Two trace gases (carbonyl sulfide and the oxygen isotopes of CO2) show promise to help disentangle carbon cycle processes, but their soil fluxes need additional characterization. As in leaves, we anticipate that carbonic anhydrase (CA) enzymes in soil microbes drive uptake of atmospheric COS by soils (COS + H2O -> CO2 + H2S) and exchange of the oxygen isotopic signature between atmospheric CO2 and water (CO2 + H2O <-> HCO3– + H+). We performed a soil survey to test whether soil microbial CA drive the soil fluxes of these two potential carbon cycle tracers. By measuring the microbial, chemical, and physical properties of a diverse set of soils, we set out to determine…