Ambient levels of ozone reduce net photosynthesis in tree and crop species
Experiments were conducted to measure the photosynthetic response of three crop and four tree species to realistic concentrations of ozone and (for tree species only) simulated acidic rain. The ozone concentrations were representative of those found in clean ambient air, in mildly to moderately polluted air such as occurs in much of the US during the summer, and in more heavily polluted air. However, the highest concentrations of ozone used were lower than those found regularly in the Los Angeles area. The mean pH of the simulated acid rain treatments ranged from more alkaline to much more acidic than the mean pH of precipitation in the US. Exposure to any increase in ozone reduced net photosynthesis in all species tested. In contrast, acidic rain had no negative effect on photosynthesis in tree species, and no interaction between ozone and acidic rain was observed. Ozone-induced reductions in photosynthesis were related to declines in growth or yield. Species with higher stomatal conductances and thus higher potential for pollutant uptake exhibited greater negative responses to similar ozone treatments. Since exposure to ozone concentrations typical of levels of the pollutant observed in the eastern half of the US reduced the rates of net photosynthesis of all species tested, reductions in net photosynthesis may be occurring over much of the eastern US. 31 references, 4 figures, 1 table.
- Research Organization:
- Cornell Univ., Ithaca, NY
- OSTI ID:
- 5885523
- Journal Information:
- Science (Washington, D.C.); (United States), Journal Name: Science (Washington, D.C.); (United States) Vol. 230; ISSN SCIEA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID RAIN
ATMOSPHERIC PRECIPITATIONS
BIOLOGICAL EFFECTS
CHEMICAL REACTIONS
GROWTH
INHIBITION
NORTH AMERICA
OZONE
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANT GROWTH
PLANTS
PRODUCTIVITY
RAIN
SYNTHESIS
TREES
USA