Soil Conductivity, Gas Flux, and Carbon Isotope Analysis: The Next - - PowerPoint PPT Presentation

Integrity  Excellence  Responsibility

Presenting Members

Soil Conductivity, Gas Flux, and Carbon Isotope Analysis: The Next Step In Locating Hydrocarbon Subsurface Plumes?

Lisa Moehlman, Kathlyne Hyde, Richard Nhan, Steven D. Siciliano, Kris Bradshaw, Morgan Sather, and Trevor Carlson

Limited amount and technology for pre-screening Pre-screening can help to:

• Improve the quality of site

assessment

• Locate unknown hot spots
• Save time and money

Pre-screening

Determine if the combination of

• Carbon flux
• Carbon isotopes
• EM maps

can be used as a screening tool

Objective

CO2 Flux Electrical magnitude maps

Background

Sihota, N.J., K.U Mayer. 2012. Characterizing vadose zone hydrocarbon biodegradation using carbon dioxide effluxes, isotopes and reactive transport modeling. Vadose Zone Journal. Soil Science Society of

• America. 2.41.

+CH4 +CH4

δC13 Isotope

• Microbes prefer C12 isotope
• PHC are high in C12-signatures
• Increased C13-signatures and decreased C12-signatures
• δC13 CO2 levels: -18 to -24 indicate PHC degradation

Background

Raymore Saskatoon Davidson

Locations

Decision units

• 1. Soil temperature and moisture
• 2. Carbon flux readings
• 3. Gas samples for Isotope analysis
• 4. EM readings
• 5. Phase II Assessment

Methods

1 3 2 6 4 9a 8 7

DU2 DU4 DU3

10 11 12 9

Slightly above background (<10 µmol m-2 s-1) Above background (>10 µmol m-2 s-1) Well above background (>50 µmol m-2 s-1)

Circles are CO2 fluxes (no colours indicate at background)

5

Raymore carbon flux results

Carbon flux and isotope results

• Fig. δ C13 of carbon dioxide vs background corrected carbon dioxide flux at Raymore, 11th&W, and Davidson bulk transfer stations

log+1 CO2 (umol m-2 s-1)

1 10 100 1000 10000

CCO2 ( ‰)

• 25
• 20
• 15
• 10
• 5

Hydrocarbon Degradation Raymore 11th W Davidson Confirmed Possible Clean Elevated CO2 Respiration

Electrical magnitude

Check list

CO2 Flux (µmol m-2 s-1) δC13 CO2 (‰) Low EM reading PHC Remediation Occurring? Yes Possibly No

Lab analysis

1 3 2 6 4 9a 8 7

DU2 DU4 DU3

10 11 12 9

Slightly above background (<10 µmol m-2 s-1) C6-C10 detectable Above background (>10 µmol m-2 s-1) C6-C10 > 400 ppm Well above background (>50 µmol m-2 s-1) C6-C10 >1000ppm

Circles are CO2 fluxes Squares are C6-C10 (no colours indicate at background)

5

Raymore carbon flux vs. lab results

Considerations

• Heavy clay
• Weather permitting
• Compacted sites
• Contamination depth

Industry implications

Conclusions

Supervisor: Steven Siciliano The Environmental Soil Toxicology Lab group and undergrads Sustainable In-situ Remediation Co-operative Alliance Federated Co-operatives limited

Acknowledgements

www.usask.ca

Questions?

Raymore EM maps 0.5 m (top left), 1 m (top right), and 3 m (bottom center)

Davidson carbon flux vs. lab results

Circles are CO2 fluxes Squares are C6‐C10 (no colours indicate at background)

Slightly above background (<40 µmol m‐2 s‐1) C6‐C10 detectable Above background (>40 µmol m‐2 s‐1) C6‐C10 > 400 ppm Well above background (>100 µmol m‐2 s‐1) C6‐C10 >1000ppm

Davidson EM maps 0.5 m (left) & 1 m (right)

Davidson EM Maps 3 m (left) & 5 m (right)

11th&W carbon flux vs. lab results

Slightly above background (<40 µmol m-2 s-1) C6-C10 detectable Above background (>40 µmol m-2 s-1) C6-C10 > 400 ppm Well above background (>100 µmol m-2 s-1) C6-C10 >1000ppm

Circles are CO2 fluxes Squares are C6-C10 (no colours indicate at background) 1 4 3 2 6 5 7 8 9 12 11 10

11th & W EM maps 0.5 m (left) & 1 m (right)

11th & W EM maps 3 m (left) & 5 m (right)