Carbon dioxide reduces pollution from leaves

Carbon dioxide has been found to reduce the amounts of a pollutant emitted from poplar trees, according to researchers at the University of Colorado at Boulder. The trees produce a hydrocarbon pollutant that contributes to ground-based ozone and enhances the life of the powerful greenhouse gas, methane.

Around 500 million tonnes of the hydrocarbon pollutant, isoprene, are emitted into the atmosphere every year, according to Ray Fall, Professor of Chemistry and Biochemistry at CU-Boulder. This includes high levels of emissions from poplars, Eucalyptus and Acacia.

Poplars in particular are becoming increasingly popular for agriforests feeding the pulp and paper industries, from which there could be unintended consequences, one of the researchers, Russell Monson, Chair of CU-Boulder’s EPO Biology Department, told edie.

However, the researchers have found that another pollutant, carbon dioxide, reduces emissions of isoprene from poplar leaves. The effect appears to be due to a carboxylase enzyme that is responsible for producing isoprene, but which is also used for the metabolism of carbon dioxide. “There is a metabolic competition going on,” said Monson.

Potentially, there could even be a point at which isoprene emission is stopped completely, he said, but the researchers have not yet been able to reach this point in the laboratory.

But why do trees produce isoprene? This isn’t known for sure, says Monson, although there are some theories, including protection against damage by high temperatures, or that it is merely a by-product of the plants metabolism.

One possible outcome of the Colorado research could be to combine it with a study of poplar genetics, with the intention of engineering poplar trees that do not produce isoprene, says Monson. “We’d be moving towards an environmentally friendly poplar,” he said.

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