A novel method to measure the 13C composition of intact bacteriohopanepolyols

Hemingway, Jordon D.; Kusch, Stephanie; Shah, S. R.; Polik, Catherine Ann; Elling, Felix J.; Pearson, Ann

doi:10.1016/j.orggeochem.2018.07.002

Cited by 24 publications

(28 citation statements)

References 11 publications

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“…Nitrogen isotope ratio (δ 15 N) values of bulk nitrogen in S5 sediment show a strong shift towards low values within the sapropel (Fig. 4a), a feature seen in most sapropels (Calvert et al, 1992;Sachs and Repeta, 1999;Struck et al, 2001;Higgins et al, 2010;Möbius et al, 2010). This could potentially be explained by either enhanced diazotrophic N 2 fixation because N was limited in the system (Möbius et al, 2010) or the preferential uptake and burial of 14 N when nitrate is present in excess and primary producers have the opportunity to fractionate maximally (Calvert et al, 1992).…”

Section: High-resolution Evidence Shows Anammox Responds To Marine Rementioning

confidence: 95%

“…In cultures, a C 30 hopene also had similar isotopically depleted values as the ladderane fatty acids. Isotopically depleted BHT isomer (δ 13 C value of 51 ‰) was detected in a singular Pliocene sapropel sample in the Ionian Basin of the eastern Mediterranean (Ocean Drilling Program, ODP, Leg 160, Site 964) (Hemingway et al, 2018). In the same sample, BHT was 21 ‰ more enriched than BHT isomer.…”

Section: Introductionmentioning

confidence: 93%

“…The reorganisation of nutrient cycles, e.g. the phosphorus (P) cycle (Slomp et al, 2004) and the nitrogen (N) cycle (Calvert et al, 1992;Higgins et al, 2010), can impact the production and preservation of organic matter during the formation of Mediterranean sapropels. It has been shown that the anoxic water column during sapropel deposition caused enhanced regeneration of sedimentary P (Slomp et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…The input of terrestrial N was likely insufficient to balance the enhanced sedimentary P remineralisation that occurred in the newly anoxic water column. This would have shifted phytoplankton communities towards diazotrophy (Higgins et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formation

et al. 2019

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Abstract. The eastern Mediterranean Sea sedimentary record is characterised by intervals of organic-rich sapropel sediments, indicating periods of severe anoxia triggered by astronomical forcing. It has been hypothesised that nitrogen fixation was crucial in injecting the Mediterranean Sea with bioavailable nitrogen (N) during sapropel events. However, the evolution of the N biogeochemical cycle of sapropels is poorly understood. For example, the role of the complementary removal reactions like anaerobic ammonium oxidation (anammox) has not been investigated because the traditional lipid biomarkers for anammox, ladderane fatty acids, are not stable over long periods in the sedimentary record. Using an alternative lipid biomarker for anammox, bacteriohopanetetrol stereoisomer (BHT isomer), we present here for the first time N removal throughout the progression, e.g. formation, propagation, and termination, of basin-wide anoxic events. BHT isomer and ladderanes were analysed in sapropel records taken from three eastern Mediterranean sediment cores, spanning S1 to Pliocene sapropels. Ladderanes were rapidly degraded in sediments, as recently as the S5 sapropel. BHT isomer, however, was present in all sapropel sediments, as far back as the Pliocene, and clearly showed the response of anammox bacteria to marine water column redox shifts in high-resolution records. Two different N removal scenarios were observed in Mediterranean sapropels. During S5, anammox experienced Black Sea-type water column conditions, with the peak of BHT isomer coinciding with the core of the sapropel. Under the alternative scenario observed in the Pliocene sapropel, the anammox biomarker peaked at onset and termination of said sapropel, which may indicate sulfide inhibition of anammox during the core of sapropel deposition. This study shows the use of BHT isomer as a biomarker for anammox in the marine sediment record and highlights its potential in reconstructing anammox during past anoxic events that are too old for ladderanes to be applied, e.g. the history of oxygen minimum zone expansion and oceanic anoxic events.

