The sequential extraction divided the PAHs accumulated
among the roots into PAHs in root exudates from CaCl2 extraction,
PAHs adsorbed on root surface from methanol extraction,
and PAHs absorbed in root tissue from accelerated
solvent extraction (ASE). For both rice nodal roots and lateral
roots, PAH16 content showed a distinct increase from the root
exudates fraction to the root surface fraction to the root tissue
fraction. PAH16 concentrations in the three extractions with
standard deviation are shown in Fig. 1