title: Investigating differential binding of polychlorinated dibenzo-p-dioxins/dibenzofurans in soil and soil components using selective supercritical fluid extraction.
abstract: Supercritical fluid extraction (SFE) with pure carbon dioxide was performed at increasingly strong conditions to investigate differential binding of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in two impacted soils, in their sieved size fractions, and in small (a few mg) samples of industry-related waste products separated from impacted soil. The binding strengths of PCDD/Fs were shown to be different in the two soils, and in their different soil particle size fractions. As might be expected based on surface area considerations, one soil showed the strongest binding in the smallest (<5μm) sieved fraction. However, the other soil showed the strongest binding in the larger sized fractions, possibly indicating that process-related particles could be controlling PCDD/F binding. Selective SFE of various types of particles including black carbon and charcoal (separated from soil), and from a suspected process anode residue did show different PCDD/F binding behavior ranging from quite weak binding (charcoal) to very strong binding (anode particles). Shifts to the stronger SFE fractions in the soils after activated carbon treatment agreed well with the decreases previously found in the uptake of PCDD/Fs by earthworms, as well as decreases in their freely-dissolved aqueous concentrations in soil/water slurries. These results show that, as previously demonstrated for PAHs and PCBs, selective SFE can be a useful tool to investigate differences in PCDD/F binding behaviors in impacted soils and sediments and their component parts, as well as a rapid tool for estimating the effectiveness of activated carbon treatments on decreasing the bioavailability of PCDD/Fs in soils and sediments.
authors.affiliation: Energy and Environmental Research Center, University of North Dakota, 15 North 23rd Street, Grand Forks, ND 58202, USA. shawthorne@undeerc.org
authors.forename: Steven B
authors.initials: SB
authors.lastname: Hawthorne
authors.forename: Yunzhou
authors.initials: Y
authors.lastname: Chai
authors.forename: Carol B
authors.initials: CB
authors.lastname: Grabanski
authors.forename: John W
authors.initials: JW
authors.lastname: Davis
authors.forename: Michael
authors.initials: M
authors.lastname: Wilken
authors.forename: Greg D
authors.initials: GD
authors.lastname: Martin
authors.forename: David J
authors.initials: DJ
authors.lastname: Miller
authors.forename: Upal
authors.initials: U
authors.lastname: Ghosh
mesh_terms: D001572:Benzofurans / Q000302:isolation & purification*; D002606:Charcoal / Q000737:chemistry; D025924:Chromatography, Supercritical Fluid / Q000379:methods; D000072338:Dibenzofurans, Polychlorinated; D019015:Geologic Sediments / Q000032:analysis; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000302:isolation & purification; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000302:isolation & purification*
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D012987:Soil; D012989:Soil Pollutants; D002606:Charcoal