Bioavailability of organophosphates in soil Tanya Caceres Supervisors: M' Mallavarapu, R' Naidu

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Bioavailability of organophosphates in soilTanya
CaceresSupervisors M. Mallavarapu, R. Naidu
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Research outline

• Focused on fenamiphos and related compounds
  (isofenphos, coumaphos)
• 1.- Soil tests
• 2.- Ecotoxicological tests
• 3.- Bioavailability in soil and bioremediation

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Fenamiphos

• Organophosphate
• Nematicide insecticide
• Water solubility 400mg/L
• Highly toxic (class 1) US. EPA

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Environmental fate

• 
  Phenols
• FSO
  
  FP
• 
  
  
• 
  
  
• 
  
  
• 
  
  FSOP
• 
  
  
• FSO2
• 
  
  
• 
  
  FSOP2

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Table 1. Half life of fenamiphos in different
soils at different temperatures
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Conclusions

• Rate of degradation of F increased with
  increment on temperatures, except under alkaline
  conditions
• FSO was identified as the major degradation
  product in all soils
• FSO2 , FP,FSOP and FSO2P were also identified
• Degradation of F was faster in alkaline soils
• Degradation of F on sterile soils was slower than
  in non sterile (microbial activity)

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Bioremdiation of fenamiphos by Novel bacteria

• Isolation of bacteria from soil
• Identification using 16 SrRNA amplification PCR
  and sequencing
• Microbacterium esteraromaticum
• In vitro (liquid medium)
• F FP
  Phenols
• FSO FSOP (no
  toxic, D. carinata)
• FSO2 FSO2P
• (24h)

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Cross degradation of organophosphates using M.
esteraromaticum

• M. Esteraromaticum
• Coumaphos Methyl parathion Isofenphos
• 
  des-N-isopropyl-O- analogue

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Bioremediation of fenamiphos in soil and ground
water

• Aged soils (fenamiphos 2 years)
• Sequential extractions F, FSO, FSO2
• Soils M. Esteraromaticum
• Residues under detection limits ( 1week) HPLC
  (DAD)
• Increment of bacteria in soil ( specific probe,
  Real time PCR, ) during 1st and 2nd weeks

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Bioremdiation of fenamiphos in soil and ground
water

• Ground water samples F,FSO, FSO2 M.
  esteraromaticum
• Phenols (96 h)

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Conclusions

• M. esteraromaticum is highly efficient on
  degradation of fenamiphos and its main oxidation
  products to phenols, which are no toxic to
  aquatic invertebrates
• The bacteria is able to detoxify fenamiphos, FSO
  and FSO2 in aged soils and ground water.

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• Acknowledgements
• Dr. Michael Beer.
• Dr. Seidu Malik.
• Thanks