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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text/csv iconMT_SQT_emission_rates_2005_v1.csv
text/csv iconMT_SQT_emission_rate_percentages_2005_v1.csv

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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.

Data Originator: 
John Ortega
 
Contact: 
John Ortega
 
Associated Researcher: 
Detlev Helmig
Alex Guenther
Harley, P. C.
Shelley Pressley
Christoph Vogel
 
Research Site: 
UMBS AmeriFlux Tower
 

Release Date:

2012-04-25
 

Referring Project:

 

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Variable Variable Abbreviation Unit Definition
Date DD/MM/YYYY
Sample Identification number associated with specific sampled plants.
Genus Genus of individual.
Species Species of the observed individual.
Total Samples total_samples Total number of samples taken from the experiment; each tree with x number of samples roughly two hours apart.
Number of Monoterpene Samples no_MT_samples The number of samples showing monoterpene presences out of the total number of samples.
Number of Sesquiterpene Samples no_SQT_samples The number of samples showing monoterpene presences out of the total number of samples.
Number of Monoterpenes no_MT The number of different monoterpene compounds identified.
Number of Sesquiterpenes no_SQT The number of different sesquiterpene compounds identified.
Minimum Bag Temperature min_bag_T celsius Minimum temperature (C) reached inside the branch enclosure.
Maximum Bag Temperature max_bag_T celsius Maximum temperature (C) reached inside the branch enclosure.
Total Monoterpene Emission Rate at 30C total_MT_ER_30C microgramsPerGramPerHour Total monoterpene emission rate at 30 degrees C. Dry weight is mass of leaves/needles after drying for 24 hours at 70 degrees C. Dry weight includes all leaves within the branch enclosure. Emission rate units are in micrograms Carbon per grams of dry weight per hour (ugC g[dry weight]-1 hr-1).
Total Sesquiterpene Emission Rate at 30C total_SQT_ER_30C microgramsPerGramPerHour Total sesquiterpene emission rate at 30 degrees C. Dry weight is mass of leaves/needles after drying for 24 hours at 70 degrees C. Dry weight includes all leaves within the branch enclosure. Emission rate units are in micrograms Carbon per grams of dry weight per hour (ugC g[dry weight]-1 hr-1).
Monoterpene Beta Value MT_B Monoterpene emission rates are primarily driven by temperature, which can be parameterized by a Beta (B)-factor (i.e. emission rate = A*exp(B*T) where A is an empirically determined constant). Branch-level emission rate measurements were plotted vs. temperature and an exponential curve fit was used to determine the B-factors for each monoterpene class and each tree species. A Beta (B) factor was then used to fit emission rates to an exponential curve.
Sesquiterpene Beta Value SQT_B Sesquiterpene emission rates are primarily driven by temperature, which can be parameterized by a Beta (B)-factor (i.e. emission rate = A*exp(B*T) where A is an empirically determined constant). Branch-level emission rate measurements were plotted vs. temperature and an exponential curve fit was used to determine the B-factors for each sesquiterpene class and each tree species. A Beta (B) factor was then used to fit emission rates to an exponential curve.
R Squared R2 The coefficient of determination: it is the proportion of variability in a data set that is accounted for by the statistical model.
Volatile Organic Compound VOC Specific volatile organic compounds associated with the sample.
Biogenic Volatile Organic Compound Class BVOC_class The class type of volatile organic compounds produced by living organisms.
Emission Rate Percentage percent_ER percent The percent of a specific compound's contribution to the total emission rate.