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The widespread detection of per- and polyfluoroalkyl substances (PFAS) throughout the world and the ongoing proliferation of environmental regulations has prompted the need for a forensic approach ...

Site investigations require the collection and analysis of representative environmental samples to delineate impacts, risks, and remediation options. When environmental samples are collected, concentrations of semi-volatile polycyclic aromatic hydrocarbons (PAHs) begin to change due to several processes, such as evaporation, adsorption, precipitation, photo, and microbial degradation. Preservation techniques are used to minimize these changes between collection and analysis. The most common techniques are refrigeration, freezing, and acidification. In the mid 1970 s, regulatory agencies developed a holding time limit of 14 days for PAHs in soil/sediment samples stored at

On or about July 25, 2010, approximately 843,000 gal of condensate diluted bitumen (dilbit, a heavy oil) was released into the Kalamazoo River near Marshall, Michigan. As the discharged Line 6B oil migrated downstream the lighter diluent volatilized, formed visible oil droplets/flakes in the water column, became denser than water and/or became aggregated with sediment and migrated to the underlying bottom sediments. Accurate identification and determination of the amount of Line 6B oil present in the sediment was a primary requirement for remediation and allocation of liability. Based on a multi-tiered application of advanced hydrocarbon fingerprinting methodology, key chemical characteristics of the spilled oil were identified that allow for distinguishing heavy oil-related contamination from the complex river sediment background hydrocarbon contamination. It was determined that among the characteristics evaluated, concentration ratios of selected tri-aromatic steranes and triterpanes were most efficient parameters for identification and quantification of the spilled oil in the environment. This quantification approach was successfully applied and validated with field sample results and is consistent with the well-established environmental stability of these petroleum biomarkers and modern hydrocarbon fingerprinting methodology.

The Deepwater Horizon (DWH) oil spill was unique because unlike most oil spills, a substantial fraction of the released oil was deposited on deep-sea floor as both particulate oil close to the Macondo well and as oily floc further from the well. In late 2010/2011 and in 2014, benthic macrofauna, including large populations of the deep-sea red crab (Chaceon quinquedens), were collected from the deep seafloor to determine if there was forensic evidence for their exposure to the spilled Macondo oil. In this study, polycyclic aromatic hydrocarbons and biomarkers (triterpane and steranes) were measured in more than 1700 dissected red crab tissue samples, in order to assess the concentrations and distributions (chemical fingerprint) of any oil present within the tissues. Results show that red crabs clearly were exposed to Macondo oil from the DWH oil spill—and as such can be considered as sentinel organisms for oil exposure in deep benthic environments. Specific results included (1) among various tissue types studied, the red crab hepatopancreas provided the most sensitive and diagnostic chemical fingerprints by which to assess exposure of these animals, (2) the highest exposures of red crabs to Macondo oil in 2010/2011 occurred closest to the well although exposures up to 14 km southwest of the well were identified, (3) detection of Macondo oil residuals in red crabs was consistent with spatial distribution of spill-impacted deep-sea sediments, and (4) exposures were lower in 2014 but still recognized, particularly within the more recalcitrant biomarkers.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in soils and sediments, particularly in urbanized environments in which the concentrations of 16 (or so) PAHs are regulated. Distinguishing among the numerous PAH sources is of practical and legal concern and thereby is often an objective of environmental forensic chemistry studies. Studies of prospective sources and impacted soils and sediments that rely upon the 16 U.S. EPA Priority Pollutant PAHs are disadvantaged, as these few compounds generally lack the specificity to distinguish among different PAH sources in the environment. Advances in analytical and interpretive methods over several decades have shown that different PAH sources can be more defensibly distinguished using modified EPA Method 8270 that, among other improvements, measure many other polycyclic aromatic compounds (PACs) that co-occur with the Priority Pollutant PAHs in different sources and in the environment. The PACs include variously-alkylated PAHs and polycyclic aromatic sulfu...

