'Vine That Ate the South' Could Also Boost Smog Levels

Fast-growing kudzu plant affects soil, potentially increasing ozone pollution, scientists warn

MONDAY, May 17 (HealthDay News) -- Many Americans know kudzu as an invasive vine that's grown out of control across southeastern states, but a new report suggests it may also be boosting ozone air pollution.

A team of researchers from Stony Brook University in New York, the University of Virginia in Charlottesville and Harvard University in Boston created a model to estimate how air pollution in the southeastern states might be affected by increased nitric oxide produced with the help of kudzu.

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In concert with chemicals called volatile organic compounds (VOCs), nitric oxide is a prime precursor to airborne ozone in the lower atmosphere.

"While documenting these impacts on soil chemistry and nitric oxide emissions is definitely important, we really wanted to see whether an invasive species could affect the atmosphere in a meaningful way," study co-author Jonathan Hickman said in a news release from Stony Brook. Hickman was a graduate student at Stony Brook University at the time of the study and is now a postdoctoral fellow at the Earth Institute at Columbia University.

One of their scenarios suggests that an extensive kudzu invasion could boost the number of high pollution days in certain regions by more than one-third versus a situation in which kudzu wasn't there. That particular scenario is considered extreme, the study authors noted in the news release, but it does provide a link between the vine and the formation of ozone.

The researchers note that the kudzu vine also emits a VOC called isoprene, which might also contribute to ozone.

"In the case of kudzu, you have a plant that is generating [nitric oxide] from the soil and emitting VOCs from its leaves -- it's like a living tailpipe. Maybe they'll start calling kudzu 'the vine that choked the South,'" Hickman said.

"Air pollution is a risk that hasn't been considered much in the conversation about invasive species, but it's something we may have to pay more attention to," Hickman added.

The study findings are published in the May 17 online edition of the Proceedings of the National Academy of Sciences.

More information

The U.S. Department of Agriculture has details on kudzu (Genus Pueraria DC).

-- Randy Dotinga