1. Bioremediation of heavy- and radioactive-metal contaminations from soil and ground water
John Hanna

2. Bioremediation
The use of biological agents, such as bacteria, fungi, or green plants, to remove or neutralize contaminants, as in polluted soil or water
Break down contaminants into less substances (e.g. Petroleum)
Act to accumulate the contaminants so they can be easily removed
Chemical reduction of heavy metal ions to insoluble forms

3. Risk-Benefit relationship between contaminants versus nutrition from the consumption of fish
Poly-unsaturated fatty acids (Omega-3) fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)
Undisputed heatlh benefits (e.g coronary heart disease
Heavy metals (e.g Mercury)
Dioxins
Polychlorinated biphenyls (PCBs)

4. Rate of CHD cohort study on risks CHD in relationship consuming fish or fish oil

5. Bioremediation methods available today to remove heavy metal contamination
Used for the removal of Mercury, among other metals such as chromium, cadmium, Zinc and radioactive Uranium from agricultural areas or groundwater reservoirs
Naturally-occurring organisms or those that have been engineered to enhance their bioremediation capability (biotechnology)
Methods include: bio-bleaching, bio-precipitation, bio-sorption, and bio-accumulation

6. Bio-bleaching Insoluble Metal + HCN  Metal-CN + H+
The use of bacteria and fungi to remove metals (e.g., Cadmium, Copper, Nickel, and Zinc) from contaminated soil
Insoluble metals are solubilized with organic acids (e.g. hydrogen cyanide) produced by the living organism to generate a soluble metal ion
Insoluble Metal + HCN  Metal-CN + H+

7. Bio-precipitation or bio-mineralization
bio-precipitation/biomineralization involves the formation of insoluble compounds following the reaction of soluble metal ions with either inorganic phosphate, carbonate, or sulfide that is released from bacteria
Selection of bacterial strains capable of enhanced organic ion secretion greatly increases the effectiveness of this method
Metal ion + HPO42-  Metal-HPO4
Metal ion + CO32-  Metal-CO3
Metal ion + H2S  Metal-S

8. Bio-sorption and bio-accumulation
The removal of soluble metals from solution by biological material.
Process are not limited to live organisms but also dead ones which in addition to bacteria also can be carried out by algae and fungi
Examples include: Engineering bacterial cells to express mercury binding protein (MerC) or phytochetalins to enhance the removal of mercury, arsenic, or cadmium

9. Bioremediation with Plants or plant/fungi combinations
Plants inoculated with specialized fungi form structures in the plant root systems known as mycorrhiza.
Working together the fungi enhances the ability of the plants to absorb materials from the soil

10. Bioremediation of Uranium contamination from ground water
Uranium is removed by the reduction of Uranium (VI) to insoluble Uranium (IV)
Same process can be also used to remove selenium and Cadmium contamination
In all cases, the chemical reduction of the contaminant is coupled to the oxidation or an organic compound produced by the organism (e.g. acetate, lactate, pyruvate, glycerol, or ethanol)
Process can be greatly enhanced by biotechnological methods

11. Conclusions
Bioremediation offers a safe and effective method to remove contaminants from the environment.
The use of bioengineered microorganisms, plants, or bacteria will continue to offer promising alternatives to the scientific community and allow the bioremediation of otherwise uninhabitable areas
However, in most cases bioremediation is not 100% effective in removing the contaminants
Research is needed to establish the Risk/Benefit relationships for individual contaminants in order to make educated decisions to treat individual cases

12. References
Mozaffarian D, Rimm EB (2003) Fish intake, contaminants, and human health evaluating the risks and the benefits. JAMA, 296(15):
Gadd GM. (2010) Metals, minerals and microbes: geomicrobiology and bioremediation. Microbiology. 156(3):
Dhankher OP, LI YJ, Rosen BP, Shi J et al (2002) Engineering tolerance and hyper-accumulation of arsenic in plants by combining arsenate reductase amd gamma-glutaminecysteine synthase expression. Nat Biotechnol 20,
Lovely DR, Phillips EJP, Gorby YA, Landa ER (1991) Microbal reduction of uranium. Nature 350,
Stolz JF, Oremland RS (1999) Bacterial respiration of arsenic and selenium in microbial metabolism FEMS Microbiol Rev 23,
Thompson-Eagle ET, Frankenberger WT, Karlson U (1989) Volatilization of selenium by Alternaria alternata. Appl Environ Microbiol 55,
Nevin KP, Finneran KT, Lovley DR. (2003) Microorganisms associated with uranium bioremediation in a high-salinity subsurface sediment. Appl Environ Microbiol. 69(6):