The stable carbon isotope biogeochemistry of acetate and other dissolved carbon species in deep subseafloor sediments at the northern Cascadia Margin

Heuer, Verena B; Pohlman, John W.; Torres, Marta E; Elvert, Marcus; Hinrichs, Kai‐Uwe

doi:10.1016/j.gca.2009.03.001

Cited by 158 publications

(143 citation statements)

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“…The decreasing δ 13 C with depth ( Fig. 1c) negatively correlated with the C content in the mofette, either indicating a change in the SOM composition towards 13 C-depleted compounds, such as lignins, lipids and their degradation products 18,19 , and/or the influence of processes with high C isotope fractionation, for example, methanogenesis or acetogenesis 8,20,21 . In both soils, the particle size of the C fraction below the litter layer was small (<0.05 mm) and suggested at least partially well decomposed organic material.…”

Section: Resultsmentioning

confidence: 99%

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

et al. 2016

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* There is only limited understanding of the impact of high p(CO 2 ) on soil biomes. We have studied a floodplain wetland where long-term emanations of temperate volcanic CO 2 (mofettes) are associated with accumulation of carbon from the Earth's mantle. With an integrated approach using isotope geochemistry, soil activity measurements and multi-omics analyses, we demonstrate that high (nearly pure) CO 2 concentrations have strongly affected pathways of carbon production and decomposition and therefore carbon turnover. In particular, a promotion of dark CO 2 fixation significantly increased the input of geogenic carbon in the mofette when compared to a reference wetland soil exposed to normal levels of CO 2 . Radiocarbon analysis revealed that high quantities of mofette soil carbon originated from the assimilation of geogenic CO 2 (up to 67%) via plant primary production and subsurface CO 2 fixation. However, the preservation and accumulation of almost undegraded organic material appeared to be facilitated by the permanent exclusion of meso-to macroscopic eukaryotes and associated physical and/or ecological traits rather than an impaired biochemical potential for soil organic matter decomposition. Our study shows how CO 2 -induced changes in diversity and functions of the soil community can foster an unusual biogeochemical profile.

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Section: Resultsmentioning

confidence: 99%

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

et al. 2016

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“…Acetate oxidation during the sediment incubations Control incubations of Gullmar Fjord and Ulleung Basin sediments that were not amended with acetate showed acetate concentrations o12 mM throughout the duration of the experiments (Figure 3) (not measured for Skagerrak incubations), which is at the lower end of reported concentrations for marine sediments (Sansone and Martens, 1982;Fukui et al, 1997;Wellsbury et al, 2002;Finke et al, 2007;Heuer et al, 2009). Acetate has been shown previously to be the most important volatile fatty acid in terms of concentration and turnover, and identified as important substrate for anaerobic terminal electron-accepting processes in marine sediments (Sørensen et al, 1981;Parkes et al, 1989;Fukui et al, 1997;Finke et al, 2007).…”

Section: Resultsmentioning

confidence: 90%

Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria

et al. 2012

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Dissimilatory manganese reduction dominates anaerobic carbon oxidation in marine sediments with high manganese oxide concentrations, but the microorganisms responsible for this process are largely unknown. In this study, the acetate-utilizing manganese-reducing microbiota in geographically well-separated, manganese oxide-rich sediments from Gullmar Fjord (Sweden), Skagerrak (Norway) and Ulleung Basin (Korea) were analyzed by 16S rRNA-stable isotope probing (SIP). Manganese reduction was the prevailing terminal electron-accepting process in anoxic incubations of surface sediments, and even the addition of acetate stimulated neither iron nor sulfate reduction. The three geographically distinct sediments harbored surprisingly similar communities of acetateutilizing manganese-reducing bacteria: 16S rRNA of members of the genera Colwellia and Arcobacter and of novel genera within the Oceanospirillaceae and Alteromonadales were detected in heavy RNA-SIP fractions from these three sediments. Most probable number (MPN) analysis yielded up to 10 6 acetate-utilizing manganese-reducing cells cm À 3 in Gullmar Fjord sediment. A 16S rRNA gene clone library that was established from the highest MPN dilutions was dominated by sequences of Colwellia and Arcobacter species and members of the Oceanospirillaceae, supporting the obtained RNA-SIP results. In conclusion, these findings strongly suggest that (i) acetatedependent manganese reduction in manganese oxide-rich sediments is catalyzed by members of taxa (Arcobacter, Colwellia and Oceanospirillaceae) previously not known to possess this physiological function, (ii) similar acetate-utilizing manganese reducers thrive in geographically distinct regions and (iii) the identified manganese reducers differ greatly from the extensively explored iron reducers in marine sediments.

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“…TOC and its stable carbon isotopic composition (d 13 C) was analyzed by continuous-flow elemental analyzer-isotope ratio mass spectrometer (EA-IRMS) as described previously . Pore-water acetate d 13 C was analyzed by isotoperatio-monitoring liquid chromatography/mass spectrometry as described by Heuer et al (2006Heuer et al ( , 2009. Isotope-ratio-monitoring gas chromatography/mass spectrometry was used to determine the d 13 C of pore-water CH 4 as described previously (Ertefai et al, 2010;Hädrich et al, 2012).…”

Section: Geochemical Analysismentioning

confidence: 99%

Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette

et al. 2014

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Effects of extremely high carbon dioxide (CO 2 ) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO 2 degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (DpH B0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1 Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH 4 ) from hydrogen (H 2 ) and CO 2 consistent with elevated CH 4 and acetate levels in the mofette soil. 13 CO 2 mofette soil incubations showed high label incorporations with B512 ng 13 C g (dry weight (dw)) soil À 1 d À 1 into the bulk soil and up to 10.7 ng 13 C g (dw) soil À 1 d À 1 into almost all analyzed bacterial lipids. Incorporation of CO 2 -derived carbon into archaeal lipids was much lower and restricted to the first 10 cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated with Methanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of 13 CO 2 . Subdivision 1 Acidobacteriaceae assimilated 13 CO 2 likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO 2 assimilation. We conclude that CO 2 -induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.

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The stable carbon isotope biogeochemistry of acetate and other dissolved carbon species in deep subseafloor sediments at the northern Cascadia Margin

Cited by 158 publications

References 89 publications

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Altered carbon turnover processes and microbiomes in soils under long-term extremely high CO2 exposure

Three manganese oxide-rich marine sediments harbor similar communities of acetate-oxidizing manganese-reducing bacteria

Carbon flow from volcanic CO2 into soil microbial communities of a wetland mofette

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