ESTCP Project #1011, Rhizosphere
Final Report
Injector temperature:
275C
Detector temperature:
325C
Column flow rate:
1 mL/min (hydrogen)
Semi-volatile FSH target ranges include:
aliphatic: (F1 fraction)
aromatic: (F2 fraction)
C>8-C10, C>10-C12, C>12-C16, C>16-C21,
C>8-C10, C>10-C12, C>12-C16
C>16-C35,C8-C40
C>21-C35,C8-C40.
These ranges correspond with the Total Petroleum Hydrocarbons Criteria Working Group
(TPHCWG) criteria.
For volatile FSH analysis, soil samples were analyzed by purge-and-trap GC/MS. Total
petroleum hydrocarbons in the C5 to C8 range were measured. The aromatic compounds that
make up the C6 to C8 FSH (benzene; toluene; ethylbenzene; and o-, m-, and p- xylenes) were
quantified and reported as the volatile aromatic FSH; the aliphatic FSH are defined and
computed as the total hydrocarbons that elute between C5 and C8, minus the aromatic FSH that
elute in this range.
Total petroleum hydrocarbons in the C5 to C40 range were defined as the sum of TPH in the C5 to
C8 range + TPH in the C8 to C40 range F1 + TPH in the C8 to C40 range F2.
A.2 GC Fingerprints TPH and PAH Degradation
Selected samples, for each treatment, can be monitored for hydrocarbon losses versus time.
Using the time-zero samples as the "source" of the contamination (a conservative starting point),
depletion of both TPH and PAHs can be tracked. Sample selection needs to be based primarily
on those soils that contained both a "degradable" material and a recalcitrant internal marker
(hopane). For this study, degradable was defined as material that has not undergone significant
alteration (weathering) and, therefore, could be used as a time-zero starting point. Those soils
containing a significantly weathered petroleum material have to some degree already been
bioremediated.
We used the GC traces from the HRGC/FID analyses to help identify the fuel types and amount
of degradation (weathering) present in the samples.
A.3 HRGC/MS Analyses (EPA Method 8270M): PAHs, Heteroatomic
Compounds, and Biomarkers
Based on the results of the GC fingerprint identifications, a subset of samples was selected for
further chemical characterization for polycyclic aromatic hydrocarbons (PAHs), diagnostic
heteroatomic compounds, and selected biomarkers. These analyses were performed under a
modified EPA method 8270 according to Battelle Standard Operating Procedures (SOP) 5-157,
Identification and Quantification of Polynuclear Aromatic Hydrocarbons (PAH) by Gas
Chromatography/Mass Spectrometry. Target analytes are listed in Table 6.
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