Fig. 3.

The molecular mechanisms proposed to explain the origin of the oxygen isotopic anomaly in atmospheric carbonates. (A). Ozone isotope exchange on existing carbonate aerosols with dissociative adsorption of water and peroxide formation. (B). In situ formation of carbonates and interaction with ozone on particle surfaces. The red circles indicate ozone isotope exchange reaction and probable hydrogen peroxide formation sites. The abbreviations on the side bar are S, solid (MO and MCO₃) such as CaO, MgO, and Fe₂O₃, CaCO₃, MgCO₃; l, liquid or adsorbed-water film; G, gas phase.