Application of the partition-limited model for plant uptake of organic chemicals from soil and water.

This study further examined the merits of the partition-limited model for the plant uptake of organic chemicals from soil and water. The influential factors on the quasi-equilibrium factor (alpha(pt)) of the model were evaluated for a number of systems. The present study manifested a generally high efficiency of the model for prediction of phenanthrene and pyrene uptake by plants. The overall model predictions are within an order of magnitude of the measured values, with the differences between the estimated and measured concentrations being less than 93.7% in most cases. Modeled root concentrations seemed to be more accurate than modeled shoot concentrations. Generally, the calculated alpha(pt) values for plant uptake of chemicals from water, including phenanthrene and pyrene on basis of our experimental data and lindane and trifluralin on basis of the available literature data, tend to be relatively constant after an initial fast increase with increasing uptake time. alpha(pt) values for root uptake of these chemicals are always greater than those for shoot uptake. In addition, alpha(pt) values for various root uptake of hydrophobic chemicals, e.g., phenanthrene and pyrene, exhibit significantly positive correlations with root lipid contents (p < 0.05, n = 10). This investigation substantiated the concept of the partition-limited model and its utility for vegetation-uptake assessment.