Modern merchant vessels are powered by marine diesel engines that utilize heavy fuels oils, which are products opportunistically blended from residual oils and refinery intermediates. Merchant vessels also employ an array of lubricating-type oils with specific properties and chemistries, formulated for special purposes ranging from engine, gear and motor lubrication to hydraulics controls. Any or all of these shipboard petroleum products are candidates for accidental or intentional release to the marine environment, and thus can become the subject of forensic chemistry studies that focus on understanding the nature, extent, and environmental impact of such spilled or discharged oil. This chapter provides an introduction into the production of heavy fuel oils and lubricants, and explores the basic chemical features that are germane to chemical fingerprinting studies of such oils in the environment. Gas chromatographic and molecular chemical characteristics of representative heavy fuel oil and lubricants are presented in order to demonstrate the general features, and the intraproduct chemical heterogeneity that can be leveraged in the forensic evaluation of these two classes of petroleum products.

Detailed chemical analysis of petroleum – often referred to as “chemical fingerprinting” – has played a vital role in the identification of oil from accidental spills in the marine and riverine environments (e.g., sediments). The analytical tools used to identify and quantify the spilled oil must provide sufficient chemical resolution to separate the oil from any pre-existing (historical or naturally occurring) background hydrocarbons ubiquitous in many environments. Qualitative chemical fingerprinting analysis is a visual comparison between various spectroscopic or chromatographic fingerprints and is most successfully applied when the oil signature is unweathered and/or not mixed with other hydrocarbon sources (e.g., background). Quantitative chemical fingerprinting is the use of target compound calibration standards during the chemical analysis (e.g., GC/MS) of the sample to quantify the concentrations of source diagnostic hydrocarbons such as polycyclic aromatic hydrocarbons and biomarkers (e.g., triterpanes and steranes). These quantitative results can then be used to develop interpretive tools, such as diagnostic ratios, that allow the forensic scientist to compare spill and source oils and also to develop mixing models capable of allocating hydrocarbons derived from the spilled oil versus any background hydrocarbon signatures. Although the utility of diagnostic ratios has been discussed extensively in regard to oil spill identification in the scientific literature, the same is not true for the development and application hydrocarbon mixing models at oil spill sites. This chapter examines the applications and limitations of qualitative and quantitative oil fingerprinting methods and provides four oil spill case studies where mixing models were used to identify and or allocate liability in complex mixtures of spilled oils and various forms of background hydrocarbons.

We describe a new and rapid quantitative approach to assess the extent of aerobic biodegradation of volatile and semivolatile hydrocarbons in crude oil, using Shushufindi oil from Ecuador as an example. Volatile hydrocarbon biodegradation was both rapid and complete-100% of the benzene, toluene, xylenes (BTEX) and 98% of the gasoline-range organics (GRO) were biodegraded in less than 2 days. Severe biodegradation of the semivolatile hydrocarbons occurred in the inoculated samples with 67% and 87% loss of the diesel-range hydrocarbons (DRO) in 3 and 20 weeks, respectively. One-hundred percent of the naphthalene, fluorene, and phenanthrene, and 46% of the chrysene in the oil were biodegraded within 3 weeks. Percent depletion estimates based on C(30) 17α,21β(H)-hopane (hopane) underestimated the diesel-range organics (DRO) and USEPA 16 priority pollutant PAH losses in the most severely biodegraded samples. The C(28) 20S-triaromatic steroid (TAS) was found to yield more accurate depletion estimates, and a new hopane stability ratio (HSR = hopane/(hopane + TAS)) was developed to monitor hopane degradation in field samples. Oil degradation within field soil samples impacted with Shushufindi crude oil was 83% and 98% for DRO and PAH, respectively. The gas chromatograms and percent depletion estimates indicated that similar levels of petroleum degradation occurred in both the field and laboratory samples, but hopane degradation was substantially less in the field samples. We conclude that cometabolism of hopane may be a factor during rapid biodegradation of petroleum in the laboratory and may not occur to a great extent during biodegradation in the field. We recommend that the hopane stability ratio be monitored in future field studies. If hopane degradation is observed, then the TAS percent depletion estimate should be computed to correct for any bias that may result in petroleum depletion estimates based on hopane.

