ENVIRONMENTAL MONITORING - A FIELD CHAMBER FOR TESTING AIR-POLLUTION EFFECTS ON MATURE TREES

A 3.6 m tall by 3 m diam. open-top chamber system built on 12-m towers for the dispensing and exclusion of air pollutants in the foliage of mature loblolly pine (Pinus taeda L.) trees was tested. Statistically significant position and height differences in O3 concentration inside the chamber were found for different wind speed categories. Calculation of a relative O3 concentration (ROC) showed remarkably similar relative O3 profiles for charcoal filtered (CF) and 2x ambient (2x) chambers. Large reductions in ROC are found above the 2.4-m level in both chambers. Ambient air intrusion was reduced in the modified chamber because it was protected by the canopy and contained a tree crown lessening air movement in the chamber. The mean temperature increase in the chamber from 1200 to 1259 h EST was 2.2-degrees-C, whereas the maximum temperature increase was 4.8-degrees-C. Statistically significant positional temperature differences were found within the chamber. The chamber system design was found useful in testing the effects of gaseous air pollutants on the crown of mature trees and is recommended for designed experiments.