FOmation and FAte of Mass-Independent Fractionation Signatures – FOFAMIFS

In this project, we propose a multidisciplinary approach to re-examine the sources of MIF in sulfates using an integrated program of novel laboratory experiments, dedicated field studies and innovative multi-scale atmospheric photochemical modeling (including both O- and S-MIF as prognostic variables). First, using the successful isotopic methodology applied to sulfate from polar snow and ice core, we will assess the potential of sulfate leached from volcanic ash as tracers of atmospheric oxidation processes. Second, we plan to carry out a new set of chamber experiments on SO2-related production of S-MIF considering environmental conditions that are as close as possible to those of the stratosphere and of the presupposed Archean atmosphere. Third, for the first time, S-MIF and O-MIF isotope chemistry schemes will be coupled and implemented in models (i.e. a photochemical box/plume model and a global chemistry-transport model).

Recently NASA has identified the resolution of the origin of S-MIF as one of the top priorities for its astrobiology program, recognizing the importance of MIF in solving the epic question of the origin of life and its interaction with the planetary environment. The identification and quantitative understanding of processes involved in creating and transferring MIF anomalies, a prerequisite for extracting the information embedded in isotopic data, would certainly lead to major advances in our comprehension of the geochemical and environmental evolution of our Earth, from its most primitive existence to the present day.
By providing a much more robust basis for quantitative inferences from S-MIF and O-MIF data, the project will yield new constraints on fundamental questions regarding the late oxygenation of the atmosphere, the shift from an anaerobic to aerobic environment for life, and the reconstruction of the impact of volcanic eruptions and human activities on atmospheric oxidizing capacity and climate.

It is foreseen that results of FOFAMIFS will be published in a collection of papers submitted to peer review international journals (e.g. Journal of Geophysical Research, Atmospheric Chemistry and Physics, etc.) following the traditional method of communication in science. Our project will be an education tools for the next generation of scientist. This project will serve as a basic support for young researchers and engineers who will find a state-of-the-art equipment to study and educate them in a multidisciplinary and transnational environment. Climate and environmental changes are at the top list of the preoccupation of the modern societies. We are thus confident that the education they will receive will serve and help the society to find the best ways to mitigate and adapt to the climate change.

Articles
1. Martin E., Bekki, S., Ninin, C. & Bindeman I. (2014). Volcanic sulfate formation in the troposphere. Journal of Geophysical Research. Atmos., 119, 12660–12673, doi 10.1002/2014JD021915
2. Le Gendre, E., Martin, E., Villemant, B., Cartigny, P., Assayag, N., (2017). A simple and reliable anion-exchange resin method for sulfate extraction and purification suitable for multiple O- and S-isotope measurements: Anion-exchange method for multiple O- and S-isotope analysis. Rapid Commun. Mass Spectrom. 31, 137–144. doi:10.1002/rcm.7771
3. Au Yang D, Landais G, Assayag N, Widory D, Cartigny P. (2016) Improved analysis of sulfur multi-isotope compositions at micro and nanomole levels by gas source isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry 30, 897–907, doi 10.1002/rcm.7513

The discovery of the mass-independent isotopic fractionations of sulfur and oxygen (S-MIF and O-MIF) has revolutionized the way fundamental geochemical questions are addressed and have produced one of the most iconic figures in geosciences, i.e. the presence of S-MIF in rocks older than 2.3 billion years and its sudden quasi disappearance thereafter. Regarding O-MIF, the majority of the anomalies observed on Earth originate from the ozone anomaly transferred to oxygen-bearing molecules. Although there are still uncertainties pertaining to the mechanisms of O-MIF transfers, they tend to pale into insignificance when compared to those on the exact processes creating S-MIF. There is now no general consensus on the origin of S-MIF in the atmosphere and all the proposed mechanisms are still highly debated in geosciences.

Recently NASA has identified the resolution of the origin of S-MIF as one of the top priorities for its astrobiology program, recognizing the importance of MIF in solving the epic question of the origin of life and its interaction with the planetary environment. The identification and quantitative understanding of processes involved in creating and transferring MIF anomalies, a prerequisite for extracting the information embedded in isotopic data, would certainly lead to major advances in our comprehension of the geochemical and environmental evolution of our Earth, from its most primitive existence to the present day.

In this project, we propose a multidisciplinary approach to re-examine the sources of MIF in sulfates using an integrated program of novel laboratory experiments, dedicated field studies and innovative multi-scale atmospheric photochemical modeling (including both O- and S-MIF as prognostic variables). First, using the successful isotopic methodology applied to sulfate from polar snow and ice core, we will assess the potential of sulfate leached from volcanic ash as tracers of atmospheric oxidation processes. Second, we plan to carry out a new set of chamber experiments on SO2-related production of S-MIF considering environmental conditions that are as close as possible to those of the stratosphere and of the presupposed Archean atmosphere. Third, for the first time, S-MIF and O-MIF isotope chemistry schemes will be coupled and implemented in models (i.e. a photochemical box/plume model and a global chemistry-transport model). As O-MIF has already largely demonstrated its capacity to probe sulfur oxidation mechanisms in the atmosphere, combining O-MIF and S-MIF analysis should represent a powerful approach to constrain better inferences on the origin of S-MIF. One of the aims is to improve our quantitative understanding of oxidation processes of volcanic and anthropogenic sulfur, and of the resulting production of aerosols. We will also assess the potential of this innovative approach for probing atmospheric chemistry in the distant past.

Overall, by providing a much more robust basis for quantitative inferences from S-MIF and O-MIF data, the project will yield new constraints on fundamental questions regarding the late oxygenation of the atmosphere, the shift from an anaerobic to aerobic environment for life, and the reconstruction of the impact of volcanic eruptions and human activities on atmospheric oxidizing capacity and climate.