Assertion: heavy water's hydrogen | /r/AtLocation | combination
Facets:
value: with oxygen
type: OTHER
value: naturally
type: MANNER
value: in natural water
type: LOCATION
Source sentences:
text: It has been known since 1931 that hydrogen occurs naturally in the form of two stable isotopes, with atomic masses of 1 and 2, both of which are present, in combination with oxygen, in natural water.