Mass‐independent sulfur isotopic compositions in present‐day sulfate aerosols

Romero, A.; Thiemens, M. H.

doi:10.1029/2003jd003660

Cited by 82 publications

(131 citation statements)

References 34 publications

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“…3), the potential exists for preservation of S MIF very close to the primary atmospheric value. If, as in some atmospheric models (e.g., cases B and C), the fractional deposition of SO 2 is small, then this SO 2 will carry large magnitudes of Δ 33 S to the surface, again as a result of the constraints of isotopic mass balance in the S MIFforming reactions. Conversely, high fractional deposition of SO 2 will lead to lower Δ 33 S magnitudes in this SO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…Sulfur isotope mass-independent fractionation (S MIF) is defined as a departure from these theoretically derived and empirically observed mass laws, and denoted Δ 33 S and Δ 36 S. S MIF is observed in modern atmospheric sulfate aerosols, as well as in sulfate-bearing layers hosted in glacial ice (2,3), but is conspicuously absent from the sedimentary record of the last 2,400 My. In contrast, older rocks of the Archean and early Paleoproterozoic eons preserve large and variable S MIF (4,5).…”

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confidence: 99%

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Production, preservation, and biological processing of mass-independent sulfur isotope fractionation in the Archean surface environment

Halevy

2013

Proc. Natl. Acad. Sci. U.S.A.

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Mass-independent fractionation of sulfur isotopes (S MIF) in Archean and Paleoproterozoic rocks provides strong evidence for an anoxic atmosphere before ∼2,400 Ma. However, the origin of this isotopic anomaly remains unclear, as does the identity of the molecules that carried it from the atmosphere to Earth's surface. Irrespective of the origin of S MIF, processes in the biogeochemical sulfur cycle modify the primary signal and strongly influence the S MIF preserved and observed in the geological record. Here, a detailed model of the marine sulfur cycle is used to propagate and distribute atmospherically derived S MIF from its delivery to the ocean to its preservation in the sediment. Bulk pyrite in most sediments carries weak S MIF because of microbial reduction of most sulfur compounds to form isotopically homogeneous sulfide. Locally, differential incorporation of sulfur compounds into pyrite leads to preservation of S MIF, which is predicted to be most highly variable in nonmarine and shallow-water settings. The Archean ocean is efficient in diluting primary atmospheric S MIF in the marine pools of sulfate and elemental sulfur with inputs from SO 2 and H 2 S, respectively. Preservation of S MIF with the observed range of magnitudes requires the S MIF production mechanism to be moderately fractionating ( ± 20-40‰). Constraints from the marine sulfur cycle allow that either elemental sulfur or organosulfur compounds (or both) carried S MIF to the surface, with opposite sign to S MIF in SO 2 and H 2 SO 4 . Optimal progress requires observations from nonmarine and shallow-water environments and experimental constraints on the reaction of photoexcited SO 2 with atmospheric hydrocarbons.W ith few exceptions, the enrichment or depletion of the rare, stable isotopes of sulfur ( 33 S, 34 S, and 36 S) relative to the abundant isotope ( 32 S) scale as the mass difference between the isotopes (1). Sulfur isotope mass-independent fractionation (S MIF) is defined as a departure from these theoretically derived and empirically observed mass laws, and denoted Δ 33 S and Δ 36 S. S MIF is observed in modern atmospheric sulfate aerosols, as well as in sulfate-bearing layers hosted in glacial ice (2, 3), but is conspicuously absent from the sedimentary record of the last 2,400 My. In contrast, older rocks of the Archean and early Paleoproterozoic eons preserve large and variable S MIF (4, 5). On the basis of experimental SO 2 photolysis and atmospheric chemistry models, the prevailing hypothesis to explain this observation is that the absence of atmospheric oxygen before ∼2,400 Ma allowed both the photochemical production of S MIF and its delivery to the surface in the reduced and oxidized products of sulfur photochemistry (4-7). Thus, S MIF is considered strong geochemical evidence for an anoxic atmosphere before ∼2,400 Ma.Although research converges on atmospheric processes as the source of S MIF, its production mechanism and the identity of its vectors to the surface remain unclear. A focus on photolysis experiments and meas...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Production, preservation, and biological processing of mass-independent sulfur isotope fractionation in the Archean surface environment

Halevy

2013

Proc. Natl. Acad. Sci. U.S.A.

