There are 33 known radioactive isotopes of Barium. You can read about them here: Isotopes of barium - Wikipedia But as others have pointed out, Barium is normally a contrast agent in X-ray examinations. read more
Barium found in the Earth's crust is a mixture of seven primordial nuclides, barium-130, 132, and 134 through 138. Barium-130 undergoes very slow radioactive decay to xenon-130 by double beta plus decay, and barium-132 theoretically decays similarly to xenon-132, with half-lives a thousand times greater than the age of the Universe. read more
Plutonium is a radioactive chemical element; practically all plutonium is man made - in the nature plutonium is extremely rare. read more