Chemicals Spilled Into Yellowstone River 'Potentially Acidifying' Water

A contamination expert has warned of the "potentially acidifying" effects in the near term of hazardous chemicals that leached into the Yellowstone River after a bridge over the waterway in Montana collapsed with a freight train on it.

Marc Glass, the principal environmental consultant at Downstream Strategies, who has advised state and federal contamination projects, told Newsweek that the asphalt and sulfur that spilled out of the rail cars combined "could be worse than either alone," expressing his worry for the aquatic wildlife in the river.

The incident occurred at around 6 a.m. local time (8 a.m. ET) on Saturday in a rural area of Stillwater County, around 40 miles west of Billings, Stillwater County Emergency Services said.

The Associated Press pictured a yellow substance leaking from the train cars, three of which it said were carrying hot asphalt and four molten sulfur. In an update on Monday, Stillwater County Unified Command said 10 cars were in the river, six of which contained asphalt and three molten sulfur—the other containing scrap metal.

"The condition of these cars, including two that are submerged, is a key unknown in the plan to remove them from the water," it said, adding that divers had attended the site to inspect the condition of the cars below the surface.

AP reported that local drinking water intakes downstream from the spill were shut down as a precautionary measure. David Stamey, Stillwater County's emergency services specialist, said the hazardous materials were being diluted by the river, which has become swollen after heavy rains.

Newsweek approached Stamey for further comment via email on Monday. Stillwater County Unified Command, which is coordinating the clean-up operation, said water testing on Saturday suggested there was no risk to public drinking water or private wells.

Glass said the "big concern" regarding sulfur was its ionic character—its ability to gain or lose electrons when it comes into contact with other compounds.

"The sulfur has a big impact on the chemistry of a lot of ionic species [atoms or molecules carrying a charge]," he said. "It can change both the pH and the ionic character of the water, and it can be very hazardous." The pH scale, evaluated from one to 14, measures how acidic or alkaline a liquid is."

Glass said that the chemical—which is used in making fertilizers and in petroleum refining—was "just a really strong reducing agent—that I worry about for the aquatic life. Just not good to have in the Yellowstone River, that's for sure."

"Water quality testing results from Saturday show no detectable levels of petroleum hydrocarbons or sulfur and samples continue to be taken and analyzed," Stillwater County Unified Command said on Monday.

When it came to the asphalt, Glass said the "big question" was how soluble it was, as that would determine how many polycyclic aromatic hydrocarbons (PAHs), chemicals that naturally occur in fossil fuels, would leach into the surrounding environment.

"One thing that has really been found having an impact on aquatic life in the salmon fisheries is the run-off from asphalt and car tires," he said. "If it's a raw asphalt product, it's just about the solubility.

"You have lots of PAHs that are typically associated with asphalt, a lot of the heavier, less refined petroleum compounds—that's basically what asphalt is; after you've refined off all the lighter fractions... what's left behind is a waste product."

Andy Garland, a spokesperson for Montana Rail Link, told AP both chemicals solidify quickly when exposed to cooler temperatures, adding: "We are committed to addressing any potential impacts to the area as a result of this incident and working to understand the reasons behind the accident."

While asphalt tended to be hard to dissolve into water, Glass added that there would be an increase in PAHs entering the river because the compound was directly in the water, though "the rate of that is going to be relatively low because of the low solubility."

He explained that placing asphalt into a riverbed "alters the ecology," which may require the physical removal of solid asphalt from the Yellowstone River. One 2015 study published in the Journal of Applied Toxicology found that bitumen, the main constituent of asphalt, once settled on a river floor "elevates the risk" to riverbed wildlife.

"Asphalt globules have been detected downstream on the banks and in the body of the Yellowstone River," Stillwater County Unified Command said. "This solid waste is not water-soluble and is not anticipated to impact water quality."

Glass warned that long-term leaching of PAHs from asphalt coupled with sulfur "potentially acidifying or changing the pH [of the water] pretty substantially for the short term—that combination could be worse than either alone."

The rail spill over the Yellowstone River in Montana is just the latest to occur this year.

In February, toxic chemicals were vented into the air and leached into the surrounding soil and waterways after the derailment of a train carrying various chemicals including toxic vinyl chloride near the town of East Palestine, Ohio.

In late April, a derailed train in Wisconsin sent cars carrying hazardous materials into the Mississippi River.

Update 06/27/23, 3:26 a.m. ET: This article was updated to include comment and further details from Stillwater County Unified Command.