A similar analysis of concentration profiles was also performed for BPMs immersed in simulated seawater (Figure -21, S24-25). The model shows very similar behavior as for the 1 M KHCO3 case with respect to the equilibria. However, due to the incredibly low concentrations of reactive carbon in the seawater electrolyte, the BPM is primarily exchanged with Na + or Cl -for the CEL or AEL, respectively. At the CEL side, the catholyte is rapidly mass-transfer limited by HCO3 -, impeding the formation of CO2 via the in-situ regeneration mechanism. However, on the AEL side, because there is a larger reactive volume of HCO3 -wherein both the AEL and anolyte contain reactive HCO3 -, the mass-transport limitations are less severe for the regeneration of the CO3 2-, suggesting that the BPM-ED system for DOC is more effective for mineralization than for CO2 release.