Coastal-plain paleosols in the 3.0 Ga Farrel Quartzite of Western Australia have organic surface (A horizon) and sulfate-rich subsurface (By) horizons, like soils of the Atacama Desert of Chile, Dry Valleys of Antarctica, and 3.7 Ga paleosols of Mars. Farrel Quartzite paleosols include previously described microfossils, permineralized by silica in a way comparable with the Devonian Rhynie Chert, a well known permineralized Histosol. Five microfossil morphotypes in the Farrel Quartzite include a variety of spheroidal cells (Archaeosphaeroides) as well as distinctive large spindles (new genus provisionally assigned to cf. Eopoikilofusa). Previously published cell-specific carbon isotopic analyses of the Farrel Quartzite microfossils, and unusually abundant sulfate considering a likely anoxic atmosphere, allow interpretation of these morphotypes as a terrestrial community of actinobacteria, purple sulfur bacteria, and methanogenic Archaea. Graphical abstract. (see figure) 1 Research highlights  There are coastal-plain paleosols in 3.0 Ga Farrel Quartzite, Western Australia  Paleosols have organic surface (A) and sulfate-rich subsurface (By) horizon. Comparable profiles are known from deserts of Chile, Antarctica, and Mars. Microfossils in paleosols included actinobacteria, sulfur bacteria, methanogens.

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Bipolar membranes (BPMs) can generate steadystate pH gradients in electrochemical cells, enabling halfreactions to occur in different pH environments, and are thus of broad interest. Forward-bias BPMs further enable new approaches to fuel cells, redox-flow batteries, and CO 2 electrolyzers. In forward bias, the gradient in electrochemical potential drives ionic charge carriers toward the bipolar junction where they can recombine. We use a H 2 -pump electrochemical cell to study H + /OH − recombination at the bipolar junction. We discover that metal-oxide nanoparticles catalyze the recombination reaction in the bipolar junction under forward bias and find evidence that H + /OH − recombination occurs via a surface mechanism on the oxide catalyst. We propose a rate equation to describe the catalytic H + /OH − recombination mechanism, supported by numerical simulations. This work thus elucidates materials-design strategies for recombination catalysts to advance forward-bias BPM technologies.

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