hto

HTO is the chemical notation for tritiated water, a molecule in which one hydrogen atom in a water molecule is replaced by tritium, a radioactive isotope of hydrogen. Like ordinary water, HTO forms clear liquid and participates in the same chemical reactions, but it carries a radioactive nucleus that decays over time.

Tritium decays by beta emission to helium-3, with a half-life of about 12.32 years. Because the radioactivity is embedded in the water molecule, internal exposure occurs mainly via ingestion or inhalation, rather than external exposure. The radiological hazard of HTO is generally lower than many other radiotracers, but it is still subject to radiation protection and regulatory controls, especially at higher concentrations or with prolonged exposure.

Production of HTO occurs in nuclear environments: natural water can become tritiated through neutron irradiation in reactors, or through exchange reactions with tritium gas in catalytic systems. It is widely used as a tracer because it behaves chemically like normal water and distributes with hydrological or biological processes. In research, HTO helps study water movement, uptake, metabolism, and exchange in ecosystems and organisms.

Measurement and safety: tritium activity in water is reported in becquerels per liter (Bq/L). Detection typically uses liquid scintillation counting or related radiometric methods; sample preparation may involve distillation or electrolytic enrichment. Handling and disposal follow radiation safety standards, with facilities required to monitor contamination, limit exposure, and manage waste in accordance with national and international regulations.

Other uses of the abbreviation HTO exist in different contexts, but tritiated water remains the most widely recognized scientific meaning.