Diagenesis of organic matter in georgia salt marshes

Fogel, Marilyn L.; Sprague, E. Kent; Giże, A. P.; Frey, Robert W.

doi:10.1016/0272-7714(89)90067-x

Cited by 89 publications

(44 citation statements)

References 29 publications

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“…Stable N isotopes -The stable N isotope compositions (615N) of fresh and decomposed Spartina were measured to gain some insights about the source(s) of immobilized N in anoxic sediments. The initial 615N of root and rhizome material was 3.1%0 (Table 4), which is more negative than previously reported values for Spartina root and rhizome material from Sapelo Island (Peterson and Howarth 1987) and nearby St. Catherine's Island (Fogel et al 1989). Although there seems to be little variation in the sta- During the first 120 d of decomposition, the 6l 5N oft he material remained fairly constant (3.2+0.47~, X + SD), which suggests that the N that was lost had a 615N similar to the remaining N (Table 4).…”

Section: Resultsmentioning

confidence: 47%

“…During this period the total N content of the material increased, indicating a net immobilization of N. If we assume that the N immobilized aboveground had an average 615N between 5 and 10% (Peterson and Howarth 1987;Fogel et al 1989), then mass balance calculations indicate that between 30 and 85% of the N associated with the material from belowground was remineralized during the last 3 months of aboveground decomposition.…”

Section: Resultsmentioning

confidence: 99%

“…The polysaccharide components of Spartina and other plants are degraded by microorganisms at rates several-fold higher than the lignin component, leading to the gradual enrichment of lignin-derived C in remaining tissues (Benner et al 19843, 1986b(Benner et al 19843, , 1987. The observation that the stable C isotope composition of Spartina shifted to more negative values during decomposition as the relative concentration of lignin increased led to the hypothesis that Spartina may contribute significantly more to pools of sedimentary and particulate organic matter in salt marshes and adjacent coastal waters than would be predicted based on the C isotopic compositions of undegraded tissues (Benner et al 1987;Ember et al 1987;Fogel et al 1989).…”

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confidence: 99%

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Diagenesis of belowground biomass of Spartina alterniflora in salt‐marsh sediments

Benner¹,

Fogel

Sprague

1991

Limnology & Oceanography

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218

103

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Belowground biomass of Spartina alterniflora lost 55% of its organic matter during 18 months of decomposition in salt-marsh sediments. Significant losses of lignin were observed under highly reducing conditions confirming previous reports of lignin degradation in the absence of molecular oxygen. The submolecular components of lignin varied in susceptibility to degradation and were ranked in the following descending order of resistance to decomposition: V-P> S-C. The preferential degradation of 1 he cinnamyl and syringyl components constrains the quantitative usefulness of these compounds for estimating the contributions ofherbaceous and angiosperm tissues to pools of dissolved and particulate organic matter. The relative concentration of lignin increased about 1.6-fold during decomposition owing to the more rapid loss of polysaccharides.Two phases in nitrogen dynamics were evident during the decomposition study. During the first 4 months of decomposition there was a net loss of N from Spartina tissues at a rate of about 10 gg N g-l tissue d-I. After this initial phase of net N loss, a phase of N immobilization was evident and was tightly coupled with rates of microbial degradation of the tissues. Net rates of N immobilization were -19 pg N g-' tissue d -I; by the end of the 18-month study more N had accumulated in the tissues than was initially present. Stable N isotope composilions of decaying Spartina were also very dynamic and reflected the sources of N that were immobilized during decomposition and the N transformations that occurred on the detrital particles.The stable C isotope composition of the polysaccharide components of Spartina was -6%~ heavier than that of the lignin component. The isotopic compositions of these components retained the 6o/oo difference throughout the 18-month study. The stable C isotope composition of the bulk tissues, however, decreased gradually during decomposition as the isotopically heavier polysaccharides were preferentially lost. Residual material was relatively enriched in the isotopically lighter, lignin-deriveci C.'

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Section: Resultsmentioning

confidence: 47%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Diagenesis of belowground biomass of Spartina alterniflora in salt‐marsh sediments

Benner¹,

Fogel

Sprague

1991

Limnology & Oceanography

Self Cite

218

103

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“…The ~ 2 ‰ depletion of 13 C of TOC LCP compared to TOC Sapelo ( Table 2) suggests further that the LCP sample might contain relatively more non-Spartina, vascular plant derived OC (i.e., 13 C-depleted) than the Sapelo sample. Stable carbon isotope systematics of salt marsh sediments in the southeastern U.S. are complex, however, as observed in the Sapelo salt marsh first by Haines (1976) and subsequently by Fogel et al (1989). The C 4 pathway of carbon fixation by Spartina gives it a δ 13 C of about −13 to −12 ‰, while other marsh macrophytes using the C 3 pathway (e.g., Juncus roemerianus and Salicornia virginica) Unexpectedly, TOC LCP was enriched in 14 C compared to TOC Sapelo (Table 2) despite the LCP sediment being significantly contaminated with 14 C-free petroleum hydrocarbons (∆ 14 C <− 950 ‰ based on LCP total and adductable hydrocarbon fractions; Table 2).…”

