Role of bacterial carbonic anhydrase during CO2 capture in the CO2-H2O-carbonate system

Abstract

Atmospheric CO2 are closely connected to climate change and global carbon cycle. Karst processes in CO2-H2O-carbonate system can absorb atmospheric CO2. Carbonic anhydrase (CA) can efficiently catalyze the interconversion between CO2 and HCO3−, which may help accelerate karst processes. To explore the influence of bacterial CA on CO2 capture capacity in CO2-H2O-carbonate system, a flow dissolution experimental device was designed to simulate CO2 absorption by rainwater infiltration or surface water flushing. Results showed that, when bacterial CA was added into the experimental system, it increased not only the rate but also the quantity of CO2 absorption, and the CO2 captured by limestone or dolomite dissolution increased by at least 18.9% and 22.1%, respectively. However, excessively high concentration of CO2 was not conducive to carbonate rock dissolution by bacterial CA. In accordance with the fixed carbon caused by global carbonate dissolution, the contribution of soil CA to the CO2 sinks may reach 0.567–1.938×1014gC/a. In summary, the addition of microbial CA could increase the CO2 capture in the form of DIC in CO2-H2O-carbonate system, thereby increasing the carbon sink potential of karst systems. The results help establish a promising approach for reducing CO2 emission by microbial CA.