Our hybrid ion source is capable of measuring 14C from CO2 gas directly. The associated CO2 feed line for the ion source is also ready for operation, both needing optimization related to ionization efficiency and conditions for optimal beam currents. This is a large part of Tomi Vuoriheimos master's thesis.
As a first measurement, Tomi measured the 14C concentration of the CO2 in a Soda Stream gas (used by us consumers to make self-made sparkling water). Why measure the 14C in Soda Stream's CO2? Well, because we can. And it is fun (to us anyway). And the 14C concentration tells us the age of any carbonaceous material, or, in the case of well-defined mixtures, the ratio of modern, renewable carbon to fossil carbon. This is the the bioportion, which we routinely measure for different fuels under the RACAF organization.
The result: Soda Stream's CO2 is 0.010 fraction-modern. This is currently the level of background with gas measurements, so we can say that over 99 percent of the CO2 is of fossil origin.
Actually, this does not come as a suprise: most of the CO2 we have from AGA are fossil too. So, next time you enjoy some sparkling beverages, you are probably taking in CO2 from fossil fuel combustion. This is certainly the case with Soda Stream waters. Well, if it's of any comfort, you will get very slightly less radiation from fossil CO2.