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“…In the present atmosphere, short UV is blocked by the O 3 layer; thus, the negative anomaly in tropospheric sulfate aerosol cannot be attributed to short-wavelength SO x photolysis. Romero and Thiemens (15) suggested possible transport of stratospheric S-isotope anomaly to the troposphere at low and mid latitudes. Considering the tropospheric S burden (16) (SO 2 from fossil-fuel combustion ∼ 78 Tg S·yr −1 , biomass burning ∼ 2 Tg S·yr −1 , and natural sources ∼ 25 Tg S·yr −1 ), it is unlikely that even a 10% transport of SSA (0.01 Tg S·yr −1 ) can produce such a significant isotopic change in tropospheric sulfate aerosols.…”

Section: Significancementioning

confidence: 99%

Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

Shaheen

Abaunza

Jackson

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Significance The highest S-isotope anomaly is observed in a nonvolcanic period, and the magnitude of anomaly is similar to the largest volcanic eruptions of the 20th century. S-quadruple isotope data provided the first evidence of how super El Niño Southern Oscillation (ENSO) events (1997–1998) have affected the transport and transformation of aerosols to the stratosphere; thus, record of paleo-ENSO events of this magnitude can be traced with the S-isotopic anomaly. High-resolution and high-precision S-isotopic fingerprinting also revealed that the tropospheric sulfate produced during fossil-fuel and biomass burning contributes to the stratospheric sulfate aerosol layer, a contribution previously unrecognized. The distribution of sulfur anomalies mimics the Archean isotope record, which is used to track the origin and evolution of oxygen on earth.

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“…KIE that have been suggested to be mass-independent include those associated with surface reaction effects [Lasaga et al, 2008], spin coupling (magnetic isotope effects (MIE)) [Buchachenko, 2000], symmetry [Gao and Marcus, 2001], self-shielding [e.g., Lyons 2008], or chance vibronic overlap of excited Romero and Thiemens [2003].…”

Section: Mechanisms For Producing Mass-independent Sulfur Isotope Anomentioning

confidence: 99%

“…For instance, Romero and Thiemens [2003] measured multiple sulfur isotope compositions in the present atmosphere from samples of North Hemisphere aerosol sulfate and found mass-independent sulfur isotope anomalies, which they attributed to stratospheric input of sulfate produced from photochemical reactions. It has been suggested that UV photooxidation in the stratosphere can leave a characteristic D…”

Section: Introductionmentioning

confidence: 99%

Identification of sources and formation processes of atmospheric sulfate by sulfur isotope and scanning electron microscope measurements

et al. 2010

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[1] Atmospheric sulfate aerosols have a cooling effect on the Earth's surface and can change cloud microphysics and precipitation. China has heavy loading of sulfate, but their sources and formation processes remain uncertain. In this study we characterize possible sources and formation processes of atmospheric sulfate by analyzing sulfur isotope abundances ( 32 S, 33 S, 34 S, and 36 S) and by detailed X-ray diffraction and scanning electron microscope (SEM) imaging of aerosol samples acquired at a rural site in northern China from March to August 2005. The comparison of SEM images from coal fly ash and the atmospheric aerosols suggests that direct emission from coal combustion is a substantial source of primary atmospheric sulfate in the form of CaSO 4 . Airborne gypsum (CaSO 4 ·2H 2 O) is usually attributed to eolian dust or atmospheric reactions with H 2 SO 4 . SEM imaging also reveals mineral particles with soot aggregates adhered to the surface where they could decrease the single scattering albedo of these aerosols. In summer months, heterogeneous oxidation of SO 2 , derived from coal combustion, appears to be the dominant source of atmospheric sulfate. Our analyses of aerosol sulfate show a seasonal variation in D 33 S (D 33 S describes either a 33 S excess or depletion relative to that predicted from consideration of classical mass-dependent isotope effects). Similar sulfur isotope variations have been observed in other atmospheric samples and in (homogenous) gas-phase reactions. On the basis of atmospheric sounding and satellite data as well as a possible relationship between D 33 S and Convective Available Potential Energy (CAPE) during the sampling period, we attribute the sulfur isotope anomalies (D 33 S and D 36 S) in Xianghe aerosol sulfates to another atmospheric source (upper troposphere or lower stratosphere).Citation: Guo, Z., Z. Li, J. Farquhar, A. J. Kaufman, N. Wu, C. Li, R. R. Dickerson, and P. Wang (2010), Identification of sources and formation processes of atmospheric sulfate by sulfur isotope and scanning electron microscope measurements,

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Mass‐independent sulfur isotopic compositions in present‐day sulfate aerosols

Cited by 82 publications

References 34 publications

Production, preservation, and biological processing of mass-independent sulfur isotope fractionation in the Archean surface environment

Production, preservation, and biological processing of mass-independent sulfur isotope fractionation in the Archean surface environment

Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

Identification of sources and formation processes of atmospheric sulfate by sulfur isotope and scanning electron microscope measurements

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