Did biogeochemical methane cycling regulate the Neoarchean atmosphere?

Lead Research Organisation: Newcastle University
Department Name: Civil Engineering and Geosciences

Abstract

Billions of years ago the young planet Earth was much different from the one we inhabit today, with wildly fluctuating temperatures and an atmosphere filled with toxic gases. Understanding how we got from that inhospitable place to the world of today, dominated by mild climates and large oxygen-based life forms, is a fundamental question in Earth sciences. One important transition occurred approximately 2.5 billion years ago (Ga), called the Great Oxidation Event (GOE), when the oxygen concentrations in Earth's atmosphere first increased from near zero to a fraction of modern levels. A major focus of research in natural science is determining how the Earth system (including life) has acted to produce such monumental changes in the environment; however, exactly how and why the GOE occurred remains a mystery.

Integral to understanding the transition to an oxygenated environment on the early Earth are quantitative estimates of the composition of the ancient atmosphere. These estimates are difficult to make using most geochemical tools, which tend to reflect processes that occurred in the marine environment instead. This study proposes to link the four stable isotopes of sulfur, which directly reflect chemical reactions that occurred in the atmosphere, with numerical models tying these geochemical signatures to atmospheric compositions. An additional set of geochemical analyses will allow us to determine the chemistry of the oceans and how the biosphere was acting at the same time. This study is unique in its combination of these multiple techniques, which we will apply to well-preserved sediments deposited directly before the GOE, to determine how the Earth's atmosphere developed during this time, and how the oceans and biosphere both contributed and responded. Understanding the interactions between the atmosphere, oceans, and life is particularly crucial during this time period, as it represents an Earth system poised at the edge of a major transition in global surface chemistry.

We have performed a preliminary set of similar analyses on ~2.65-2.5 Ga sediments that paint a tantalizing picture of an unusual Earth environment directly before the GOE. These analyses point to an atmosphere that was not only very low in oxygen, but was also periodically dominated by a layer of organic particles (termed "haze") produced at high methane levels, similar to that seen on Saturn's moon Titan. We will expand upon the hypotheses developed from these preliminary analyses and explore their significance for the development of Earth surface chemistry and the evolution of life during this critical period in Earth history.

Planned Impact

Beneficiaries and Relevance of Research:

The beneficiaries of this research beyond the scientific community will be the public sector and the general public, through outreach activities planned by the principal investigators. The question of how life evolved on Earth and how the planet became habitable are topics of great interest to the general public, and are amenable to outreach activities that can easily be presented to a broad audience. In turn, this fosters increased interest in and understanding of environmental science by the broader community. In addition, this research focuses on a critical time period in Earth history that is associated with the run-up to one of the most fundamental changes in the surface of our planet, the Great Oxidation Event. An increased understanding of the interactions between the atmosphere, oceans, and biosphere from this time period is critical to recognizing and interpreting the driving forces and response to major environmental change, and as such is of great interest to the general public as well. This work will additionally strengthen the quality and international recognition of research in England by fostering strong international collaborations with North America (the US), and by promoting interdisciplinary research within the environmental sciences (geochemistry and atmospheric chemistry). The post-doctoral researcher and student will receive a wide range of training that will enhance their skills in fields including analytical geochemistry, biogeochemical cycling, atmospheric and biogeochemical modelling, and Earth system history. These are ideal transferable skills to the employment sector, in either the academic realm or in industry, in consideration of global issues related to environmental changes on Earth.

Engagement with Users and Beneficiaries:

The principal investigators plan to highlight their work to the public wherever possible via public talks, popular science articles, and public outreach activities. The researchers involved in this study all have excellent records in this regard, and will continue to build upon this important area of activity. For example, PI Zerkle has contributed to numerous outreach programs aimed at the general public, including Space Day (at Pennsylvania State University) and Maryland Day (at the University of Maryland), and is planning a public exhibit at the Hancock Great North Museum in Newcastle on Earth surface oxygenation. Co-I Poulton gave a keynote lecture on the oxygenation history of the ocean at the 2009 British Science Festival and has given several other public lectures. Co-I Claire has developed planetarium shows for the Pacific Science Center (Seattle, WA) and is a founding member of Blue Marble Space Institute, which has partnered with NASA to bring the Cheltenham Festival's flagship science communication activity - FameLab - to the United States.

In particular, as part of this project we will host two workshops highlighting research on the Precambrian Earth, as discussed in Academic Beneficiaries above. Each of these workshops will entail a public lecture to be delivered by an international guest speaker (PP Farquhar is confirmed for one of these lectures, see letter of support). We are further committed to advertising our findings through the media and through popular articles. We also propose to highlight major outcomes of this proposal, as they are generated, through press releases at Newcastle University and the University of East Anglia. In addition we will engage with colleagues at these workshops and at international and national scientific meetings and foster future scientific development and additional collaborations.

