TM99-01 Change in reporting unit for relative abundances of helium isotopes

The National Water Quality Laboratory (NWQL), under a contract with Lamont Doherty Earth Observatory of Columbia University, has been reporting low-level tritium (3 H) total dissolved helium (He) (61038), total dissolved neon (Ne) (61046), and the helium-3/helium-4 isotope ratio ( 3 He/4 He) of dissolved helium (61040) for purposes of ground-water dating based on the tritium/helium-3 (3 H/ 3 He) method.