Carbon‑nitrogen compounds, alcohols, mercaptans, monoterpenes, acetates, aldehydes, ketones, SF6, PH3, and other fire gases in coal-mining waste heaps of Upper Silesian Coal Basin (Poland) - a re-investigation by means of in situ FTIR external database approach.

Coal-fire gas jets emanating from waste heaps are chemically very complex and variable mixtures, as proved by our former studies. The current paper is a result of further exploration of the GASMET FTIR system via an iterative external databases search. This allowed to pinpoint a number of subsequent chemicals, both in terms of (semi)quantitative analysis and occurrence probability (fit). Some compounds represent new finds. The most likely candidates found, with fit often >90%, are CN compounds - especially hydrogen cyanide and isocyanic acid; acetylene, various alcohols, monoterpenes, formic acid. Acetaldehyde is the most common aldehyde, followed by 2-ethylhexylaldehyde. Tetrachloroethylene quite commonly occurs, but with worse fit values. An interesting find concerns methane- and ethanethiol being enriched at a vent with an intense and cumulative sulfur (S8) mineralization. Other less frequent or worse fit compounds include arenes, COS, some alcohol derivatives, other aldehydes, hydrocarbons, nitriles (acrylonitrile), ketones, acetates, ethers, acetone, acrolein (propenal), triethylamine, and methyl metacrylate. Important and relatively frequent inorganic gas is PH3, while SF6 is very rare. However, the occurrence of the later seems to be a very important discovery: SF6 is recognized by the Intergovernmental Panel on Climate Change as the most potent greenhouse gas.