Original sentence: There are about 94 elements found naturally on Earth (up to plutonium, elemenScientists estimate that the elements which occur naturally on Earth (some only as radioisotopes) occur as 339 isotopes (nuclides) in total
Edited sentence: Scientists estimate that the elements which occur naturally on Earth (some only as radioisotopes) occur as 339 isotopes (nuclides) in total.There are about 94 elements found naturally on Earth (up to plutonium, element 94, inclusive), though some are detected only in very tiny amounts, such as plutonium-244