Mike Reynolds US Army-Engineer Research and ...Mike Reynolds US Army-Engineer Research and...
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Phytoremediation Are we there yet? Mike Reynolds US Army-Engineer Research and Development Center Cold Regions Research and Engineering Laboratory (CRREL) Third International Phytotechnologies Conference April 20-22, 2005 Atlanta
Transcript of Mike Reynolds US Army-Engineer Research and ...Mike Reynolds US Army-Engineer Research and...
PhytoremediationAre we there yet?
Mike ReynoldsUS Army-Engineer Research and Development CenterCold Regions Research and Engineering Laboratory
(CRREL)
Third International Phytotechnologies ConferenceApril 20-22, 2005 Atlanta
• Isn’t this just natural attenuation? • Which plants do we use?• Are there better plants to use? • Depth?• How do we fertilize the plants?• Cost?
• Money• Time
• How do we know that it is working?• What if an animal grazes on the plant?• How long does it take?
User QuestionsUser Questions
One View of the History of Phytoremediation
TimeThen Now
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Exponential Growth“hype”
Lag
Crash, unmasking phase
Continued science-based phytoremediation phase
Potential Cost Benefits are Tempered by Potential Cost Benefits are Tempered by Treatment TimeTreatment Time
Low InputHigh Input
Natural attenuation
IncinerationDig and haul
LandfarmingAir sparging and bioventing
CompostingBioslurry reactors
Low temperature thermalSoil washing
COST
Phytoremediation
T I M E oo
Much of the Cost is Related to the Much of the Cost is Related to the UncertaintyUncertainty
Less CertainCertain
Natural attenuation
IncinerationDig and haul
LandfarmingAir sparging and bioventing
CompostingBioslurry reactors
Low temperature thermalSoil washing
COST
Phytoremediation
T I M E oo
Relative InputsRelative Inputs andand Monitoring StrategiesMonitoring Strategiesforfor RemediationRemediation
MonitoringEmerging
MonitoringKnown
Natural attenuation
IncinerationDig and haul
LandfarmingAir sparging and bioventing
CompostingBioslurry reactors
Low temperature thermalSoil washing
COST
Phytoremediation
T I M E oo
Early Monitoring
Are we there yet?...Does this work?It depends on who you ask…and where
“there” isJoint Interagency Phytoremediation Research
Program PI and PM Meeting, January 2004– Consensus of 3 breakout groups included
“monitoring” as a priority
If you are a researcher, you wonder – why your results from field tests did not show
statistical significance– or why they did
If you work with users or potential users, the question that always surfaces is:
“How do I monitor?”
Hypothesized Trends in Community Structure Changes in Field Soil Samples and Resulting Contaminant Removal
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Contaminant - Control
ContaminantRhizosphere TreatedMicb. Community
Changes - Control
Micb. Community ChangesRhizosphere Treatment
Rapid Changes(weeks-months-seasons?)
Long Term Changes(months-years?)
A really clever way to monitor - Control
A really clever way to monitor -Phytoremediation
Contaminant - Phytoremediation
Contaminant - control
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What might early monitoring do for us?Hypothesized Trends in Contaminant and Monitoring
Variable
Substrate ProductSpatial variability at many scales ∴ difficult to measure changes
Substrate Product
Enzyme(s)
(catalysts) Products
Enzyme
Enzyme now is substrate
We usually measure• Substrate loss or • Product formation• Measure “Microorganisms” or
Enzyme activity?• But they are ephemeral in soil…?
Product
Enzyme
Substrate
Product
Enzyme
Substrate
There is now also Temporal VariabilityMeasure enzyme production, • Measure the expression of the genes that code for enzymes• AND measure when the expression is likely to be happening
Molecular techniques
Coupled with field “realities”
What might work?
Hypothesized Trends in Community Structure Changes in Field Soil Samples and Resulting Contaminant Removal
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Contaminant - Control
ContaminantRhizosphere TreatedMicb. Community
Changes - Control
Micb. Community ChangesRhizosphere Treatment
Rapid Changes(weeks-months-seasons?)
Long Term Changes(months-years?)
A really clever way to monitor - Control
A really clever way to monitor -Phytoremediation
Contaminant - Phytoremediation
Contaminant - control
Con
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Hypothesized Trends in Contaminant and Monitoring Variable
Possibly optimum times to look for indicator
What might field realities be?
One month of soil water and soil temperature dynamic in CRREL’s backyard
Soil water
Soil Temperature
Surface
50 cm
Time
Dynamic Nature of Surface Soil
Concepts that can be easily overlooked
• What resolution do we need?– David Crowley’s clever picture analogy
• A healthy plant may or may not be a good indicator– David Sylvia, Sick looking plants have great
mycorrhizal fungi
• Apply the right approach to the problem at hand– Phytoremediation is complex and claims are easily
inflated…– It is a “system of systems”– It is up to us to keep it grounded
PUBMED Citations by Year
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"Phytoremediation" AND"monitor"
Are we getting there?
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Collision of not-so-obviously related events can lead to significant change
Similar to “Liebig’s Law of the Minimum” in biological growth
• Rate limiting step• Governing Process• Unstable equilibrium to stable
equilibrium
Gladwell explains dramatic change in many fields using epidemiology analogies
The Tipping Point: How Little Things Can Make a Big Difference - by M. Gladwell
Research and this conference will further answer the science questions How do we field these technologies?
What convincing arguments can we make?
Science Same approach can be used for understanding phytoremediation in all its many forms
ApplicationCan the same approach be used for appropriately increasing the use of phytoremediation?
What is limiting?How can we fix it?
Can we identify what we need to do or know to tip the barriers to phytoremediation use?
Can we understand how soil-GW-contaminant-plant-microbe systems converge to go across the tipping point for remediation?
Status• We know it can be successful• We know much about mechanisms
important to phytoremediation– And there are MANY mechanisms
• We sometimes can predict where phytoremediation will work – And for which contaminants
• We are less good at predicting how long it will take
• We struggle with monitoring– There remains a large element of uncertainty
• There are still misconceptions– But far fewer over-enthusiastic claims
Lunch Draws NearClosing thoughts
• Are we there yet?• Include “metadata” in reporting, leading to:
– A series of reviews of field studies by “situation” identifying limitations. What worked, what didn’t, and why.
• A “long term” series of phyto-sites with staggered monitoring would make sense
• During the conference - keep in mind the dual tracks of science and application. – Talk with those who look at it differently
• You won’t find a better group of scientists and practitioners with which to associate
