Media reports about marine pollution have tended to fixate on the idea of "great garbage patches"--huge floating islands of waste circulating in the gyres of the major oceans. Outlets have often spoken of patches "twice the size of Texas", giving the impression of trash blankets easily visible from planes or satellite.
The reality, say scientists, is something less tangible, though no less alarming. The trash--most of it plastic--may not be easy to see. But it is there, suspended in tiny pieces, on the surface, and below the waves. And new research indicates that the problem may even be worse than previously understood.
According to Giora Proskurowski, a project scientist at the University of Washington, what lies on the top of oceans is only a fraction of what lies beneath. On average, the next 100 feet below the waterline contains 2.5 times the plastic of what’s on the surface, he says. And, when winds are really churning up the water, there could be as much 27 times more plastic in the water column.
"When you take a surface measurement, you are only sampling a small percentage of what’s integrated below," he says. "With 20-knot winds, say, there is a significant amount of turbulence, and that will mix up a large percentage of the top layer of plastics that were on the surface, and distribute them in the top 100 feet."
The finding, which is detailed in the journal Geophysical Research Letters, is important because it may show that previous research--which didn’t account for winds pushing debris below the water--have significantly underestimated the amount of plastic in the oceans.
"What we’re saying is that, in addition to gathering the sample, you have to gather the environmental conditions about how you took the sample, because they are extremely important to how much plastic is truly there," Proskurowski says.
Based on their work, Proskurowski and his colleagues plan to publish a "recipe" that other researchers can use to combine data, and gain more consistency. Hopefully, that should help dispel myths about marine plastics, while drawing attention to the true scope of the problem.
"We don’t need the hyperbole," Proskurowski says. "This is massive problem impacting millions of square miles of each of the major oceans, and so there really isn’t the need to exaggerate about being able to walk on something twice the size of Texas. That is just noise that can come back to haunt you."