1 / 56

Environmental Forensics

Environmental Forensics. R. Paul Philp, School of Geology and Geophysics, University of Oklahoma, Norman, OK. 73019. Environmental Forensics. What is “Environmental Forensics”?

jmurley
Télécharger la présentation

Environmental Forensics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Environmental Forensics R. Paul Philp, School of Geology and Geophysics, University of Oklahoma, Norman, OK. 73019

  2. Environmental Forensics • What is “Environmental Forensics”? • “Environmental Forensics” can be defined as a scientific methodology developed for identifying petroleum-related and other potentially hazardous environmental contaminants and for determining their sources and time of release. It combines experimental analytical procedures with scientific principles derived from the disciplines of organic geochemistry and hydrogeology. Environmental Forensics provides a valuable tool for obtaining scientifically proven, court admissible evidence in environmental legal disputes. • Much of the information required in this approach will not be obtained from the data obtained using the conventional EPA methods

  3. Crude Oils and Related Products

  4. Basic Environmental Forensic Questions • What is the product? • Is there more than one source and, if so, which one caused the problem? • How long has it been there? • Is it degrading?

  5. Fingerprinting and Correlation • What are the most commonly used techniques for such purposes? Gas chromatography Mass Spectrometry Gas chromatography-Isotope Ratio Mass Spectrometry (GCIRMS)

  6. 0 7 14 21 28 35 42 49 56 63 70 70 0 7 14 21 28 35 42 49 56 63 70 Minutes Minutes 0 7 14 21 28 35 42 49 56 63 70 0 7 14 21 28 35 42 49 56 63 GC Fingerprints of Different Products Condensate JP4 Gasoline Diesel Minutes

  7. GC Fingerprints of different products • Although GC permits product identification, many gasoline samples, for example, will be chromatographically similar, even if from different sources. • Refined products generally do not contain biomarkers making GCMS of little consequence. • If refined products are from different sources, stable isotopes may provide a potential solution. Minutes

  8. Crude Oil Chromatogram C17 Pristane Phytane C35 0

  9. Biomarker Distributions

  10. Utilization of Stable Isotopes • What is the product? NO • Is there more than one source and, if so, which one caused the problem? YES • How long has it been there? NO • Is it degrading? YES

  11. Why do compounds derived from different feedstocks have different isotope values? Utilization of Stable Isotopes

  12. Carbon Isotopes • Carbon in fossil fuels is initially derived from atmospheric CO2. During photosynthesis, fractionation of the two isotopes occurs with preferential assimilation of the lighter isotopes.

  13. Carbon Isotopes • Extent of fractionation during photosynthesis depends on factors such as: plant type; marine v. terrigenous; C3 v. C4 plant types; temperature; sunlight intensity; water depth. • (C3Temperate plants; trees; not grasses; 95% plant species -22 to -30; C4 plants grasses; sugar cane; corn; higher temps and sunlight-10 to -14 per mil)

  14. Stable Isotope Determinations ISOTOPIC VALUES CAN BE MEASURED IN TWO WAYS: • BULK ISOTOPES • ISOTOPIC COMPOSITIONS OF INDIVIDUAL COMPOUNDS

  15. d13C -35 -30.06 -29.68 -29.50 -29.52 -30 -25.66 -25 -23.45 -23.27 -20 Katalla Crude Cook Inlet Crude North Slope Crude Unknown Source Monterey Source NSC Source Monterey Crude Petroleum Source Isotope Values of Crude Oils Vary with Source

  16. BP “American Trader” Accident 5/7/90 - Huntington Beach, CA California Crude Oils Other Southern California Beach Tars d13C of Saturates (‰, PDB) Alaska Crude Oils Huntington Beach Tars and Spilled Oil d13C of Aromatics (‰, PDB) Correlations Using Carbon Isotopes

  17. MW-2 MW-5 MW-11 dD (‰) MW-4 Brand A Gasoline Brand B Gasoline d13C (‰) Correlation Using Bulk Isotope Ratios Contamination in monitoring wells had two possible sources; GC fingerprints were similar since both were contemporary gasolines; isotopically distinct since derived from different crude oils

  18. EXXON VALDEZ • March 24th, 1989 • 258,000 barrels of Alaskan North Slope crude oil spilled into Prince William Sound

  19. Residues from Prince William Sound

  20. Terpanes in Prince William Sound Residues -24.5 -29.1 -24.1 -28.7

  21. Stable Isotope Determinations ISOTOPIC VALUES CAN BE MEASURED IN TWO WAYS: • BULK ISOTOPES • ISOTOPIC COMPOSITIONS OF INDIVIDUAL COMPOUNDS

