Monday,
October 14, 2024
6:00 - 7:30 pm
For those attending in-person this meeting
will be held at the following location:
Pellissippi State Community College
Room location is TBD
Note: ETGS members participating virtually will receive an email with info for attending/logging into the meeting.
October Presentation
Pyrite Oxidation in Rocks: From Atomic Observation to Global Implications
By
Xin Gu
Geochemist
Oak Ridge National Laboratory (ORNL)
Abstract
Pyrite oxidation is a crucial
reaction influencing geochemical cycles of iron, sulfur, carbon, and
oxygen. To interpret pyrite oxidation throughout Earth's geologic
history, we must first understand the current controls on its
oxidation rate. We propose a model for pyrite oxidation across
various scales: grain, clast, borehole, and watershed. At the atomic
scale, the oxidation rate is limited by the interfacial reaction
between oxygen and sulfide. At the pyrite grain scale, evidence
suggests that oxygen diffusion to the oxidation front limits the
rate. At the pedon scale, diffusion is constrained by fracture
formation rates. Finally, at the borehole scale, the rate at which
oxygenated water reaches unoxidized pyrite at depth is limited by
the erosive removal of overlying soil and weathered rock. Thus, as
the scale of observation increases, the rate-limiting step for
pyrite oxidation transitions from chemical reaction → diffusion →
fracturing → erosion.
Biography
Xin Gu is a broadly trained critical zone scientist with degrees in
Environmental Engineering (B.E., Tsinghua University), Forest
Resources (M.S., Penn State University), and Geosciences and
Biogeochemistry (Ph.D., Penn State University). From 2018 to 2021,
he worked at the Earth and Environmental Systems Institute at Penn
State as a PostDoc and later as an Assistant Research Professor.
Since 2021, he has been an experimental geochemist in the
Environmental Division at Oak Ridge National Laboratory. His
research focuses on how geochemical reactions at pore scales drive
macroscopic processes such as chemical weathering, watershed
hydrology, and landscape evolution.
Greetings, and welcome to the October 14, 2024 ETGS virtual meeting.
If you attend via Zoom as a courtesy please mute your cell phone or the microphone in your laptop/tablet to minimize background noise and feedback echos. We will also make an effort to mute all participants - at least until the presentation is finished. Please use the chat feature to type any comments or questions you may have. We recommend that you send questions for the speaker to "everyone" so all participants can see the question. In the interest of time, we may hold the Q&A at the end of the presentation.
We will create an in-person and virtual attendance list. It is not always possible
to tell who is participating on-line, especially for those joining by phone,
so please email
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to be listed on the attendance sheet. Let us know exactly how your
name should appear on the list. We will add a note explaining the
lack of signatures due to remote participation and have an ETGS officer sign as usual.
Thank you for your patience and understanding as we try this online
format. As always, we welcome and appreciate your feedback and
suggestions for improvement.
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Tennessee and beyond. Please email us at
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J.
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