[ESS] Daniel Ibarra (Brown)

“The role of lithology and the cryosphere on chemical weathering and global carbon fluxes”

The long-held hypothesis that a strong negative feedback exists between chemical weathering of silicate rocks and atmospheric carbon dioxide (CO2) concentrations is complicated by other less thoroughly explored sinks and sources to the long term global carbon cycle. Namely, processes such as sulphuric acid dissolution of carbonates and petrogenic organic carbon oxidation increase atmospheric pCO2, and thus the balance of these competing weathering fluxes dictate the net impact of weathering on atmospheric CO2. While modern river chemistry studies are contending with these complications, deep-time analysis of CO2-producing weathering reactions remains hampered by limited tools. Here we summarize ongoing work investigating the role of lithologic variation, and glaciers and ice sheets, in modifying river chemistry utilizing a suite of isotope system measurements (uranium-series, lithium, strontium), a proxy for organic carbon oxidation (rhenium), dataset compilations, inverse geochemical modeling and reactive transport modeling. This work seeks to disentangle how different processes strengthen or weaken the ability of the terrestrial land surface to consume carbon dioxide and deliver alkalinity to the ocean, with implications for carbon dioxide removal strategies such as enhanced rock weathering.

Earth Science Seminar —

Lecture portion of the EAPS graduate-level class 12.571, covering current research in geophysics, geology, geochemistry, and geobiology. All members of the MIT community are welcome to join for presentations by guest speakers, held approximately every two weeks during the term.

Contact: earth-science-seminar-info@mit.edu