The new findings, published online in April in Geophysical Research Letters, indicate that much of the ozone entering pine forests in the Sierra Nevada could be reacting with natural hydrocarbons emitted by plants. One outcome of this reaction is the formation or growth of aerosols.
"We care about aerosols in the atmosphere because they can affect human health and visibility," said Allen Goldstein, associate professor of biogeochemistry at UC Berkeley's College of Natural Resources and principal investigator of the study. Aerosols also potentially impact climate by increasing the formation of clouds and scattering sunlight. They are generally believed to have a cooling effect on the environment.
The study has implications for managing both air quality and air pollution impacts on forests. Previous studies have shown that air pollution from manmade sources such as car exhaust and power plants travels up from the Central Valley to the Sierra Nevada Mountains. The ozone formed from those emissions is considered damaging to forest health - it leads to discoloration and loss of needles from pine trees, inhibits growth and potentially increases susceptibility to diseases.
"In order to relate the dose of ozone to the damage, we need to do a better job of quantifying uptake by the trees," said Meredith Kurpius, lead author of the study and a former UC Berkeley graduate student in ecosystem science.
"The forest acts as a type of 'sink,' a place where a lot of the ozone generated as pollution ends up being taken up by the trees, deposited on surfaces or transformed in chemical reactions in the air
Contact: Sarah Yang
University of California - Berkeley