High sorption of phenanthrene in agricultural soils.

摘要

We studied the sorption and desorption of 14C-labelled phenanthrene, a polycyclic aromatic hydrocarbon, on soils, both in the laboratory using batch experiments and during 6 months of natural conditions using lysimeters. The laboratory results showed that phenanthrene was strongly adsorbed, yielding empirical constants of sorption isotherms Kf of 163 for the clay soil and of 77 for the sandy loam soil. This result is unexpected because phenanthrene has a relatively high water solubility of 1.1 mg/l. Phenanthrene is also poorly desorbed, as shown by leaching of only 30% of initially sorbed phenanthrene. The natural condition results showed that 27% of the initial phenanthrene occurs as non-available, bound residues after 6 months. The leaching of 14C phenanthrene derivatives amounts to less than 2% of the applied phenanthrene. The 14C phenanthrene derivatives leached included 80% of polar products. Analysis of the extractable residues from soils by high-performance liquid chromatography (HPLC) showed the occurrence of 9,10-phenanthrenedione, a toxic degradation product, in notable quantities of 2-3% of extractable compounds..