DESORPTION AND BIODEGRADATION OF SORBED STYRENE IN SOIL AND AQUIFER SOLIDS

Approximately 40 and 18% of styrene freshly added to Lima loam and aquifer solids, respectively, was mineralized in 50 d. Although measurements of equilibrium desorption under abiotic conditions showed that only 7.2 and 5.7% of sorbed styrene were present in aqueous solution at 150 h, 61.0 and 66.7% of the compound were desorbed from the soil and aquifer solids, respectively, in 16 d under nonequilibrium conditions. Much of the nondesorbed styrene freshly added to the environmental samples could be extracted with methanol. Approximately 20% of the freshly added styrene not removed from columns of soil that had been repeatedly leached with water was mineralized in 49 d. Styrene freshly added to a muck soil also was extensively mineralized. However, if the compound was in soil for increasingly long periods in the absence of microbial activity, the extent of biodegradation by subsequently added microorganisms became progressively lower until <3% was mineralized in soils in which the chemical was present for four months. Most of the styrene freshly added to Lima loam and Edwards muck could be extracted with acetonitrile, but <4% was extracted from soils containing the chemical for 123 d. The biodegradation of styrene that has been in natural environments for some time thus is probably different from the transformations that occur with the freshly added compound.