Mechanisms and Strategies for Phytoremediation of Cadmium

INTRODUCTION
    Phytoremediation
    Advantages of  Phytoremediation
    Limitations of Phytoremediation

BIOAVAILABILITY OF CADMIUM 
    Cation Exchange Capacity (CEC)
    pH
    Soil Amendments
    Competitive Cations
    Fertilizer
    Mycorrhizae
    Chelation
       Phytochelatins (PCs)
       Phytochelatin Effectiveness
       Role of Sulfur in PCs
       Oxidative Stress
       Translocation
       Metallothioneins
       Organic Acids
       EDTA / EGTA

CADMIUM TOLERANCE AND
ACCUMULATION IN PLANTS
    Cell Wall Binding
    Reduced Transport
    Compartmentalization
    Chelation
    Phytoextraction factors
       Table 1.  Plant Accumulation
       Hyperaccumulators

CONCLUSIONS

LINKS

BIBLIOGRAPHY

 
Chelation

     Cations of heavy metals, even under optimal soil conditions of low pH and low organic matter, are often bound to soil particles in significant amounts because of soil cation exchange capacity. The binding affinity of cations also impedes cation movement in vascular plants, particularly in the negatively charged cells of the xylem. A general solution to this problem is chelation, which is generally meant as the process of a cation binding to a compound which results in a neutrally-charged complex that can move more freely through a variety of substrates. Several chelators, both natural and synthetic, are known to perform this very function in soil and in plants. 
 
 

Natural Synthetic
Phytochelatin (PC)  EDTA (ethylene diamine tetra acetic acid)
Metallothionene (MT) EGTA (ethyene glycol tetra acetic acid)
Organic acids

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Page Created 4-18-00
Sam Cox
Department of Horticulture
Colorado State University
samcox@lamar.colostate.edu
http://lamar.colostate.edu/~samcox/index.htm