Complex mixtures of volatile organic chemical (VOC) vapors can exist over subsurface accumulations of non-aqueous phase liquids (NAPLs) and contaminated soils. The ability to predict the relative soil gas chemical composition arising from such NAPLs is relevant to studies of the sources and fate of soil gas, and in assessing the possible intrusion of soil gas chemical constituents to indoor air. However, it is difficult to directly compare the chemical ‘fingerprints’ of NAPL and vapor because the differences are significant in liquid-gas partitioning coefficients among the many volatile hydrocarbons that compose the liquid NAPL. In this article, detailed chemical characterization data from analysis of liquid NAPLs are used to calculate equilibrium vapor phase distributions of 66 diagnostic paraffin, isoparaffin, aromatic, naphthene, and olefin (PIANO) compounds. Measured NAPL and predicted vapor phase chemical composition are presented for a diverse group of 10 hydrocarbon products that include crude oil,...

The release of gasoline at retail service station sites can result in the presence of gasoline-derived constituents dissolved in ground water. Due to regulatory requirements or remediation objectives the concentrations of these constituents often are monitored regularly for several years or decades. This study aims to demonstrate the utility of a large historic dataset for gasoline-impacted groundwater through the evaluation of spatial and temporal trends over 8 years of quarterly benzene, toluene, ethylbenzene, and o, m, and p-xylene polymers (BTEX) data from a plume emanating from a service station site. A novel aspect explored herein was to convert the historic, time-series BTEX concentration data into relative mole fractions in a corresponding four-component (BTEX), hypothetical non-aqueous phase liquid (NAPL), i.e., “NAPL-GW fingerprints”, in order to: 1) minimize the influence of factors affecting absolute BTEX concentrations over the 8 years of data collection (e.g., groundwater elevation in relati...

Virtually all environmental forensics investigations focus on addressing questions pertaining to the nature, source, age, and ownership of site-related contamination. Contamination, particularly at complex historic sites, is usually a multifarious mixture of both organic and inorganic chemicals. Thus, the forensic investigator is typically faced with “unravelling” a complicated mixture of chemicals into component parts in order to better link the chemicals to their historic origins and differentiate them from often similar types and sources of contaminants. This chapter describes advanced methods of chemical analyses that have evolved, and continue to be refined by environmental chemists to address the specific needs of the forensic investigator and focuses on arguably some of the most important organic contaminants commonly encountered in terrestrial and sediment investigations: petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAH). The details of advanced methods for the measurement of these chemicals in multiple media (water, soils, sediment, air, and biological tissues) are presented. Laboratory techniques, including sample preparation, instrumental analysis, and quality control and quality assurance procedures are presented so that the reader can readily adapt forensic measurement techniques to suit his or her specific site investigation activities. Case studies are presented throughout the text that demonstrate the application of advanced methods of chemical analysis to varying kinds of complicated, real world forensic instigations.

†Drs. Scott A. Stout, Gregory S. Douglas, and Allen D. Uhler are principals at NewFields Environmental Forensics Practice, LLC, in Rockland, Massachusetts. They each have over 15 years experience in the chemical characterization of petroleum and related contaminants in the environment. Their firm specializes in the application of chemical fingerprinting and other forensic tools in assessing liability associated with environmental contamination in soils, groundwater, surface water, and sediments, including expert consulting and technical support in the course of litigation.

