Disc covered in sediment used to detect microplastics in Anacosita and Potomac rivers
Credit: Bridget Reed Morawski

It was a gloomy Tuesday at National Harbor, with enough rainfall to soak your socks and render your eyeglasses useless. Save for a few rollicking ducks, few bothered to venture to the water’s edge on such a dreary day.

Except for Jesse Meiller and J. Adam Frederick, that is. They crouched over a dock at the casino and convention hub, marveling at the marine life that had accumulated on aluminum discs they had submerged into this notch of the Potomac River.

In the two weeks since the researchers last examined the discs and sunk them into the waterway, a miniscule menagerie of puffy sponges and gelatinous, mossy creatures known as bryozoans had formed. But while biodiversity is an essential component of their project, the work that Meiller and Frederick are conducting with the discs has evolved since it began: Now, they also want to investigate the presence of microplastics that may stick to the organisms.

Meiller and Frederick, who work respectively for American University and Maryland Sea Grant, are among the small cadre of local researchers, educators, and advocates seeking to further the area’s collective knowledge about just how pervasive microplastics are in D.C.’s waterways.

As the name implies, microplastics are tiny bits of plastic either intentionally created that way or bits of larger plastic products that have broken apart. The mere existence of microplastics in D.C.’s waterways is no singular circumstance. Microplastics have been found in waterways across the country, from shellfish on an Alaskan island to 10,000 feet above sea level in Colorado’s Rocky Mountain National Park. Closer to home, microplastics have been found in more than 50 Pennsylvanian waterways.

However, urban areas like D.C. tend to have higher concentrations of microplastics in their watersheds than the waterways of less populated areas, according to Matt Robinson, an environmental protection specialist with the District’s Department of Energy & Environment.

But even though microplastics have been found in waterways and other ecosystems around the country, they’re an understudied topic and it’s currently unclear just how many have accumulated in the Anacostia and Potomac rivers. D.C. doesn’t have a continuous monitoring program in place for microplastics, says Robinson.

“The one thing we have been doing for the past 10 years is we’ve been monitoring the macroplastics [and] the trash in the Anacostia and Potomac [rivers] and Rock Creek,” Robinson says. Because the Anacostia River is one of the most polluted rivers in the country, the federal government has put the city on a “pollution diet” known as a total maximum daily load. Complying with the TMDL essentially means that a jurisdiction must make sure a waterway identified as needing help meeting water quality standards cannot exceed a predetermined amount of pollutants.

To adhere to the TMDL and minimize the amount of plastics that end up in its waterways, Robinson says the District has installed trash traps along the Anacostia, in addition to street sweeping programs, illegal dumping enforcement, and litter clean-ups. But much of the trash in the waterways isn’t necessarily coming from the District, he says, particularly since the city instated the plastic bag fee in 2010.

“If we can highlight the ecological impacts, the human health impacts, and even the economic impacts from plastic pollution, specifically microplastic pollution, then we can potentially get other jurisdictions to do more, and help us with reducing plastic pollution in our waterways and waterways downstream,” he says. In D.C., “We’re heavily impacted by upstream sources of pollution, yet we’re less than 17 percent of the Anacostia watershed.”

“One reason we’re pushing microplastics research now is that a lot of the TMDL implementation is inspired by aesthetic impacts from trash pollution: We don’t want to see our waterways full of trash,” he adds. “However, there’s been very, very little work done on the ecological impacts of plastic pollution,” especially microplastics, he says, characterizing already published research on our waterways as “very disturbing.”

Still, certain educated assumptions can be made, since we have a sizable volume of visible trash and larger plastics in these waterways, and because microplastics are often shed from such litter, Meiller says.

But scientists prefer concrete research over mere assumptions, which is why, to identify whether or not fish in different parts of the Potomac River’s food chain consume different amounts of microplastics, a team composed of consulting firm Tetra Tech and the University of Maryland researchers will begin dissecting around 200 fish—blue catfish, mummichogs, largemouth bass, and striped bass—from across the Potomac River’s food chain this week.

