Final answer:
Increased radioactivity in ice cores after Chernobyl implies ongoing radioactive decay or fission reactions within the Chernobyl sarcophagus, leading to release of radioactive particles into the environment.
Step-by-step explanation:
In the aftermath of the Chernobyl disaster, a significant amount of radioactive materials, including cesium-137 (137Cs), was released into the environment. The ruins of the Chernobyl reactor were enclosed in a large concrete sarcophagus to contain these materials. However, the increased radioactivity noted in ice cores after the incident, as well as during periods when rainwater penetrates the sarcophagus, suggests ongoing fission reactions or residual decay within the containment. This can result in varying amounts of radioactive particles being washed out of the structure and released into the environment. The large initial radioactivity level, noted as 6.0 MCi of 137Cs alone, combined with the presence of other isotopes, highlights that the consequences were severe and that the radioactive contamination persisted in the environment, absorbed into the ice over time.