Dry Deposition of Ozone to Freshwater Lake Surfaces

The reaction of ozone (O₃) with iodide and dissolved organic carbon (DOC) in the sea surface microlayer is a major pathway for O₃ loss from the troposphere. The impact of O₃ dry deposition to freshwater surfaces (e.g., inland lakes) is understudied, where current regional air quality models are unconstrained by experimental measurements of O₃ deposition rates. Since iodide concentrations in lake water are typically negligible, O₃ reactions at these surfaces are likely controlled by the reaction of O₃ with DOC. This study aims to better constrain the reactive loss of O₃ to inland waters by measuring the reactivity of O₃ with samples collected from freshwater lakes in Wisconsin and Michigan. We find that the reactivity of O₃ to lake water is comparable to seawater and suggest that the O₃ dry deposition rate can be parametrized as a function of lake water DOC concentration. Calculated deposition velocities and the resulting O₃ loss rates highlight that dry deposition to freshwater lakes reduces net production of O₃ particularly in shallow boundary layers.