Starting in the late 1990s, a mysterious “something” in road runoff was killing coho salmon in the Pacific Northwest.
It wasn’t until 2021 that scientists identified a chemical from car tires as the apparent source of the problem – specifically, a chemical called 6PPD-quinone, which forms when the additive 6PPD used in tires reacts with ozone from the air.
It got some Minnesota scientists wondering if this same toxic chemical could be impacting fish here. And then NRRI Environmental Chemist, Bridget Ulrich, took that thought one step further.
“We’re not seeing mass fish kills like they did in the Pacific Northwest, so maybe we shouldn’t focus only on that one compound,” she wondered. “What else could be out there that we’re not catching? That’s what led to the ‘Catch and Reveal’ project.”
A Wide Net
After receiving funding from the Legislative Citizens Commission for Minnesota Resources, Ulrich hired graduate student Ian Mundy to lead the project. Mundy is in his second year at UMD’s Water Resources Science doctoral program.
So without actually catching a single fish (Mundy says he’s definitely not an angler), he is setting out to find toxins in local streams that may impact fish.
What interests him about this project is the “non-targeted” approach – casting a wide net (pun intended) to see what chemicals they catch – using passive samplers and mass spectrometry. Back in 2020, NRRI acquired a Liquid Chromatography High Resolution Mass Spectrometer that allows researchers to acquire a snapshot of complex mixtures of compounds present in environmental samples, not just the ones that we already know to look for.
“It’s more like detective work, piecing together what the structure might be and where the fragments came from,” said Mundy. “It’s more creative and tickles a different part of the brain to work with that kind of data.”
Another UMD student in the Water Resources master’s degree program, Chloe Mellgren, is deploying sediment samplers to collect and measure tire wear particles and contaminants that leach from them in the sediment.
Pilot Study
A new sampling method was trialed last summer with passive samplers, a technique that passively takes up compounds in water over time. Mundy deployed the small disks, which contain internal adsorbents covered by diffusive gel layers, in a creek near the Duluth Air National Guard base. After a month in the stream, they’re collected and taken back to the NRRI lab to see what chemicals or compounds they picked up.
And it’s time-consuming work. NRRI has many decades of experience sampling water for things like nutrients and water clarity in parts-per-million concentrations. But analyzing organic contaminants like PFAS is much more challenging because they’re working in parts-per-trillion concentrations.
Their limited pilot study was interesting.
“We found some chemicals in the non-target screening that wouldn’t show up in a standard EPA method that only detects about 40 PFAS contaminants,” said Mundy. “So that’s the ‘reveal’ part—we’re identifying compounds that typical monitoring might miss.”
The “detective work” – a full season of field work – will take place through summer 2025. The team could detect new or widespread contaminants, or identify chemicals that haven’t yet been tested for toxicity. And the new sampling methods could be useful for future monitoring.
“It’s exciting to be part of a project that can guide future research about what’s in our environment and what the risks might be,” Mundy added.
Funding for this three-year project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).