EFFECT OF SURFACTANTS AT LOW CONCENTRATIONS ON THE DESORPTION AND BIODEGRADATION OF SORBED AROMATIC-COMPOUNDS IN SOIL

A study was conducted to determine the effect of low concentrations of surfactants on the biodegradation of sorbed aromatic compounds in soil. The nonionic alcohol ethoxylate surfactants Alfonic 810-60 and Novel II 1412-56 increased the extent of desorption of phenanthrene from a mineral soil. Alfonic 810-60 enhanced desorption of biphenyl from this soil at one concentration tested, but Novel II 1412-56 did not. Less than 0.01 parts per thousand of the added phenanthrene and biphenyl was present in solution after their introduction into an organic soil, and the surfactants did not promote desorption. The two surfactants at 10-mu-g/g of soil markedly increased the extent of biodegradation of phenanthrene in both the mineral and the organic soil; the stimulation was greater in the organic soil. Biphenyl mineralization in the mineral soil was not affected by either surfactant, but biodegradation in the organic soil was enhanced by Alfonic 810-60 at 100-mu-g/g. We suggest that surfactants at low concentrations may promote the mineralization of sorbed aromatic compounds in polluted soils, even when surfactant-induced desorption is not appreciable.