In Australia, Gold Grows on Trees    [08-11-2013] Although money doesn’t grow on trees, if you visit the Australian Outback, you can find gold growing on leaves! In Western Australia, an area known for its vast gold deposits, gold has been discovered on the leaves of eucalyptus trees. Recently, researchers at CSIRO, the country’s national scientific agency, conducted a study to determine whether the gold is blown from the atmosphere or comes up from underground. They compared the leaves of the eucalyptus trees near a gold prospecting site with those from trees growing about 900 m away. The researchers found that the leaves of most of the trees that were close to the gold deposits “contained microscopic particles of the precious metal,” while others did not. So how does the gold get on the leaves? According to researchers, eucalyptus trees have deep root systems. In times of drought, their roots dig deep in search for water. They can dig so deeply that some trees strike gold. However, the gold is toxic to the plant, so the trees move the tiny particles of gold to their leaves and branches. “The eucalyptus acts as a hydraulic pump-its roots extend tens of meters into the ground and draw up water containing gold,” said Mel Lintern, a geochemist at CSIRO. “As the gold is likely to be toxic to the plant, it’s moved to the leaves and branches where it can be released or shed to the ground.” Although this is exciting, it’s important to note that the amount of gold is less than 0.000005 percent of the weight of each leaf. That amount is so small that not only is it invisible to the naked eye, but a person would have to remove all the leaves from 500 eucalyptus trees to have enough gold to make a gold band. But this discovery is helpful, because it will allow Australian gold mining companies to prospect for gold more intelligently. It is also beneficial to the environment, because it reduces unnecessary drilling. Staff reporter Jessica Kim (jessicakim@timescore.co.kr)     출처: 어린이 영자신문 키즈타임즈 (www.kidstimes.net)