REDUCED BIODEGRADABILITY OF DESORPTION-RESISTANT FRACTIONS OF POLYCYCLIC AROMATIC-HYDROCARBONS IN SOIL AND AQUIFER SOLIDS

Less of the desorption-resistant fractions of phenanthrene and naphtha lene than freshly added phenanthrene and naphthalene was mineralized i n columns of aquifer solids, loam, or muck. Slurrying columns of hydro carbon-amended aquifer solids, loam, or muck enhanced the rate and ext ent of mineralization of desorption-resistant phenanthrene and naphtha lene, but degradation was still less than in slurries amended with fre sh compound. A substantial portion of the desorption-resistant compoun d remained undegraded in the slurry. A surfactant and methanol increas ed the mineralization of resistant phenanthrene in slurries of loam. A mixed culture of microorganisms enriched on desorption-resistant phen anthrene degraded twice as much of this fraction of compound as a pseu domonad. We suggest that predictions of the environmental fate of toxi c chemicals require information on the biodegradability of the fractio n of a compound that is resistant to desorption.