Measuring Air Pollutant Uptake by Plants: A Direct Kinetic Technique

Available chamber designs and experimental techniques have not permitted a critical appraisal of uptake of gaseous pollutants by plants. This work describes an approach that treats this process from a chemical kinetics viewpoint; it has led to the design of a chemical reactor system suitable for plant growth and exposure, while meeting criteria necessary to apply the concept of a continuous stirred tank reactor. Use of the system to study nitrogen dioxide uptake by corn [Zea mays (L.) 'Pioneer Brand 3369A'] and soybean [Glycine max (L.) Merr. 'Davis'] under several exposure conditions is presented. The system provided precise data that were readily amenable to mathematical modeling. The concept of a second-order rate constant for uptake is demonstrated, which is shown to be independent of nitrogen dioxide concentration and leaf surface area, but directly dependent upon inverse total diffusion resistance.