Scientists from the International Union of Glaciology (IFJPAN) have discovered that there are significant differences in the accumulation of plutonium isotopes in different hemispheres, and that their unique anomalies are related to events such as the crash of the Mars-96 spacecraft. Their large-scale study of cryolite on glaciers revealed cryolite's key role in concentrating radioactive contaminants, raising ecological concerns and prompting further research.
A recent investigation by scientists at the Institute of Nuclear Physics PAN provides new insights into the accumulation of plutonium isotopes on glaciers in the Southern Hemisphere.
By analyzing glacial sediments that formed and accumulated on the glacier, the researchers not only discovered significant differences in isotope concentrations between the two hemispheres, but also unprecedented anomalies. These anomalies may be related to events such as the crash of the Mars-96 spacecraft.
Glaciers are not only a feature of mountainous landscapes, but also play a vital role in global freshwater reserves. However, melting glaciers caused by global warming pose a serious threat. These threats include rising sea levels and shrinking water resources critical to hydropower generation.
Additionally, as glaciers melt, they release radionuclides and other pollutants that may migrate into nearby ecosystems. There, these pollutants can accumulate, enter the food chain, and potentially disrupt the environmental balance.
Radioactive elements are present in the environment due to natural processes and human activities. Artificial radionuclides, such as plutonium, are released into the environment primarily through nuclear testing, reactor accidents, or malfunctions of satellites and space probes containing radioactive energy sources.
These materials travel primarily through the atmosphere and accumulate in different ecosystems, including glaciers, in the form of dark sediments called cryolite. A typical cryolite cave is no more than a few dozen centimeters in diameter and depth. At its base, there is a dark deposit called cryolite. It contains organic substances and pollutants, namely radionuclides, heavy metals, pesticides, microplastics or antibiotics. These sediments may pose a potential threat to local ecosystems.
Latest research by the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJPAN) using novel mass spectrometry methods has allowed researchers to establish a database of plutonium isotopes (238, 239, 240Pu) in glaciers in the northern and southern hemispheres.
The cryolite samples analyzed came from 49 glaciers in nine regions around the world, including the Arctic, Alps, Himalayas and Antarctica. The material was collected between 2000-2020 by an international team of researchers funded by a project of the National Science Center.
"This is the first time such a large-scale analysis of plutonium concentrations in cryogenic meteorite samples has been carried out" - said Dr. EdytaŁokas (IFJPAN), the initiator and first author of the article published in the journal Science of the Total Environment.
The results provide unique information about the accumulation, distribution and origin of plutonium isotopes in glaciers. Concentrations of 239+240 plutonium activity are much higher in the Northern Hemisphere than in the Southern Hemisphere, reflecting uneven deposition of plutonium from nuclear weapons testing between the two hemispheres. In the Northern Hemisphere, Scandinavia and the Alps have the highest plutonium concentrations. In the case of 238Pu, no relevant differences between hemispheres were found. Southern Hemisphere cryolites are highly heterogeneous in both plutonium activity and mass ratio.
An isotope ratio of 238Pu/239+240Pu was first observed in moraines from the Exploradores glacier in Patagonia, which has never been seen in the literature so far. Researchers speculate that the excess of 238Pu may be related to the fall of the Soviet space probe MARS-96. The space probe contains a generator of 238Pu, which may be responsible for the higher concentrations of this isotope on nearby glaciers. The result is the first observation of abnormal plutonium isotope ratios in the Southern Hemisphere.
In addition, cryolite samples from South American glaciers show a mass ratio of 240Pu/239Pu that deviates significantly from the mass ratio found in the literature, which may indicate that the main source of plutonium is related to low-altitude nuclear tests in French Polynesia.
"The concentrations of plutonium activity we observed in cryoliths - particularly in the Northern Hemisphere - are orders of magnitude higher than those in other environmental matrices used to monitor the environment, such as lichens, mosses, soils and sediments. Our findings also highlight the importance of cryogenic soils in accumulating radioactive contaminants that could pose a potential threat to surrounding flora and fauna, while also helping us to track the spread of these contaminants." Dr. EdytaŁokas noted.
The research team from IFJPAN will continue their work. The next survey, conducted in collaboration with AGH University in Kraków, was conducted at the Jostdalbring Ice Cap in Norway. The expedition, organized in August 2024, aims to better understand the accumulation process of pollutants in glaciers and their sources.
Compiled from /ScitechDaily