About 2000 tons of mercury from human-generated sources enter the environment every year, but tracing natural versus human sources, and sorting out local pollutants from distant sources, has been been a problem. University of Michigan scientists say they’ve taken a big step towards reading mercury “fingerprints.”

“For some time, we weren’t sure that it was going to be technically possible, but now we’ve cracked that nut and have shown significant differences not only between mercury from coal and, say, metallic forms of mercury that are used in industry, but also between different coal deposits,” [ecologist Joel] Blum said.

How it works:

The fingerprinting technique relies on a natural phenomenon called isotopic fractionation, in which different isotopes (atoms with different numbers of neutrons) of mercury react to form new compounds at slightly different rates. In one type of isotopic fractionation, mass-dependent fractionation, the differing rates depend on the masses of the isotopes. In mass-independent fractionation, the behavior of the isotopes depends not on their absolute masses but on whether their masses are odd or even. Combining mass-dependent and mass-independent isotope signals, the researchers created a powerful fingerprinting tool.

[Image: Christopher Gruver]