Hydrogen Sulphide (H2S)
Hydrogen Sulphide is a gas which smells strongly like rotten egg odor. It results from the decay of organic matter with organic sulphur and the presence of certain types of bacteria. Even very low concentrations are offensive as well as highly corrosive (silver tarnishes almost immediately upon contact with H2S).
Because it is in the form of a gas, H2S cannot be collected in a sample bottle for laboratory analysis. Therefore its presence must be reported when a sample is submitted for a treatment recommendation.