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.