Berta Karlik (Vienna 1904 – 1990) was a doctor of physics and the first woman professor at the University of Vienna. Working with Ernst Foyn, she published a paper on the radioactivity of seawater and discovered that astatine is produced from the decay of uranium and thorium. He brought together his knowledge of oceanography and radioactivity. His work helped to discover the biological problem of uranium contamination in seawater.