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BIOGENIC VOLATILE ORGANIC COMPOUND EMISSIONS (BVOCS) I. IDENTIFICATIONS FROM THREE CONTINENTAL SITES IN THE U.S.
Citation:
Helmig, D., L. Klinger, A. Guenther, L. Vierling, C D. Geron*, AND P. Zimmerman. BIOGENIC VOLATILE ORGANIC COMPOUND EMISSIONS (BVOCS) I. IDENTIFICATIONS FROM THREE CONTINENTAL SITES IN THE U.S. CHEMOSPHERE 38(9):2163-2187, (1999).
Description:
Vegetation composition and biomass were surveyed for three specific sites in Atlanta, GA; near Rhinelander, WI; and near Hayden, CO. At each research site, emissions of biogenic volatile organic compounds (BVOCs) from the dominant vegetation species were sampled by enclosing branches in bag enclosure systems and sampling the equilibrium head space onto multi-stage solid adsorbent cartridges. Analysis was performed using a thermal desorption technique with gas chromatography (GC) separation and mass spectrometry (MS) detection. Identification of BVOCs covering the GC retention index range (stationary phase DB-1) from approximately 400 to 1500 could be achieved (volatilities C4 - C15). Overall, 63 vegetation species were sampled, and a total of 114 BVOCs were detected and characterized. Structural chemical identification was achieved on approximately 60% of all compounds, tentative identification on 26%, and 14% remained unidentified. Identified compounds include isoprene and BVOCs of the classes of monoterpenes, sesquiterpenes, carbonyl compounds, alcohols, and esters. The MS data was further used to derive emission rate estimates of the identified BVOCs. Even though these data have substantial margins of error, it allows grouping BVOCs into major and minor emissions and deriving conclusions on the relative contributions of individual compounds to the overall BVOC flux. Results obtained by this method show that besides terpenoid compounds (isoprene, monoterpenes and sesquiterpenes), oxygenated compounds may contribute a rather significant fraction of the total BVOC flux. Compounds of particular importance are cis-3-hexene-ol and its derivatives. Limitations of the branch enclosure technique are critically discussed and the validity of the method is evaluated.