This subject tends to be emotive and controversial, for instance The Low Level Radiation Campaign has a very different view from that held by BNFL. The barium was present in the form of the nitrate in the chemical explosives used while the plutonium was the fissile fuel used.Just because a radioisotope lands on the surface of the soil, does not mean it will enter the human food chain. The The action of neutrons on stable isotopes can form radioisotopes, for instance the neutron bombardment (neutron activation) of nitrogen-14 forms carbon-14.Mohenjo-daro is an archeological site of one of the largest Indus Valley civilizations that thrived around 2000 BCE.
Jiří Hála's textbook (Radioactivity, Ionizing Radiation and Nuclear Energy, ISBN 807302053X explains how cattle only pass a minority of the strontium, cesium, plutonium and americium they ingest to the humans who consume milk and meat. For a discussion of the physics of neutron activation see Neutron activation analysis. The releases from nuclear reactor accidents and bomb detonations will contain a greater amount of the shortlived radioisotopes (when the amounts are expressed in activity ).The proffered evidence is rife with pseudoscience; One difficulty with the nuclear blast claim at Mohenjo-daro is immediately apparent when photographs of the dig site are examined.The buildings were made with kiln fired mud bricks. How an unreinforced mud brick wall withstands a nuclear blast never seems to be addressed.For instance, leaks in underground water pipes can be discovered by running some tritium-containing water through the pipes and then using a Geiger counter to locate any radioactive tritium subsequently present in the ground around the pipes.(Recall that tritium is a radioactive isotope of hydrogen.) Tracers can also be used to follow the steps of a complex chemical reaction.Radioactive isotopes have a variety of applications.