The Effect of Grain Size on Porewater Radiolysis

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dc.contributor.authorDeWitt, J.
dc.contributor.authorMcMahon, S.
dc.contributor.authorParnell, J.
dc.date.accessioned2023-08-16T15:48:37Z
dc.date.available2023-08-16T15:48:37Z
dc.date.issued2022-05-16
dc.descriptionThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs.en_US
dc.description.abstractThe radiolysis of porewaters by uranium, thorium, and potassium in mineral grains is a recognized source of molecular hydrogen in rock-hosted and sediment-hosted fluids. This radiolytic hydrogen is of geomicrobiological interest as a potential energy source (electron donor) for microbial metabolism, especially in energy-limited settings such as the marine deep biosphere or the subsurface of Mars. Previous efforts to predict the production of radiolytic hydrogen from columns of rock and sediment have tended to rely upon analytic models that cannot account for the attenuation of mineral radiation by grains larger than ∼30 μm. To address this, we have developed a Monte Carlo method to simulate the physics of mineral radiation and evaluate the production of H2 as a function of mineral grain size and radioisotope composition. The results confirm that grain size is a major control on radiolytic H2 yield. For example, using the standard geological classification of grain sizes, we find that clay can produce up to an order of magnitude more H2 per unit time than sand. The magnitude of this effect is illustrated using compositional data from real geological units in order to demonstrate the dependence of radiolytic hydrogen flux on natural radionuclide concentration and bulk porosity.en_US
dc.description.sponsorshipECU Open Access Publishing Support Funden_US
dc.identifier.citationDeWitt, J., McMahon, S., & Parnell, J. (2022). The Effect of Grain Size on Porewater Radiolysis. Earth and Space Science, 9(6), e2021EA002024. https://doi.org/10.1029/2021EA002024en_US
dc.identifier.doi10.1029/2021EA002024
dc.identifier.urihttp://hdl.handle.net/10342/13107
dc.relation.urihttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021EA002024en_US
dc.subjectradiolysisen_US
dc.subjectporewatersen_US
dc.subjectgeomicrobiologicalen_US
dc.subjectmicrobialen_US
dc.subjectradiolytic hydrogenen_US
dc.subjectmarine deep biosphereen_US
dc.titleThe Effect of Grain Size on Porewater Radiolysisen_US
dc.typeArticleen_US
ecu.journal.issue6en_US
ecu.journal.nameEarth and Space Scienceen_US
ecu.journal.pagese2021EA002024en_US
ecu.journal.volume9en_US

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