es0607032_si_001.pdf (1.08 MB)
Role of Weathered Coal Tar Pitch in the Partitioning of Polycyclic Aromatic Hydrocarbons in Manufactured Gas Plant Site Sediments
journal contribution
posted on 2006-09-15, 00:00 authored by Muhammad F. Khalil, Upal Ghosh, Joseph P. KreitingerPolycyclic aromatic hydrocarbons (PAHs) in manufactured
gas plant (MGP) site sediments are often associated
with carbonaceous particles that reduce contaminant
bioavailability. Although black carbon inclusive partitioning
models have been proposed to describe elevated PAH
partitioning behavior, questions remain on the true loading
and association of PAHs in different particle types in
industrially impacted sediments. In the studied MGP
sediments, the light density organic particles (coal, coke,
wood, and coal tar pitch) comprised 10−20% of the total
mass and 70−95% of the PAHs. The remainder of the
PAHs in sediment was associated with the heavy density
particles (i.e., sand, silt, and clays). Among the different
particle types, coal tar pitch (quantified by a quinoline
extraction method) contributed the most to the bulk sediment
PAH concentration. Aqueous partition coefficients for
PAHs measured using a weathered pitch sample from the
field were generally an order of magnitude higher than
reported for natural organic matter partitioning, and
match well with theoretical predictions based on a coal
tar−water partitioning model. A pitch-partitioning inclusive
model is proposed that gives better estimates of the
measured site-specific PAH aqueous equilibrium values
than standard estimation based on natural organic matter
partitioning only. Thus, for MGP impacted sediments
containing weathered pitch particles, the partitioning
behavior may be dominated by the sorption characteristics
of pitch and not by natural organic matter or black
carbon.
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Polycyclic Aromatic Hydrocarbonsweathered pitch particlesAqueous partition coefficientsquinoline extraction methodMGPWeathered Coal Tar Pitchbulk sediment PAH concentrationweathered pitch samplecoal tar pitchManufactured Gas Plant Site SedimentsPolycyclicparticle typesmatter partitioningPAH partitioning behaviormodel
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