Sea's Surface "Microlayer" Polluted By Paint Dust

September 10, 2014- Ocean science researchers have determined that plastic pollution in the form of microscopic flecks of abraded paint and fiberglass is accumulating in the sea's topmost microlayer.

In an article entitled "Sea Polluted By Paint Dust," ScienceMag.org is reporting the tiny particles of paint, abraded from the decks and hulls of fishing vessels, are floating in the ocean could pose a threat to tiny creatures called zooplankton, which are an important part of the marine food web.

Kara Law, an oceanographer studying plastic pollution at the Sea Education Association in Woods Hole, Massachusetts (not involved in the study) tells ScienceMag.org, "The discovery is continuing to open our eyes to how many small synthetic particles are in the environment.

Won Joon Shim, an environmental chemist at the Korea Institute of Ocean Science and Technology in Geoje-shi, South Korea, along with other researchers, focused on the ocean's microlayer. The millimeter-thick skin of the ocean differs from the underlying water because surface tension and sticky secretions from microbes keep tiny particles within the layer.

Earlier studies scanning the ocean for plastic pollution had never specifically considered the microlayer. Instead, bulk samples were collected from the surface and below. Also, earlier studies used coarser nets to capture the tiniest particles.

Shim and his colleagues collected water samples along the southern coast of Korea, up to 16 kilometers offshore. Using a sieve with 2-millimeter-wide holes, they were able to collect water from the microlayer. The plastics found were well known: polyethylene, polypropylene and expanded polystyrene. But, surprisingly, these made up just 4% of the particles.

"Eighty-one percent of the synthetic particles in the microlayer consisted of alkyds, a binder in paints, the team reported online ahead of print in Environmental Science & Technology," writes ScienceMag.org. "Another 11% were polyester resins used in paint and fiberglass. On average, a liter of water from the microlayer contained 195 particles—this concentration is 10 to 100 times higher than microplastic particles in water collected by other methods."

From the dark green and dark blue colors, the paint and fiberglass particles were determined to be coming from the more than 17,000 small fishing boats of the same colors that ply the Korean waters.

Lab tests using infrared spectroscopy matched the particles with paint chips that the researchers collected from local shipyards. Because alkyd paints are used above water, the researchers assume the coatings (and the fiberglass) end up in the water after being abraded by nets, ropes, or anchors, or when the boats are scraped and repainted.

Shim and the researchers did not find particles of antifouling paint, which is used on hulls and contains toxic chemicals. Presumably, these chips are dense and sink; previous studies have found them in bottom sediments in maintenance areas.

ScienceMag.org writes that Shim and his colleagues now plan to study the metals and organic chemicals on the paint particles and determine whether they can harm marine life.

Read the full ScienceMag.org post here.

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