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Titolo:
ESTIMATES OF REGIONAL NATURAL VOLATILE ORGANIC-COMPOUND FLUXES FROM ENCLOSURE AND AMBIENT MEASUREMENTS
Autore:
GUENTHER A; ZIMMERMAN P; KLINGER L; GREENBERG J; ENNIS C; DAVIS K; POLLOCK W; WESTBERG H; ALLWINE G; GERON C;
Indirizzi:
NATL CTR ATMOSPHER RES,DIV ATMOSPHER CHEM,POB 3000 BOULDER CO 80307 WASHINGTON STATE UNIV,DEPT CIVIL & ENVIRONM ENGN PULLMAN WA 99164 US EPA,OFF RES & DEV RES TRIANGLE PK NC 27711
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
fascicolo: D1, volume: 101, anno: 1996,
pagine: 1345 - 1359
Fonte:
ISI
Lingua:
ENG
Soggetto:
EMISSION RATE VARIABILITY; ISOPRENE; MODEL; HYDROCARBONS; INVENTORY; FOREST;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
A. Guenther et al., "ESTIMATES OF REGIONAL NATURAL VOLATILE ORGANIC-COMPOUND FLUXES FROM ENCLOSURE AND AMBIENT MEASUREMENTS", JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 101(D1), 1996, pp. 1345-1359

Abstract

Natural volatile organic compound (VOC) emissions were investigated at two forested sites in the southeastern United States. A variety of VOC compounds including methanol, 2-methyl-3-buten-2-ol, 6-methyl-5-hepten-2-one, isoprene and 15 monoterpenes were emitted from vegetation at these sites. Diurnal variations in VOC emissions were observed and related to light and temperature. Variations in isoprene emission from individual branches are well correlated with light intensity and leaf temperature while variations in monoterpene emissions can be explainedby variations in leaf temperature alone. Isoprene emission rates for individual leaves tend to be about 75% higher than branch average emission rates due to shading on the lower leaves of a branch. Average daytime mixing ratios of 13.8 and 6.6 ppbv C isoprene and 5.0 and 4.5 ppbv C monoterpenes were observed at heights between 40 m and 1 km above ground level the two sites. Isoprene and monoterpenes account for 30% to 40% of the total carbon in the ambient non-methane VOC quantified in the mixed layer at these sites and over 90% of the VOC reactivity with OH. Ambient mixing ratios were used to estimate isoprene and monoterpene fluxes by applying box model and mixed-layer gradient techniques, Although the two techniques estimate fluxes averaged over different spatial scales, the average fluxes calculated by the two techniques agree within a factor of two. The ambient mixing ratios were used to evaluate a biogenic VOC emission model that uses field measurements of plant species composition, remotely sensed vegetation distributions, leaf level emission potentials determined from vegetation enclosures, andlight and temperature dependent emission activity factors. Emissions estimated for a temperature of 30 degrees C and above canopy photosynthetically active radiation flux of 1000 mu mol m(-2) s(-1) are around 4 mg C m(-2) h(-1) of isoprene and 0.7 mg C m(-2) h(-1) of monoterpenes at the ROSE site in western Alabama and 3 mg C m(-2) h(-1) of isoprene and 0.5 mg C m(-2) h(-1) of monoterpenes at the SOS-M site in eastern Georgia. Isoprene and monoterpene emissions based on land characteristics data and emission enclosure measurements are within a factor oftwo of estimates based on ambient measurements in most cases. This represents reasonable agreement due to the large uncertainties associated with these models and because the observed differences are at least partially due to differences in the size and location of the source region (''flux footprint'') associated with each flux estimate.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/07/20 alle ore 12:20:30