Future of PAH Monitoring Post Oil Spills
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Presentation summarizes the physical chemical properties of compounds found in crude oil and how these properties drive the behavior of the compounds during a spill event. PAHs are presented as a complex mixture of multiple compounds that could be measured but most studies are limited to the main 16 priority PAHs. The family of PAH compounds can be used to distinguish source as used in environmental forensics studies. Lastly, a look to the future as a result of all the research into the gulf oil spill reveals that the science of monitoring of oil spills is about to change. It will not involve many more compounds and likely trigger more regulated substances.
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Future of PAH Monitoring Post Oil Spills
- 1. The Macondo Spill Effect The Changing Times for PAH Monitoring Court Sandau, PhD, PChem Phil Richards, PhD, PChem CLRA Alberta Chapter AGM February 27, 2014
- 2. Talk Summary • Macondo Spill (Deepwater Horizon oil spill) • Crude oil is complex • What to measure for a spill? • How do we always end up with PAHs? • How to measure PAHs, as a family (very big family)? • What is next for PAH monitoring? CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 2
- 3. Deepwater Horizon Oil Spill • Began on April 20, 2010 • 780,000 m3 of crude oil released over 87 days • Initial rig explosion killed 11 people (injured 17 others) • US gov’t created $20 billion spill response fund CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 3
- 4. Deepwater Horizon Oil Spill • 400+ cases pending • Worth estimated at $37.6 billion • $16 billion Clean Water Act • Many cases will rely on environmental forensics for link to BP (or other sources) Also, $500 million to fund research CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 4
- 5. Complexity of Crude Oil? Conventional GC Analysis UCM Unresolved Complex Matter Nelson et al. Environmental Forensics, 7:33–44, 2006 CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 5
- 6. GC-FID Chromatograms of Very Different Crude Oils CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 6
- 7. Complexity of PHCs How many compounds are in…. • The atmospheric aerosol from a coniferous forest? • 50 compounds (Kallio, 2006) • The volatile fraction of roasted coffee beans? • 1,000 compounds (Mondello, 2004) • Cigarette smoke? • 6,000 compounds (van Mispelaar, 2005) • Crude oil? • 7,500-10,000 compounds (Dalluge, 2002) • 17,000+ CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 7
- 8. What to Measure in an Oil Spill? (Compounds with guidelines) • Benzene, Toluene, Ethyl-Benzene, Xylenes • Petroleum Hydrocarbon Fractions F1, F2, F3, and F4 • Polycyclic Aromatic Hydrocarbons (PAHs) CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 8
- 9. CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. Free Phase Oil Dissolved Phase Phytoplankton Particle Bound Oil Walleye Northern Pike Small Fish Rainbow Trout Mountain Whitefish Cutthroat Trout Medium Fish Large Fish Brook Trout Sediment Zooplankton Benthic Invertebrates Sediment Bottom Feeders 9
- 10. Weathering • The influence of physical, chemical and biological forces on the physical and chemical composition of contaminants in the environment – Volatilization – Solubilization – Biodegradation • biotransformation CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 10
- 11. Volatility • For free phase product, related to the vapour pressure • High vapour pressure = more volatile 10.4 Pa 12,700 Pa naphthalene 57,900 Pa pentane benzene 20,200 Pa 0.0161 Pa hexane 3800 Pa toluene 1880 Pa phenanthrene octane 0.0006 Pa pyrene Most volatile compounds are gone within weeks of spill CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 11
- 12. Solubilization • Moving from oil phase (lipophilic) to water phase (hydrophilic) • Driven by: – Solubility – Kow (octanol:water partitioning) CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 12
- 13. Solubility • Amount of compound that will dissolve in pure water • For compounds with C and H, basically related to size of molecule – Larger = less soluble 1790 mg/L 38 mg/L 31 mg/L naphthalene pentane benzene 9.5 mg/L 1.1mg/L hexane 470 mg/L toluene 0.66 mg/L phenanthrene octane Big molecules don’t dissolve in water. Solubility in competition with Kow. CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 0.13mg/L pyrene 13
- 14. Octanol:Water Partitioning • Model for lipid partitioning • Also works for organic carbon • Kow = Coctanol / Cwater • Log scale • Unitless 2.13 3.37 3.45 naphthalene pentane benzene 4.11 4.46 hexane 2.69 toluene 5.18 phenanthrene octane Big molecules stay in free phase or bind to organic matter (i.e. sediment) CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 8.8 pyrene 14
- 15. Susceptibility to Biodegradation Most susceptible C5-C6 Hydrocarbons Olefins n-Alkanes Monoaromatics Isoalkanes Parent PAH > 2 ring C1-alkyl PAH C2-alkyl PAH C3-alkyl PAH C4-alkyl PAH Triterpanes Steranes Diasteranes Aromatic Steranes Porphyrins N H N N H N Less susceptible CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 15
- 16. Biotransformation PAH ⇌ AhR NUCLEUS hsp90 PAH ARNT PAH hsp90 PAH ARNT CYP1A AhR XREs CYP1A mRNA ENDOPLASMIC RETICULUM Other mRNAs apo–CYP1A X GT EH R CYP1A PAH-OH further metabolism PAH ⇌ R = NADPH-cytochrome P450 reductase EH = epoxide hydroxylase GT = glutathione transferase X = UDP-glucuronosyl transferase AhR PAH CYP1A enzymes present in humans, birds, fish, invertebrates CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 16
