Landscape emission rates of monoterpenes and sesquiterpenes, reactive biogenic volatile organic compounds, from a mixed northern hardwood forest

Landscape emission rates of monoterpenes and sesquiterpenes, reactive biogenic volatile organic compounds, from a mixed northern hardwood forest


Abstract: 
Diurnal branch-level emission rates of biogenic volatile organic compounds (BVOC) including monoterpenes (MT) and sesquiterpenes (SQT) were determined at the University of Michigan Biological Station for the tree species balsam fir (Abies balsamea), red maple (Acer rubrum), red oak (Quercus rubra), paper birch (Betula papyrifera), white pine (Pinus strobus), red pine (Pinus resinosa), trembling aspen (Populus tremuloides), and big tooth aspen (Populus grandidentata). Significant MT emissions were found from four of the eight tree species. MT emissions from three of these were both light- and temperature-dependent and were approximately one order of magnitude greater than light-independent MT emissions. SQT emissions were identified from three of the eight tree species.
 

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Methods: 

Branch-level BVOC emission rates were deter-mined from red maple (Acer rubrum), red oak (Quercus rubra), paper birch (Betula papyrifera), white pine (Pinus strobus), red pine (Pinus resinosa), balsam fir (Abies balsamea), trembling aspen (Populus tremuloides), and big tooth aspen (Populus grandidentata). Leaf dry weight values represent averages from 26 litter traps (0.18m2 per trap) in the 1.3 ha plot (60m radius) within the fetch of the UMBS-AmeriFux tower. These eight species account for approximately 95% of the overstory leaf area.

The primary objective was to measure diurnal profiles of monoterpenes (MT) and sesquiterpenes (SQT). Sampling and analysis were performed at the site using a field-deployable system with simultaneous gas chromatography with flame ionization detection (GC-FID) and gas chromatography mass spectrometry (GC-MS). The entire process of sample collection/focusing, thermal desorption, chromatography, and data collection was performed in the field, thus eliminating the need for transferring and storing samples. Ozone was removed from the sampling stream. The detection limit for MT and SQT using these techniques was 1 ngC. This equates to a mixing ratio of 2.5 pptv for MT and SQT in a 10 liter gas sample collected from vegetation emitting at a rate of 0.01 mgCg-1 h-1. The estimated uncertainties of these emission measurements are 20% of MT and 35% for SQT.

Dynamic enclosures were placed on live, sunlit branches during the middle of the growing season (see data collection dates). The bag enclosed a volume of 50 liters of a material transparent to photosynthetically active radiation.

Please see the following for complete methods:

Ortega J, Helmig D, Guenther A, Harley P, Pressley S, Vogel C. 2007. Flux estimates and OH reaction potential of reactive biogenic volatile organic compounds (BVOCs) from a mixed northern hardwood forest. Atmospheric Environment 41(26): 5479 - 5495.

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Release Date:

2012-04-25
 
 

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