Bioremediation Research by the US Environmental Protection Agency (EPA) Using Duckweeds

Remediation of:  DDT Residues   |   Organophosphorus Residues


1: J Agric Food Chem 2000 Dec;48(12):6121-7

Uptake and Phytotransformation of o,p'-DDT and p,p'-DDT by Axenically Cultivated
Aquatic Plants.

Gao J, Garrison AW, Hoehamer C, Mazur CS, Wolfe NL.

National Exposure Research Laboratory, U.S. Environmental Protection Agency, 960
College Station Road, Athens, Georgia 30605, and Department of Biochemistry and
Molecular Biology, University of Georgia, Athens, Georgia 30605.

The uptake and phytotransformation of o,p'-DDT and p,p'-DDT were investigated in
vitro using three axenically cultivated aquatic plants: parrot feather
(Mariophyllum aquaticum), duckweed (Spirodela oligorrhiza), and elodea (Elodea
canadensis). The decay profile of DDT from the aqueous culture medium followed
first-order kinetics for all three plants. During the 6-day incubation period,
almost all of the DDT was removed from the medium, and most of it accumulated in
or was transformed by these plants. Duckweed demonstrated the greatest potential
to transform both DDT isomers; 50-66% was degraded or bound in a nonextractable
manner with the plant material after the 6-day incubation. Therefore, duckweed
also incorporated less extractable DDT (32-49%) after 6 days than did the other
plants. The capacity for phytotransformation/binding by elodea is between that
of duckweed and parrot feather; approximately 31-48% of the spiked DDT was
degraded or bound to the elodea plant material. o,p'-DDD and p,p'-DDD are the
major metabolites in these plants; small amounts of p,p'-DDE were also found in
duckweed (7.9%) and elodea (4.6%) after 6 days. Apparently, reduction of the
aliphatic chlorine atoms of DDT is the major pathway for this transformation.
This study, which provides new information on plant biochemistry as related to
pollutant accumulation and phytotransformation, should advance the development
of phytoremediation processes.

PMID: 11312785 [PubMed - in process]
 
 


2: J Agric Food Chem 2000 Dec;48(12):6114-20

Uptake and phytotransformation of organophosphorus pesticides by axenically
cultivated aquatic plants.

Gao J, Garrison AW, Hoehamer C, Mazur CS, Wolfe NL.

National Exposure Research Laboratory, U.S. Environmental Protection Agency, 960
College Station Road, Athens, Georgia 30605, and Department of Biochemistry and
Molecular Biology, University of Georgia, Athens, Georgia 30605.

The uptake and phytotransformation of organophosphorus (OP) pesticides
(malathion, demeton-S-methyl, and crufomate) was investigated in vitro using the
axenically aquatic cultivated plants parrot feather (Myriophyllum aquaticum),
duckweed (Spirodela oligorrhiza L.), and elodea (Elodea canadensis). The decay
profile of these OP pesticides from the aqueous medium adhered to first-order
kinetics. However, extent of decay and rate constants depended on both the
physicochemical properties of the OP compounds and the nature of the plant
species. Malathion and demeton-S-methyl exhibited similar transformation
patterns in all three plants: 29-48 and 83-95% phytotransformation,
respectively, when calculated by mass recovery balance during an 8-day
incubation. No significant disappearance and phytotransformation of crufomate
occurred in elodea over 14 days, whereas 17-24% degraded in the other plants
over the same incubation period. Using enzyme extracts derived from duckweed,
15-25% of the three pesticides were transformed within 24 h of incubation, which
provided evidence for the degradation of the OP compounds by an organophosphorus
hydrolase (EC 3.1.8.1) or multiple enzyme systems. The results of this study
showed that selected aquatic plants have the potential to accumulate and to
metabolize OP compounds; it also provided knowledge for potential use in
phytoremediation processes.

PMID: 11312784 [PubMed - in process]
 
 
 
 



 

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Revised:  April 25, 2003