NAI
2009 Annual Science Report
VPL at University of Washington
Reporting | JUL 2008 – AUG 2009
Understanding Past Earth Environments
Project Summary
This project examines the evolution of the Earth over time. This year we examined and expanded the geological record of Earth’s history, and ran models to help interpret those data. Models were also used to simulate what the early Earth would look like if viewed remotely through a telescope similar to NASA’s Terrestrial Planet Finder mission concept. We focused our efforts on the Earth as it existed in prior to and during the rise of atmospheric oxygen 2.4 billion years ago, as this was one of the most dramatic and important events in the evolution of the Earth and its inhabitants.
Project Progress
Chemical evolution of the early Earth:
Investigations of early biogeochemical cycling and microbial evolution included nitrogen isotopic studies of latest Archean drill-core which showed that, as a result of a pre-Great Oxidation Event “whiff” of atmospheric oxygen, an aerobic nitrogen cycle including nitrification and denitrification existed well before previously recognized. Because marine nitrification is, as far as we known, overwhelmingly performed by only two groups of microbes on terminal branches of the Tree of Life, this implies that microbial macro-evolution was largely complete by the end of the Archean. (Garvin et al., 2009). Studies of early Archean sediments confirmed the very early evolution of microbial sulfate reduction but failed to find any evidence for sulfur disproportionation (Shen, et al., 2009). Organic geochemistry of earliest Paleoproterozoic oily fluid inclusions showed that biomarker molecules indicated the earlier evolution of oxygenic photosynthesis and eukaryotic organisms (Buick et al., 2009). Thus, three major metabolisms and corresponding redox-sensitive biogeochemical cycles were extant before the atmosphere became permanently oxygenated.
We also contributed to a report of a radical decline in the amount of Ni in Proterozoic oceans, as measured by the amount of nickel precipitated in BIFs. Under low-Ni conditions, methanogens are put at a competitive disadvantage and less methane is emitted into the atmosphere. The Ni decline was attributed to the cooling of the Earth, and is a demonstration a geological influence on biological evolution.
In addition to our work on Archean biogeochemistry, we have also made progress in our ability to measure the atmospheric surface pressure of the Archean.
Modeling Archean Surface Environments:
Model improvements were made to our 1-D photochemical code so that it can simulate the transition from anoxic to oxic conditions; this also allows us to model a wider variety of expolanets. Our climate code has been improved through the addition of new greenhouse gases and particle species. Our atmospheric escape code now includes multiple species (Feng et al., 2008).
Models were used to simulate Archean climate (Haqq-Misra, et al., 2008, Figure 1 below) and produce spectra of Archean-like planets. These spectra included the effects of organic Sulfur species that may be signatures of anoxic biospheres (Domagal-Goldman et al., 2009; see also VPL Project Report on Detectability of Biosignatures).
This figure shows predicted surface temperatures from our climate model (Haqq-Misra et al., 2008) for atmospheres similar to the one thought to have existed on the early (Archean) Earth. These atmospheres are low in O2, but high in the greenhouse gases carbon dioxide (CO2), methane (CH4), and ethane (C2H6). They also have organic hazes that impart a cooling effect on the climate through absorption and reflection of incoming solar radiation. We show predicted surface temperatures (y-axis) for a given CO2 pressure (x-axis) and CH4 concentration (solid lines). The C2H6 and organic haze concentrations are a function of the concentrations of CO2 and CH4, and water concentrations are a function of the temperature of the atmosphere. Also shown on this figure are two dashed lines, representing limits on temperature and CO2 from geological data. Because there are not any known global “snowball Earth” glaciations prior to the rise of O2, the average surface temperature must have been above the freezing point of water (horizontal dashed line). We also have an upper limit on CO2 at various temperatures from paleosol data (diagonal dashed line). According to these interpretations of the rock record, the early Earth should be plotted above and to the left of these two lines; we have no model runs consistent with this scenario. However, the paleosol limit is dependent on the paleolatitude of the samples, which is poorly constrained. We account for this uncertainty by showing the “harder” limit at ~0.03 bars of CO2 (arrow at top of diagram). Our model is consistent with these higher CO2 concentrations, as there are a number of simulations that satisfy both this constraint and that on average surface temperatures.
The NASA Ocean Biogechemical Model (NOBM) was run with cyanobacteria acting as the only photosynthetic group in the oceans. Total primary production decreased about 19% from the standard configuration because cyanobacteria are relatively slow growers compared to modern phytoplankton. The reduced growth led to less efficient uptake, resulting in increases in nitrate and dissolved iron in the surface ocean.
Finally, we have improved our ability to probe the Earth’s oceanic redox history with applied quantum mechanical predictions of Fe isotope fractionation from redox reactions (Domagal-Goldman, et al., 2008 and Domagal-Goldman and Kubicki, 2009).
