Plastic Is Blowing in the Wind.

• Position: EYE ON ECOLOGY - Microplastics

As the plastics in our oceans break up into smaller and smaller bits without breaking down chemically, the resulting microplastics are becoming a serious ecological problem. A study by the Weizmann Institute of Science, Rehovot, Israel, reveals another troubling aspect of microplastics (defined as particles smaller than five millimeters across): they are swept up into the atmosphere and carried by the wind to far-flung parts of the ocean, including those that appear to be plastic-free.

Analysis reveals that such minuscule fragments can stay airborne for hours or days, spreading the potential to harm the marine environment and, by climbing up the food chain, to affect human health.

"A handful of studies has found microplastics in the atmosphere right above the water near shorelines, but we were surprised to find a non-trivial amount above seemingly pristine water," says researcher Miri Trainic.

While the way in which oceans absorb materials from the atmosphere has been well studied, the opposite-direction's process--aerosolization, in which volatiles, viruses, algal fragments, and other particles move from seawater into the atmosphere--has been much less investigated.

The researchers detected high levels of common plastics--polystyrene, polyethylene, polypropylene, and more--in their samples. Next, by calculating the shape and mass of the microplastic particles, along with the average wind directions and speeds over the oceans, the team showed that the source of these microplastics was most likely the plastic bags and other plastic waste that had been discarded near the shore and made their way into the ocean hundreds of miles away.

Checking the seawater beneath the sample sites showed the same types of plastic as in the aerosols, providing support for the idea that microplastics enter the atmosphere through bubbles on the ocean surface or by being picked up by winds, and are transported on air currents to remote parts of the ocean.

"Once microplastics are in the atmosphere, they dry out, and they are exposed to UV light and atmospheric components with which they interact chemically," explains Trainic. "That means the particles that fall back into the ocean are likely to...