Precipitation of hydrogen peroxide during winter storms and summer typhoons.

Hydrogen peroxide (H2O2) affects the activity of microbes, including archaea, and thereby influences the biogeochemical cycles of critical elements in marine and terrestrial environments. In this study, we measured the levels of H2O2 associated with three classes of extreme wet precipitation events: winter storms, tropical storms, and typhoons. In conjunction with precipitation data, the measured H2O2 concentration in a seawater reservoir receiving precipitation was used to estimate rainwater H2O2 concentration and flux. The rainwater H2O2 concentration during winter storms and coexisting storms (storms having combined maritime and continental origins) was a factor of 2-3 higher than the levels observed during the typhoons. Fluxes of H2O2 in rainwater of 6 μM min-1 or greater resulted in H2O2 concentrations ~1 μM in the seawater reservoir. During all precipitation events, the H2O2 concentration in the seawater reservoir was dominated by wet precipitation and reached levels greater than would be produced in situ by photochemical processes. During winter and coexisting storms, the rainwater H2O2 concentrations were likely to have been enhanced by atmospheric photochemical reactions probably involving pollutants. An increase in the H2O2 concentration in surface aqueous environments during extreme precipitation events will directly affect the microbial cycling of nitrogen and organic carbon.