Polluting plants

时间:2019-03-07 02:05:00166网络整理admin

By Joanna Marchant PLANTS release the smog-forming compound toluene when stressed, according to three studies by German researchers. Because toluene in the air was thought to originate only from human sources such as car exhausts, the finding could complicate pollution measurements. Ralph Koppmann, Jürgen Wildt and their colleagues at the Jülich Research Centre near Cologne reported in May that sunflowers and Scots pines emit toluene when they are stressed by injury or nutrient deprivation ( Geophysical Research Letters, vol 26, p 1283). But their findings were met with scepticism, as there is no known biochemical pathway by which plants could produce toluene. Now new results from two ongoing studies suggest that the Jülich researchers may be right. Jürgen Kesselmeier of the Max Planck Institute of Chemistry in Mainz has been measuring plant emissions in Amazonian rainforests. He was surprised to find a peak in levels of toluene in the rainforest canopy far from any human sources. “At the moment we cannot explain this by anthropogenic pollution,” he says. In a separate project, Thomas Schmitz, also at Jülich, has been measuring toluene levels around Berlin as an indicator of car emissions. Schmitz detected toluene in rural areas near Berlin even when the wind was blowing toward the city and other pollutants were absent. “In very clean air conditions, we saw more toluene than we expected,” he told New Scientist. He says the extra toluene may be coming from plants. Brian Jones, who measures toluene emissions in Britain for the National Environmental Technology Centre near Abingdon, was surprised by the finding. “We have not seen evidence for a strong natural source of toluene.” But he says that if the German figures are accurate,