  22. GCIRMS System

  23. Crude Oil Chromatogram C17 Pristane Phytane C35 0

  24. n-alkanes C13 C15 C17 C19 C21 C23 C25 C27 C29 C31 C33 C35 24D 36D -25 -26 -27 -28 -29 13C (‰) -30 U8-106-1 d -31 Paris Basin -32 Middle East -33 Oklahoma -34 Mahakam -35 GCIRMS DATA FOR SELECTED OILS

  25. Hydrocarbon Spills and Weathering • Major effects of weathering from a geochemical perspective are : • Evaporation • Water washing • Biodegradation

  26. Tar Ball Chromatograms

  27. C29-Hop. C30-Hop. Terpanes in Tar Ball Samples 18a-Oleanane

  28. GCIRMS – Tar Balls

  29. The Erika Oil Spill. Sampling locations of oil residues and oiled bird feathers collected along the Atlantic Coast of France after the Erika oil spill. Mazeas et al., EST, 36(2), 130-137, 2002

  30. The Erika Oil Spill. Bulk isotope values

  31. The Erika Oil Spill. Molecular n-alkane isotopic compositions of the oil residues collected in the north Atlantic shoreline (mean of S2-S12), on the Crohot Beach (S13), in the Arcachon Bay area (mean of S14-S18), and of bird feathers (mean of S19-S28) are compared with Erika oil.

  32. The Erika Oil Spill. Compound specific isotopic composition of oil residues and oiled bird feathers collected along the Atlantic Coast of France compared with Erika oil isotopic composition.

  33. Diesel Fingerprints

  34. Isoprenoid Isotope Fingerprints California Oklahoma

  35. Forensic Geochemistry B Site A MW 1 Groundwater flow direction C MW6 Site B

  36. Weathered and Unweathered Diesel * Pr Diesel MW 1 * * * * Ph * Diesel MW 6 C17

  37. Carbon Isotope Values for Isoprenoids

  38. Gasolines • Gasolines from different sources often have very similar chromatograms, making it difficult to distinguish such samples • Gasolines are also devoid of biomarkers, further limiting correlation possibilities • One solution here is to use GCIRMS for both the hydrocarbons and additives

  39. Comparison of Gasolines by GC

  40. Gasoline Database 117 30 31 119 97 Retail stations locations 122 83 52 78 94 144 90 62 102 66 67 89 91 148 126 118 135 109 151 152 107 123 143 149 113 133 150 114 Aromatics δ13C + dD, oxygenates (MTBE, TBA) 136 108 138 Samples provided by Dr. J.Graham Rankin, Marshall University, WV 138 Aromatics δ13C only 108

  41. δ13C Fingerprints of 39 Gasolines -22 Trend reflects the manufacturing process -23 δ13C offset reflects the crude oil feedstock -24 Crude oil feedstock variable -25 δ13C (‰) -26 -27 -28 -29 A H EB o-X TOL m/p-X Naph proBz 1m2eBz 1m3eBz 1,3,5-TMB 1,2,4-TMB 1,2,3-TMB

  42. CSIA of Gasoline 1,2,4-trimethylbenzene δ13C = –26.7 ‰ ethylbenzene δ13C = –24.6 ‰ o-xylene δ13C = –25.1 ‰ m,p-xylene δ13C = –26.0 ‰

  43. A B Gasolines – GC Signals mp-Xyl 1,2,4-TMB

  44. A -22 -23 -24 B -25 δ13C (‰) -26 -27 -28 -29 -30 H A EB o-X TOL Naph m/p-X proBz 1m2eBz 1m3eBz 1,3,5-TMB 1,2,4-TMB 1,2,3-TMB Gasolines – Different δ13C Fingerprints

  45. PCE Degradation Site Study Hunkeler et al., J. Contaminant Hydrology, 74, 265-282,2004.

  46. -33 -27 -25 PCE Source Evaluation Study Hunkeler et al., J. Contaminant Hydrology, 74, 265-282,2004.

  47. PCBs • Study by Yanik et al., OG, 239-253, 34, 2003 showed that different Aroclors may be isotopically different and thus useful for source discrimination although there is some slight enrichment from degradation.

  48. M/z 44 Chromatogram for Aroclor 1245

  49. Variations in Isotopic Composition of Various Congeners

  50. PAHs and Stable Isotopes • Current interest is centered around whether carbon isotopes can be used to discriminate PAHs derived from former manufactured gas plant (MGP) wastes versus those from general urban background aromatics • Urban backgrounds have a fairly narrow range and small differences may be related to source differences

More Related