A Sulfur Dioxide Climate Feedback on Early Mars

Halevy, Itay; Zuber, M. T.; Schrag, Daniel P.

doi:10.1126/science.1147039

Cited by 176 publications

(199 citation statements)

References 38 publications

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“…However, such levels of methane would require a methane source exceeding that of the modern terrestrial biosphere because methane is destroyed relatively rapidly in geologic time by ultraviolet photolysis and oxidation. Others have proposed that volcanic SO 2 , which is also a greenhouse gas, could have warmed Mars' early climate (Halevy et al 2007;Johnson et al , 2009Postawko and Kuhn 1986). However, the photochemistry of SO 2 rapidly produces sulfate aerosols (even in reducing atmospheres), and sulfate aerosols reflect sunlight efficiently, producing a net global cooling (Tian et al 2010).…”

Section: Warm/wet Environmentsmentioning

confidence: 99%

“…Indeed, based on the abundance and character of sulfur on Mars, it is possible that it has played the same role as carbon plays in the weathering process on the Earth (Halevy et al 2007). Among the possible acidic gases of geological origin, SO 3 is the most soluble and has the lowest acidity constant, its aqueous form being sulfuric acid.…”

Section: Acid Vs Alkalinementioning

confidence: 99%

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Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Niles¹,

Catling²,

Berger³

et al. 2012

Quantifying the Martian Geochemical Reservoirs

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Ongoing research on martian meteorites and a new set of observations of carbonate minerals provided by an unprecedented series of robotic missions to Mars in the past 15 years help define new constraints on the history of martian climate with important cross- cutting themes including: the CO 2 budget of Mars, the role of Mg-, Fe-rich fluids on Mars, and the interplay between carbonate formation and acidity.Carbonate minerals have now been identified in a wide range of localities on Mars as well as in several martian meteorites. The martian meteorites contain carbonates in low abundances (<1 vol.%) and with a wide range of chemistries. Carbonates have also been identified by remote sensing instruments on orbiting spacecraft in several surface locations as well as in low concentrations (2-5 wt.%) in the martian dust. The Spirit rover also identified an outcrop with 16 to 34 wt.% carbonate material in the Columbia Hills of Gusev Crater that strongly resembled the composition of carbonate found in martian meteorite ALH 84001. Finally, the Phoenix lander identified concentrations of 3-6 wt.% carbonate in the soils of the northern plains.The carbonates discovered to date do not clearly indicate the past presence of a dense Noachian atmosphere, but instead suggest localized hydrothermal aqueous environments with limited water availability that existed primarily in the early to mid-Noachian followed by low levels of carbonate formation from thin films of transient water from the late Noachian to the present. The prevalence of carbonate along with evidence for active carbonate precipitation suggests that a global acidic chemistry is unlikely and a more complex relationship between acidity and carbonate formation is present.

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Section: Warm/wet Environmentsmentioning

confidence: 99%

Section: Acid Vs Alkalinementioning

confidence: 99%

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Niles¹,

Catling²,

Berger³

et al. 2012

Quantifying the Martian Geochemical Reservoirs

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“…More sulfates would form later in Mars' history as older sulfites were exposed to the oxidizing atmosphere. Aqueous oxidation of sulfites to sulfates [Halevy et al, 2007] and ferrous to ferric iron [Chevrier et al, 2006;Tosca et al, 2008b] where siderite co-precipitated with sulfites, whether in situ as the water table fluctuated [McLennan et al, 2005;Grotzinger et al, 2005] or during aqueous transport by oxidizing solutions, would have released acidity, caused dissolution or leaching of coexisting phyllosilicates and left deposits of sulfates, Fe-oxides and hydrated silica. The most soluble cations would perhaps form chloride minerals.…”

Section: Discussionmentioning

confidence: 99%

“…This mineral, hannebachite (CaSO 3 Â 1 2 H 2 O), is $90 times more soluble than the least soluble calcium carbonate (calcite), but SO 2 is much more soluble than CO 2 and a much stronger acid (Table 1). Accounting for this, thermodynamics predict that at ratios of the partial pressure of SO 2 to CO 2 (pSO 2 :pCO 2 ) as low as 5.3 Â 10 À8 hannebachite saturates at Ca 2+ concentrations lower than those required for calcite saturation [Halevy et al, 2007]. This means that $50 parts-per-billion (ppb) SO 2 in 1 bar of CO 2 , for example, are enough to prevent calcite from precipitating, not due to acidification of the water, but because hannebachite precipitation buffers the Ca 2+ concentration at values too low for saturation and precipitation of calcite.…”

