CONTROLLED ENVIRONMENT FUMIGATION CHAMBERS FOR THE STUDY OF REACTIVE AIR POLLUTANT EFFECTS ON PLANTS

The design and construction of eight 1-m3 fumigation chambers for expo sing plants to reactive air pollutants at low concentrations are repor ted. Teflon surfaces are used where possible to minimize the adsorptio n, absorption, desorption and chemical reaction of the pollutants. A p urified ambient air supply, to which metered quantities of gaseous pol lutants are added, is used to give two air changes per minute at const ant, low, pollutant concentrations. Comparative analysis of the chambe rs indicates that conditions may be maintained with a significant degr ee of precision, i.e. temperature +/-0.3-degrees-C, RH +/-6%, light in tensity +/- 5 mumol m-2 s-1. Boundary layer analysis from models of ch erry tree (Prunus avium) leaves indicate that the minimum conductance value within these chambers is 2 cm s-1.