Aqueous geochemical and microbial variation across discrete depth intervals in a peridotite aquifer assessed using a packer system in the Samail Ophiolite, Oman | CU Experts

; The potential for molecular hydrogen (H-OH; -; groundwaters bearing up to 4.05 μmol⋅L; -1; H; 2; , 3.81 μmol⋅L; -1; methane; (CH; 4; ) and 946 μmol⋅L; -1; sulfate; (SO; 4; 2-; ) revealed an ecosystem; dominated by Bacteria affiliated with the class Thermodesulfovibrionia,; a group of chemolithoheterotrophs supported by H; 2; oxidation coupled to SO; 4; 2-; reduction.; In shallower, oxidized; Mg; 2+; -HCO; 3; -; groundwaters, aerobic and denitrifying heterotrophs were relatively more; abundant. High δ; 13; C and δD of CH; 4; (up; to 23.9 ‰ VPDB and 45 ‰ VSMOW , respectively), indicated microbial; CH; 4; oxidation, particularly in; Ca; 2+; -OH; -; waters with evidence of; mixing with; Mg; 2+; -HCO; 3; -; waters.; This study demonstrates the power of spatially resolving groundwaters to; probe their distinct geochemical conditions and chemosynthetic; communities. Such information will help improve predictions of where; microbial activity in fractured rock ecosystems might occur, including; beyond Earth.;

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