An Investigation into Seasonal Trends of Terpene Emissions from Biogenic Sources: A Focus on Monoterpene and Sesquiterpene Emissions of Native Colorado Tree Species

摘要

Plants naturally emit a variety of highly reactive hydrocarbon compounds, classified as biogenic volatile organic compounds (BVOC), which are known to have large implications for atmospheric chemistry. Once released into the troposphere, BVOC participate in reactive nitrogen, hydroxyl and ozone chemistry as well as secondary organic aerosol formation. The resulting air quality impacts warrant a thorough understanding of BVOC emission behavior, critical for effective regional modeling and legislative decision-making. This work aims to improve the database and algorithms used in biogenic emission models by examining the seasonal trends of two classes of BVOC, monoterpene (MT) and sesquiterpene (SQT) hydrocarbons. A field site established at a local tree nursery provided an opportunity to easily monitor the emissions of naturally growing vegetation throughout a growing season. The emission rates of five tree species native to Colorado forests were measured monthly between February 2009 and February 2010. Biogenic emissions were found to exhibit seasonal variation with higher emission rates observed between spring and late summer, falling to a low through winter months. The seasonal behavior of BVOC emissions proves to be very complex. These findings are discussed and call into question the methods used for estimating annual emission rates.