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Biogenic H2 accumulates in permeable sediments in situ
a, Pore-water concentrations of H2 in subtidal sediment cores sliced every 2 cm. The centre values show mean concentrations and the error bars show standard deviations from three separate cores. b, Concentration and isotopic composition of H2 from water samples overlying subtidal sediments. Samples were collected over an 11 h time course, including low tide (10:30) and high tide (16:00). c, A Keeling plot showing the isotopic composition (δ²H) of the H2 source in the water column. Data are from the time course from b, with an outlying value (9:00) excluded. The line was fitted by linear regression (ordinary least squares fit) and extrapolated (dashed lines) to the y intercept (−762.4 ± 18.8‰). R² values are based on the Pearson correlation coefficient.

Biogenic H2 accumulates in permeable sediments in situ a, Pore-water concentrations of H2 in subtidal sediment cores sliced every 2 cm. The centre values show mean concentrations and the error bars show standard deviations from three separate cores. b, Concentration and isotopic composition of H2 from water samples overlying subtidal sediments. Samples were collected over an 11 h time course, including low tide (10:30) and high tide (16:00). c, A Keeling plot showing the isotopic composition (δ²H) of the H2 source in the water column. Data are from the time course from b, with an outlying value (9:00) excluded. The line was fitted by linear regression (ordinary least squares fit) and extrapolated (dashed lines) to the y intercept (−762.4 ± 18.8‰). R² values are based on the Pearson correlation coefficient.

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Permeable (sandy) sediments cover half of the continental margin and are major regulators of oceanic carbon cycling. The microbial communities within these highly dynamic sediments frequently shift between oxic and anoxic states, and hence are less stratified than those in cohesive (muddy) sediments. A major question is, therefore, how these commun...

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... Hydrogen metabolism is crucial in energy cycling in marine environments [53]. Gemmatimonadota, except for Group 1, have different types of [NiFe] hydrogenases ( Supplementary Fig. 15) and few [FeFe] hydrogenases (mainly in Group 2) (Supplementary Fig. 16), suggesting hydrogen is coupled to metabolic pathways in these bacteria [54,55]. ...
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