MODELING THE BIOCONCENTRATION OF ORGANIC-CHEMICALS IN PLANTS

Uptake of several organic chemicals by growing barley was investigated in a closed laboratory model ecosystem (volume 9.4 L). To discriminate between root and foliar uptake, the soil was divided into test soil contaminated with 2 mg/kg 14C-labeled chemicals and unpolluted control soil. Air was exchanged at a rate of 10 mL/min. Concentrations of 14C chemicals in air, soil, roots, and shoots and bioconcentration factors were simulated with a mathematical model based on fugacity. Bioconcentration in the plant is dependent on transfer rates and the ratio of Kow and Koc values. Uptake into foliage is mainly from air for chemicals with a high Kow and a Henry's law constant high enough for volatilization. Chemicals with medium Kow are translocated with the transpiration stream. Metabolites are also taken up. Chemicals in the roots of the barley plants reach equilibrium with the soil, whereas those in foliage are in equilibrium with the air in most cases. © 1990, American Chemical Society. All rights reserved.