High sorption of phenanthrene in agricultural soils

We studied the sorption and desorption of C-14-labelled phenanthrene, a polycyclic aromatic hydrocarbon, on soils, both in the laboratory using batch experiment experiments and during 6 months of natural conditions using using lysimeters. The laboratory results show that using phenanthrene is strongly adsorbed, yielding empirical empirical constants of so l sorption isotherms isotherms K-f of 163 for the clay soil and of 77 for the sandy loam soil. This result is unexpected because phenanthrene 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 natura natural condition results show that 27% l of the initial phenanthrene occurs as non-nonavailable, bound residues after available, 6 months. The leaching of C-14 phenanthrene derivatives amounts to less C than 2% of the applied phenanthrene. The C-14 phenanthrene derivatives leached leached included 80% of polar products. Analysis of the 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.