Alkyl amides in two organic-rich anoxic sediments: A possible new abiotic route for N sequestration

McKee, Georgina A.; Hatcher, Patrick G.

doi:10.1016/j.gca.2010.08.004

Cited by 47 publications

(35 citation statements)

References 51 publications

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“…This issue has not yet been examined in sediment pore waters, although given the important role of proteins (in general) and amino acids (in particular) in sedimentary carbon and nitrogen remineralization (Burdige and Martens, 1988;Henrichs and Farrington, 1987) and preservation (e.g., Moore et al, 2012), amide or amine (NH 2 ) functionality for much of the pore water DON seems likely. The factors controlling the preservation of nitrogen in marine sediments is an important topic of research (Derenne et al, 1998;McKee and Hatcher, 2010) and reactions involving DON intermediates might be expected to play some role in the preservation process (see discussions in Burdige, 2001;Schmidt et al, 2011).…”

Section: F Don and The C/n Ratio Of Pore Water Dommentioning

confidence: 99%

Sediment Pore Waters

Burdige¹,

Komada²

2015

Biogeochemistry of Marine Dissolved Organic Matter

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Section: F Don and The C/n Ratio Of Pore Water Dommentioning

confidence: 99%

Sediment Pore Waters

Burdige¹,

Komada²

2015

Biogeochemistry of Marine Dissolved Organic Matter

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“…Alkylamides maximize at n-C 16 AA for both the algae and algaenan oil. As mentioned above, we believe that alkylamides are incorporated into the algae from amidation reactions of ammonia with triglycerides (McKee and Hatcher, 2010;Chiaberge et al, 2013). The algae oil, in addition, contains small amounts of C 1 -C 2 quinolines (various isomers) and C 2 -quinoxaline.…”

Section: Gc â Gc-tofmsmentioning

confidence: 98%

“…This is an indication that the majority of these derive from the non-algaenan component of whole algae, probably the proteins which contain aromatic amino acids. Likewise, the alkylamides found only in the whole algae oil are derived from non-algaenan components (GC Â GC-TOFMS analysis, Section 3.4.2, shows some are also detected in the algaenan oil), probably alkylamides incorporated into the algae from amidation reactions, e.g., reactions of ammonia with triglycerides (McKee and Hatcher, 2010;Chiaberge et al, 2013). Also notable is the distribution of methyl ketones observed in the algaenan isolate and present in only trace amounts in the whole algae.…”

Section: General Informationmentioning

confidence: 99%

Hydrous pyrolysis of Scenedesmus algae and algaenan-like residue

Obeid

Salmon

Lewan

et al. 2015

Organic Geochemistry

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“…A final explanation for preferential preservation of N is the formation of alkyl amides via abiotic amidation of esters with NH 4 + produced by organic matter degradation (McKee & Hatcher, 2010). However, this process has only been studied in organic-rich anoxic sediments and whether that reaction is viable in oxic, carbon-poor sediments remains unknown.…”

Section: Preferential Carbon Sequestration And/or Utilizationmentioning

confidence: 99%

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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Alkyl amides in two organic-rich anoxic sediments: A possible new abiotic route for N sequestration

Cited by 47 publications

References 51 publications

Sediment Pore Waters

Sediment Pore Waters

Hydrous pyrolysis of Scenedesmus algae and algaenan-like residue

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

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