Emission rates of organics from vegetation in California's Central Valley

Sesquiterpene (SQT) and montoterpene (MT) emissions from loblolly pine (Pinus taeda L.) were studied by branch enclosure experiments at Duke Forest in Chapel Hill, NC. Four SQT (b-caryophyllene, a-bergamotene, a-humulene, b-farnesene), five MT (a-pinene, b-pinene, b-myrcene, b-phellandrene, limonene), and the oxygenated MT linalool were identified. Emission rates of both compound classes increased exponentially with temperature, albeit SQT temperature coefficients (0.12-0.18 K À1 ) were higher than for MT (0.068-0.15 K À1 ), resulting in an increased contribution of SQT to the overall biogenic volatile organic compound (BVOC) flux during warm temperature conditions. The highly correlated variables of light and temperature conditions preclude a rigorous characterization of their individual roles in driving these emissions. However, the observations indicate that there may be both temperature-only and temperature/light-dependent components contributing to SQT emission variations. When normalized to 30 1C using the best-fit temperature algorithm, total SQT basal emission rate was 450 ng g À1 h À1 . The potential contribution of SQT from all pine trees (based on the loblolly pine emission factors) to secondary, biogenic organic aerosol in 12 southeastern US states was estimated to be 7 Â 10 6 kg for the month of September which constitutes an appreciable portion of the overall PM 2.5 emission budget. r

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“…Winer et al, 1992;Helmig et al, 1999). Quantitative SQT emission rate and landscape flux estimates have been scarce and are highly uncertain.…”

Section: Introductionmentioning

confidence: 99%

Sesquiterpene emissions from loblolly pine and their potential contribution to biogenic aerosol formation in the Southeastern US

Helmig

Ortega

Herrick

et al. 2006

Atmospheric Environment

133

108

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“…In addition to the anthropogenic sources, many VOCs are produced naturally by vegetation. Biogenic emissions of hydrocarbons are likely to exceed anthropogenic emissions in heavily vegetated and forested regions (Winer et al, 1992;Arya, 1999). The mechanisms and products of atmospheric reactions of biogenic organics are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Volatile organic compounds in some urban locations in United States

2002

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Importance of this paper: Air pollution in urban locations contains many components that originate from a wide range of industrial, motor vehicle, and natural emissions sources. Some of these components include compounds known or suspected to be carcinogenic, and some of them play important roles in atmospheric chemistry such as tropospheric ozone pollution and stratospheric ozone depletion. Therefore, it is essential to characterize the composition, magnitude, and the distribution of urban air pollution through extensive ambient air monitoring and assess the impact of these components on human health and global atmospheric chemistry. AbstractVolatile organic compounds (VOCs) have been determined to be human risk factors in urban environments, as well as primary contributors to the formation of photochemical oxidants. Ambient air quality measurements of 54 VOCs including hydrocarbons, halogenated hydrocarbons and carbonyls were conducted in or near 13 urban locations in the United States during September 1996 to August 1997. Air samples were collected and analyzed in accordance with US Environmental Protection Agency-approved methods. The target compounds most commonly found were benzene, toluene, xylene and ethylbenzene. These aromatic compounds were highly correlated and proportionally related in a manner suggesting that the primary contributors were mobile sources in all the urban locations studied. Concentrations of total hydrocarbons ranged between 1.39 and 11.93 parts per billion, by volume (ppbv). Ambient air levels of halogenated hydrocarbons appeared to exhibit unique spatial variations, and no single factor seemed to explain trends for this group of compounds. The highest halogenated hydrocarbon concentrations ranged from 0.24 ppbv for methylene chloride to 1.22 ppbv for chloromethane. At participating urban locations for the year of data considered, levels of carbonyls were higher than the level of the other organic compound groups, suggesting that emissions from motor vehicles and photochemical reactions strongly influence ambient air concentrations of carbonyls. Of the most prevalent carbonyls, formaldehyde and acetaldehyde were the dominant compounds, ranging from 1.5-7.4 ppbv for formaldehyde, to 0.8-2.7 ppbv for acetaldehyde. Ó

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“…Plants are known to produce a large variety of VOCs (Isidorov et al, 1985;Winer et al, 1992;Teranishi et al, 1993;Guenther et al, 1994Guenther et al, , 1995. These VOCs play a number of roles in plant physiology and signaling, in plant-herbivore relationships, and in defense against microorganisms (reviewed by Roshchina and Roshchina, 1993).…”

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Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

et al. 1995

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We recently reported the detection of methanol emissions from leaves (R. MacDonald, R. Fall 119931 Atmos Environ 27A: 1709-171 3). This could represent a substantial flux of methanol to the atmosphere. Leaf methanol production and emission have not been investigated in detail, in part because of difficulties in sampling and analyzing methanol. In this study we used an enzymatic method to convert methanol to a fluorescent product and verified that leaves from severa1 species emit methanol. Methanol was emitted almost exclusively from the abaxial surfaces of hypostomatous leaves but from both surfaces of amphistomatous leaves, suggesting that methano1 exits leaves via stomates. The role of stomatal conductance was verified in experiments in which stomates were induced to close, resulting in reduced methanol. Free methanol was detected in bean leaf extracts, ranging from 26.8 pg g-' fresh weight in young leaves to 10.0 pg g-' fresh weight in older leaves. Methanol emission was related to leaf development, generally declining with increasing leaf age after leaf expansion; this is consistent with volatilization from a cellular pool that declines in older leaves. It is possible that leaf emission could be a major source of methanol found in the atmosphere of forests.

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Emission rates of organics from vegetation in California's Central Valley

Cited by 218 publications

References 35 publications

Sesquiterpene emissions from loblolly pine and their potential contribution to biogenic aerosol formation in the Southeastern US

Sesquiterpene emissions from loblolly pine and their potential contribution to biogenic aerosol formation in the Southeastern US

Volatile organic compounds in some urban locations in United States

Methanol Emission from Leaves (Enzymatic Detection of Gas-Phase Methanol and Relation of Methanol Fluxes to Stomatal Conductance and Leaf Development)

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