Revisiting the role of hydrogen peroxide in atmospheric and planetary chemistry: an isotopic perspective

Hydrogen peroxide (H2O2) is a chemically reactive molecule that actively participates in atmospheric and planetary chemistry. The role of H2O2 in atmospheric and planetary evolution in the geological past is however difficult to identify because H2O2 cannot be preserved in sedimentary and meteoritic records. Triple oxygen isotope compositions of secondary aerosols and minerals are powerful proxies for understanding terrestrial and planetary atmospheric chemistry as well as chemical evolution in the solar nebular. This research approach requires a complete understanding of isotope effects in H2O2 chemistry. Here, we carry out experiments to understand kinetics and isotope effects in aqueous H2O2 self-decomposition, a fundamental and important reaction. Based on our experimental results and compiledtriple oxygen isotope data of natural H2O2, ozone, various oxyanions formed in the atmosphere (sulfate, nitrate, and carbonate) and oxygen-bearing secondary minerals in meteorites, we argue that H2O2 chemistry may be essential for the formation and alteration of secondary minerals in our solar system including aerosols, sediments, and meteorites. Our results shed fresh insights into recent debates on the role of H2O2 in the formation of these secondary minerals in the modern Earth, geological past, and other planets.