Assertion: gas's hydrogen sulfide | /r/AtLocation | the absence of oxygen gas
Facets:
value: often
type: TEMPORAL
value: such as in swamps
type: LOCATION
Source sentences:
text: Hydrogen sulfide is often produced from the microbial breakdown of organic matter in the absence of oxygen gas, such as in swamps and sewers; this process is commonly known as anaerobic digestion which is done by sulfate-reducing microorganisms.