From: Andy Soos, ENN
Published April 29, 2013 08:24 AM
Trees and Smog
Trees breathe in CO2 and exhale Oxygen A natural way to refresh the
air or so it seems. Smog is a form of pollution. After years of
scientific uncertainty and speculation, researchers at the University of
North Carolina at Chapel Hill show exactly how trees help create one of
society’s predominant environmental and health concerns: air pollution.
It has long been known that trees produce and emit isoprene, an abundant
molecule in the air known to protect leaves from oxygen damage and
temperature fluctuations. However, in 2004, researchers, contrary to
popular assumptions, revealed that isoprene was likely involved in the
production of particulate matter, tiny particles that can get lodged in
lungs, lead to lung cancer and asthma, and damage other tissues, not to
mention the environment.
Isoprene emissions appears to be a mechanism that trees use to combat
abiotic stresses. In particular, isoprene has been shown to protect
against moderate heat stresses (~ 40 °C). It was proposed that isoprene
emission was specifically used by plants to protect against large
fluctations in leaf temperature.
Isoprene is incorporated into and helps stabilize cell membranes in
response to heat stress, conferring some tolerance to heat spikes.
Isoprene also confers resistance to reactive oxygen species. The amount
of isoprene released from isoprene-emitting vegetation depends on leaf
mass, leaf area, light, and leaf temperature.
Jason Surratt, assistant professor of environmental sciences and
engineering at the Gillings School of Global Public Health, now reveals
one mechanism by which isoprene contributes to the production of these
tiny, potentially health-damaging particles.
The study found that isoprene, once it is chemically altered via
exposure to the sun, reacts with man-made nitrogen oxides to create
particulate matter. Nitrogen oxides are pollutants more often created by
cars, trucks, aircrafts, coal plants and other large scale sources.
"The work presents a dramatic new wrinkle in the arguments for reducing
man-made pollutants worldwide," said Surratt, whose work was published
this month in the Proceedings of the National Academy of Sciences.
"Isoprene evolved to protect trees and plants, but because of the
presence of nitrogen oxides, it is involved in producing this negative
effect on health and the environment."
With the precise mechanism now revealed, researchers can plug it into
air quality models for better predicting episodes of air pollution and
potential effects on earth’s climate. The advance would allow
researchers and environmental agencies to evaluate and make regulatory
decisions that impact public health and climate change.
"We observe nature’s quirks, but we must always consider that our
actions do have repercussions," said Surratt. "It’s the interaction
between these natural and man-made emissions that produces this air
pollution, smog and fine particulate matter — and now we know one reason
for how it happens."
For further information see
Smoggy Trees
or
Article.
Tree image via Wikipedia.
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