R6 AM Plant Uptake of Organic Pollutants - Processes and Modeling
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in 324-326

(GEN-1117-225643) Plant species differ in movement of hydrophobic organic chemicals: Measurements and modeling.

Gent, M¹, White, J¹, Eitzer, B¹, Mattina, M¹, ¹ Connecticut Agricultural Experiment Station, New Haven, CT, USA

ABSTRACT- The pathway for uptake of organic chemicals into plants is important when considering the risks associated with soil contamination. The pathway is likely to differ, depending on the molecular weight and hydrophobicity of the contaminant. We conducted studies under controlled conditions in which DDE, a very hydrophobic chemical, was supplied to plants at a constant concentration over two weeks in hydroponics solution. The concentration and amount of DDE were assayed at various times in solution and in various tissues of cucumber and zucchini plants. These studies were designed to test quantitatively a model of the uptake and movement of hydrophobic chemicals into plants. Simulations using a discrete-compartment model based on fugacity indicated that the primary route of movement of DDE was in the transpiration stream, rather than through the air. However, the apparent fugacity, or tendency of DDE to partition to xylem water, appeared to be more than 10 fold greater in zucchini than in cucumber. Thus, plant species may vary dramatically in this aspect of the transpiration pathway. Further work is needed to characterize this behaviour in other plant species, as it has a fundamental effect on the rate of movement of organic contaminants from soil into the aerial parts of plants.

Key words: Cucurbitacea, transpiration, fugacity, p,p'-dichlorophenyl-dichloroethylene