plastics over the twenty-two years of the study, the concentration has not increased.

The whereabouts of the "missing plastic" is unknown.

Which is disturbing on many levels, and the report itself offers some seemingly possible explanations, although measurably improved efforts at preventing or recapturing spilled industrial resin pellets is not considered likely, as such residue constitutes but a small fraction of the overall material; and dispersal through anomalous currents and eddies is not considered capable of having offset the fourfold increase in input over the course of the study.

Possible sinks for floating plastic debris include: fragmentation, sedimentation, shore deposition, and ingestion by marine organisms.

Although it's considered unlikely that enough plastics could have broken down that much over the study's timeframe, and there's no evidence suggesting much of it sinks.

Because the cohort of pelagic organisms that ingest plastic, their ingestion rates, and the fate of ingested plastics are unknown, it is impossible to estimate the size of this sink.

In other words, we just don't know. The remaining accumulation is massive, but even more is missing, and there are no good explanations. Not that any truly plausible explanations could be defined as "good," anyway.

Further, the model indicates that the minimum time for surface tracer (i.e. drifter or plastic) to reach the collection center from the U.S. eastern seaboard is less than 60 days, at least half the time required to travel from Europe or Africa. The influence of the Gulf Stream is particularly evident in some of the fastest propagation times – 40 days from Washington, DC and Miami, FL, for example – in which tracer traveled along the coast before entering the gyre interior. While not indicative of the size or location of landbased sources, or of the age of debris, these estimates demonstrate how quickly plastic entering the ocean near major U.S. population centers could impact an area more than 1000 km offshore.

Just another contribution of our fossil fuel economy to the world's ecosystems.

Turkana :: 3:41 PM :: Comments (5) :: Digg It!