Publications

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Farquhar J (2013) Pathways for Neoarchean pyrite formation constrained by mass-independent sulfur isotopes. in Proceedings of the National Academy of Sciences of the United States of America

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Izon G (2015) Multiple oscillations in Neoarchaean atmospheric chemistry in Earth and Planetary Science Letters

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Izon G (2017) Biological regulation of atmospheric chemistry en route to planetary oxygenation. in Proceedings of the National Academy of Sciences of the United States of America

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Mettam C (2017) High-frequency fluctuations in redox conditions during the latest Permian mass extinction in Palaeogeography, Palaeoclimatology, Palaeoecology

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Meyer NR (2017) Sulphur cycling in a Neoarchaean microbial mat. in Geobiology

Related Projects

Project Reference Relationship Related To Start End Award Value
NE/J023485/1 01/12/2012 31/03/2013 £265,054
NE/J023485/2 Transfer NE/J023485/1 16/05/2013 14/07/2016 £239,455
 
Description See response to NE/J023485/2.
Exploitation Route See response to NE/J023485/2.
Sectors Environment

 
Description Palaeontological Association Undergraduate Research Bursary
Amount £1,200 (GBP)
Funding ID PA-UB201504 
Organisation Palaeontological Association 
Sector Learned Society
Country United Kingdom
Start 06/2015 
End 06/2016
 
Description Postdoctoral and Early Career Researcher Exchanges to North America (to team member PDRA G Izon)
Amount £5,000 (GBP)
Organisation Scottish Alliance for Geoscience, Environment and Society (SAGES) 
Sector Academic/University
Country United Kingdom
Start 09/2014 
End 10/2014
 
Description Leeds 
Organisation University of Leeds
Country United Kingdom 
Sector Academic/University 
PI Contribution We funded two sampling trips to the Pretoria core library for sampling Neoarchean, Paleoproterozoic, and Phanerozoic samples
Collaborator Contribution Use of facilities for sample prep, analyses of carbon and nitrogen isotopes; also several papers in prep from samples we collected together
Impact Zerkle, A. L., Poulton, S. W., Newton, R. J., Bekker, A., and Claire, M. W. (2014) Rapid expansion of the aerobic nitrogen cycle during the Great Oxidation Event: Nature, in revision. Izon, G.*, Zerkle, A. L., Zhelezhinskaya, Y., Farquhar, J., Newton, R. J., Poulton, S. W., Eigenbrode, J. L., and Claire, M. W. (2014) Rapid oscillations in atmospheric chemistry in the prelude to the Great Oxidation Event: EPSL, in review.
Start Year 2010
 
Description NASA Goddard 
Organisation National Aeronautics and Space Administration (NASA)
Department Goddard Space Flight Center
Country United States 
Sector Public 
PI Contribution geochemical analyses (multiple S isotopes, Fe speciation, trace element analyses) of Neoarchean cores
Collaborator Contribution core materials, geological expertise
Impact Izon, G., Zerkle, A. L., Zhelezhinskaya, Y., Farquhar, J., Newton, R. J., Poulton, S. W., Eigenbrode, J. L., and Claire, M. W. (2015) Multiple oscillations in Neoarchean atmospheric chemistry: Earth & Planetary Science Letters 431, 264-273.
Start Year 2013
 
Description UMD 
Organisation University of Maryland, College Park
Country United States 
Sector Academic/University 
PI Contribution We have provided samples and initial bulk rock sulfur isotope data
Collaborator Contribution They have provided SIMS sulfur isotope data and use of Mat253 for multiple sulfur isotope work; this has resulted in one publication and several projects in prep
Impact Farquhar, J., Cliff, J., Zerkle, A. L., Kamyshny, A., Jr., Poulton, S. W., Claire, M. W., Adams, D., and Harms, B. (2013) Pathways for Neoarchen pyrite formation constrained by mass-independent sulfur isotopes: Proceedings of the National Academy of Sciences, 110 (44), 17638-17643. Zerkle, A. L., Claire, M. W., Domagal-Goldman, S. D., Farquhar, J., and Poulton, S. W. (2012) A bistable organic-rich atmosphere on the Neoarchaean Earth: Nature Geoscience 5, 359-363.
Start Year 2010
 
Description WashU 
Organisation Washington University in St Louis
Country United States 
Sector Academic/University 
PI Contribution my undergraduate student visited the SIMS lab to measure multiple sulfur isotopes on Neoarchean microbial mats at the sub-micron scale
Collaborator Contribution they provided the SIMS and technical support
Impact Meyer N, Zerkle AL, and Fike D (in prep) Sub-micron scale sulfur isotopes of Neoarchean MISS (for submission to Geobiology)
Start Year 2015
 
Description Edinburgh Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact In April 2016 I gave a public seminar at the National Museum of Scotland, within the theme "Life in the Extremes" at the Edinburgh Science Festival.
Year(s) Of Engagement Activity 2016
URL http://www.whatsoninedinburgh.co.uk/event/029858-life-in-the-extremes/
 
Description Invited Public Lecture - Edinburgh Geological Society 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact 50 members of the public and professional geologists attended this lecture, which sparked questions and discussion afterwards.
Year(s) Of Engagement Activity 2017
 
Description Invited Public Lecture - St Andrews Open Association 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact 50 members of the local public attended this public lecture, which sparked questions and discussion afterwards.
Year(s) Of Engagement Activity 2017
 
Description Media coverage 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Local press release leading to international media coverage; In the top 5% of all research outputs scored by Altmetric; picked up by 16 news outlets (including the Daily Mail), 2 blogs, 9 tweeters.
Year(s) Of Engagement Activity 2017
URL http://www.dailymail.co.uk/sciencetech/article-4310772/Earth-s-atmosphere-toxic-fog-methane.html