J3.6
Biogenic aerosols and forest carbon sequestration
Jordan G. Barr, University of Virginia, Charlottesville, VA; and J. D. Fuentes, J. C. Zieman, and J. W. Bottenheim
There is ample experimental evidence indicating that forests increase their carbon sequestration efficiency with increasing trends in diffuse photosynthetically active irradiance (PAR). The increased levels of diffuse irradiance are the consequence of increases in cloudiness and atmospheric turbidity. Over the continental eastern North America, one reason for this increased in atmospheric turbidity may be related to the greater loads of fine aerosols resulting from the photooxidation of biogenic hydrocarbons. Compared to 50 years ago, eastern North America is becoming more forested, thus providing greater substrates for hydrocarbon production. The terrestrial ecosystems in eastern North America release into the atmosphere biogenic hydrocarbons at rates exceeding the flux from anthropogenic sources. Terpenes are one important hydrocarbon family and comprise 31% of total biogenic hydrocarbon emissions in North America. Terpenes can be rapidly oxidized to produce oxygenated compounds, which homogeneously condense to form secondary organic aerosols. Once in the atmospheric boundary layer, these fine aerosols can substantially modify the quantity and quality of incoming photosynthetically active irradiance. Therefore, in this presentation we will provide results on the aerosol yields from terpene oxidation and determine the PAR modulation resulting from "biogenic aerosols" in the local boundary layer. We will also report on the influence of the PAR modulation on forest carbon sequestration. Our results will evaluate the hypothesis that airborne aerosols, resulting from phytogenic sources, generate high levels of diffuse irradiance which in turn contribute to enhanced carbon sequestration.
Joint Session 3, Plant/atmosphere chemical interactions: sources and sinks of chemical species (Joint with the Fourth Symp. Urban Environment, 12th Joint Conf. on the Applications of Air Pollution Meteorology with A&WMA, and 25th Conf. Agricultural & Forest Meterology; Cosponsored by the AMS STAC Committee on Atmospheric Chemistry)
Thursday, 23 May 2002, 8:15 AM-10:15 AM
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