In a geological illustration of what goes around comes around, researchers at the University of Florida found lead deposits from hydrothermal vents associated with an underwater volcano off the coast of Italy. Hydrothermal springs release water often at high temperature that has traveled deep under the seabed and subsequently heated by subterranean geothermal activity and in the process left dissolved metals and minerals from the surrounding rocks. At first they assumed the lead was from local deposits in the Mediterranean but on closer examination using a (get this) Multi-Collector Inductively Coupled Plasma Mass Spectrometer – researchers found the lead matched deposits from Broken Hill in Australia. Apparently lead deposits, a little like human DNA, can be traced to their source by matching the isotope profile. The most likely explanation, according to the researchers, is the lead was mined, shipped to Europe and turned into fuel in the days when lead additives were prevalent. The exhaust fumes were then washed out into the atmosphere, seeping underground to be gradually recycled and combined with other mineral deposits on the seabed deposited by the hydrothermal activity, just as the original Broken Hill deposits were laid down millions of years ago.
If correct it has some telling lessons for us about the use and release of potentially harmful products, especially heavy metals, into our environment. They are rarely lost. Nature has her own way of recycling and concentrating these metals in ways we are still learning about. As commentators have rightly pointed out there are other explanations as to how deposits with such similar isotope profiles could have come about. We just liked the idea that in another thousand years of hydrothermal activity maybe BHP can go mine it’s lead again, only this time in the Mediterranean rather than in Australia.