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Comparison of Two Methods for Estimating Time of Release
for Diesel Fuel NAPL
Jeffery H. Hardenstine, NewFields Environmental Forensics
Practice, LLC, 100 Ledgewood Place, Suite 302, Rockland,
MA 02370, Tel: 781-681-5040, Fax: 781-681-5048, Email: jhardenstine@newfields.com
Gregory S. Douglas, NewFields Environmental Forensics
Practice, LLC, 100 Ledgewood Place, Suite 302, Rockland,
MA 02370, Tel: 781-681-5040, Fax: 781-681-5048, Email: gdouglas@newfields.com
Kevin J. McCarthy, NewFields Environmental Forensics
Practice, LLC, 100 Ledgewood Place, Suite 302, Rockland,
MA 02370, Tel: 781-681-5040, Fax: 781-681-5048, Email: kmccarthy@newfields.com
One of the most challenging tasks facing forensic chemists
today is identifying when a petroleum product was released
to the environment. This is an important issue because it
has a direct impact on who is financially liable for the
site cleanup, and what insurance policy was in place at
the time of release.
Several methods are currently used to estimate time
of release. For
example, in gasoline NAPL, specific additives such as MTBE
or tetraethyllead may provide vital chemical data do
determine ownership and liability for the NAPL
contamination. Distilled
and blended petroleum products such as diesel fuel
however, do not have any time specific additives that can
be used to reliably age date a diesel fuel release.
Diesel fuel age dating methods rely on two
technical approaches. The most common approach currently used to age date diesel
fuel is the Christensen and Larsen method.
This method relies on the disparity in the rate of
biodegradation among hydrocarbon classes such as n-alkanes
(e.g., n-C17)
and isoprenoid alkanes (e.g.,pristane).
Christensen and Larsen calibrated the rate of n-C17/pristane degradation at 12 sites in northern Europe
soils where one-time release of diesel fuel/fuel oil #2
reportedly occurred at a known time.
The degradation rates determined in this study have
been used at multiple sites in the United States to
estimate the time of release in soil and NAPL samples with
a purported error of approximately 2 years.
The second approach to diesel fuel age dating is to
utilize the regulated reduction in sulfur content to
constrain the age of the diesel NAPL. Two case studies
involving diesel fuel NAPL will be examined where both
methods will be used to estimate the time of release.
The advantages and limitations of each method to
age date diesel fuel NAPL will be discussed.
Improved
Chemical Fingerprinting of Heavy Petroleum Fuels, Residua,
Lubricants, Asphalts, Waxes, and Acid Sludge Waste using
Conventional and High Temperature Gas Chromatography
Edward Healey,
NewFields, 100 Ledgewood Place, Suite 302, Rockland, MA
02370, Tel: 781-681-5040, Fax: 781-681-5048, Email:
ehealey@newfields.com
Scott A. Stout, NewFields,
100 Ledgewood Place, Suite 302, Rockland, MA 02370, Tel:
781-681-5040, Fax: 781-681-5048, Email: sstout@newfields.com
Dan C. Villalanti, Triton Analytics Corporation,
16840 Barker Springs #302,Houston, TX 77084, Tel:
281-578-2289, Fax: 281-578-2295, Email: villalanti@earthlink.net
Chemical fingerprinting of
hydrocarbon contamination, which is commonly used in
forensic investigations involving the nature and source(s)
of contamination, is generally conducted using
conventional gas chromatography (GC) using fused-silica,
capillary columns with a non-polar stationary phase, often
with a flame ionization (FID) or mass spectrometry (MS)
detection. Conventional
GC can provide “fingerprints” of hydrocarbons boiling
between about C5-C44, with the upper
boiling limit constrained by the stability of the GC
column’s stationary phase (e.g. EPA Methods 8015 or 8270
and ASTM D2887).
High temperature simulated
distillation (HTSD) is an adaptation of conventional
GC/FID that utilizes a non-polar, low bleed stationary
phase column (0.05-0.15 mm film thickness and 0.53 mm
internal diameter), which safely can withstand
temperatures up to 430°C.
The high phase ratio of the column permits the
elution of hydrocarbons 260 to 316°C below their true
boiling points, and thereby permits elution and
quantification of the percent mass of hydrocarbons with
boiling points up to 750°C – i.e., up to C120.
When combined with cryogenic initial GC conditions,
HTSD can expand the carbon range “fingerprint” from C5-C120,
and allows the forensic expert to evaluate hydrocarbon
distributions that conventional GC cannot.
Some loss of chromatographic resolution of
hydrocarbons in the C5-C44 range is
experienced by HTSD, but this is overcome when
conventional GC and HTSD fingerprinting are used in
parallel. The
combination of conventional and high temperature GC
provides added information in forensic investigations
involving high boiling contamination, such as heavy fuels
and crude oils, petroleum asphalts, waxes, greases, and
petroleum or tar residua.
The HTSD method is amenable to soils, sediments,
and products (including semi-solids and solids).
