Hydroperoxides in dew water in downtown Santiago, Chile. A comparison with gas-phase values

Gas phase and dew incorporated concentrations of hydrogen peroxide were measured during late autumn at downtown Santiago, Chile. Dews were collected in non-stabilized and stabilized (HgCl2 rinsed) Teflon collectors. The values measured in both type of collectors were considerably lower than those predicted from gas-phase concentrations and Henryʹs law, suggesting a lack of equilibration between dew droplets and the surrounding air mass. Concentrations of hydrogen peroxide measured in dews collected in stabilized samplers are considerably higher than those measured in non-stabilized samplers. This difference is related to the decomposition of the peroxides in the collected dews. It is proposed that this decomposition is, at least partially, associated to the oxidation of S(IV) by hydrogen peroxide. This is supported by a slower rate of decomposition of externally added hydrogen peroxide after removal of S(IV) compounds from dew matrices.