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Section: High-resolution Evidence Shows Anammox Responds To Marine Rementioning

confidence: 95%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formation

et al. 2019

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“…BHT II accumulates under suboxic and anoxic conditions (Sáenz et al, 2011b;Matys et al, 2017) and, more recently, it has been used as a proxy for anammox bacteria when present in high abundance relative to BHT [BHT II ratios; BHT II/(BHT + BHT II)] (Rush et al, 2014(Rush et al, , 2019Matys et al, 2017). Support for an anammox origin of BHT II comes from its significantly δ 13 C-depleted values (-50.6%) in a Mediterranean Sea sediment (Hemingway et al, 2018). Hypoxia usually extends along the continental shelf to the west of our study area (e.g., in 2002) 1 although it is generally less well documented directly off the Mississippi River mouth.…”

Section: Diagenetic and Redox Influence On Bhp Distributionsmentioning

confidence: 99%

Origin of Sedimentary BHPs Along a Mississippi River–Gulf of Mexico Export Transect: Insights From Spatial and Density Distributions

2019

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We investigated the origin of sedimentary bacteriohopanepolyols (BHPs) in low-density (<1.6 g cm −3), mesodensity (1.6-2.0 and 2.0-2.5 g cm −3) and high-density fractions (>2.5 g cm −3) as well as unfractionated bulk samples in a highly dynamic coastal setting along a transect spanning from the Mississippi Delta into the Gulf of Mexico (GOM). We observe selective partitioning of BHPs among density fractions both in total abundance and structural diversity. BHPs primarily accumulate in the low-density fraction at all sites. Good correlation with other particle properties [surface area-normalized organic carbon loadings (OC/SA), C/N ratios, 14 C values, and lignin phenol abundances] and the spatial distribution of absolute and relative BHP abundances suggests that a significant fraction of BHPs are terrestrially sourced and entrained in the OC pool that is stabilized on clay particles or associated with plant fragments. Only a small subset of BHPs seems to have a significant autochthonous origin at the station furthest offshore and they are associated with the low and mesodensity fractions. While provenance and hydrodynamic sorting of particles across the shelf seem to primarily determine BHP inventories along the transect, the samples also harbor an unusual diversity of aminofunctionalized BHPs. A subset of these BHPs appears to derive from aerobic methane oxidizing bacteria and are likely exported with particles from the coastal swamps in the Mississippi Delta. Other amino-functionalized BHPs seem to derive from aerobic ammonia oxidizing bacteria thriving in the nutrient-rich Mississippi River plume. We find no evidence for anaerobic ammonium oxidizing bacteria related to recurring seasonal hypoxia on the Louisiana Shelf.

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Linking diatom-diazotroph symbioses to nitrogen cycle perturbations and deep-water anoxia: Insights from Mediterranean sapropel events

Elling

Hemingway

Kharbush

et al. 2021

Earth and Planetary Science Letters

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compound-specific δ 13 C diatom-diazotroph symbioses N 2 -fixation Mediterranean sapropels Elevated organic matter (OM) export flux promotes marine anoxia, thus increasing carbon sequestration efficiency and decreasing atmospheric carbon dioxide levels. However, the mechanisms that trigger and sustain anoxic events-particularly those associated with nutrient-poor, oligotrophic surface watersremain poorly constrained. Mediterranean Sea sapropels are well-preserved sediments deposited during episodic anoxic events throughout the Plio-Pleistocene; as such, they may provide unique insight into the biogeochemical and ecological drivers of-and responses to-marine anoxia. Using biomarker distributions, we demonstrate that anaerobic ammonium oxidizing (anammox) bacteria and diazotrophic endosymbionts of mat-and/or raft-forming diatoms were both abundant during sapropel events, particularly in the Ionian and Libyan seas. In these sapropels, the carbon isotope compositions of anammox biomarkers directly capture progressive 13 C-depletion in deep-water dissolved inorganic carbon, indicating sustained carbon sequestration. To explain these observations, we propose a reinforcing feedback whereby initial nutrient and/or circulation perturbations promote fixed nitrogen loss via intensified anammox and heterotrophic denitrification, which in turn favors proliferation of rapidly sinking diatom-diazotroph symbiotic consortia, increases OM burial flux, and sustains anoxia. This mechanism resolves the long-standing conundrum that small and buoyant diazotrophs are apparently associated with high OM export during periods of marine anoxia and oligotrophy.

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A novel method to measure the 13C composition of intact bacteriohopanepolyols

Cited by 24 publications

References 11 publications

Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formation

Biomarker evidence for the occurrence of anaerobic ammonium oxidation in the eastern Mediterranean Sea during Quaternary and Pliocene sapropel formation

Origin of Sedimentary BHPs Along a Mississippi River–Gulf of Mexico Export Transect: Insights From Spatial and Density Distributions

Linking diatom-diazotroph symbioses to nitrogen cycle perturbations and deep-water anoxia: Insights from Mediterranean sapropel events

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