Bioremediation as Remedy for Soils with Copper Ores (Health Hazard) for Growing Food Crops

Open pit copper mining in Marinduque

Copper mine tailing

Jatropha seedlings grown on copper mine tailings (Photos courtesy of Ms. Cyreene S. Fontanilla)

Bioremediation is the technology that remedies soils with metal ores for growing food crops

Some metal ores in land surface are poisonous to man if ingested in overdose. For example, copper; in overdose causes Wilson’s disease.

“Wilson disease is a rare autosomal recessive inherited disorder of copper metabolism. The condition is characterized by excessive deposition of copper in the liver, brain, and other tissues. The major physiologic aberration is excessive absorption of copper from the small intestine and decreased excretion of copper by the liver” (Internet. February 13,2013).

Autosomal means a kind of gene that is not involved in sex determination, like XX for female and XY for male. HbA is an autosomal gene that controls the production of normal hemoglobin (Cummings, M. Human Heredity, Principles and Issues. 2009).

Wilson's disease is a genetic disorder in which copper builds up in the body, mainly in the liver and brain. Without any treatment, the build-up of copper can cause serious symptoms. Treatment is with medication to remove the excess copper and/or to prevent a further build-up of copper.

This disease was first described by Dr. Samuel Wilson in 1912, that is why the name.

"Too much copper in the liver cells (the hepatocytes) is harmful and leads to liver damage. Damage to brain tissue mainly occurs in an area called the lenticular nucleus...." (Wilson's disease. Internet. Nov. 29,2013).

Also too much copper blocks the absorption of zinc that results in another disorder. Lack of zinc results in inadequate production of enzymes in the glutathione system that is essential in the control of free radicals and derivatives in the body. This system consists of glutathione peroxidase, glutathione reductase, and glutathione synthase.

Glutathione peroxidase dismantles hydrogen peroxide in the body, by adding one electron. Hydrogen peroxide is derived from superoxide, the by-product of the metabolism of sugar (glucose) in the production of energy. Glutathione reductase returns one electron to glutathione peroxidase, thus recycles it. Glutathione synthase makes glutathione from nutrition like glutamate, cysteine, cystine, and cofactors selenium, zinc, lipoic acid and vitamin B2.

Free radicals and derivatives cause cancer, heart disease, stroke, diabetes and other so-called degenerative disease.

What level of copper is hazardous for a person sick of Wilson's disease?

“If the level of copper in drinking water is over 0.1 ppm (parts per million) (which is 0.1 mg/L), I recommend an alternative source. While 0.1 ppm isn't particularly hazardous, it indicates that significant copper is coming from somewhere….”(George J. Brewer, M.D. Department of Human Genetics, University of Michigan Medical School. Internet February 13,2013).

Copper in Marinduque

Marinduque is a province of the Philippines where copper ores are found near the land surface. Some portions are being mined. The larger portion is planted to crops like rice, fruits trees, and vegetables. Of course, the harvests are consumed.

Residents partaking of crops are at risk of contracting Wilson’s disease.

How to remedy soils with metal ores for use in growing food crops?

Bioremediation

Use plants that absorb the metals. This technology is called bioremediation.

Some crops absorb copper. Others are accumulators of metals. For example, cashew stores selenium in its nuts. Amaranthus, a vegetable, accumulates zinc (Prasad, M. Heavy Metals in Plants.1999). A species of fern (Pteris vittata L.) accumulates arsenic from the ground. The eucalyptus tree (Eucalyptus deglupta) absorbs gold. Tobacco absorbs radioactive materials like polonium and lead.

Jatropha (Jatropha curcas) accumulates copper. It needs only 20 parts per million (ppm). It accumulated 356 ppm in 6.5 months from germination in an experiment done at the University of the Philippines Los Baños in 2009. Seedlings grew vigorously on copper mine tailings used as growing medium. This was found out by Ms. Cyreene S. Fontanilla in her undergraduate thesis in the same university (see picture).

It goes without saying that the copper ores in Marinduque are over the 0.1 ppm limit that is hazardous to man. Mine tailing means the by-product of first-step copper ore extraction. The original ore contains much more copper.

In fact the copper mining in Marinduque is called open pit mining. The reason is that copper ores are found near the surface. The top soil is scrapped or dug up and the ores are separated. After the first processing a lot of copper is still left in the by-product called mine tailing.

Bioremediation should be applied on soils in Marinduque that are planted to food crops.

The method is straight forward. Plant a lot of jatropha seedlings close to each other. That way, the roots of one tree would almost overlap with that of another tree in terms of lateral growth. The trees should be maintained for a long period of time.

Of course, the target is to reduce the copper content of soil down to 0.1 ppm. This could be determined by periodic analysis of jatropha and the soil.

If the crop area is a private land, the owner can participate in the bioremediation program. The landowners should be given a training in raising jatropha and bioremediation technology.

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