Correlating Selective Supercritical Fluid Extraction with Bioremediation Behavior of PAHs in a Field Treatment Plot

Abstract

Selective supercritical fluid extraction (SFE) behavior of PAHs from manufactured gas plant (MGP) site soils was determined on untreated soil and on soils collected after 1/2 year and 1 year of bioremediation in a field land treatment plot. Sequentially stronger SFE conditions gave selective extraction of PAHs associated with “fast” (or “rapidly desorbing”), “moderate,” “slow,” and “very slow” sites on the soil collected before and during bioremediation. While all PAHs from the untreated soil showed “stair-step” extraction curves (with molecules in each of the four “fast” to “very slow” SFE fractions), two- and three-ring PAHs were found mostly in the “fast” fraction, while the five- and six-ring PAHs were found almost completely in the “slower” fractions. SFE comparisons of the untreated and bioremediated soils showed that bioremediation only removed PAH molecules which were found in the “fast” fractions by SFE and that remediation for 1 year did not result in the migration of PAHs from “slower” to “fast...