Rainfall Chemistry and Potential Beneficial/Detrimental Impact to Indigenous Vegetation

摘要

This research project was designed to evaluate the effects of air pollutants on forests in southwestern Virginia. Extensive field studies utilizing tree coring techniques and open-top chamber experiments have shown that air pollutants for RAAP have periodically caused foliar injury to air pollution-sensitive trees and suppressed forest growth. Laboratory studies showed the genetic basis for interspecific differences in air pollution sensitivity and showed pollutants generally caused reductions in transpiration and photosynthesis. Field and laboratory studies carried out between 1974 and 1980 are reviewed in this report. More recent studies have documented patterns of ozone dispersion through the ridge-valley Appalachian Mountains. Higher elevation sites tended to have higher ozone concentrations. Rainfall chemistry has also been characterized for a station in southwestern Virginia. A rainfall simulator has been designed and built in order to reproduce rainfall in controlled laboratory experiments. This simulator provides natural-sized raindrops, distributes droplets evenly over a surface, and is chemically inert. Studies on defining the role of rainfall chemistry and ozone impact on plants are now underway.