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).

Strong and selective isotope effect in the vacuum ultraviolet photodissociation branching ratios of carbon monoxide

“…The underlying mechanism for such isotope effect is general for any indirect predissociation processes 34 , like that in O 2 , N 2 . This could potentially have great impact on the current photochemical models for understanding the various isotope fractionation phenomena observed in the fields of astrochemistry, geochemistry, and planetary atmospheric chemistry 35,36 .…”

Deglacial volcanism and reoxygenation in the aftermath of the Sturtian Snowball Earth

“…Like mercury, sulfur can undergo both MDF (S-MDF) and MIF (S-MIF) (57)(58)(59)(60). S-MIF occurs during gaseous-phase photochemical reactions and often produces Δ 33 S > +0.2‰ or < −0.2‰ (57).…”

“…Volcanic eruptions are known to have played a critical role in climate changes and oceanic anoxia, and the largest climate impacts occur when volcanic eruptions reach the stratosphere (79). The sulfur ejected from stratospheric volcanic eruptions will be exposed to ultraviolet radiation at or above the ozone layer, which induces an S-MIF as observed in polar snow, ice cores, and rock record (60,(80)(81)(82). In contrast, volcanogenic sulfur emitted from tropospheric eruptions is rapidly oxidized to sulfate which is washed out of the atmosphere in the order of weeks (79,83).…”

Lifetimes and decay mechanisms of isotopically substituted ozone above the dissociation threshold: matching quantum and classical dynamics

“…As an example, such studies can provide an insight into the climate in the past, measuring isotope composition of compounds preserved in ancient terrestrial materials, ice and sediment cores. [1][2][3][4][5][6] Oxygen is one of the most abundant elements on the Earth that has three stable isotopes: 16 O, 17 O and 18 O. The origin and abundance of these isotopes could provide information on nuclear processes in nova and supernova stars: [7][8][9][10][11][12] ejected traces of stars were found in unusual isotopic abundance in several-billion-year-old meteorites.…”

“…This particularly concerns the symmetry driving effects, for which additional research is needed. 82 It is now well established [4][5][6] that the ozone MIF is not a minor and exotic phenomenon of a limited impact: its effect is photochemically transferred to many oxygen-bearing species including atmospheric CO 2 , O 2 , and water in the early solar system. 6,91,92 There is a wide area of interdisciplinary scientific fields, including atmospheric physics, geo-and cosmochemistry or climate research, 5,[93][94][95][96][97] where the ozone isotope composition, or molecular effects of isotope fractionation, plays a major role.…”