Experimental method to measure gaseous uptake of 14C-toluene by foliage

Abstract

An experimental method is described to measure foliar uptake and translocation of volatile organic compounds in plants. A flow-through exposure chamber was designed to determine phytoxicity of volatile organic compounds; an air-tight chamber was used for exposure of whole plants to radiolabeled test compound. 14C-toluene uptake by soybean ( Glycine max) foliage was measured as an example of the experimental approach. Leaf tissue concentrations of 14C-toluene were measured over a 55.5-hr exposure period during light and dark periods. Photosynthetic rate was not affected by chronic atmospheric exposure to 27 μmole cm −3 hr toluene. During a 55.5-hr exposure to 7.2 μmoles cm −3 hr 14C-toluene (1.94 Bq cm −3), deposition velocities were greatest in the light phases and showed a marked decrease during the dark phases of exposure, suggesting that stomatal uptake as well as surface deposition contributed to toluene uptake. 14C was translocated from foliage to the roots. These data indicate that deposition of volatile organic compounds to vegetation may constitute a mechanism leading to herbivore exposure to volatile hazardous organics at waste sites. The experimental method described can be used to measure foliar uptake and translocation of volatile organic compounds to whole plants under laboratory conditions.