Oil spills of unknown origin, so-called “mystery” spills, occur routinely in rivers, open water, and navigable coastal waterways. The natural resources damage (NRD) liability associated with even a small volume of oil released into the environment warrants that a thorough chemical characterization of the spilled oil be conducted by agencies and potentially responsible parties (PRPs). Chemical fingerprinting methods have played an important role in the identification of mystery oil spills. These methods fall into two categories, viz., qualitative and quantitative. The qualitative approach relies upon visual comparison of various chromatographic fingerprints obtained by GC/FID and GC/MS analysis of spill and candidate source oils and are represented ASTM methods. The quantitative approach relies upon measurements of the concentrations (relative or absolute) of dozens of diagnostic chemicals, typically PAHs and biomarkers, and a subsequent statistical or numerical analysis of various diagnostic parameters ca...

Diamondoids are a class of naturally occurring, saturated hydrocarbons in petroleum that consist of three or more fused cyclohexane rings, which results in a “diamond-like” structure. The diamondoids that can be found in light petroleum liquids (e.g., natural gas condensates), intermediate petroleum distillates (e.g., naphthas), and finished petroleum products (e.g., automotive gasoline) include adamantane (boiling point ∼ 190°C) and diamantane (boiling point ∼272°C), and their various substituted equivalents. Previous petroleum geochemistry studies indicate these naturally occurring compounds are extremely resistant to weathering. As such, their distribution and relative abundance in environmental samples can be useful in the chemical fingerprinting of light petroleum and gasoline. In this article, the application of diamondoids in the chemical fingerprinting of lower boiling petroleum in environmental samples is introduced and demonstrated. Specifically, the relative abundance of C0- to C4-alkylated ada...

To evaluate the sources, transport, bioremediation, fate, and effects of spilled petroleum and petroleum products, environmental studies often measure parent and alkylated polycyclic aromatic hydrocarbons (PAH), alkanes, and chemical biomarkers (e.g., triterpanes). Accurate data for low analyte concentrations are required when environmental samples contain hydrocarbons from multiple sources that need to be resolved and quantified. The accuracy and usefulness of the analyses can be improved by lowering the method detection limits (MDLs) for these compounds. Misidentification of hydrocarbon source can result when the MDLs are too high. Modifications to standard analytical methods (i.e., U.S. Environmental Protection Agency Method 8270) can lower MDLs by factors ranging from 10 to 1000. This reduction has important implications for ecological-risk assessments. Modifications having the greatest impact on the MDL include GCMS analysis in the selected-ion-monitoring mode (SIM), increased sample size, column cleanup of the extract, and decreased preinjection volume (volume of final extract prior to injection into instrument). In one study in which a benthic sediment sample was spiked with low levels of topped (heated to remove more volatile PAH that are naturally enriched in crude oil) Alaska North Slope crude, MDLs for individual PAH analytes and biomarkers were determined to be less than 0.5 ng/g (ppb) dry weight and less than 5 ppb dry weightfor individual alkanes. Similar results were obtained when the sediment was spiked with the 16 EPA priority pollutants. In addition, a method has been developed to estimate MDLs for source-specific alkylated PAH analytes and chemical biomarker compounds for which standards are not commercially available or are prohibitively expensive. These improved analytical techniques have been used to identify and quantify low levels of hydrocarbons, derived from both natural and anthropogenic sources, found in the benthic sediments of Prince William Sound, AK.

On January 30, 2000, an accidental oil release occurred from a fracture in the OSSA II pipeline where it crosses over the Rio Desaguadero in Bolivia, South America. This paper addresses the composition of the spilled oil and the unique weathering processes that occurred after the spill. Samples of oil, oiled sediment, water, and vegetation were collected from the riverbank and surrounding areas for approximately one year after the initial release. The samples were analyzed by gas chromatography with a flame ionization detector and by gas chromatography coupled with mass spectrometry to characterize the weathered product. Laboratory studies were also performed to evaluate the maximum extent of evaporation of the pipeline oil, and the extent of water solubility. Based on these chemical analyses, several conclusions were reached: • There was a rapid and substantial loss of the benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH) oil fractions. • The BTEX and PAH losses were due primarily to evaporation. • The stranded residual oil consisted primarily of heavy, immobile hydrocarbons. • Photooxidation of PAHs, including benzo(a)pyrene, was observed. • A unique weathering mechanism was observed that selectively removed mid-range hydrocarbons (C20 through C39) from the bulk oil. • The overall environmental risk of the spilled oil has been reduced due to the extensive weathering of the oil.