Section: Introductionmentioning

confidence: 99%

“…Recent photochemical studies indicate that during episodes of vigorous volcanic activity, the atmospheric lifetime of SO 2 may have been sufficiently long for it to have helped maintain liquid water on the surface of Mars [Johnson et al, 2008;Halevy et al, 2007; S. S. Johnson et al, The fate of SO 2 in the ancient Martian atmosphere: Implications for transient greenhouse warming, submitted to Journal of Geophysical Research, 2009] and perhaps to have regulated the climate through a negative feedback between the atmospheric abundance of SO 2 and the rate of chemical weathering of silicate minerals [Halevy et al, 2007]. Like CO 2 , SO 2 is a weak diprotic acid (sulfurous acid or H 2 SO 3 ) whose conjugate base, sulfite (SO 3 2À ), can form a mineral with calcium.…”

Section: Introductionmentioning

confidence: 99%

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Sulfur dioxide inhibits calcium carbonate precipitation: Implications for early Mars and Earth

Halevy¹,

Schrag²

2009

Geophysical Research Letters

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[1] Recent studies have suggested a role for sulfur dioxide (SO 2 ) in maintaining relatively warm surface temperatures on early Mars. Here we show experimentally, that SO 2 concentrations orders of magnitude lower than those required for it to have been of climatic importance strongly affect the aqueous chemistry and the precipitated mineral assemblage. At near-neutral pH, part-per-billion concentrations of SO 2 prevent the formation of calcium carbonate in favor of hannebachite, a hydrated calcium sulfite. In the presence of iron, possible precursors to phyllosilicate minerals and iron carbonate co-precipitate with hannebachite. This provides an explanation for the existence of early Noachian phyllosilicates in the apparent dearth of outcrop-scale calcium carbonates. Oxidation of this precipitated assemblage produces sulfates, iron oxides and acidity, consistent with evidence for late Noachian -early Hesperian acid-sulfate dominated environments. For early Earth, the results allow placing an upper limit on atmospheric SO 2 concentrations for any period in which carbonates exist in the geologic record.

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Sulfur-bearing phases detected by evolved gas analysis of the Rocknest aeolian deposit, Gale Crater, Mars

McAdam

Franz

Sutter

et al. 2014

J. Geophys. Res. Planets

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The Sample Analysis at Mars (SAM) instrument suite detected SO 2 , H 2 S, OCS, and CS 2 from~450 to 800°C during evolved gas analysis (EGA) of materials from the Rocknest aeolian deposit in Gale Crater, Mars. This was the first detection of evolved sulfur species from a Martian surface sample during in situ EGA. SO 2 (~3-22 μmol) is consistent with the thermal decomposition of Fe sulfates or Ca sulfites, or evolution/desorption from sulfur-bearing amorphous phases. Reactions between reduced sulfur phases such as sulfides and evolved O 2 or H 2 O in the SAM oven are another candidate SO 2 source. H 2 S (~41-109 nmol) is consistent with interactions of H 2 O, H 2 and/or HCl with reduced sulfur phases and/or SO 2 in the SAM oven. OCS (~1-5 nmol) and CS 2 (~0.2-1 nmol) are likely derived from reactions between carbon-bearing compounds and reduced sulfur. Sulfates and sulfites indicate some aqueous interactions, although not necessarily at the Rocknest site; Fe sulfates imply interaction with acid solutions whereas Ca sulfites can form from acidic to near-neutral solutions. Sulfides in the Rocknest materials suggest input from materials originally deposited in a reducing environment or from detrital sulfides from an igneous source. The presence of sulfides also suggests that the materials have not been extensively altered by oxidative aqueous weathering. The possibility of both reduced and oxidized sulfur compounds in the deposit indicates a nonequilibrium assemblage. Understanding the sulfur mineralogy in Rocknest materials, which exhibit chemical similarities to basaltic fines analyzed elsewhere on Mars, can provide insight in to the origin and alteration history of Martian surface materials.

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A Sulfur Dioxide Climate Feedback on Early Mars

Cited by 176 publications

References 38 publications

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Geochemistry of Carbonates on Mars: Implications for Climate History and Nature of Aqueous Environments

Sulfur dioxide inhibits calcium carbonate precipitation: Implications for early Mars and Earth

Sulfur-bearing phases detected by evolved gas analysis of the Rocknest aeolian deposit, Gale Crater, Mars

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