The forensic application of the combination of
conventional GC/FID and HTSD is demonstrated for various
petroleum fuels, residua (flux), various specialty
asphalts produced via oxidation of flux, petroleum waxes,
and lube oil acid sludge.
Distinguishing Fuel from Non-Fuel Contamination in Soils at a
Former Petroleum Terminal and Rail Yard using Chemical
Fingerprinting
Scott A. Stout, NewFields, 100 Ledgewood Place,
Suite 302, Rockland, MA 02370, Tel: 781 681-5040, Fax: 781
681-5048, Email: sstout@newfields.com
Vincent Maresco, Groundwater & Environmental Services,
Inc., 300 Gateway Park Dr., North Syracuse, New York
13212-3763, Tel: 315 452-5700, Email: VMaresco@gesonline.com
A peninsula located at the confluence of two rivers in
upstate New York has had a long anthropogenic history,
which has included an Indian village and French
(1749-1760), and later British (1760-1783) and American
(1783-1812), fortification.
By the late 1800’s the site was developed as a
commercial/industrial area which included use as a
municipal dump and large rail yard, and by about 1920
there was a small petroleum fuel terminal (west) and a
barge dock (east) connected by ~1500′ of underground
piping that spanned the rail yard (central) site.
Rail yard operations ceased in the 1970s and
petroleum handling operations ceased in 1984.
Soils throughout the former rail yard and petroleum terminal
were impacted with hydrocarbons, including PAHs, that
required determination of the “nature and extent”
prior to remediation. NYDEC prescribed analytical methods,
viz., (1) NYDOH 310-13 TPH fingerprinting, (2) EPA Method
8260 full analytes and TICs, and (3) EPA Method 8270 full
analytes and TICs, which were augmented using “advanced
chemical fingerprinting” based upon modified EPA Method
8015B and 8270.
The regulatory-required data were unable to recognize the
eight predominant hydrocarbon sources – four petroleum
sources and four non-petroleum sources - identified by
advanced chemical fingerprinting.
The normalized distribution of the 44 PAH analytes
provided detailed fingerprints that, with the aid of
numerical analysis (PCA), readily distinguished the eight
hydrocarbon sources.
The widespread occurrence of non-petroleum (pyrogenic)
PAH associated with coal soot/ash and creosote was
responsible for many TAGM clean-up criteria exceedences
– and not petroleum.
As such, the remedial investigation (RI) of complex sites can
benefit from advance chemical fingerprinting data, which
provides additional “forensic” detail compared to
regulatory-required data.
In this case, the soils were shown to contained
significant TPH and PAH attributable to non-petroleum
sources.
Environmental Stability of PAH Source Indices in Pyrogenic
Tars
Allen D. Uhler, NewFields, 100 Ledgewood Place,
Suite 302, Rockland, MA 02370, Tel: 781-681-5040, Fax:
781-681-5048, Email: auhler@newfields.com
Stephen Emsbo-Mattingly, NewFields, 100 Ledgewood Place,
Suite 302, Rockland, MA 02370, Tel: 781-681-5040, Fax:
781-681-5048, Email: smattingly@newfields.com
Bo S. Liu, NewFields, 100 Ledgewood Place, Suite 302, Rockland,
MA 02370, Tel: 781-681-5040, Fax: 781-681-5048, Email:
smattingly@bliu.com
Polycyclic aromatic hydrocarbons (PAHs) are widespread
environmental contaminants found in soil, sediments, and
airborne particulates. While low levels of PAHs in the
environment have natural origins, the majority of PAHs
found in modern soils and sediments arise from myriad
anthropogenic petrogenic and pyrogenic sources.
Tars and tar products such as creosote produced
from the industrial pyrolysis of coal or oil at former
manufactured gas plants (MGPs) or in coking retorts are
viscous, oily substances that contain significant
concentrations of PAH, usually in excess of 30% w/w.
Environmental chemists often are tasked with
identifying pyrogenic tars and tar products in the
environment, and distinguishing the chemical signatures of
such substances from other point sources of PAHs, and/or
ubiquitous anthropogenic background PAHs. Combustion and
pyrolysis of organic matter can yield source-specific
distributions of PAH compounds. Pyrogenic tars and tar products have unique PAH patterns
(source signatures) that are a function of their
industrial production. Among pyrogenic materials, certain
diagnostic ratios of environmentally recalcitrant 4-, 5-
and 6-ring PAHs have been identified as useful
environmental markers for tracking the signature of tars
and petroleum in the environment.
The use of selected PAH source ratios is based on
the concept that PAHs with similar properties (i.e.,
molecular weight, partial pressure, solubility, partition
coefficients, and biotic/abiotic degradation) will weather
at similar rates in the environment thereby yielding
stable ratios. In
this poster, we evaluate the stability of more than 30
high molecular weight PAH ratios during controlled studies
of tar evaporation and aerobic biodegradation.
The starting materials in these experiments
consisted of relatively unweathered tars derived from coal
and petroleum, respectively.
The PAH ratios from these laboratory studies are
compared to those measured in PAH residues found in
tar-contaminated soils at a former MGP that operated with
a carburetted water gas process.
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