Puget Sound microplastic pollution 'everywhere we've surveyed for it,' study shows
BREMERTON — Walk any Puget Sound beach and you're bound to find plastic garbage — a soda bottle, a chunk of foam, maybe a dog's lost chew toy.
But that's just the plastic pollution you can see. The results of a recent volunteer-powered research project suggest there are tiny particles of plastic suspended in nearly every jarful of water along the shoreline.
Non-profit Puget Soundkeeper Alliance teamed up with the University of Puget Sound to analyze water samples gathered last fall by volunteers around the Sound. They found an average of 2.8 pieces of microplastic (plastic bits smaller than 5 millimeters) per 150 milliliter water sample (roughly 1 gulp, to use an unscientific term). A sample taken in Bremerton produced four pieces of microplastic.
The first year of the monitoring program didn't produce enough data to support a published paper, but UPS conservation biologist Peter Hodum said even the anecdotal results highlight how pervasive microplastics have become.
"It's incredible," Hodum said. "It's a little scary."
Microplastic pollution is a fast-expanding area of study, as plastic debris has been found in the digestive tracts of animals ranging from mussels to albatrosses.
In Puget Sound, microplastics appear in myriad forms, from myriad sources. Some are fragments broken loose from deteriorating pieces of trash, crumbs rubbed off car tires on the highway, or fibers shed from those synthetic fleece pullovers Washingtonians are so fond of. Storm and wastewater systems dump microplastics into streams and the ocean while the wind sprinkles plastic particles from above.
Hodum said there is no good estimate for how much microplastic exists in Puget Sound, but research has shown plastic is present from the surface to the sediment.
"Everywhere we've surveyed for it... we do find plastic at some level," he said.
Puget Soundkeeper Alliance mobilized its volunteer network to add to the body of knowledge on Puget Sound microplastics. A year ago, the group organized freshwater sampling effort along the Green and Duwamish river basin. Those samples, analyzed by UPS students, turned up an average of 3 pieces of microplastic per 150 milliliters.
Last fall, Puget Soundkeeper expanded its study to the marine waters of Puget Sound, shipping sampling jars to volunteers taking part in the yearly International Coastal Cleanup. Participants returned 45 samples for analysis, which was completed this spring.
Samples revealed widespread microplastic pollution. Kathryn Davis with Soundkeeper said the majority of the plastic pieces identified were fibers. Much of the material could only be seen under microscopes. The most plastic-laden sample analyzed carried 11 bits of microplastic.
Davis said the sampling work was useful both as a citizen science project and a conversation starter.
"We thought it would be a great way to understand how microplastic is distributed in Puget Sound and get people involved," she said. "... It makes us realize there's a lot out there that we can't see."
While it's clear microplastics are abundant in Puget Sound, the effects of the pollution are still largely unknown.
"Where it gets harder is the 'so what?' question," Hodum said.
Scientists know microplastic can have a direct impact on animal species by gumming up the digestive tracts of small organisms. The bits of plastic also act as sponges, absorbing compounds from the surrounding water. Organisms that ingest plastic receive a dose of contamination. As with other types of pollution, those toxins can become progressively more concentrated, or biomagnified, as they're passed up the food chain to larger animals such as salmon, seals and whales.
"That can ultimately have implications for humans, too," Hodum said, adding much more research is needed to determine the extent of the health risks posed by microplastics.
Devising strategies to prevent the spread of microplastics is tricky because the pollution is so widespread and varied. Large-scale strategies could include filtering for microplastics at wastewater treatment plants.
For individuals, reducing the use of single-use plastic items like carryout bags and water bottles is a good place to start, Davis and Hodum agreed.
"Just be intentional about your use of plastics," Hodum said. "Where are they appropriate? Where can I avoid using it?"
Davis noted some companies have begun marketing filtration bags that capture fibers from synthetic clothing as it's laundered. (Patagonia's Guppyfriend washing bag sells for $29.75.)
Puget Soundkeeper Alliance plans to keep sampling for microplastics each fall. People interested in volunteering can contact Davis at email@example.com.