Lj. Pinto et Mm. Moore, Release of polycyclic aromatic hydrocarbons from contaminated soils by surfactant and remediation of this effluent by Penicillium spp., ENV TOX CH, 19(7), 2000, pp. 1741-1748
Studies in which surfactants have been employed to increase the bioavailabi
lity of soil-bound polycyclic aromatic hydrocarbons (PAHs) have not yielded
consistent results. Surfactant mobilization of high molecular weight (MV)
PAHs from contaminated soils has not been extensively studied; therefore, t
he purpose of this research was to compare the extent of release of freshly
added high MW C-14-PAH with aged PAM from four different PAH-contaminated
soils using a nonionic detergent, Tween 80, and to determine whether Tween
80-solubilized C-14-PAH in soil washings could be degraded by indigenous mi
croorganisms or by added Penicillium spp. Only very high concentrations of
Tween 80 (>1,000 times the critical micelle concentration [CMC] for 3 of 4
soils) were able to mobilize bound C-14-pyrene, -chrysene, and -benzo[a]pyr
ene. The concentration of surfactant required to release 50% of bound C-14-
PAH (the SC50 value) ranged from 5 to 30 gn depending on soil type; a modes
t correlation was found (0.512) between the fraction of organic carbon in t
he soil and the SC50 value. At 10(4) x CMC, Tween 80 released an average of
75% of bound C-14-PAH and 64% of the aged PAM, indicating that the C-14-PA
H release only slightly overestimated PAM mobilization from weathered soil.
An exception was one soil that had been previously remediated in which <30
% of the PAHs were released. The PAM structure had a negligible effect on t
he mobilization by surfactant because the solubilization curves for all thr
ee PAHs were very similar. Tween 80-solubilized C-14-pyrene readsorbed to s
oil when the surfactant concentration dropped below 10(3) x CMC. Greater th
an 90% of the C-14-pyrene in the soil washing effluent could be removed by
the addition of spores of active PAM-oxidizing Penicillium spp. plus nutrie
nts. In contrast, <10% of C-14-pyrene was oxidized by the indigenous soil b
acteria under the same conditions.