Dynamic root uptake model for neutral lipophilic organics

摘要

In current European risk assessment, and equilibrium approach is used to estimate chemical uptake from soil into root vegetables. Here a dynamic model for uptake of neutral lipophilic compounds from soil into roots is presented. Using experimental results, it is compared with the equilibrium approach. Very lipophilic compounds(e.g., DDT) diffuse very slowly into plant tissue, so they are likely to remain in the peel of root vegetables. In addition, a dynamic (steady-state) flux model for uptake with transpiration water into thick roots is presented. The model considers input from soil and output to stem with the transpiration stream plus first-order metabolism and dilution by exponential growth. For chemicals with low or intermediate lipohilicity(log K_OW <2), there was no relevant difference between dynamic model and equilibrium approach.