- 17. PAHs • • • • • Not very volatile Not soluble in water Resist biodegradation Potential to bioaccumulate Known toxicity (mediated through Ah receptor) • Constitutes low % quantities of crude oil CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 17
- 18. US EPA Priority Pollutants PAH Compounds LMW naphthalene acenaphthylene anthracene acenaphthene 2-ring 3-ring fluoranthene chrysene pyrene benzo[b]fluoranthene benzo[a]anthracene 4-ring HMW benzo[k]fluoranthene f luorene phenanthrene dibenz[a,h]anthracene benzo[a]pyrene 5-ring List predates 1977 CLRA AB AGM Feb 2014 www.chemistry-matters.com © 2014 Chemistry Matters Inc. benzo[ghi]perylene indeno[1,2,3-cd]pyrene 6-ring 18
- 19. Relative Response Analysis of PAHs S Retention Time CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 19
- 20. Additional PAHs – Biogenic (transformation of natural precursors)(Tan et al. 1996) Phenanthrene Retene Perylene – Petrogenic (fossil fuels) dibenzothiophene – Pyrogenic (burning of organic materials) CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 20
- 21. Expanding the List of PAHs Alkylated-PAHs and Other PAHs 9 10 8 7 2 6 C1-Phenanthrenes Phenanthrene 1 5 4 3 C2-Phenanthrenes C3-Phenanthrenes CH3 CH3 CH3 CH3 CH3 CH3 CH3 (5) CH3 H2C H 3C CH2 CH 3 (30) C4-Phenanthrenes… (?) CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. CH2 (?) 21
- 22. Chromatography Gets Busy C1-DBT C2-DBT Dibenzothiophene Each parent PAH has potentially 100s of alkylated homologues CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. C3-DBT C4-DBT 22
- 23. PAHs • Although different sizes and shapes, PAHs move in environment as a group • Similar sized compounds behave similarly phenanthrene dibenzothiophene fluoranthene anthracene pyrene CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 23
- 24. Petrogenic vs. Pyrogenic CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 24
- 25. 8 8 6 6 4 4 2 2 0 CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. BF/BP C1 C2 14 12 BaA/Chry C1 C2 C3 C4 10 16 FI/Py C1 C2 C3 C4 Well 5 – Secondary Source Diben C1 C2 C3 C4 18 Phen/An C1 C2 C3 C4 20 18 F C1 C2 C3 20 FI/Py C1 C2 C3 C4 BF/BP C1 C2 BaA/Chry C1 C2 C3 C4 22 Bph C1 C2 22 Acl C1 14 12 % Total 16 Diben C1 C2 C3 C4 Phen/An C1 C2 C3 C4 F C1 C2 C3 Bph C1 C2 Acl C1 Naph C1 C2 C3 C4 % Total 18 Naph C1 C2 C3 C4 BF/BP C1 C2 BaA/Chry C1 C2 C3 C4 FI/Py C1 C2 C3 C4 Diben C1 C2 C3 C4 Phen/An C1 C2 C3 C4 16 F C1 C2 C3 Bph C1 C2 Acl C1 Naph C1 C2 C3 C4 % Total PAH Patterns 22 20 On Site Product 14 12 10 8 6 4 2 0 Well 1 – Primary Source 10 0 25
- 26. More PAHs than you thought… • There are 100s of parent PAHs to choose from • Each PAH has potentially 100s of alkyl-substituted homologues • Additional PAHs can help elucidate source – remember PAHs are ubiquitous CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 26
- 27. • • • • ‘New’ PAHs EPA List of priority PAHs dates back pre-1977 ‘New kids on the block’ Upwards to 40 ‘parent’ PAHs potentially to monitor Starting to look at heterocycles (O, N, S containing) 7H-dibenzo(c,g)carazole dibenzo(a,h)acridine CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 3-methyl chlolanthrene 27
- 28. Conventional GC Analysis Nelson et al. Environmental Forensics, 7:33–44, 2006 CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 28
- 29. 2D-GC-TOF Nelson et al. Environmental Forensics, 7:33–44, 2006 29
- 30. Advanced Analyses 2D-GC-TOF-MS • Routine analyses cannot resolve all the compounds eluting from a crude sample • 2D-GC uses 2nd dimension to resolve ‘UCM’ • Compound families group together • TOF analysis allows library search to identify unknowns Diesel 30
- 31. Naphthalene Congeners Naphthalene C1 Naphthalene C2 Naphthalene C3 Naphthalene C4 Naphthalene CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 31
- 32. Middle East Crude Oil Investigation Alkyl Phenanthrenes/Anthracenes Alkyl Naphthalenes Alkyl Benzenes Alkanes CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 32
- 33. The Macondo Spill Effect • Reddy et al. sampled oil directly above well to conduct comprehensive characterization – Gas isotopes, GOR, fluid characteristics, API etc. – Fingerprinted with 2D-GC-TOF – Could distinguish between crudes Reddy et al. 2011, PNAS Early Edition, p.1-6 CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 33
- 34. The Macondo Spill Effect • • • Hall et al. took 41 samples (slicks, scrapings off rocks, grasses and debris, sand patties etc) Oxidized hydrocarbons comprised of more than 50% of extractable hydrocarbons Used 2D-GC-TOF of samples compared to oil to assess weathering of oil spill using chemometric techniques Hall et al. 2013, Marine Pollution Bulletin, in press CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 34
- 35. Conclusions • Change is slow but monitoring spills is about to get much more complex • More PAHs to be included • Advanced analytical techniques to follow? • Once research begins to wrap up, US researchers will be looking north CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc. 35
- 36. Questions? Contact Info: Chemistry Matters Inc. Court Sandau URL: chemistry-matters.com Twitter: @EnviroCertainty Slideshare: www.slideshare.net/csandau CLRA AB AGM Feb 2014 © 2014 Chemistry Matters Inc.