SO Sub 2 , Vegetation Effects, and the Air-Quality Standard: Limits of Interpretation and Application

摘要

The paper discusses indices of plant response, variations in sensitivity among plant species, the influence of environmental variables and other air pollutants on plant sensitivity, and certain specific aspects of describing phytotoxic potential of SO sub 2 exposures. These factors are presented in the context of regional differences in potential for SO sub 2 to cause adverse effects in terrestrial ecosystems. Evaluation of our existing data on SO sub 2 effects on both visible foliar injury and plant growth and yield suggests that the present 3-hr standard of 0.5 ppM (2600 mu g/m exp 3 ) is not adequate to protect vegetation in areas such as the eastern US where multiple pollution sources, high frequency of air stagnation events, and abundant moisture supply combine to make vegetation maximally sensitive to air pollution stress. In the southwest, however, the present NSAQS may be more stringent than is required to protect xeric vegetation. Based on regional differences in expected sensitivity of vegetation, different levels of protection for three zones of the US are suggested and discussed. (ERA citation 07:044829)