Evaporative and other processes in bodies of water, and also ground water processes, also differentially alter the ratios of heavy hydrogen and oxygen isotopes in fresh and salt waters, in characteristic and often regionally distinctive ways.
32.
Surrounding it, 10, 000 very sensitive light detectors are arrayed to register the tiny flashes of blue light created when an electron neutrino hits a heavy hydrogen atom's nucleus ( a proton plus a neutron ), and sends an electron hurtling through the water.
33.
Because the heavy hydrogen and oxygen isotopes used in the standard doubly labeled water measurement are non-radioactive, and also non-toxic in the doses used ( see heavy water ), the doubly labeled water measurement of mean metabolic rate has been used extensively in human volunteers, and even in infants and pregnant women.
