Plutonium isotope anomaly discovered in Southern Hemisphere glaciers

The latest findings carried out by scientists at the PAN Institute for Nuclear Physics shed new light on the process by which plutonium isotopes accumulate in glaciers in the Southern Hemisphere. Analyzing samples of cryoconite, a sediment deposited in glaciers, not only reveals differences in concentrations between hemispheres, but also unprecedented findings that could be linked to accidents such as the fall of the Mars 96 spacecraft. Isotopic anomalies were also shown.

Glaciers not only add majestic charm to mountain landscapes, but they also play an important role in the supply of fresh water. Their melting, caused by global warming, could have serious consequences, ranging from rising sea levels to diminishing water resources, which are crucial for energy production in hydropower plants. Additionally, radionuclides and other contaminants released from the ice can migrate to nearby ecosystems, where they accumulate and affect the food chain.

Radioactive elements exist in the environment as a result of natural processes and human activities. Man-made radionuclides, such as plutonium, are released into the environment primarily through nuclear tests, reactor accidents, or failures of satellites and spacecraft containing radioactive energy sources.

These materials are transported primarily through the atmosphere and accumulate in various ecosystems, including glaciers, in the form of black deposits called cryoconite. A typical cryoconite hole is only a few tens of centimeters in diameter and depth. At its bottom is a black deposit called cryoconite. It contains organic substances and pollutants: radionuclides, heavy metals, pesticides, microplastics, and antibiotics. This sediment can pose a potential threat to local ecosystems.

In the latest study conducted at the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN), using a new mass spectrometry method, researchers created a database of plutonium isotopes (238,239,240Pu) in northern and southern glaciers. I was able to create . hemisphere. The cryoconite samples analyzed were collected from 49 glaciers in nine regions of the world, including the Arctic, Alps, Himalayas, and Antarctica. This material was collected by an international research team between 2000 and 2020.

“This is the first time that plutonium concentrations in cryoconite samples have been analyzed on such a large scale,” said Dr. Edita Wochus, the initiator and first author of the paper published in Science of the Total Environmental. (IFJ PAN) says.

The results of the study provided unique information on the accumulation, distribution, and source of plutonium isotopes in glaciers. The concentration of 239+240Pu radioactivity was found to be much higher in the Northern Hemisphere than in the Southern Hemisphere. This reflects the uneven deposition of Pu due to interhemispheric nuclear weapons testing.

Regarding the Northern Hemisphere, the highest concentrations are observed in Scandinavia and the Alps. For 238Pu, no relevant differences between hemispheres were observed. Southern Hemisphere cryoconite is characterized by high heterogeneity both in terms of Pu activity and mass ratio.

The isotope ratio of 238Pu/239+240Pu is unprecedented in the literature and was first observed in cryoconite from the Exploradres Glacier in Patagonia. Researchers hypothesize that an excess of 238Pu may be involved in the fall of the Soviet space probe MARS-96, which sank into the ocean off the coast of Chile in 1996.

The spacecraft carries a generator containing 238Pu, which could explain the high concentrations of this isotope in nearby glaciers. The results of this study are the first observations of their kind showing anomalies in plutonium isotope ratios in the Southern Hemisphere.

Furthermore, cryoconite samples taken from glaciers in South America show mass ratios of 240Pu/239Pu that deviate significantly from mass ratios found in the literature, indicating that the main Pu source is from French territory. This may indicate a connection to low-altitude nuclear tests in the Polynesian region.

“The concentrations of plutonium radioactivity in cryoconite that we observed are orders of magnitude higher than in other environmental matrices used to monitor the environment, such as lichens, mosses, soils, and sediments, especially in the northern hemisphere. These findings are They highlight the importance of cryoconite in the accumulation of radioactive contaminants that can pose a potential threat to surrounding flora and fauna, and at the same time they require us to track the spread of those contaminants.” points out Dr. Wochus.