Mapping Microplastics

Chemist Melissa Maurer-Jones is on a quest to map Minnesota’s microplastics. The University of Minnesota Duluth professor runs a lab studying two things. First, her team is looking into how different environmental stressors, like sunlight, change and break down plastics. Second, they are investigating how abundant microplastics—plastics less than 5 millimeters in length—are in Minnesota’s natural environment. In one study, Maurer-Jones and colleagues found that plastics in the St. Louis Estuary were bigger and more diverse than those in Lake Superior. “All of this makes sense because [the harbor] is closer to where things are being deposited,” she says. “When you get out into the open lake, there’s more time for the plastics to break down.” Maurer-Jones wants a comprehensive picture of microplastics in Minnesota. Her small team is limited in the sampling it can do in our lakes, streams, and rivers. But roughly four years ago, the chemist had an idea. She could build a kit and distribute it to middle school and high school students so they could sample water bodies, count the microplastics, and load their results into what will become an online public database. The project will provide a detailed look at microplastics’ presence in time and place across the state. We called her up to learn more.

Q | How does the project work?
High school and middle school classrooms across the state can request to borrow kits, follow protocols, and get outside. Right now, we’re just looking for volunteer classrooms to continue to deploy these kits. The ultimate goal is to develop a publicly accessible database that will house all of the protocols and information for teachers or other citizens. That database will be up and running around the end of 2027.

Q | What's in a kit?
Most importantly there’s a sieve stack we use to collect particles out of water. There’s also a bucket. Participants collect 10 buckets of water and pass them through sieves. They get the particles off the sieves and onto a filter. They use digital USB microscopes to look at the filters under a microscope and count particles.

Q | Why did you engage students in the project?
First off, there’s a lot of evidence that if you have trained scientists leading citizen science, you tend to get more accurate results. By going through classrooms, we have teachers trained to be scientists. Second, by having many students in one classroom doing measurements, we’re getting replicates. Third, a lot of evidence exists in the education literature that if you get kids doing things in the environment, they build a sense of stewardship and a sense of curiosity about the world around them.

Q | How big of a problem are microplastics in Minnesota?
Microplastics are everywhere. We use a lot of plastics, from the clothes we wear to the chairs we sit on to street sweepers and snow removers with plastic in their bristles. In Minnesota, we’re seeing microplastics in all the lakes tested. They’re not as heavily impacted as some more populous regions of the world. So that’s a positive. Now, the question of, “How much microplastics is bad”—we don’t know yet. And so there are no policies in place yet in terms of regulatory levels or limits or threshold.

Q | What can we say about the impacts of microplastics?
Just like big plastics can cause turtles to have full stomachs and not eat, microplastics can do the same thing for small filter feeders. We’re finding that smaller size ranges, nanoplastics, have the potential to cross biological barriers. Some harm can come from all the things that plastics can carry. Plastics are hydrophobic oil-like particles able to pick up other pollutants, including heavy metals or other organic pollutants. And plastics are a complex mixture with additives and pigments, and they can leach out those additives and pigments. They also seem to persist in the environment.

Q | How will knowing the amount of plastics help us?
If we understand how much microplastics are in our water bodies and, importantly, how they might change given different times of year or different years, we can better understand what’s causing the pollution to happen and potentially mitigate some of that. For example, perhaps there’s an opportunity to put a filtration system in a stormwater system that would help pull out some of the microplastics.

Q | What should a Minnesotan concerned about microplastics do?
Plastics serve an important purpose. We use them in a lot of ways in our day-to-day life—for healthcare items, for insulation around cabling. I don’t want to demonize plastic. My advice and encouragement is try to use fewer things that include single-use plastic. Getting involved in cleanups can be really important. Lastly, it’s important to continue conversations on a local government level. Even a small nominal nickel charge for single-use plastic bags seems to encourage people to choose reusable options when they have that opportunity.