Portland’s toxic hotspots discovered as an after-thought

Two U.S. Forest Service researchers had an ambitious plan in 2012, new in its scope.

They wanted to test an entire city for the kind of air pollution that comes from smoke and exhaust. The goal? To see if trees sponge up pollution.

They think their results proved that. But what they also learned along the way was something completely unrelated to either trees or car exhaust, leading to discoveries about two glass manufacturers that are roiling Portland four years later.

The research showed, for the first time, where cancer-causing cadmium was concentrated around the city. State environmental regulators have been under fire ever since making results public Feb. 3, eight months after learning about the scientists’ discovery from the forest service.

Now, in addition to shaking up the local regulatory environment overnight, the pair’s unusual approach is poised to revolutionize the way we pinpoint and curtail toxic air polluters nationally.

It started because the two researchers needed data on pollution spanning the entire city. The cheapest way to do that was to enlist the help of a little green helper: Orthotrichum Iyelli, a moss with star-shaped leaves that often grows on trees.

Moss absorbs whatever’s in the air and water and stores it inside its cells and on its surface, Sarah Jovan, one of the researchers, said. It doesn’t have roots, which means whatever you find in it didn’t come from the soil. And the stuff grows everywhere there are trees, she said, allowing Jovan, a research ecologist with a Ph.D from Oregon State University and Geoffrey Donovan, a research forester with a Ph.D from Colorado State University, to collect it from all around the city.

It was hard work. For about two and a half weeks in December, 2013, Jovan and Donovan got up by sunrise. Donovan drove and Jovan gave directions, as they circled the city from randomly selected address to randomly selected address: 346 in all.

They put on gloves and climbed up a ladder they had strapped to the back of the teal government van. Perched high on each tree trunk, they carefully removed about two handfuls of moss, if it was dry, and about 10 times as much if it was wet.

“After about your twentieth one, you’re bored,” Jovan said.

It took about an hour and a half of cleaning per batch to get rid of the dirt and insects and prepare it for lab testing. They then sent the batches to a lab, which ground the moss samples, broke them down with acid, and tested for pollutants.

The study was focused on the pollutant polyclic aromatic hydrocarbons emitted from cars and wood smoke.

But on top of testing for that chemical, Jovan wanted to have the moss screened for heavy metals, too.

Donovan wasn’t hot on the idea and needed convincing, he said. The metals testing wasn’t part of the main project, he said. But the low cost of the analysis sealed the deal. At $50 dollars per sample to test 25 metals, it was a bargain, Donovan said.

Analyzing samples from locations all over the city cost $20,000 compared to $150,000 for a single air monitor in one spot.

Jovan wrote an email telling a Department of Environmental Quality official that they were going to analyze heavy metal concentrations in the city. She got a phone call within five minutes from an official who said there was a “cadmium mystery” that the agency would like solved.

State and city officials have known for more than a decade that Portland had high levels of cadmium, but they didn’t know where it was coming from. State regulators have only a few air monitors in the city, not enough to pinpoint the specific sources.

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Uroboros in North Portland. (Kelly House/Staff)

Teresa Mahoney

The scientists noted the state environmental agency’s interest in the data and went to work.

After the test results came back from the lab, there was still a long road ahead before Jovan and Donovan could turn them into research they could use. That’s why Jovan said she thinks it hadn’t been done before. Scientists have known since the 1970s that moss is a good indicator of pollution, Jovan said, but nobody has used it to test detailed pollution across an entire city.

She and Donovan used the data to test their initial hypothesis about trees acting as pollution sponges. They compared the area of tree cover in each sector with the amount of soot-related pollution in the moss. Indeed, more trees were associated with less car pollution.

They started working on a paper.

But first, they thought they would see what the rest of the lab results showed for heavy metals.

The researchers wanted to see if trees did the same thing to metals as they did to the pollutant emitted with car exhaust.

Part of the analysis, a “secondary goal,” was to make a map. They started with cadmium because of the Department of Environmental Quality’s interest in identifying a source of emissions for the metal in Portland’s area, Jovan said.

It turned out trees do not absorb cadmium. But what Jovan and Donovan discovered by making the map shocked them much more than that finding.

There are facilities that use cadmium in the city in Northwest Portland and in North Portland. They expected hot spots to be confined to those areas. Instead, they saw them in Southeast and near the east end of the Fremont Bridge.

“Both of us felt really distressed,” Jovan said. “It looked serious.”

At that point, they said, they decided they had little choice but to tell the Department of Environmental Quality. That was in May 2015.

The department went on to confirm the findings in moss with air monitors in October, which allowed Jovan and Donovan to confirm that their moss data was accurate. The department asked two glass manufacturers near the hotspots to stop using cadmium and ultimately some other heavy metals, which they did.

The director since then has promised to change state rules overseeing air toxics, and U.S. Sen. Ron Wyden said the federal environmental protection agency is working on fixing a loophole that allowed the two stained-glass manufacturing companies to freely emit heavy metals.

State officials say they continue to gather soil samples to more firmly establish the risk level in brightly colored areas of Jovan and Donovan’s maps.

Such hot spots in Portland exist for hazardous metals other than cadmium, including arsenic, lead and nickel, as shown on new maps released by the environmental quality department.

For Donovan and Jovan, the best part about what happened is that they were able to help people.

To do research that changes lives is “The ultimate thing you can hope to do with your time,” Jovan said.

And the two are already scheduled to do more research along the same lines.

They said their technique can be used anywhere moss or lichen grows.

A children’s hospital in Cincinnati has been getting kids with high levels of cadmium and mercury in their systems. So the two – with assistants, this time – will collect lichen from across the city to see where it might be coming from.

— Fedor Zarkhin

fzarkhin@oregonian.com

503-294-7674; @fedorzarkhin