The effect of pH on rates of reaction and hydrogen generation during serpentinization
McCollom, Thomas M.
MetadataShow full item record
A series of three laboratory experiments were conducted to investigate how pH affects reaction pathways and rates during serpentinization. Two experiments were conducted under strongly alkaline conditions using olivine as reactant at 200 and 230°C, and the results were compared with previous studies performed using the same reactants and methods at more neutral pH. For both experiments, higher pH resulted in more rapid serpentinization of the olivine and generation of larger amounts of H2 for comparable reaction times. Proportionally greater amounts of Fe were partitioned into brucite and chrysotile and less into magnetite in the experiments conducted at higher pH. In a third experiment, alkaline fluids were injected into an ongoing experiment containing olivine and orthopyroxene to raise the pH from circumneutral to strongly alkaline conditions. Increasing the pH of the olivine-orthopyroxene experiment resulted in an immediate and steep increase in H2 production, and led to far more extensive reaction of the primary minerals compared to a similar experiment conducted under more neutral conditions. The results suggest that the development of strongly alkaline conditions in actively serpentinizing systems promotes increased rates of reaction and H2 production, enhancing the flux of H2 available to support biological activity in these environments.
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in McCollom, T. M., Klein, F., Solheid, P., & Moskowitz, B. The effect of pH on rates of reaction and hydrogen generation during serpentinization. Philosophical Transactions.Series A, Mathematical, Physical, and Engineering Sciences, 378(2165), (2020): 20180428, doi: 10.1098/rsta.2018.0428.
Suggested CitationMcCollom, T. M., Klein, F., Solheid, P., & Moskowitz, B. (2020). The effect of pH on rates of reaction and hydrogen generation during serpentinization. Philosophical Transactions.Series A, Mathematical, Physical, and Engineering Sciences, 378(2165), 20180428.
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Hydrogen generation and iron partitioning during experimental serpentinization of an olivine-pyroxene mixture McCollom, Thomas M.; Klein, Frieder; Moskowitz, Bruce; Berquo, Thelma S.; Bach, Wolfgang; Templeton, Alexis S. (Elsevier, 2020-05-26)A series of laboratory experiments was conducted to investigate serpentinization of olivine–pyroxene mixtures at 230 °C, with the objective of evaluating the effect of mixed compositions on Fe partitioning among product ...
Ultramafic clasts from the South Chamorro serpentine mud volcano reveal a polyphase serpentinization history of the Mariana forearc mantle Kahl, Wolf-Achim; Jons, Niels; Bach, Wolfgang; Klein, Frieder; Alt, Jeffrey C. (2014-11)Serpentine seamounts located on the outer half of the pervasively fractured Mariana forearc provide an excellent window into the forearc devolatilization processes, which can strongly influence the cycling of volatiles ...
Connelly, Douglas P.; German, Christopher R.; Asada, Miho; Okino, K.; Egorov, A.; Naganuma, T.; Pimenov, N.; Cherkashev, G.; Tamaki, K. (American Geophysical Union, 2007-08-28)We report first evidence for hydrothermal activity from the southern Knipovich Ridge, an ultra-slow spreading ridge segment in the Norwegian-Greenland Sea. Evidence comes from optical backscatter anomalies collected during ...