Phenanthrene sorption by fruit cuticles and potato periderm with different compositional characteristics.

Phenanthrene sorption by fruit cuticles (tomato, apple, and grape), potato tuber periderm, and their fractions were investigated to elucidate effects of compositional characteristics on affinity of plant cuticle (above-ground) and periderm (below-ground) with hydrophobic organic contaminants (HOCs). The distinct roles of the extractable lipids (waxes), the depolymerizable lipids (cutin/suberin), the nonsaponifiable lipids (cutan/suberan) and polysaccharide are discussed. The cutin/suberin rather than waxes dominates the sorption properties of bulk cuticle/periderm, but the sorption coefficient (K(d)) is linearly correlated with the total lipid contents. Polysaccharide plays a negative role in HOC sorption due to its obviously poor affinity with HOCs and restriction effect on the other powerful sorptive regions in cuticle/periderm. The significantly lower sorption of periderm than cuticle is attributed to the former having higher polysaccharide and lower depolymerizable lipids. The linear correlation of K(d) of bulk cuticle/periderm with polysaccharide content is observed for a potential prediction of plant uptake.