The gold ring around your finger may symbolize “till death do us part” for you, but for scientists, it poses a problem.
That shiny band probably cost a small fortune at the jewelry store, but gold is actually abundant on the Earth’s surface (which helps explain why it’s the ideal form of money). The difficulty is, when scientists apply what they know about how the solar system formed, it’s hard to explain how all that gold (and other precious metals that bond easily to iron, like palladium and platinum) got into the Earth’s crust, where bling-loving humans could get at it. A new study in Science sets forth an explanation: In the Earth’s younger days, impacts by huge objects—perhaps even one as big as Pluto—may have brought it here.
To explain this theory, let’s start with the most dramatic impact in our planet’s history: the one that formed the moon and re-melted the solidifying Earth in the process.
Moon rocks brought back during the Apollo missions led to the now widely accepted theory that the moon formed when a Mars-size object crashed into early Earth. Energy from the impact would have spurred the still forming Earth to develop its mostly iron core. When this happened, iron-loving metals should have followed molten iron down from the planet’s mantle and into the core. But we know that gold and other iron-lovers are found in modest abundances in Earth’s mantle. [National Geographic]
The name Titanic means so many things: the gigantic, disastrous ship; a record-breaking and award-winning movie; and now, a new iron-eating bacterium found in the boat’s underwater grave. Says maritime historian Dan Conlin:
“What is fascinating to me is that we tend to have this idea that these wrecks are time capsules frozen in time, when in fact there [are] all kinds of complex ecosystems feeding off them, even at the bottom of that great dark ocean.” [Our Amazing Planet]
The new species of bacteria, named Halomonas titanicae, is described in this month’s International Journal of Systematic and Evolutionary Biology. The bacteria is slowing eating away at the 50,000 tons of iron in the wreck, which has been under the ocean for 98 years. H. titanicae appears to digest iron and turns it into knobs of corrosion products.
A recent volcanic eruption let scientists watch Mother Nature try out one of the geoengineering schemes that has been proposed to reduce the amount of carbon dioxide in the air, and therefore cool the planet. But the results of this natural experiment left a lot to be desired.
The geoengineering technique known as ocean fertilization calls for scientists to dump iron into the ocean to “fertilize” it and spur blooms of phytoplankton. These tiny photosynthetic organisms will suck up CO2 as they grow, the thinking goes, but will then die and tumble down to the sea floor, where the CO2 will be safely stored in the heaps organic matter.
The same thing can happen naturally, though, if a volcano happens to erupt and spews iron particles over the ocean. That’s exactly what happened in the summer of 2008.
In August 2008, scientists in the northeastern Pacific Ocean were shocked to witness a sudden, huge spike in the area’s plankton population. Their investigation traced the bloom to an ash cloud from a volcano that had erupted in the Aleutian Islands only a few days before. The ash, it turned out, had fertilized the ocean with thousands of tons of iron, on which the plankton gorged. [ScienceNOW]