The need to determine the source(s) of fugitive gasoline in the environment is common when multiple candidate sources co-exist nearby to the discovery or when gasoline is discovered subsequent to a property transfer. Process forensics is the component of environmental forensics that relies upon a detailed understanding of the current and historic refining and engineering practices and how these practices would predictably have affected the chemical composition of the automotive gasoline manufactured at different refineries at different times. Since not all gasoline is ‘created equal’, when the detailed “chemical fingerprint” of a fugitive gasoline in the environment is interpreted in light of process forensics, a more thorough understanding of the production practices used to refine the fugitive gasoline can emerge. In some circumstances this knowledge can help to implicate a particular source(s) of the gasoline.

The identification and allocation of multiple hydrocarbon sources in marine sediments is best achieved using an holistic approach. Total organic carbon (TOC) is one important tool that can constrain the contributions of specific sources and rule out incorrect source allocations in cases where inputs are dominated by fossil organic carbon. In a study of the benthic sediments from Prince William Sound (PWS) and the Gulf of Alaska (GOA), we find excellent agreement between measured TOC and TOC calculated from hydrocarbon fingerprint matches of polycyclic aromatic hydrocarbons (PAH) and chemical biomarkers. Confirmation by two such independent source indicators (TOC and fingerprint matches) provides evidence that source allocations determined by the fingerprint matches are robust and that the major TOC sources have been correctly identified. Fingerprint matches quantify the hydrocarbon contributions of various sources to the benthic sediments and the degree of hydrocarbon winnowing by waves and currents. TOC contents are then calculated using source allocation results from fingerprint matches and the TOCs of contributing sources. Comparisons of the actual sediment TOC values and those calculated from source allocation support our earlier published findings ( 5 ) that the natural petrogenic hydrocarbon background in sediments in this area comes from eroding Tertiary shales and associated oil seeps along the northern GOA coast and exclude thermally mature area coals from being important contributors to the PWS background due to their high TOC content.

Prince William Sound (PWS), Alaska has an extensive history of human and industrial activity that has produced a complex organic geochemistry record in subtidal sediments of embayments throughout the sound. In addition to contributions from recent oil spills and a regional background of natural petroleum hydrocarbons originating from active hydrocarbon systems in the northern Gulf of Alaska (GOA), pyrogenic and petrogenic PAH were, and continue to be introduced to subtidal sediments at numerous sites of past and present human activities. These sites include villages, fish hatcheries, fish camps and recreational campsites in addition to abandoned settlements, canneries, sawmills, and mines. A holistic approach is used to fingerprint and quantify hydrocarbon contributions from multiple sources in a sediment sample. It involves acquiring a comprehensive understanding of the history of the area to identify potential sources, collection of representative samples, and accurate quantitative analyses of the sourc...

Simple evaporation of spilled oil is usually thought to be restricted to the smaller hydrocarbons (

Polycyclic aromatic hydrocarbons (PAH) are sensitive recorders of past human activities in Prince William Sound, Alaska. In the nearshore subtidal sediments of bays, the fingerprints of the pyrogenic (combustion-derived) PAH record numerous sites of both present and historical human activities including active settlements, fish hatcheries, fish camps and recreational campsites, in addition to abandoned settlements, canneries, sawmills, and mining camps. In instances, there are high levels of PAH attributable to past human activities even though there is little remaining visual evidence of these activities on the shorelines. Forest fires are also an important source of pyrogenic PAH in subtidal sediments at certain time periods and locations and pyrogenic PAH from atmospheric fallout forms part of the regional PAH background. These pyrogenic PAH fingerprints are superimposed on a regional background of natural petroleum hydrocarbons derived from seeps in the eastern Gulf of Alaska. In isolated locations, weathered traces of the Exxon Valdez oil spill were detected as a minor part of the total PAH present from all sources.