The fish, euthanized before being wrapped in aluminum foil, were collected this past spring, summer, and fall and stored at a Baltimore area lab, in a walk-in cooler large enough for Tetra Tech fisheries ecologist Bob Murphy to lay down in. (Not that Murphy has—it’s much too cold, he says, joking).

The dissection project was created after Robinson and Murphy gave presentations at a 2019 workshop that highlighted that “we still have little idea of the magnitude and distribution of microplastics within the watershed, much less the potential impact microplastic pollution may be having on living resources,” according to a report summarizing the workshop’s findings.

The workshop was convened by a committee that advises the Chesapeake Bay Program, a partnership of regional governments that have made various agreements to reduce sources of pollution in the watershed and revitalize the ecosystem. One of the recommendations that came out of that workshop was to “collaborate on utilizing the existing bay and watershed monitoring networks to monitor for microplastic pollution,” which led to federal and regional funding of the dissection project and other related projects.

These projects aren’t the only local efforts, or even the only efforts that these researchers are undertaking. Meiller is also examining sediment and water samples taken with Barbara Balestra, another American University environmental science professor.

And at Nash Run, an Anacostia River tributary near the Kenilworth Park & Aquatic Gardens, American University graduate student Elisa Davey is studying sediment samples. She has already found a “pretty diverse” amount of microplastics, from fibers and bits of Styrofoam to beads. 

According to Meiller, if Davey’s research gets published, it will be one of the first published papers on the Anacostia River and microplastics.

In terms of published scientific literature, “There’s been enough research that has definitely shown some negative [health] effects” from microplastics in general, Murphy says. 

Still, what’s published and available doesn’t encompass the entire “family of potential issues that are associated with microplastics,” says Ryan Woodland, an associate professor of coastal ecology with the University of Maryland involved in the fish dissection project. Some of those problems could include bits of plastic obstructing a fish’s digestive system, or the toxins in the plastics leaching into the fish’s tissues and organs, he adds.

“It’s really hard to tease apart all of those possible negative impacts on an organism, because it has to be done experimentally,” Woodland says, adding that other external factors, such as rainfall, complicate the question. “And I don’t know that we have the body of research yet to really understand the full range of possible negative effects.”

The unknown public health impacts aren’t limited to the direct impact of just the microplastics. “Plastics that are out in the environment can actually carry other contaminants, too, along with them,” Meiller says, pointing out potential indirect consequences of traveling microplastics. 

“So it’s not just what was intentionally put into [the plastics], but also things that are unintentionally hitching a ride on them,” including certain pesticides, she adds.

Ultimately, research like this can hopefully impact how policymakers understand and subsequently respond to this and other environmental concerns. And while unpublished research can still promote better common understanding, published research has the potential to effect change.

“Peer-reviewed publications are best and are the gold standard,” Murphy says. When it comes to helping policymakers understand the scale or importance of a problem, “even if there is reliable, unpublished research that can provide context to a discussion, only the peer-reviewed, published research is typically considered in decision-making,” Woodland adds.

But policymakers aren’t the only people who researchers hope will learn from studies of this issue. Educators, academics, and local nonprofits have formed partnerships to help young students understand the ecological impact of their polyester T-shirts or single-use water bottles.

Meiller and Frederick, the researchers sampling at National Harbor, aren’t collecting the discs just for their own research. They’re also bringing the discs to a Maryland school district so students can see the pervasiveness of the microplastics problem with their own eyes and hoping to soon involve D.C. classrooms and teachers.

The discs are “a passive platform, and we bring them in and see what’s landing on them,” says Christopher “Rusty” LaMotte, a Carroll County Public Schools teacher for the past 16 years. “Not only do we talk about how much [microplastic] is being found there, but this is just a small little disc in a fairly sizable body of water.”

Which leaves the kids asking, “What else is out there?” LaMotte says.