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An international team of scientists have found a way to grow and harvest gold from crop plants.

The technique is called phytomining, using plants to extract particles of gold from the soil. Some plants are naturally able to take up and concentrate metals through their roots, such as nickel, camium, and zinc in their leaves and shoots. These plants have been coined as hyperaccumulators, which scientists have explored their use for pollution removal.

There are no known hyperaccumulators for gold as the precious metal does not easily dissolve in water, providing no natural way for taking the particles in through the plant's roots.

"Under certain chemical conditions, gold solubility can be forced," said Chris Anderson, an environmental geochemist and gold phytomining expert at Massey University in New Zealand.

Fifteen years ago, Anderson first showed it was possible to get mustard plants to suck up gold from chemically treated soil containing gold particles, according to LiveScience.

The procedure requires a fast-growing plant with an abundant aboveground leafy mass, such as mustard, sunflowers or tobacco. The crop must be planted on soil that contains gold such as waste piles or tailings surrounding old gold mines are a good place to look. Since conventional mining can't remove 100 percent of the gold from surrounding minerals, some of the gold will go to waste. As crops reach their full height, the soil must be treated with a chemical that can make gold soluble. When the plant transpires, pulling water up and out through tiny pores on its leaves, it will take up the golf water from the soil and accumulate it in its biomass. After this occurs, the crop is ready for harvest.

Getting the gold into plants is simple. Extracting the gold has proved to be more difficult, according to Anderson.

"Gold behaves differently in plant material," Anderson told LiveScience.

For example, if the plants are burned some of the gold will stay attached to the ash, while some will disappear. Processing the ash poses difficulties as it requires the use of huge amounts of strong acids, which can be dangerous to transport.

The gold found in plants are nanoparticles, so there may be great potential for the chemical industry, which uses gold nanoparticles as catalysts for chemical reactions, Anderson said.

Gold phytomining is not meant to take the place of traditional gold mining nor will it, Anderson said. "The value of it is in the remediation of polluted mine sites," he added.

The chemicals necessary to make gold soluble also induce the plants to take up other contaminants in the soil such as mercury, arsenic and copper. These common pollutants found in mine waste can pose a risk to humans, as well as the environment.

"If we can generate revenue by cropping gold while remediating the soil, then that is a good outcome," said Anderson.

Anderson is currently working with researchers in Indonesia to develop a sustainable system for small-scale artisanal gold miners to use the technique in hopes of reducing the mercury pollution from their operations.

However, growing gold would mean using hazardous chemicals such as Cyanide and thiocyanate, which are also used by mining companies to get gold to leach out of rock. These chemicals would also be necessary to dissolve gold particles in soil water, making some scientists question the environmental risks.

"The process itself could create environmental problems," said J. Scott Angle, an agronomist at the University of Georgia.