Carbonic acid for foods
Our carbon dioxide is used in the food industry, not least as carbonic acid in drinks.
In addition to all the regular bottled carbonated beverages found in stores, carbonic acid is also often added directly to drinks in restaurants and bars. For example, when you buy a drink in a fast food restaurant, you will add gas by pushing your cup against the bar on a machine. CO2 cartridges are also available in stores for the carbonating sold for home use.
It is very likely that the bubbles come from our carbon which means they are produced by 'green' carbonic acid originating in the natural cycle.