Section: Resultsmentioning

confidence: 99%

Natural-abundance radiocarbon as a tracer of assimilation of petroleum carbon by bacteria in salt marsh sediments

Wakeham¹,

McNichol²,

Kostka³

et al. 2006

Geochimica et Cosmochimica Acta

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The natural abundance of radiocarbon ( 14 C ) provides unique insight into the source and cycling of sedimentary organic matter. Radiocarbon analysis of bacterial phospholipid lipid fatty acids (PLFAs) in salt-marsh sediments of southeast Georgia (USA) -one heavily contaminated by petroleum residues -was used to assess the fate of petroleum-derived carbon in sediments and incorporation of fossil carbon into microbial biomass. PLFAs that are common components of eubacterial cell membranes (e.g., branched C 15 and C 17 , 10-methyl-C 16 ) were depleted in 14 C in the contaminated sediment (mean ∆ 14 C value of +25 ± 19 ‰ for bacterial PLFAs) relative to PLFAs in uncontaminated "control" sediment (∆ 14 C = +101 ± 12 ‰). We suggest that the 14 Cdepletion in bacterial PLFAs at the contaminated site results from microbial metabolism of petroleum and subsequent incorporation of petroleum-derived carbon into bacterial membrane lipids. A mass balance calculation indicates that 6-10% of the carbon in bacterial PLFAs at the oiled site could derive from petroleum residues. These results demonstrate that even weathered petroleum may contain components of sufficient lability to be a carbon source for biomass production by marsh sediment microorganisms.Furthermore, a small but significant fraction of fossil carbon is assimilated even in the presence of a much larger pool of presumably more-labile and faster-cycling carbon substrates.3

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“…To deduce the original biological sources, bulk methods such as carbon and nitrogen stable isotope analyses can be used. If the original molecular structures are sought, a common technique is to thermally fragment the polymer (pyrolysis), followed by quantitative identification of the individual molecules by gas chromatography-mass spectrometry (gc-ms) [18]. Pyrolysis can produce artefacts.…”

Section: Humic Acids In Soilsmentioning

confidence: 99%

C14-22 n-alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-alkanes?

Bowles¹,

Bowles²,

Giże³

2018

Preprint

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:Soil above a platinum-group element (PGE)-bearing horizon within the Freetown Layered Intrusion, Sierra Leone contains anomalous concentrations of n-alkanes (CnH2n+2) in the range C14 to C22 not readily attributable to an algal or lacustrine origin. Longer chain nalkanes (C23 to C31) in the soil were derived from the breakdown of leaf litter beneath the closed canopy humid tropical forest. Spontaneous breakdown of the longer chain n-alkanes to form C14-22 n-alkanes without biogenic or abiogenic catalysts is unlikely as the n-alkanes are stable. In the Freetown soil, the catalytic properties of the PGE (Pt in particular) may lower the temperature at which oxidation of the longer chain n-alkanes can occur. Reaction between these n-alkanes and Pt species such as Pt 2+ (H2O)2(OH)2 and Pt 4+ (H2O)2(OH)4 can bend and twist the alkanes, and significantly lower the Heat of Formation. Acknowledging the possibility of microbial catalysis and the difficulty of identifying a direct organic geochemical source of the lighter n-alkanes, this paper explores the theoretical potential for abiogenic Pt species catalysis as a mechanism of breakdown of the longer n-alkanes to form C14-22 alkanes. This novel mechanism could substantiate the presence of the PGE in solution predicted by soil geochemistry and illustrate processes involving the PGE. Graphical AbstractThe anomalous proportion of C14 to C22 n-alkanes with a C31 molecule distorted by Pt 4+ (H2O)2(OH)4

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Diagenesis of organic matter in georgia salt marshes

Cited by 89 publications

References 29 publications

Diagenesis of belowground biomass of Spartina alterniflora in salt‐marsh sediments

Diagenesis of belowground biomass of Spartina alterniflora in salt‐marsh sediments

Natural-abundance radiocarbon as a tracer of assimilation of petroleum carbon by bacteria in salt marsh sediments

<strong>C<sub>14</sub>-<sub>22</sub> n-alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-alkanes?</strong>

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