Welcome to GeoUnion, the graduate student body of the Department of Earth, Environmental and Planetary Sciences. GeoUnion strives to supplement the overall graduate student experience at Rice and DEEPS. GeoUnion represents DEEPS in the overall Rice grad student community, acts as a liaison between students and faculty and organizes a number of intra- and inter-departmental events throughout the academic year.
GCA: The speciation of carbon, nitrogen, and water in magma oceans and its effect on volatile partitioning between major reservoirs of the Solar System rocky bodies
Damanveer S. Grewal, Rajdeep Dasgupta, Alexandra Farnell
The composition of atmospheres and the resulting potential for planetary habitability in the rocky bodies of our Solar System and beyond is strongly controlled by the volatile exchange between their silicate reservoirs and exospheres. The initial budget and speciation of major volatiles, like carbon (C), nitrogen (N) and water (H2O), in the silicate reservoirs and atmospheres was set during the formation stages of rocky bodies. However, the speciation of these major volatiles in reduced silicate melts prevalent during the differentiation stages of rocky bodies and its effect on the partitioning of volatiles between major rocky body reservoirs is poorly known. Here we present SIMS and vibrational spectroscopy (FTIR and Raman) data, determining C solubility, H content, and speciation of mixed C-O-N-H volatiles in graphite saturated silicate glasses from high P (1–7 GPa)-T (1500–2200 °C) experiments reported in Grewal et al., 2019a, Grewal et al., 2019b. The experiments recorded oxygen fugacity (log fO2) between IW–4.3 and IW–0.8. C-O-N-H speciation varied systematically as function of fO2 at any given P–T. We find out that C-N−, , N2, and OH− are the dominant species in the oxidized range (>IW–1.5), along with some contributions from C-H, N-H, and C-O bearing species. Between IW–3.0 and IW–1.5, C is bonded as C-O either in the form of isolated C-O molecules or Fe-carbonyl complexes, or as C-H in hydrocarbons, or as combination of both in esters, while almost all of the H is bonded with the dominant N species, i.e., NH2− or . At the most reduced conditions (<IW–3.0), C is present mostly in the form of C-H bearing species, while anhydrous N3− followed by N-H bearing molecules are the dominant N bearing species. Magma oceans (MOs) in highly reduced bodies like Mercury would contain most of their C as graphite if MO is carbon saturated and the dissolved C and N would be chemically bonded with the silicate network either in the form of anhydrous C4− and N3−, or hydrogenated C-H and N-H bearing species depending on H content of the silicate melts. MOs relevant for Mars, the Moon, Vesta, and angrite parent body would contain C and N mostly in the form of C-O and N-H bearing species, respectively. If the composition of Earth’s accreting material evolved from reduced to oxidized, then initially a significant amount of the C and N budget would be locked in the silicate reservoirs, which would subsequently be released to the proto-atmosphere(s) at later stages. The retention of proto-atmosphere(s) formed by MO degassing on Earth could have provided important precursors for prebiotic chemistry which possibly led to the eventual habitability of our planet. Additionally, based on the dominant speciation of N versus C in silicate melt as a function of fO2, we also predict that is unaffected by fH2 under highly reduced conditions (<IW–3), while is affected. Therefore, caution must be taken during the application of experimentally determined and to nominally anhydrous MOs.
Grewal, D. S., Dasgupta, R., & Farnell, A. (2020). The speciation of carbon, nitrogen, and water in magma oceans and its effect on volatile partitioning between major reservoirs of the Solar System rocky bodies. Geochimica et Cosmochimica Acta 280: 281-301. doi:10.1016/j.gca.2020.04.023
Original article COVID-19 RESEARCH FUNDS BACK SIX NEW INITIATIVES by MIKE WILLIAMS
Grants to Rice faculty support diagnostic, environmental, social projects
The Rice University COVID-19 Research Fund Oversight and Review Committee announced it will fund six additional projects by faculty working to mitigate the effects of the new coronavirus.
Researchers at Rice, some with the help of off-campus colleagues, plan to develop a device that rapidly identifies high-risk COVID-19 patients; a mobile phone-based test to detect the virus; a project to show how images, narratives and histories shape pandemic response; a study of how COVID-19 response policies impact air quality; a survey of Harris County residents to identify barriers to staying at home; and a study of the environmental impact of COVID-19 in Texas.
Six new projects represent the second round to be backed by the fund; the initial four projects were announced on April 20. The application window has recently closed and additional awards will be announced in the coming weeks, according to the committee led by Marcia O’Malley, the Stanley C. Moore Professor of Mechanical Engineering and a professor of electrical and computer engineering and of computer science. O’Malley is a special adviser to the provost on educational and research initiatives for collaborative health.
The EEPS-led project proposed by Sylvia Dee, Ted Loch-Temzelides, Caroline Masiello and Mark Torres will take advantage of a “crucial but short-lived research window” to evaluate the short-term impacts of rapid environmental mitigation during the coronavirus crisis and how environmental pollution and economic activity affect each other. The crisis, they suggest, provides a glimpse of how Earth’s environment and its climate system might respond to aggressive, fast-paced carbon-mitigation. It also provides an opportunity to assess which sectors of the economy — energy production, the restaurant industry or grocery supply chains — contribute maximally to environmental pollution, given explicit knowledge of closure and shelter-in-place policy timelines.
To aggressively monitor and capture environmental change from several months before the pandemic through the return to business as usual, undergraduate researchers will gather and synthesize data to build a mapping software tool for Texas. Users will be able to zoom in on their home counties and see how COVID-19 policies affected local environmental pollution conditions in real time, in both mapped and graphical visualizations.
Dee and Torres are assistant professors of Earth, environmental and planetary sciences. Loch-Temzelides is the George and Cynthia Mitchell Chair in Sustainable Development and a professor of economics. Masiello is a professor of Earth, environmental and planetary sciences.
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