Biologic Markers of Air-Pollution Stress and Damage in Forests (1989) / Chapter Skim
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Free-Radical Mediated Processes as Markers of Air Pollution Stress in Trees
Free-Radical Mediated Processes as Markers of Air Pollution Stress in Trees
Pages 251-260
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From page 251... ...
Di Giulio Norman E Tandy School of Forestry and Environmental Studies Duke University ABSTRACT Some of the air pollutants believed responsible for the decline of forests, particularly 03, NOx, H2O2, and SO2 can generate toxic oxygen-free radicals when introduced into biological systems.
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intermediates as shown in Figure 1. In addition to direct oxidative degradation of lipids, destruction of intercellular and extracellular proteins, including enzyme inactivation, or DNA damage, indirect toxic effects like mutagenicity and carcinogenicity have been related to oxygen radical formation (Kappus 1987)
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. MATERIALS AND METHODS Plant Material And Treatments: Detailed information outlining our experimental design, treatment levels and methods are found in Richardson and Di Giulio ( 1987~.
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A model of how SO2 affects plant chloroplasts and cytoplasm as proposed by Schulz (modified form Schulz 1986~/ Activity of Px, SOD, and catalase in needles of Pinus sylvestris (scotch pine) after 240 hours of exposure to 0.3 ppm of SO2 was shown to depend on needle age and reached a maximum in November (Fig.
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and catalase in needles of Pinus sylvestris after 240 hours of exposure to 0.8 ppm of SO2 (modified from Schulz, 1986~. SOD Activity in Intercellular Fluid of Ozone-Exposed NonNay Spruce Seedlings 600 1 200 800 400 o Filtered Ambient Treatment i~ 2-day 30-day Outside Ozone Figure 5.
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all the seedlings had a reduced photosynthetic rate from the August high values. The 3.0 treatment could not be measured since the seedlings displayed premature senescence of the 1987 first flush fascicles, which normally function for 2 complete growing seasons.
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The responses of Px, a key enzymatic component of the anti-oxidant defense, showed almost the same pattern of increases as MDA under increased exposure from 1.5 to 3.0 X ambient ozone compared to CF (Figs.
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From page 258... ...
A seasonal comparison of the change from controls in photosynthetic rates and antioxidants SOD and Px in loblolly pine in response to 24 hours of exposure to 1.5 and 3.0 times ambient ozone levels found in Durham, North Carolina. A seasonal comparison of photosynthetic rates, SOD and Px response averaged over all 3 families reveals that highest levels of these antioxidants are found under the 3.0 treatments in June and August when photosynthesis was reduced by 33% and 67%, respectively (Fig.
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From page 259... ...
Future research should employ combinations of ozone with other free radical generating pollutants, such as sulfur dioxide, nitrogen dioxide, and hydrogen peroxide to test the effect of complex gas mixtures on plant biochemical response. ACKNOWLEDGMENTS The loblolly pine research was funded by a USDA Forest Service grant through the Southern Commerical Forest Research Cooperative (29-260)
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From page 260... ...
T Di Giulio.
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