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New soil remediation strategies New soil remediation strategies targeted at reduction of PACs targeted at reduction of PACs contaminant exposure and contaminant exposure and
mobilitymobility
National Environmental Research Institute
Aarhus University
Geoffrey Marchal
Environmental Fate
• Polycyclic aromatic compounds (PACs) do not dissolve easily in water and they bind to particles, and settle to the bottom of lakes and rivers.
• Due to their lipophilic nature and their affinity for organic carbon, PACs become sequestered to the soil matrix for a long time.
I. Concept & hypothesis
PhD Studentship REMTEC presentation 10/09 - 09
Two and three ring PAC are weakly bound to soil particles and 4-7 ring PAC are strongly bound to organic soil particles.
Phenanthridine Benz[a]anthracene FluorantheneFluoranthene
New bioremediation concepts for the reduction of environmental and human risks will be developed and validated by turning the
limitation of existing remediation technology (limited bioavailability) into an advantage (reduction of mobility and uptake).
BIOSTABILISATIONBIOSTABILISATION
A number of soil amendments will be investigated for their potential to facilitate
chemical degradation | Biodegradation | transformation into non accessible forms
while, if possible, at the same time improving other core functions of the soil.
PhD Studentship REMTEC presentation 10/09 - 09
I. Concept & hypothesis
1. Biochara: biomass-derived black carbon (incomplete combustion) made from wood-char.
2. Charcoalb: 1 – 100 µm particles made from incomplete combustion of organic matter with identifiable morphological features of the original fuel.
3. Activated carbon: Activated carbon (particule size 0.15 to 1 mm) is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.
4. Black carbonb: the remnants carbon rich matter of incomplete combustion.
And also Compost and Artificial humus
PhD Studentship REMTEC presentation 10/09 - 09
Soils amendments:
I. Concept & hypothesis
a. Lehmann J et al. . 2006 Bio-char sequestration in terrestrial ecosystems – a review. Mitigation and Adaptation Strategies for Global Change 11, 403 - 427.
b. Cornelissen G et al. . 2005. Extensive Sorption of Organic Compounds to Black Carbon, Coal, and Kerogen in Sediments and Soils: Mechanisms and Consequences for Distribution, Bioaccumulation, and Biodegradation. Environmental science and technology 39, 6881-6895.
I. Concept & hypothesis
(1a) add stable organic matters(1a’) add high porous matters
(1b) bind and sequester PACs
(2) transform to increase inaccessibility(2’) sequester PACs inside pores
(3) increase hydrophobicity(3’) block pores by oil/lipid/bacteria
(4) increase stabilization by interaction with mineral surfaces
(5) Transform into highly recalcitrant matter
PhD Studentship REMTEC presentation 10/09 - 09
TOPSOIL
I. Concept & hypothesis
SOIL amendment
PACs
bacteria
Fungi
bacteria and fungi can reach PACs
PhD Studentship REMTEC presentation 10/09 - 09
•add amendment
•bind and sequester PACs
•sequester PACs inside pores
•Decrease chemical activity and mobility of PACs in soil.
•Increase PACs concentration on amendment. Chemical activity on amendment?
•growth of PACs degrader bacteria increase on amendment loaded with PACs
•PACs degrader fungi hyphae grow into pores of amendment
•Decrease total concentration of PACs
II. Experimental Approach
First Experiment - Screening of soil amendments:
We study the sequestration capacities of amendment. The purpose of this experiment is to screen and to select different amendments for the future experiments.
Mass balance study:measure PAC trapped to amendment and not trapped to amendment
simple system:cyclodextrin solution (140 mg L-1)14C labeled single PACspecific C-amendment
PhD Studentship REMTEC presentation 10/09 - 09
Soil amendments :
• Biochar
• Activated carbon
• Charcoal
• Compost
• Artificial humus
PACs :
• Anthracene
• Fluoranthene
• Phenanthrene
• Phenanthridine
• Pyrene
step 3
step 1
step 2
III. General Method
PhD Studentship REMTEC presentation 10/09 - 09
Loading vials with 14C labeled PAC methanol solution
Evaporation of methanol solution
Add amendment with cyclodextrin solution
Shake vials for 0, 2, 6, 12, 24, 48, 72, and 144h at room temperature
Filter each vials
Measure 14C in the solution
Measure 14C on the filter (amendment)
Calculation of mass balance
estimate PACs sequestration capacity of amendment
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V. Future Prospect
2nd experiment:
Screening of soil amendments with bacteria. Repetition of first experiment with bacteria and/or fungi
3th experiment:
Studying interaction among a few selected amendments with effects on chemical activity and indigenous bacteria extracted from soil.
4th experiment:
“fungal highway”: study capacity of hyphae to improve bacterial biodegradation of inaccessible PAC sequester into pores of amendment.
PhD Studentship REMTEC presentation 10/09 - 09