things to wonder about

Things I Wonder About in the Restoration of Oil and Brine-

Impacted SitesKerry Sublette,

Eleanor Jennings, Dan Weber, Carla Landrum, Shoeb Munshi,

Melissa Barton, J. Berton Fisher

Center for Applied BiogeosciencesUniversity of Tulsa

Greg ThomaUniversity of Arkansas

Kathleen DuncanUniversity of Oklahoma

Tim ToddKansas State University

Remediation vs. Restoration• How do we define the remediation endpoint?

– Reduction in concentration of contaminants (hydrocarbons, brine)• Regulatory limit• Risk to human health or environmental receptors• Land use

• Remediation is not restoration– Both the original spill and the remediation process disrupt soil

ecology• Disruptions in N and P cycling• Reduced diversity of soil microbes and invertebrates• Loss of vegetation

– All levels of ecosystem affected• Producers (plants)• Consumers (bugs, worms, mites, nematodes, etc.)• Decomposers (microbes)

• What constitutes restoration?– It depends

• Land use• Landowner wishes (within reason)• Restoring ecosytems

Remediation vs. Restoration

• Remediation of oil and brine spill relatively mature science

• Lots of questions remain about restoration– Do we really understand the impacts of the spills

and the remediation process?– How do you restore ecosystems in a cost-effective

manner?– How can you measure your progress?

Things I Wonder About in the Restoration of Oil and Brine-Impacted

Sites

• What about soil hydrophobicity in crude oil spill sites?

• What about boron in brine spill sites?

• Where does all the salt go (and not go)?

Soil Hydrophobicity

• Hydrophobicity is caused by the coating of soil particles with hydrophobic or “water repelling” organic matter

• Hydrophobicity has been shown to be associated with some, but not all, crude oil spill sites

• Is it a problem in restoration?

Barley Growth in Crude Oil Impacted Soil

Shoot dry massRoot dry mass

Yield

Growth Parameter

0

20

40

60

80

100

120

140g

dry

wt.

Control Soil 4% TPH 2% TPH Bio

Li et al., Plant and Soil, 192, 219-226 (1997)

Li et al., Plant and Soil, 192, 219-226 (1997)

Effect on plants was not toxicity – it was too little moisture.

In hydrocarbon impacted soils water followed preferential paths and drained rapidly.

J6N

TPH 33,500 mg/kg

J6S

TPH 4,800 mg/kg

January 1999

Tilled Hay Tilled Hay and Fertilizer

Tilled Hay

Tilled Hay and Fertilizer

J6S

J6N

J6 – Prairie

(No Treatment)

J6N -Control (Tilled Hay)

J6S – Control (Tilled Hay)

J6N Post-remediation TPH2001-2002

J6N-F J6N-NF

Plot

0

1000

2000

3000

4000

5000

6000

7000

TPH

(mg/

kg)

EPA 418.1 EPA 1664

Molarity of Ethanol Droplet2006

J6NPJ6N-NF

J6N-FJ6C

J6S-NFJ6S-F

J6SP

Plot

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Soil

MED

MED = Lowest concentration of ethanol absorbed by soil in < 10 s.

TPH by Methylene Chloride ExtractionJune 2006

J6NPJ6SP

J6SFJ6C

J6-NPJ6SNF

J6NNFJ6NF

Test Plot

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

TPH

(mg/

kg)

TGA of J6N Soils

100 200 300 400 500 600 700 800 900 1000 1100

T (C)

0

1

2

3

4

5

6

7

% L

oss

in W

eigh

t

J6N-F

J6N-NF

J6N Vegetation AnalysisMay 2005

J6NP J6N-NF J6N-F J6C

Plot

0

20

40

60

80

100

120

140

160

180

200

g dr

y w

t/m2

Live Forbs Dead Forbs Live Grass Dead Grass

J6 Vegetation AnalysisJune 2006

J6NP J6N-NF J6N-F J6C

Plot

020406080

100120140160180200220240260280300

g dr

y w

t/m2

Live Forbs Dead Forbs Live Grass Dead Grass

Nematode Community Structure

• Two types of nematode community structure analyses:– Trophic structure – what feeding groups are present in what

relative amounts– Life-style structure – colonizer-persister (c-p) classes

c-p 1 c-p 5

Short regeneration timeHigh reproduction ratePollution tolerantMicrobivores

Long life spanLow reproduction ratePollution intolerantOmnivores and predators

NP C F NF

Treatment

0

50

100

150

200

250

300To

tal H

erbi

vore

s (#

/100

g s

oil)

Is this an effect of hydrophobicity?

NP C F NF

Treatment

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6Fr

ee-li

ving

Mat

urity

Inde

x

MI = Σ vi fi

Is this an effect of hydrophobicity?

What can we do about soil hydrophobicity?

• Hydrophobicity is counteracted by hydrophilic organic matter (hay or manure, for example)– Increases water holding capacity of the soil– Increases contact of water with hydrophobic soil

particles making them more likely to wet– Stimulates activity of soil invertebrates

• I don’t think it’s a show stopper but we need to be aware of it, measure it, and treat it

What about boron?TGP Produced Water Samples

C8 B3 P18

Well #

0

2

4

6

8

10

12

14

16

Boro

n (m

g/L)

Boron - Hot Water Extracts-2006

R NR C H

Classification

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0B

(mg/

kg)

Redwood Brine Storage Tank Site Average [B] = 10.6 ± 0.2 mg/kg

Some unanswered questions about boron• How is boron distributed in the soil column at

a spill site? Surface soils only? In the root zone?

• What is the effect of boron on soil invertebrates and nematodes?

• What is the effect of boron on salt-stressed vegetation?

• Can the concentration of boron in soil be an indicator of past exposure to brine?

Control 1

Control 2

Site 5

Salt Wandering from Brine Scars

Site 5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Depth (m)

0

2

4

6

8

10

12

14

16

18

20

22

24

EC (m

S/cm

)

Control 1Control 2

Site 5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Depth (m)

0

5

10

15

20

25

30

35

SAR

Control 1Control 2

Site 1

Control 1

Control 2

Site 1

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Depth (m)

0

2

4

6

8

10

12

14

16

18

20

22

24

EC (m

S/cm

)

Control 1Control 2

Site 1

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Depth (m)

0

10

20

30

40

50

SAR

Control 1Control 2

Clay

Topsoil

Subsoil

Salt

Historic Brine Scar

Clay Subsoil

SaltSalt

Recontoured Brine Scar

1975 2003

Conclusions

• Remediated oil and brine spills have a lot in common with other types of disturbed sites– Disruption of soil structure– Loss of soil invertebrate communities– Disruption in N and P cycling– Loss of vegetation

• Restoration of these sites presents some unique challenges and there is a lot to left to learn

Acknowledgements

• This work was funded by the Integrated Petroleum Environmental Consortium (IPEC)

• We thank The Nature Conservancy for access to field sites