A method for open-air exposure of plants to ozone

Abstract

The great advantage of using open-air exposure systems instead of closed or semi-closed chambers to study the effects of air pollutants on plants is that the microclimate (temperature, light, air movement) around the plants will remain natural. In the computer-controlled, chamberless open air system described in this paper, ozone is released from perforated tubes surrounding the plants under study. Fumigation was carried out day and night to simulate the diurnal fluctuation of the ozone concentration. The ozone concentration was monitored continuously at the centre of the ex posure area and at four additional measuring points at the edges of the area. The system was good at maintaining the desired elevated ozone concentration (twice as high as the ambient level) at the centre of the exposure area. At the edges of the area, the long-term mean was also close to that targeted, but the hourly concentrations showed more fluctua tion, depending on the wind direction. However, no very high, acutely toxic peak concentrations were detected. Larger ozone generators are recommended to ensure still more uniform and controllable distribution