Assessing the Partition of Polycyclic Aromatic Hydrocarbons in Rice Rhizosphere with Bayesian Linear Cosolvent Model.

In view of the current lack of understanding the fate of polycyclic aromatic hydrocarbons (PAHs) adsorption in rice rhizosphere, the partitioning of PAHs in rice rhizosphere was estimated with partition coefficients based on Bayesian linear cosolvent models. Iron plaque restricted the adsorption of high hydrophobic PAHs on root surfaces. The partition coefficients of PAHs on root materials without lipids decreased by 4.5% to 80%. In light of greater surface area of roots after extracting lipids, the partition coefficients of PAHs on roots without lipids should have been overestimated. The partition coefficient values validated with Bayesian linear cosolvent model are higher than the literature data. This could be mainly attributed to the underestimation of partition coefficients determined with batch sorption experiment in pure water system. Although the partition coefficients of PAHs on soils were one to two orders of magnitude less than on root materials, PAHs in rhizosphere were majorly adsorbed on soil particles. The contribution of biosorbents to adsorption of phenanthrene in rice rhizosphere was more than 20 percent, whereas, the adsorption of pyrene and benzo[a]pyrene by biosorbents is likely to be neglected.