Advances in environmental chemistry laboratory and data interpretation techniques (i.e. chemical fingerprinting) contributed to a better understanding of the biological impact of the 1989 Exxon Valdez oil spill and the fate of the spilled oil. A review of the evolution of petroleum chemical fingerprinting techniques is presented followed by a summarization of how new approaches were used to characterize and differentiate among different petroleum sources in the Prince William Sound region after the spill. An assessment of the initial data suggested that multiple sources of polycyclic aromatic hydrocarbons (PAH) were present. These findings were further substantiated, even in samples of low part-per-billion PAH concentrations, by using refined and extended laboratory techniques including the analysis of saturate biomarkers. To interpret these mixtures of sources, fingerprint-analysis flow charts and source allocation techniques were developed and applied to the data, leading to the quantification of the spilled oil as a small increment on the natural hydrocarbon background in subtidal sediments.

A natural regional petroleum hydrocarbon background has been identified in the subtidal sediments of Prince William Sound that is readily distinguished from Exxon Valdez spill oil by chemical fingerprinting methods. This hydrocarbon background is derived from natural petroleum seeps in the eastern Gulf of Alaska. The Alaska Coastal Current carries fine-grained sediments and associated hydrocarbons from seep areas to the east into Prince William Sound, where they are deposited on the seafloor. The analysis of age-dated sediment cores indicates that this process has been going on for the past 160 years, and probably for many thousands of years. In addition, results of a stratified random study of nearshore subtidal sediments conducted in 1990 show that this is a general phenomenon throughout the sound and is significant even in shallow water (3 to 30 m). For example, oleanane, a saturate petroleum biomarker found in Prince William Sound prespill background petroleum and seep sources but not in Exxon Valdez petroleum, is present in subtidal sediment samples from locations throughout the sound. This supports the conclusion that seep areas to the east are major sediment sources for the sound. Moreover, polycyclic aromatic hydrocarbon mixing model calculations show that, although Exxon Valdez spill-oil residues are present in nearshore subtidal sediments, they generally form a small increment on the natural background. The recognition of preexisting natural and anthropogenic hydrocarbon sources in a spill area is a fundamentally important component of any natural resource damage assessment.

Weathering and biodegradation alter the composition of spilled oil, making it difficult to identify the source of the release and to monitor its fate in the environment. Using intertidal sediment and terrestrial soil data that cover a wide range of oil weathering states, we show that ratios of alkylated dibenzothiophenes and phenanthrenes are useful for source identification even up to 98% depletion of total polycyclic aromatic hydrocarbons (PAHs). Furthermore, we find that some ratios of alkylated naphthalenes, phenanthrenes, and chrysenes can qualitatively assess the extent of weathering an oil has undergone since a spill. These source and weathering ratios appear to successfully describe oil depletion and to identify sources in subtidal sediment data from the M/C Haven spill in Italy, the Exxon Valdez spill in Alaska, and a North Sea oil spill.

On April 11, 1991, an explosion on the M/C Haven resulted in a fire and the release of approximately 145,500 metric tons (t) of heavy Iranian crude oil near Genoa, Italy, in the industrialized coastal region of the northern Ligurian Sea. Approximately 30,000 t of cargo oil was released to the sea, of which only one-tenth reached the shoreline beaches along the Italian Riviera. An environmental assessment of the affected region indicated injury from the spilled oil to subtidal Posidonia/Cymodocea (seagrass) beds and the deep-sea benthic community and associated commercial fisheries. This was one of the first oil spills in which it was documented that oiled, shallow subtidal sediments (

