Micro- and nano-environments of carbon sequestration: Multi-element STXM–NEXAFS spectromicroscopy assessment of microbial carbon and mineral associations

Solomon, Daniel; Lehmann, Johannes; Harden, Jennifer W.; Wang, Jian; Kinyangi, James; Heymann, Karen; Karunakaran, Chithra; Lu, Yingshen; Wirick, S.; Jacobsen, Chris

doi:10.1016/j.chemgeo.2012.02.002

Cited by 149 publications

(156 citation statements)

References 95 publications

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“…These statistical techniques, however, function best when identifying major differences in spectra and where chemically distinct compounds are not co-occurring Keiluweit et al, 2012;Solomon et al, 2012;Knopf et al, 2014), in contrast to observations in this study. Here, the variation in relative proportions of functional groups is less but there are still quantifiable differences in carbon composition across samples.…”

Section: Spatial Distribution and Composition Of Organic Carbon On Thcontrasting

confidence: 55%

“…We therefore examine spatial variation in chemical composition in an attempt to determine both average composition and recalcitrance of pelagic OC. A majority of studies employing STXM-NEXAFS to examine carbon composition find statistically different chemical compositions in morphologically distinct regions of samples Solomon et al, 2012;Knopf et al, 2014). These studies emphasize the chemical heterogeneity of carbon on a very small spatial scale.…”

Section: Spatial Distribution and Composition Of Organic Carbon On Thmentioning

confidence: 99%

“…For instance, Solomon et al (2012) emphasize the heterogeneity of soil aggregates, finding pyrogenic carbon sequestered a few microns from microbially-produced carbon. In marine particles, also find significant heterogeneity, but determine that POM retains the same four basic classes of carbon, in varying proportions, at all depths.…”

Section: Environmental Applications Of Near-edge X-ray Absorption Finmentioning

confidence: 99%

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Geochemical controls on the distribution and composition of biogenic and sedimentary carbon

Estes¹

2017

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Organic carbon (OC) preserved in marine sediments acts as a reduced carbon sink that balances the global carbon cycle. Understanding the biogeochemical mechanisms underpinning the balance between OC preservation and degradation is thus critical both to quantifying this carbon reservoir and to estimating the extent of life in the deep subsurface biosphere. This work utilizes bulk and spatially-resolved X-ray absorption spectroscopy to characterize the OC content and composition of various environmental systems in order to identify the role of minerals and surrounding geochemistry in organic carbon preservation in sediments. Biogenic manganese (Mn) oxides formed either in pure cultures of Mn-oxidizing microorganisms, in incubations of brackish estuarine waters, or as ferromanganese deposits in karstic cave systems rapidly associate with OC following precipitation. This association is stable despite Mn oxide structural ripening, suggesting that mineral-associated OC could persist during early diagenetic reactions. OC associated with bacteriogenic Mn oxides is primarily proteinaceous, including intact proteins involved in Mn oxidation and likely oxide nucleation and aggregation. Pelagic sediments from 16 sites underlying the South Pacific and North Atlantic gyres and spanning a gradient of sediment age and redox state were analyzed in order to contrast the roles of oxygen exposure, OC recalcitrance, and mineral-based protection of OC as preservation mechanisms. OC and nitrogen concentrations measured at these sites are among the lowest globally (<0.1%) and, to a first order, scale with sediment oxygenation. In the deep subsurface, however, molecular recalcitrance becomes more important than oxygen exposure time in protecting OC against remineralization. Deep OC consists of primarily amide and carboxylic carbon in a scaffolding of aliphatic and O-alkyl moieties, corroborating the extremely low C/N values observed. These findings suggest that microbes in oxic pelagic sediments are carbon-limited and may preferentially remove carbon relative to nitrogen from the organic matter pool. As a whole, this work documents how interactions with mineral surfaces and exposure to oxygen generate a reservoir of OC stabilized in sediments on at least 25-million year time scales.

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Section: Spatial Distribution and Composition Of Organic Carbon On Thcontrasting

confidence: 55%

Section: Spatial Distribution and Composition Of Organic Carbon On Thmentioning

confidence: 99%

Section: Environmental Applications Of Near-edge X-ray Absorption Finmentioning

confidence: 99%

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Geochemical controls on the distribution and composition of biogenic and sedimentary carbon

Estes¹

2017

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“…The spectrum shown ( Figure S4, second bloom, organic salt aggregate) has equal-intensity peaks at 288.3 eV for K 1s → π* (R−NH(C*O)R) and 288.7 eV for K 1s → π* (R(C* O)OH) consistent with peptidoglycan, a component of bacterial cell membranes. 52 Other occasionally resolved features of the NEXAFS spectrum are the absorbance at 289.5 eV for K 1s → 3pσ* (RC*OH) and 286.7 eV for K 1s → π* (R(C*O)R or C*OH). The alcohol presumably comes from polysaccharides, and the carbonyl group is possibly attributed to acetylated polysaccharides.…”

Section: Acs Earth and Space Chemistrymentioning

confidence: 99%

Biological Impacts on Carbon Speciation and Morphology of Sea Spray Aerosol

Pham

O’Brien

Fraund

et al. 2017

ACS Earth Space Chem.

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Sea spray aerosol (SSA) can have complex carbon speciation that is affected by biological conditions in the seawater from which it originates. Biologically derived molecules can also interact with other longer-lived organic and inorganic carbon species in the sea surface microlayer and in the process of bubble bursting. An isolated wave channel facility was used to generate sea spray aerosol during a 1 month mesocosm study. Two consecutive phytoplankton blooms occurred, and sea spray aerosol was sampled throughout. Scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS) was used to determine spatially resolved carbon speciation within individual particles from 0.18 to 3.2 μm. During phytoplankton blooms, coarse-mode particles exhibited an increased abundance of carboxylic acid-rich needlelike structures. The extent of organic enrichment in fine-mode particles correlates with the occurrence of aliphatic-rich organic species, as detected by an intense C 1s → σ(C−H)* excitation. These aliphatic-rich species had a strong association with graphitic carbon, as detected by a C 1s → σ* exciton excitation. This enrichment was unique to particles collected in the aerodynamic size range 0.18−0.32 μm and corresponded with the decrease in hygroscopicity. Aliphatic organics can significantly suppress the particle hygroscopicity when they replace salt, thus influencing the effect of sea spray aerosol on light scattering and cloud formation. These results suggest that graphitic carbon is concentrated in the sea surface microlayer during phytoplankton blooms and released through wave action. These results may have implications for radiative transfer and carbon cycling in the ocean−atmosphere system.

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“…Although procedures for data analysis of similar datasets are already available for transmission techniques such as scanning transmission X-ray microscopy (STXM) (e.g. Solomon et al [12] ) or for (synchrotron radiation-based) Fourier transform infrared ((SR-)FTIR) (e.g. Kansiz et al, [13] Webster et al [14] ), these still need to be fully developed for XRF techniques.…”

mentioning

confidence: 99%

Hard X-ray synchrotron biogeochemistry: piecing together the increasingly detailed puzzle

2014

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Micro- and nano-environments of carbon sequestration: Multi-element STXM–NEXAFS spectromicroscopy assessment of microbial carbon and mineral associations

Cited by 149 publications

References 95 publications

Geochemical controls on the distribution and composition of biogenic and sedimentary carbon

Geochemical controls on the distribution and composition of biogenic and sedimentary carbon

Biological Impacts on Carbon Speciation and Morphology of Sea Spray Aerosol

Hard X-ray synchrotron biogeochemistry: piecing together the increasingly detailed puzzle

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