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Phytogenic or Petrogenic Hydrocarbons - Using Biomarkers for Delineation


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Presentation on the use of petroleum biomarkers for delineation of petroleum impacts in a high organic soil area (muskeg). Phytogenic hydrocarbons are natural compounds that are misidentified by standard analytical methodologies of high organic content soils as petroleum hydrocrabons. This artificially biases the measurements high for organic rich soils. Petroleum hydrocarbon products have distinct petrogenic biomarkers that can be used to identify if a sample contains petroleum or not. These biomarkers were used in this presentation to determine where petroleum impacts in the soil end and limit the unnecessary excavation of a muskeg chasing samples that were above guidelines due to the presence of natural hydrocarbons. Presentation shows how environmental forensics and petroleum forensics investigations can be used in an environmental site assessment.

Published in: Environment

Phytogenic or Petrogenic Hydrocarbons - Using Biomarkers for Delineation

  1. 1. Applying Petroleum Biomarkers as a Tool for Confirmation of Petroleum Hydrocarbons in High Organic Content Soils Presented at INEF Conference Calgary, AB August 31, 2009 © 2015
  2. 2. Presentation • This presentation was given as part of the INEF 2009 meeting in Calgary, AB. • Find link to book here regarding this work. © 2015 Chemistry Matters Inc.
  3. 3. Problem • Hydrocarbon releases on organically rich soils • How to differentiate impacted soil from naturally high background values © 2015 Chemistry Matters Inc.
  4. 4. Phytogenic vs. Petrogenic Phytogenic hydrocarbons: hydrocarbon compounds derived from plants Petrogenic hydrocarbons: hydrocarbon compounds associated with petroleum products or petroleum sources © 2015 Chemistry Matters Inc.
  5. 5. 1,000,000s of years Elevated pressure Elevated temperatures Phytogenic vs. Petrogenic 100s of years Atmospheric pressure Atmospheric temperature Click the link below to read a blog about a natural PAH – retene. © 2015 Chemistry Matters Inc.
  6. 6. Petroleum Biomarkers • Petroleum Biomarkers are chemical fossils that can act as unique tracers for petroleum contaminants • They originate from formerly living organisms • They closely resemble their parent molecules found in living organisms © 2015 Chemistry Matters Inc.
  7. 7. Examples of Biomarker OH CH3 CH3 H CH3 HCH3 CH3 CH3 H H OH OH OH CH3CH3 CH3 H CH3 HCH3 CH3 CH3 H H Bacteriohopanetetrol in Prokaryotic Organisms Hopanes found in Crude Oil The Biomarker Guide, Volume 1, Peters, Walters & Moldowan Bake under pressure @ 60o C for 200M years N N N N Mg 2+ O O O O Chlorophyll a CH3 CH3 CH3 CH3 CH3 Farnesane © 2015 Chemistry Matters Inc.
  8. 8. Case Study: The Site • Former oil well, residual hydrocarbon impacts on site • Previous remedial work involved admixing of soil • Organic matter (low-lying marshland and forest) overlying clay • Client seeking reclamation certificate • Diverse Ecosystem © 2015 Chemistry Matters Inc.
  9. 9. Case Study: Initial Assessment • 25 site samples & background samples collected • Most exceedances for petroleum hydrocarbons F3 fraction (C16 – C32) – Alberta PHC F3 guideline = 300 mg/kg – F3 also the typical range for phytogenic compounds • 10 site samples with F3 exceedances • 5 background samples with F3 exceedances © 2015 Chemistry Matters Inc.
  10. 10. Analytical Approach • Silica gel treatment – Removes any organic, polar compounds co- eluting with the petroleum hydrocarbons • Specialized GC-MS – Unambiguous identification of petroleum biomarkers • Multiple biomarker targets – including acyclic isoprenoid compounds, PAH compounds, terpanes, hopanes, and triaromatic steranes © 2015 Chemistry Matters Inc.
  11. 11. Silica Gel Treatment F2 = ND F3 = 5500 mg/kg F4 = 4200 mg/kg F2 = ND F3 = 1800 mg/kg F4 = 760 mg/kg Silica gel clean-up removed ~75% © 2015 Chemistry Matters Inc.
  12. 12. Biomarkers in site samples Note that the sample is severely weathered. Biomarkers have become the predominant peaks Petroleum Biomarker Standard Site Sample © 2015 Chemistry Matters Inc.
  13. 13. Biomarker Peak Identification Library spectra are available for a number of petroleum biomarker compounds. In this case, the sample showed a perfect match! Pristane (2,6,10,14 – tetramethylpentadecane) © 2015 Chemistry Matters Inc.
  14. 14. Results Showing F3 exceedances Concentration(mg/kg) Site Samples 10,000 8,000 6,000 4,000 2,000 0 Petrogenic Phytogenic © 2015 Chemistry Matters Inc.
  15. 15. © 2015 Chemistry Matters Inc.
  16. 16. Conclusions • Natural hydrocarbons can be present in concentrations above guidelines • Site specific conditions must be taken into account when evaluating remedial targets • Biomarker analysis can differentiate phytogenic and petrogenic materials • Conclusive assessment and remediation tool • Definitive Closure • Cost/Time Efficient • Everyone Wins • Lab - “Good” science • Consultant - sound decisions • Client - closure and assurance • Site - minimal disturbance in a diverse ecosystem © 2015 Chemistry Matters Inc.
  17. 17. Questions? Contact Info: Chemistry Matters Inc. Court Sandau Email: Twitter: @Chem_Matters Slideshare: Please visit our website for related information, case studies and blogs. Got a question, post it to our website, HERE. © 2015 Chemistry Matters Inc.