elevation noun [C/U]. âº âheight above the âsurface of the âearth, or an âarea that is âhigher than the âsurrounding âland: [C] At âhigher elevations, the âair is âcolder. (Definition of elevation from the Cambridge Academic Content Dictionary Â© Cambridge University Press).
A dissolved gas is, simply enough, gas that has been dissolved into another material. This creates a solution, a mixture, where the gas is the solute, the minor component, and the other material, generally a liquid, is the solvent, the main component.
Sewer gas is a complex mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage.