Radioactive particles in Pacific sediments could mark the beginning of a new era

Radioactive particles in Pacific sediments could mark the beginning of a new era

Scientists claim to have precisely determined the beginning of the Anthropocene.
Scientists think they have precisely determined the beginning of the Anthropocene through particular biomarkers – radioactive material discovered in marine sediments and corals in the northwestern Pacific Ocean, off the coast of Japan.

That material comes from atomic tests carried out in the region during the 1950s and represents a clear change in the ocean environment.

Based on the data collected, the research team proposes that the Anthropocene era began in 1954. “Our task was to find clear indications of relapses from 1950 until 1963, when testing largely stopped. We took carrot samples from the bay area and there are clear signs of plutonium from relapse, “says geoscientist Yusuke Yokoyama of the University of Tokyo in Japan.” However, we also collected coral skeletons from Ishigaki Island, a southwest of Okinawa, which contained relapses.

Comparing the sediments with the corals allows us to date the signatures we see in the sediments with greater precision ”. What makes collecting these samples so difficult is that sediments can be dispersed over a large area and moved very easily by ocean currents and other factors. While they don’t give scientists much information about the state of water, they are a good complement to sedimentary material in terms of dates.

A variety of chemical analysis techniques have been used to study the sampled sediment slices in detail, including accelerator mass spectrometry or AMS, which distributes accelerated ions in order to identify individual isotopes in sediments.

“It was difficult to analyze the plutonium within our samples, as during the period in question, three tons of plutonium were released into the sea and the atmosphere, but those three tons dispersed far and wide. So we’re actually looking for incredibly small signatures. “At the moment, no one can decide when the Anthropocene should begin: perhaps the industrial revolution, or the start of rising carbon emissions.

But for the scientists behind this new study, there is a distinct point where it begins. This work is important not only for solidifying the definition of the Anthropocene, but also because the effective use of our method means it could also be used to improve ocean and climate models, or even help explore past tsunamis and other risks.