Scientists, lead by Virginia Tech, discover rare potentially hazardous material in burning coal

Published: Aug. 9, 2017 at 10:20 PM EDT
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Environmental scientists say they've found evidence of a rare possible toxin created by burning coal.

The group leader, Virginia Tech Distinguish Professor Michael Hochella, said it was entirely by chance.

Hochella and his team came across the nanoparticle, called titanium suboxide, while studying a 2014 coal ash spill in the Dan River, North Carolina. During the study of the downstream movement of toxic metals in the ash in the Dan River, the team discovered and recognized the presence of small amounts of the highly unusual titanium suboxide.

The group later produced the titanium suboxide nanoparticles when burning coal in a lab simulation.

Before that, titanium suboxide were believed to only be found in some meteorites and moon rocks, and on Earth, only in a small area of Greenland.

But Hochella said his team found the particles are much more common than ever believed.

He said in a phone call with WDBJ7 Wednesday, "It turns out that it's made by the millions of tons over many years of burning huge amounts, and it will end up in the coal ash or in the gases that leave the power plant."

During coal burning, titanium oxides burn with the coal. The team found those convert into the titanium suboxide, which was never known before to occur.

The particles are as small as 100 millionths of a meter, and when inhaled can enter the lungs and potentially the bloodstream.

The particles were tested on the embryos of zebra fish, commonly used in bio-toxicity testing.

They were found to be toxic when applied in darkness instead of light, which is key as human lungs are in darkness.

But Hochella said coal miners won't have to be worried, as the particles are only dangerous during burning.

And U.S. power plants have better protections than in developing countries.

He explained, "When you're in China or India and there's huge amounts of smog in the air, in part, because the coal burning power plants aren't as well protected for removing these particles. Some of the particles in the air will be these titanium suboxides."

The team said the nanoparticles were found on city streets, sidewalks, and in standing water in Shanghai, China.

Also on the team is Yi Yang, a professor at East China Normal University in Shanghai.

“I could not believe what I have found at the beginning, because they had been reported so extremely rarely in the natural environment,” said Yang, who once worked as a visiting professor in Virginia Tech’s Department of Geosciences with Hochella. “It took me several months to confirm their occurrence in coal ash samples.”

But the particles can spread locally, regionally, and even globally, if not captured by high-tech particle traps.

Hochella was asked if these findings could hurt the coal energy business, which has been under some scrutiny recently.

He answered about the industry, "It seems to have more disadvantages than any other common form of generating energy. Our discovery doesn't help that situation in terms of turning around, that's for sure."

He also admitted these kinds of experiments are not always definitive and scientists will always question each other.

But with these findings, Virginia Tech, the Department of Energy National Lab, and other labs around the world will test human lungs to determine these particles direct affect.

Hochella expects a good indication one way or the other in a year. Then testing gets much more complex and could take several years for a precise answer.

But why did the discovery occur now? According to the report published in the latest issue of Nature Communications, nearly all coal contains traces of the minerals rutile and/or anatase, both “normal,” naturally occurring, and relatively inert titanium oxides, especially in the absence of light. When those minerals are burned in the presence of coal, research found they easily and quickly converted to these unusual titanium suboxide nanoparticles. The nanoparticles then become entrained in the gases that leave the power plant.

This new potential air pollution health hazard builds on already established findings from the World Health Organization. It estimates that 3.3 million premature deaths occur worldwide per year due to polluted air, Hochella said. In China, 1.6 million premature deaths are estimated annually due to cardiovascular and respiratory injury from air pollution. Most Chinese mega-cities top 100 severely hazy days each year with particle concentrations two to four times higher than WHO guidelines, Yang said.

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