General

1
Phytoremediation of soils pollutedwith
chloroacetanilide herbicides
phyto- plant-relatedremediare make
something usable again
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Phytoremediation - growing plants in polluted soil

• Crops, weeds
• In theory simple (?)
• Take pollutants up
• Transport, evaporate
• Detoxify
• metabolism
• accumulation
• harvest removal

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Good - not so good

• Advantages
• inexpensive (vs. traditional)
• agricultural - "green"
• public acceptance very good
• Limitations
• time consuming
• bioavailability
• season-dependent
• final pollution
• pollutant phytotoxic, such as herbicides - project

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Research project - phytoremediation of a polluted
site

• 3 km from Lake Balaton
• Chemical plant's "waste pond" 45 ha, ca. 6 m
  deep
• Phytotoxic cocktail
• pesticides, heavy metals, explosives,
  intermediates...
• Goal reduce/eliminate
• Chose the right plant(s)
• Chloroacetanilide herbicides at ca. 10-4 M

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Chloroacetanilide herbicides

• Widely used in several crops
• Monoculture - large quant.
• Hazard
• environmental toxicity
• human health
• Selective action
• due to differential metabolic rates
• role of glutathione

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Glutathione (GSH)

• Tripeptide ?-L-Glu-L-Cys-Gly

• Presence of thiol (-SH) group highly reactive
• reducing agent
• nucleophile
• In phytoremediation
• protection against oxidative stress
• pollutant detoxification via GSH-conjugation

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GSH conjugation of chloroacetanilides
Detoxification systems capacity GSH levels
enzyme activity Experimental plants maize and
poplars
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Why maize plants?

• Excellent candidates
• rapid growth
• large biomass
• large genetic pool
• tolerance to CAs

Why poplar trees?

• Excellent candidates
• rapid growth
• large biomass
• large genetic pool
• root depth

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Laboratory studies

• Ability of maize (14 hybrids) to take up,
  tolerate, and detoxify 8 CA herbicides -
  excellent
• effects of GSH/GST modifyers
• Ability of poplars (11 clones) to take up,
  tolerate, and
• detoxify 8 CA herbicides - good, marginal
• effects of GSH/GST modifyers
• Rates of herbicide uptake and translocation
• Identity of herbicide metabolites
• Rates of herbicide metabolism
• Best hybrids and clones selected for field studies

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Field studies

• April 1999 1200 maize plants MG-191 - vigorous
  growth
• discontinued deep pollution, hungry boars
• March 2002 900 small poplar trees - poor
  survival
• drought, hungry deers
• April 2003 700 small poplar trees (7 clones) -
  ca. 40 survive in 2004

• 2005 maintenance, monitoring (plants,
  pollutants, soil microbial life) - AASW 2006

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The End
Portoroz 2005