Here's an unusual resource for extracting rare earth elements from toxic ore waste: salmon semen. Researchers affiliated with several academic and research facilities in Japan have discovered that salmon sperm, of all things, is a natural "miracle" product for scrubbing waste of its valuable, reusable elements, reports Phys.org.

What possessed researchers to mix salmon semen into liquid ore waste? Back in 2010, another team of researchers discovered that phosphate on the surface of some types of bacteria attracted rare earth elements (REEs), and that this was 10 times as efficient as conventional methods for retrieving the REEs. The only problem with this method was that growing cultures of these bacteria for use on an industrial scale is impractical.

But, it turns out, salmon semen also has phosphate in the sperm DNA, which the researchers surmised might also be able to attract REEs the same way that the bacteria could. Salmon semen is also more plentiful, cheaper and easier to gather. 

To test the idea, researchers poured dried semen into a beaker that already contained a rare earth solution. They found that the salmon semen did indeed absorb REEs from the solution. The REEs could then be safely extracted after the resultant substance was placed in a centrifuge. In fact, the process was even able to extract two very expensive elements, thulium and lutetium.

This breakthrough is particularly important because conventional methods for extracting REEs from waste rely on toxic and sometimes radioactive chemicals, which are major environmental pollutants. Salmon semen, on the contrary, is a natural substance and causes none of these environmental hazards.

Before salmon semen can replace industrial pollutants, however, cooperation from commercial fisheries will be required. Since fish semen is typically seen as a worthless byproduct by fisheries, often simply trashed, this shouldn't be a long term problem. But in the short term an infrastructure will have to be established for capturing the semen and processing it at its source.  

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