Water Contaiminants- Part 2 Brief information limits of contaiminants for safe drinking water and Health effects 7- Helium (He) and water Helium as a noble gas and after hydrogen, it is the most prevalent element in the universe that is 5 ppm in the atmosphere, 4-7 ppt in sea water and usually do not react with any other particles. As it does not react with water or any particles, but can produce non-stable compounds as VHe3+ and HePtHe2+. Helium is the most less soluble in water that is 1.5mg/l at 20oc at I bar pressure. Helium used as a coolant for nuclear reactors, applied as gas lasers, used as a protective coating, remain in liquid below -269oc. helium E939 used as food additive. Uranium minerals contain small amounts of helium. Helium may escape through splits in the earth's crust. However, it does not end up in water directly and used to find leaks, nuclear weapon testing, to determine radioactivity and water conta...