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BRANCH CHAMBER SYSTEM AND TECHNIQUES FOR SIMULTANEOUS POLLUTANT EXPOSURE EXPERIMENTS AND GASEOUS FLUX DETERMINATIONS
Citation:
Ennis, C., A. Lazrus, G. Kok, P. Zimmerman, AND R. Monson. BRANCH CHAMBER SYSTEM AND TECHNIQUES FOR SIMULTANEOUS POLLUTANT EXPOSURE EXPERIMENTS AND GASEOUS FLUX DETERMINATIONS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/214 (NTIS PB91117481), 1990.
Description:
We describe an experimental system and techniques for use in simultaneous pollutant exposure experiments and gaseous flux determinations. he system uses flexible Teflon bag-like chambers to enclose entire individual branches of young trees. ive gaseous fluxes (CO2, H2O, SO2, O3, and H2O2) are measured once per hour for each of two branches. echniques for determining chamber surface loss corrections and methods of estimating needle surface area of conifers are described. hree-week continuous test was run in order to evaluate system performance. nlet concentrations of the five gases were extremely stable, with uncertainties of < 2.2% in all cases and day-to-night differences of <4 %. omparison of two branch chambers, one with clean air and one with the added pollutant gases H2O2, SO2, and O3, showed that between-chamber differences were < 2% for the average inlet concentrations of H2O and CO2. ollutant losses to chamber surfaces were significant but were generally smaller than losses to the branch itself. hamber loss corrections were different for daytime and nighttime conditions and also evolved as the three-week experiment proceeded.
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BRANCH CHAMBER SYSTEM AND TECHNIQUES FOR SIMULTANEOUS POLLUTANT EXPOSURE EXPERIMENTS AND GASEOUS FLUX DETERMINATIONS