Binding characteristics of perylene, phenanthrene and anthracene to different DOM fractions from lake water

Six hydrophobic and hydrophilic fractions were isolated using XAD-8 and XAD-4 resins, and were extensively characterized. Partition coefficients of perylene, phenanthrene and anthracene binding to the six fractions were determined by fluorescence quenching titration. The Kdoc values obtained for the polycyclic aromatic hydrocarbons (PAHs) binding to the hydrophobic fractions were larger than those to the hydrophilic fractions. Nonlinear Stern-Volmer plots were observed when binding phenanthrene and anthracene to some hydrophilic fraction samples, suggesting saturation of polar interaction binding sites. A significant correlation of logKdoc values with molecular weights and molar absorptivities at 280 nm was observed, while atomic ratio of C/H was found to be a poor indicator for aromaticity. Other structural descriptors such as paraffinic carbon and polarity influenced the DOM-fraction ability to bind PAHs. Different interaction mechanisms underlying binding of the different fractions to the PAHs were also discussed.