text: Observed atmospheric Xe is depleted relative to Chondritic meteorites by a factor of 4 to 20 when compared to Kr. In contrast, the stable isotopes of Kr are barely fractionated. This mechanism is unique to Xe since Kr ions are quickly neutralized via
  Therefore, Kr can be rapidly returned to neutral and wouldn't be dragged away by the charged ion wind in the polar region. Hence Kr is retained in the atmosphere.