A new study unexpectedly found that vegetation plays an increasingly important role in cleansing the atmosphere than previously thought. In a study conducted by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., used observations, gene expression studies, and computer simulations to show that plants shed their leaves to absorb more chemicals to the third common type of air pollutants than before considered.
The new analysis, the results of which will be published in the journal Science Express, was conducted in collaboration with scientists from the University of Northern Colorado and the University of Arizona. Financial support was provided in part by the National Science Foundation, the sponsor of NCAR.
"Plants clean our air much more than we realize," - says NCAR scientist and lead author Carl Thomas (Thomas Karl). "They actively consume certain types of air pollution."
The research team focused its attention on the class of chemicals known as volatile organic compounds oxygenated (oVOC), which can have long term effects on the environment and human health.
"The team has made significant progress in understanding the complex interactions between plants and the atmosphere," - said Anna Maria Shmoltner (Anne-Marie Schmoltner) from the center of the financial support for the study.
Compositions of matter are formed in abundance in the atmosphere from hydrocarbons and other chemicals that stand out as natural sources, including plants, and some related to human activity, including machinery and waste construction materials. They help shape atmospheric chemistry and influence climate. Ultimately, some substances are transformed into oVOC small particles in air, known as aerosols that have a significant effect on the cloud as well as on human health.
OVOC measuring the levels of substances in a variety of ecosystems in the United States and other countries, the researchers determined that plants shed their leaves, it turns out, absorb harmful compounds with unexpectedly rapid indicator, four times faster than previously anticipated.
Absorption was especially rapid in dense forests where the observations measure the absorption of substances oVOC reached 97%.
Professor Karl and his colleagues then tried to answer the following question: how plants are able to absorb such large amounts of these chemicals?
To do this, they moved their research in the lab and stopped at the poplar trees. The group discovered that when the trees were studied stress due to physical damage or due to external stimuli such as ozone pollution, they began sharply increasing absorption oVOC substances.
At the same time, the changes and the levels of expression of certain genes, indicating increased metabolic activity in the poplars.
Absorption oVOC substances, the conclusions of the scientists, was part of a more intensive metabolic cycle.
Plants may produce chemicals to protect against irritants and insect pests, just as the human body can increase the production of white blood cells in response to infection.
But an excess of these chemicals can be toxic to the plants themselves.
In order to metabolize these chemicals to the plants begin to increase the levels of enzymes which convert them into less toxic substances.
At the same time, it turned out, the plant absorbs more oVOC substances that can be metabolized by the enzymes.
"Our results show that plants can actually adjust their metabolism and increase the absorption of atmospheric chemicals as a response to various types of stress," - said one of the study’s authors. "This complex metabolic process of plants has a cleansing effect of our atmosphere."
Once they have determined the extent of absorption by plants oVOC substances, the research group has resorted to the information a computer model that simulates chemicals in the atmosphere worldwide.
The results indicated that, at the global level, plants absorb 36% more oVOC substances than before it was established research chemical composition of the atmosphere. Also, since plants capable of directly removing oVOC substance becomes less substances in the aerosol.
"It really changes our understanding of some fundamental processes taking place in our atmosphere" - concluded Carl.
Original: Sciencedaily Translation: M. Potter