Hydrogen sulfide

Hydrogen sulfide

       A wiki link on the subject can be found at:  Hydrogen sulfide

               Warning:  Hydrogen sulfide gas (H2S) is poisonous to humans.  Often around the world, the gas that comes up from oil drilling is often H2S gas and is routinely burned off for many reasons, including our safety. In the USA the oil well gas tends to be more methane than H2S, by the way.

Here's two links on the "rotten egg" smell in water: 

                              http://www.mrwa.com/watersmellrotteneggs.htm

                              http://www.extension.purdue.edu/extmedia/WQ/WQ-11.html