Hopanes are common constituents of crude oils, and they are very resistant to biodegradation. They can therefore serve as conserved internal standards for assessing the biodegradation of the more degradable compounds in the oil. Here we address two important questions that attend such use. The first is whether the [open quotes]internal standard[close quotes] is being created during the biodegradation process itself, for this could result in an overestimate of the extent of biodegradation. The second is whether the internal standard is indeed relatively resistant to biodegradation on time scales of relevance to the biodegradation process under study; for if it was not, this could result in an underestimate of the extent of biodegradation. We find that 17[alpha](H),21[beta](H)-hopane is neither generated nor biodegraded during the biodegradation of crude oil fractions on time scales relevant to estimating the cleansing of oil spills, and so it has the appropriate characteristics to serve as an internal standard for studying the biodegradation of crude oil in the environment. 20 refs., 4 figs.

Battelle Ocean Sciences has developed an analytical approach to identify and’ quantify petroleum products, coal products, and individual hydrocarbon components at trace levels in complex environmental matrices. The hydrocarbon analysis strategy uses capillary gas chromatography/flame ionization detection for alkane and total oil analysis, combined with gas chromatography/mass spectrometry for polynuclear aromatic hydrocarbon analysis. The method provides environmentally realistic analyte detection limits (parts per trillion in water, parts per billion in sediments) and an analyte list that is designed specifically for petroleum and coal‐based products. Results are compared to a detailed computerized library of total, water‐soluble, and degraded hydrocarbon products. The systematic data interpretation strategy maximizes the accuracy of petroleum and coal product identification in environmental matrices and represents a vast improvement over standard EPA methodology.

Advanced hydrocarbon fingerprinting methods and improved analytical methods make possible the quantitative discrimination of the multiple sources of hydrocarbons in the benthic sediments of Prince William Sound (PWS) and the Gulf of Alaska. These methods measure an extensive range of polycyclic aromatic hydrocarbons (PAH) at detection levels that are as much as two orders of magnitude lower than those obtained by standard Environmental Protection Agency methods. Nineteen hundred thirty six subtidal sediment samples collected in the sound and the eastern Gulf of Alaska in 1989, 1990, and 1991 were analyzed. Fingerprint analyses of gas chromatography-mass spectrometry data reveal a natural background of petrogenic and biogenic PAH. Exxon Valdez crude, its weathering products, and diesel fuel refined from Alaska North Slope crude are readily distinguished from the natural seep petroleum background and from each other because of their distinctive PAH distributions. Mixing models were developed to calculate the PAH contributions from each source to each sediment sample. These calculations show that most of the seafloor in PWS contains no detectable hydrocarbons from the Exxon Valdez spill, although elevated concentrations of PAH from seep sources are widespread. In those areas where they were detected, spill hydrocarbons were generally a small increment tomore » the natural petroleum hydrocarbon background. Low levels of Exxon Valdez crude residue were present in 1989 and again in 1990 in nearshore subtidal sediments off some shorelines that had been heavily oiled. By 1991 these crude residues were heavily degraded and even more sporadically distributed. 58 refs., 18 figs., 5 tabs.« less

Because of their preponderant use as fuel in marine vessels, marine residual fuels are often the focus of maritime oil spill investigations. Residual fuels, often referred to generically as heavy fuel oil or HFO, pose a variety of challenges to oil spill investigators. Variability in the composition of modern heavy marine fuels provides unique opportunities for chemical “fingerprinting” of HFOs in the environment. This chapter focuses on the forensic chemistry of HFO—the most widely used of the commercial marine fuel oils—and chemical features of these fuels pertinent to oil spill investigations. Two most popular groups of heavy fuel oils, IFO 180 and IFO 380, differ largely in their blending formulas. From a forensic chemistry standpoint, it is the combination of the refining and blending processes that impose unique chemical “fingerprints” on IFO 380 HFOs, which oil spill investigators can use to identify and track spilled fuel in the environment. Gas chromatographic analysis of petroleum fuels reveals the distinctive boiling point distribution of the chromatographable hydrocarbons that compose the fuels.

The modern chemical fingerprinting analytical methods used have evolved over the past two decades, largely due to the development and increased sophistication of analytical instrumentation. The chemical fingerprinting approaches available for the identification of oil spill sources and potentially impacted samples fall into two categories: qualitative and quantitative. The qualitative approach relies upon visual comparison of various chromatographic fingerprints and is exemplified by the ASTM D3328 and D5739 methods. The cornerstone of modern petroleum fingerprinting is high-resolution capillary gas chromatography. Qualitative chemical fingerprinting analysis of spilled oil, candidate sources, and background materials can be best described as a visual comparison between various spectroscopic or chromatographic fingerprints. Such comparisons inescapably introduce a degree of subjectivity to the source identification evaluation, which is an undesirable feature of science. The quantitative approach is preferable for most oil spill investigations because the means of interpretation are more objective and robust in the sense that they facilitate numerical comparison of diagnostic details and reduce interpretation bias.

For petroleum fingerprinting in support of natural resource damage assessments (NRDA) and other regulatory and litigation-driven scientific studies, the state of the art now focuses on polycyclic aromatic hydrocarbons (PAH) and saturated biomarker analyses, coupled with ratio and/or principal component analysis techniques, for advanced chemical fingerprinting (ACF) and allocation of petroleum mixtures to multiple sources. This strategy is being applied to oil spills, in-ground petroleum releases, and coal tar-petroleum source differentiation scenarios. The National Oceanic and Atmospheric Administration's (NOAA) draft injury guidance on NRDA recommends the application of ACF to oil spill assessments under the Oil Pollution Act of 1990.

(2002). “Total Petroleum Hydrocarbons” Detected in Naturally Occurring Materials. Soil and Sediment Contamination: An International Journal: Vol. 11, No. 3, pp. 412-412.

Dissolved organic copper and chromium complexes were measured in both overlying and interstitial waters of Narragansett Bay and mesocosm sediments using C18 reverse-phase liquid chromatography and atomic absorption spectroscopy. In the interstitial and overlying waters, the isolation procedure recovered 22–67% of the total dissolved copper, 23–55% of the total dissolved chromium and 14–40% of the dissolved organic carbon. The distribution of both total and organic copper decreased with depth in the cores and exhibited a subsurface maximum near the zero Eh level (z = 2–4 cm). Below that depth, both forms of copper continued to decrease until an apparent equilibrium with sulfide minerals was established (7–8 cm). Dissolved chromium exhibited a different geochemistry, with both total and organic chromium increasing in concentration with depth in the cores, possibly due to remobilization from some mineral phase such as chromic hydroxide or chromite.

The upper region of the Pettaquamscutt River, Rhode Island, is a fjord-type estuary with two deep basins separated by a shallow sill. The water column in these basins remains stable for periods of several years with only partial mixing occurring. Dissolved organic copper isolated by C18 reverse-phase extraction was determined in the uppermost basin; these values ranged from 0.29 μg kg−1 in the oxic surface waters to

Publisher Summary Environmental forensic investigations typically attempt to determine the criminal and civil liabilities associated with the impact of anthropogenic contamination on human health or the environment. The evolving requirements for gasoline's combustibility, antiknock quality (octane), chemical stability, volatility, gum content, and combustion emission yields, combined with the refiners' varying approaches to meet these performance requirements, has led to a steady change in the composition of gasoline over time. Consequently, generalizations regarding the chemical composition of typical automotive gasoline are often oversimplified. As a result, the forensic investigator can use this variability to distinguish different types and thereby sources of gasoline in the environment. Determining the liability associated with gasoline-derived contamination is one of the most common objectives of environmental forensics for the many reasons. This chapter addresses various issues relevant to environmental forensic investigations of gasoline. The environmental forensics of gasoline poses multiple challenges. An understanding of the effects the history, refining, additive use, and environmental weathering of gasoline, along with specific fingerprinting data, can provide the investigator with a means to reliably address the objectives surrounding source and age of gasoline-derived contamination in the environment.