Publications
-
Buick, R. (2008). When did oxygenic photosynthesis evolve?. Philosophical Transactions of the Royal Society B: Biological Sciences, 363(1504), 2731–2743. doi:10.1098/rstb.2008.0041
-
Domagal-Goldman, S. D., & Kubicki, J. D. (2008). Density functional theory predictions of equilibrium isotope fractionation of iron due to redox changes and organic complexation. Geochimica et Cosmochimica Acta, 72(21), 5201–5216. doi:10.1016/j.gca.2008.05.066
-
Domagal-Goldman, S. D., Paul, K. W., Sparks, D. L., & Kubicki, J. D. (2009). Quantum chemical study of the Fe(III)-desferrioxamine B siderophore complex—Electronic structure, vibrational frequencies, and equilibrium Fe-isotope fractionation. Geochimica et Cosmochimica Acta, 73(1), 1–12. doi:10.1016/j.gca.2008.09.031
-
Garvin, J., Buick, R., Anbar, A. D., Arnold, G. L., & Kaufman, A. J. (2009). Isotopic Evidence for an Aerobic Nitrogen Cycle in the Latest Archean. Science, 323(5917), 1045–1048. doi:10.1126/science.1165675
-
George, S. C., Dutkiewicz, A., Volk, H., Ridley, J., Mossman, D. J., & Buick, R. (2009). Oil-bearing fluid inclusions from the Palaeoproterozoic: A review of biogeochemical results from time-capsules >2.0 Ga old. Science in China Series D: Earth Sciences, 52(1), 1–11. doi:10.1007/s11430-009-0004-4
-
Haqq-Misra, J. D., Domagal-Goldman, S. D., Kasting, P. J., & Kasting, J. F. (2008). A Revised, Hazy Methane Greenhouse for the Archean Earth. Astrobiology, 8(6), 1127–1137. doi:10.1089/ast.2007.0197
-
Konhauser, K. O., Pecoits, E., Lalonde, S. V., Papineau, D., Nisbet, E. G., Barley, M. E., … Kamber, B. S. (2009). Oceanic nickel depletion and a methanogen famine before the Great Oxidation Event. Nature, 458(7239), 750–753. doi:10.1038/nature07858
-
Shen, Y., Farquhar, J., Masterson, A., Kaufman, A. J., & Buick, R. (2009). Evaluating the role of microbial sulfate reduction in the early Archean using quadruple isotope systematics. Earth and Planetary Science Letters, 279(3-4), 383–391. doi:10.1016/j.epsl.2009.01.018
-
Zahnle, K. (2008). Atmospheric chemistry: Her dark materials. Nature, 454(7200), 41–42. doi:10.1038/454041a
- Buick, R. (2008). Earth’s earliest records of life. Mars Science Laboratory 3rd Workshop. Monrovia CA.
- Buick, R. (2008). When did oxygenic photosynthesis evolve – the geological evidence. University of Southern California New Approaches to Deep Time Symposium. Santa Catalina CA.
- Buick, R. (2009). Evidence of early life from drilling in the Pilbara. European Science Foundation Archaean Environment Conference. Mekrijarvi Finland.
- Domagal-Goldman, S.D. (2008). Planetary biosignatures: Back to the future. Seattle, WA.
- Domagal-Goldman, S.D. (2009). Density functional theory and Fe isotope fractionation. Tempe, AZ.
- Domagal-Goldman, S.D. (2009). False positives and false negatives for life on extrasolar planets. Pasadena, CA.
- Domagal-Goldman, S.D. (2009). Quantum astrochemistry: Densitry functional theory in astronomy. Seattle, WA.
- Domagal-Goldman, S.D. (2009). Searching for smelly planets: sulfur gases as anoxic biosignatures. Tempe, AZ.
- Domagal-Goldman, S.D., Kasting, J.F. & Meadows, V.S. (2008). Examining the ability of sulfur-bearing gases to act as biosignatures on anoxic planets. EOS, Transactions of AGU.
- Foriel, J., Stüeken, E.E., Nelson, B.K. & Buick, R. (2009). Selenium biogeochemistry as a deep-time redox proxy. Goldschmidt Conference. Davos Switzerland.
- George, S.C., Dutkiewicz, A., Volk, H., Ridley, J. & Buick, R. (2009). Stability of complex hydrocarbons within fluid inclusions in rocks exposed to high temperatures. Goldschmidt Conference. Davos Switzerland.
-
PROJECT INVESTIGATORS:
-
RELATED OBJECTIVES:
Objective 1.1
Formation and evolution of habitable planets.
Objective 1.2
Indirect and direct astronomical observations of extrasolar habitable planets.
Objective 2.1
Mars exploration.
Objective 4.1
Earth's early biosphere.
Objective 4.2
Production of complex life.
Objective 4.3
Effects of extraterrestrial events upon the biosphere
Objective 5.1
Environment-dependent, molecular evolution in microorganisms
Objective 5.2
Co-evolution of microbial communities
Objective 5.3
Biochemical adaptation to extreme environments
Objective 6.1
Effects of environmental changes on microbial ecosystems
