Thermodynamics of heterogeneous iron—Carbon systems: Implications for the terrestrial primitive reducing atmosphere

An iron shuttle for deepwater silica in Late Archean and early Paleoproterozoic iron formation

“…Finally, the discovery of anoxygenic photosynthesis with iron as a primary electron donor (Widdel et al, 1993;Ehrenreich and Widdel, 1994) gave concrete support to previous ideas that the biological oxidation of iron might occur in the absence of molecular oxygen, requiring only photocatalysis (equation 4) (Garrels et al, 1973;Baur, 1978;Hartman, 1984;Walker, 1987):…”

Rates of fixation by lightning of carbon and nitrogen in possible primitive atmospheres

“…Although laboratory experiments by Bar Nun et al [22] in hydrocarbon-rich environments suggest that electrical discharges are more efficient than ultraviolet radiation, detailed photochemical models are needed, to concretely establish this fact. In a CO 2 atmosphere, organic material may have been formed from photoactivated reactions, such as the reduction of CO2 by ferrous ion in the primitive ocean and various heterogeneous reactions recently identified in laboratory studies [23][24][25][26][27][28]. Whether these latter processes could have been adequate sources of organic molecules depends upon their kinetic characteristics, which have yet to be established.…”

Iron Formations: Their Origins and Implications for Ancient Seawater Chemistry

“…Anoxygenic photosynthetic oxidation -photoferrotrophyis another metabolic Fe(II) oxidation pathway. This pathway was predicted to be common on early Earth and linked to IF deposition (e.g., Baur, 1979;Hartman, 1984) before organisms capable of this metabolism were first cultured in the early 1990s (Widdel et al, 1993). Since then, a variety of phylogenetically diverse strains of anoxygenic Fe(II)-oxidizing phototrophs have been recognized, including strains of purple sulfur, and purple nonsulfur and green sulfur bacteria.…”