  Certain subterranean environments of Earth have naturally accumulated
long-lived radionuclides, such as 238U, 232Th and 40K, near the presence of
liquid water. In these natural radioactive environments (NRE), water radiolysis
can produce chemical species of biological importance, such as H2. Although the
proposal of radioactive decay as an alternative source of energy for living
systems has existed for more than thirty years, this hypothesis gained strength
after the recent discovery of a peculiar ecosystem in a gold mine in South
Africa, whose existence is dependent on chemical species produced by water
radiolysis. In this work, we calculate the chemical disequilibrium generated
locally by water radiolysis due gamma radiation and analyse the possible
contribution of this disequilibrium for the emergence of life, considering
conditions of early Earth and having as reference the alkaline hydrothermal
vent (AHV) theory. Results from our kinetic model points out the similarities
between the conditions caused by water radiolysis and those found on alkaline
hydrothermal systems. Our model produces a steady increase of pH with time,
which favours the precipitation of minerals with catalytic activity for
protometabolism, as well as a natural electrochemical gradient in this aqueous
environment. In conclusion, we described a possible free-energy conversion
mechanism that could be a requisite for emergence of life in Hadean Earth.
