title: The geologic history of seawater pH.
abstract: Although pH is a fundamental property of Earth's oceans, critical to our understanding of seawater biogeochemistry, its long-timescale geologic history is poorly constrained. We constrain seawater pH through time by accounting for the cycles of the major components of seawater. We infer an increase from early Archean pH values between ~6.5 and 7.0 and Phanerozoic values between ~7.5 and 9.0, which was caused by a gradual decrease in atmosphericpCO2in response to solar brightening, alongside a decrease in hydrothermal exchange between seawater and the ocean crust. A lower pH in Earth's early oceans likely affected the kinetics of chemical reactions associated with the origin of life, the energetics of early metabolisms, and climate through the partitioning of CO2between the oceans and atmosphere.
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel. itay.halevy@weizmann.ac.il.
authors.forename: I
authors.identifier: 0000-0002-7325-8139
authors.initials: I
authors.lastname: Halevy
authors.affiliation: School of Earth, Energy and Environmental Science, Stanford University, Stanford, CA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Bachan