Up the River

In these rivers, you can find jewelry, shards of glass, ceramics, and the rusty machinery that brought the Industrial Revolution to the U.S. As this economy brought more people to urban centers, pollution only increased with water flowing down the same pathways from cities to rivers to the bay, as they have for hundreds of years. At the same time, the very first plastics were being invented. Today, a product of that era of invention and industrialization is concerning researchers and grabbing public attention: Microplastics. 

Microplastics are pieces of plastic less than 5mm long. Sunlight, chemicals, and friction all contribute to the degradation of larger plastics into these minuscule particles, while some plastics such as microbeads are designed to be that small. Due to their size, they infiltrate waterways and float into the atmosphere, with some airborne plastic traveling thousands of miles from its original source. A large percentage of airborne microplastics are hurled upward from tires when you press on your brake; a  three-year study  done by a British company, Emissions Analytics, found that a car’s tires collectively spew out one trillion particles every kilometer [0.6 miles] driven. This tumultuous journey often ends with the microplastics in the bodies of organisms, including humans.

This summer, Kate Zmich, studying environmental science at the University of Rhode Island, and Ally Fennell, a student double-majoring in chemistry and chemical engineering at Roger Williams University, are collecting and analyzing microplastic samples, contributing to a larger,  long-term data collection project  led by Dr. Lillian Jeznach, professor of civil and environmental engineering at RWU. Their study will examine water quality on three major rivers, the Pawtuxet, Woonasquatucket, and Blackstone, in Rhode Island, as well as microplastic deposition from the atmosphere onto the Roger Williams University campus. With this data, they hope to establish how wastewater treatment plants and population density impacts microplastics.

Part of their goal is also to use data collection and analysis processes accessible to undergraduate students studying science and engineering so that more data can be collected in coastal areas where there are lots of university students. 

“Our goal is to try to show that if you live by the water, you can easily afford to do this,” says Ally. “Then we could get an account of the microplastics around the world and get a better idea of how many there are.”

Wastewater treatment plants, which remove pathogens, chemicals, and solid waste, are not designed to remove microplastics. Due to their small size and low density, microplastics surpass filters and chemical cleansing to make their journey into larger waterways. A focus of the project is to understand how the dumping of wastewater affects microplastic concentrations downstream to show that wastewater treatment plants could be technologically expanded to remove microplastics.

“A major source of microplastics is from wastewater treatment plants,” says Jeznach. “Much of the clothes that we wear has microplastics. So you do the laundry at your home, your dryer vent is blowing microplastics into the air and your wastewater from the laundry machine is going to the wastewater treatment plant.”

Providence is at the bottom of the Narragansett Bay watershed close to the outlet that drains into Narragansett Bay and, because of its urban concentration, has a high percentage of impervious cover, or material that is impermeable to precipitation. The watershed has 14% impervious cover while the immediate coastal lands that drain to the bay are 20% impervious, according to the recent Narragansett Bay Estuary Program environmental condition report,  Currents of Change . Every time there’s a storm, polluted runoff and plastics travel easily from roads, sidewalks, and parking lots into rivers and streams, and eventually Narragansett Bay. 

“For two reasons [this research] is important for Rhode Island: The first is because we're so urban, we're going to have a lot of pollutants. We're going to have a lot of pavement. The second reason is, it's all ending up in the bay,” says Jeznach. “The coastal economy is really important to us, the tourism economy, the seafood. I love oysters, but I've read articles that say every oyster has microplastics in it. They're filter feeders, right? I still enjoy oysters, but I always think about it.”

Out in the field, Kate wades into the Woonasquatucket River and holds a cone-shaped filtration net underwater for five minutes, during which microplastics are funneled into a canister at the end of the net. Using distilled water so as not to contaminate the sample, Ally and Jeznach spray out the canister’s contents into a sample jar. 

To sample the atmospheric microplastics, a different canister is located on the RWU campus to collect precipitation that contains the airborne microplastics. 

“I wanted to see how weather affected microplastic accumulation,” says Kate. “I'm starting to put out the canister in rain periods to see if precipitation influences microplastics because we know that wind influences it a lot.” 

By using accessible equipment, students anywhere could contribute to this project by measuring concentrations in their own backyard. With more data, a clear connection can be drawn between population, infrastructure, and microplastic deposition, which will affect plastic product design, policy changes, and integration of microplastic-removing technology. Over time, a model could be developed that predicts future deposition based on previous patterns observed by the team.

“[This summer] we're only studying it in three different spots, freshwater-wise, and one spot atmospheric,” says Ally. “So for us to really make an impact and tell people, we have to make it more widespread, so that more people can relate to it, like ‘Oh, this is in my area. I should care’.

In the lab, Kate and Ally open up a fridge full of the microplastic samples collected over the summer. Before examination, they use a process called digestion to remove organic matter, leaving only inorganic particles including the microplastics. Fibers from textiles are the most visible in samples and are counted using an optical microscope. 

“We treat the fresh water with a KOH chemical, potassium hydroxide, to kill the organic stuff. We call it digestion, and it basically just gets rid of a lot of the organic matter so when we look at it, it's not as busy,” says Ally. 

For smaller plastic fragments, a chemical stain called Nile Red absorbs into the surface of the fragments and makes them glow under blue light. With the tiny fragments now visible, Kate and Ally count the types of plastic in the sample, creating a population study of the microplastics in locations along the rivers and in the atmosphere.

Often, research focuses on things we can see, so things that are invisible are sometimes ignored. However, Jeznach believes that the COVID pandemic changed that pattern. “You see the uptick in attention on indoor air pollution,” says Jeznach. “We're masking and we're worried about droplets of water and the virus in people's breath. Perhaps this has made us think more generally about our air quality inside and outside.”

In the future, these studies could be used to create “a map of Rhode Island with a bunch of different pie charts showing how much difference in microplastic accumulation there is along the rivers that lead into Narragansett Bay,” says Ally. “Then, we can see where to focus technology to remove microplastics in certain areas.”

As microplastics gain more attention and research exposes their ubiquitous presence and adverse effects on health, technology, science, and policy can work together to inspire design that directly improves our lives. 

“It’s important to think about designing products more sustainably, thinking about what materials to use, thinking about the whole life cycle of a product,” says Jeznach. “From the design perspective, we're such a consumer society and we're going to keep buying these plastic products. So how can we change consumer behavior and design things better from the start?”