Citation:

Ennis, C., A. Lazrus, P. Simmerman, AND R. Monson. FLUX DETERMINATION AND PHYSIOLOGICAL RESPONSE IN THE EXPOSURE OF RED SPRUCE TO GASEOUS HYDROGEN PEROXIDE, OZONE, AND SULFUR DIOXIDE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/215 (NTIS PB91117473), 1990.

Description:

We report on the 3-week exposure of a branch of a forest-grown red spruce (Picea rubens) sapling to the combination of gaseous hydrogen peroxide. ozone, and sulfur dioxide. he exposure was conducted continuously using concentrations of H2O2, O3, and SO2 that have been observed during the summertime on the summit of Whiteface Mountain, New York. luxes of H2O, CO2, and the three pollutants were determined throughout the exposure. t weekly intervals, measurements of chlorophyll fluorescence, stomatal conductance, and hydrocarbon emissions were made. he response of the branch was compared to an equivalent branch of the same tree which received no ollutants but was otherwise treated identically. he exposure produced no visible injury symptoms but did produce an increase in dark respiration: he respiration rate more than doubled during the 21-day exposure period. et photosynthesis was unaffected for both the experimental and the control branches. ighttime fluxes of SO and H2O2 to external plant surfaces were significant. he stomatal component of O3 uptake by the branch displayed a linear increase during the experiment, and showed no evidence of saturating. aytime and nighttime fluxes of H2O2 were increasing at the end of the experiment. e observed that isoprene is emitted from red spruce, but saw no clear-cut change in emission rate in response to the exposure experiment. ossible relationships between our experimental results and observations of red spruce decline in the orests of the northeastern United States are suggested for further investigation.

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