Science | Money can’t grow on trees, but gold can…

As the saying goes, ‘money doesn’t grow on trees’. Student living would be much easier if it did. However, a recent study published in Nature Communications suggests that the opposite of this idiom might actually hold some truth, with researchers discovering traces of gold in the leaves of certain plant species.

Research has been carried out in this area before; microscopic particles of gold have been found on leaf samples whilst many studies have additionally demonstrated plants ability to absorb gold through their root system. However, these studies have been found to use much higher concentrations of Au than those found in the natural environment, whilst also using plant species that aren’t suited for mineral exploration. Similarly no conclusive evidence had been found that proved the gold concentrations measured on leaves weren’t simply the result of sample contamination.

A group led by Dr Lintern of Australia’s national science agency CSIRO looked to resolve this dispute and conducted a experiment on both greenhouse grown and wild eucalyptus trees. Trees were sampled from the Freddo Gold Prospect in Western Australia; leaves were selected from trees growing directly over the gold deposit and from successive intervals further away. These leaves were then studied for the presence of gold particles using x-ray elemental imaging which concluded the presence of higher concentrations of gold in those leaves growing near the deposit. Lab experiments were run alongside this experiment to test eucalyptus seedlings grown in soil containing high concentrations of gold and no gold. The microscopic particles of gold found in the leaf samples grown in gold rich conditions resembled that of those found in leaves growing over the deposit, proving that the gold enters the plant via the root system and therefore isn’t the result of contamination.

Dr Lintern was reported as commenting, “We believe that the trees are acting like a hydraulic pump. They are bringing life-giving water from their roots, and in so doing, they are taking smaller dissolved gold particles up through the vascular system.” These Au particles thought to be drawn from over 35 metres below ground, are pushed to the plants extremities to reduce the likely poisonous effect of gold.

The actual amount of gold in each leaf is negligible, so stripping eucalyptus trees of their leaves in the hope of getting rich quick wouldn’t prove successful. However with gold discoveries down 45% over the last decade alone, novel discoveries such as this could provide an opportunity for the development of new mineral exploration techniques, allowing for deeply hidden gold deposits to be accessed.


Louise White 

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