Use of Isotope Effects To Understand the Present and Past of the Atmosphere and Climate and Track the Origin of Life

Abstract

Stable isotope ratio measurements have been used as a measure of a wide variety of processes, including solar system evolution, geological formational temperatures, tracking of atmospheric gas and aerosol chemical transformation, and is the only means by which past global temperatures may be determined over long time scales. Conventionally, isotope effects derive from differences of isotopically substituted molecules in isotope vibrational energy, bond strength, velocity, gravity, and evaporation/condensation. The variations in isotope ratio, such as 18O/16O (δ18O) and 17O/16O (δ17O) are dependent upon mass differences with δ17O/δ18O=0.5, due to the relative mass differences (1 amu vs. 2 amu). Relations that do not follow this are termed mass independent and are the focus of this Minireview. In chemical reactions such as ozone formation, a δ17O/δ18O=1 is observed. Physical chemical models capture most parameters but differ in basic approach and are reviewed. The mass independent effect is observed in atmospheric species and used to track their chemistry at the modern and ancient Earth, Mars, and the early solar system (meteorites).

Large mass-independent sulphur isotope anomalies link stratospheric volcanism to the Late Ordovician mass extinction

“…4). Though the exact underlying mechanisms to produce the S-MIF are debated, all the Archean-early Paleoproterozoic and modern stratospheric volcanic sulphate data with large Δ 33 S anomalies have been ultimately linked to photochemical reactions [16][17][18][19][20]28,[44][45][46][47] . There is little reason to assume that this would not be the case for our Late Ordovician S-MIF.…”

“…17,19,45,46 , and the rock record data (grey circles) are compiled from refs. 27,28,30,31,44,47 . GOE: Great Oxidation Event.…”

“…The Archean-early Paleoproterozoic rock record (filled grey circles) are compiled from refs. 27,28,30,31,44,47 , and the polar record from ice core and snow pits (filled blue circles) are from refs. [16][17][18]45,46,49 .…”

Fe isotope composition of Archean sulfides do not record progressive oxygenation of the ocean

“…Indeed, Archean sulfate and sulfides from sediments older than 2.45 Ga display S-MIF up to 10 ‰ (see Ono, 2017, for a review), while sulfates and sulfides from younger sedimentary rocks have close to 0‰ S-MIF. The consensual mechanism for producing the S-MIF in sulfur isotopes is photochemical dissociation of volcanic SO 2 in an anoxic atmosphere (Farquhar et al, 2000;Thiemens et Lin, 2019) with O 2 levels below 10 −5 × the present atmospheric level (PAL), though alternative views exist (see Oduro et al, 2011). In the past decades, numerous studies have documented in detail the timing of, extent of, and processes responsible for the GOE (Claire et al, 2006;Halevy, 2013;Zahnle et al 2013;Lyons et al, 2014;Luo et al, 2016).…”

In Situ Fe and S isotope analyses in pyrite from the 3.2 Ga Mendon Formation (Barberton Greenstone Belt, South Africa): Evidence for early microbial iron reduction

“…Photochemical reactions of dissociation of volcanic SO 2 in an anoxic atmosphere can produce both elemental sulfur and sulfate aerosols with positive and negative Δ 33 S values, respectively. Although alternative views exist (Oduro et al, ), it is generally acknowledged that O 2 levels below 10 –5 present atmospheric level (PAL) are critical for the production and preservation of S‐MIF in the geological record (Farquhar et al, ; Harman, Pavlov, Babikov, & Kasting, ; Thiemens & Lin, ; Ueno, Ono, Rumble, & Maruyama, ; Zhelezinskaia, Kaufman, Farquhar, & Cliff, ). Both photochemical experiments and studies of sedimentary sulfides and sulfate have then confirmed that Archean sulfate has negative Δ 33 S values while elementary sulfur has positive Δ 33 S values (Endo, Danielache, & Ueno, ; Farquhar et al, ; Farquhar, Wu, Canfield, & Oduro, ; Halevy, ; Harman et al, ; Muller et al, ; Ueno et al, ; Zhelezinskaia et al, ).…”