scholarly journals Multiscale Microbial Preservation and Biogeochemical Signals in a Modern Hot-Spring Siliceous Sinter Rich in CO2 Emissions, Krýsuvík Geothermal Field, Iceland

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 263
Author(s):  
Jose Javier Álvaro ◽  
Mónica Sánchez-Román ◽  
Klaas G.J. Nierop ◽  
Francien Peterse
Keyword(s):  
Fatty Acids ◽  
Dissolved Inorganic Carbon ◽  
Hot Spring ◽  
Carbon Isotopic Composition ◽  
Methanogenic Archaea ◽  
Geothermal Field ◽  
Carbon Isotopic ◽  
Siliceous Sinter ◽  
Episodic Fluctuations ◽  
Abandoned Meanders

The microbial communities inferred in silica sinter rocks, based on multiscale morphological features (fabrics and textures) and the presence of lipid biomarkers and their carbon isotopic composition, are evaluated in the Krýsuvík geothermal area of Iceland. Close to vent environments (T > 75 °C and pH 1.7‒3), stream floors are capped with homogeneous vitreous crusts and breccia levels, with no distinct recognizable silicified microbes. About 4 m far from the vents (T 75‒60 °C and pH 3‒6) and beyond (T < 60 °C and pH 6‒7.6), microbial sinters, including wavy and palisade laminated and bubble fabrics, differ between abandoned meanders and desiccated ponds. Fabric and texture variances are related to changes in the ratio of filament/coccoid silicified microbes and associated porosity. Coatings of epicellular silica, less than 2 µm thick, favor identification of individual microbial filaments, whereas coalescence of opal spheres into agglomerates precludes recognition of original microbial textures and silicified microbes. Episodic fluctuations in the physico-chemical conditions of surface waters controlled the acidic hydrolysis of biomarkers. Wavy laminated fabrics from pond margins comprise fatty acids, mono- and dialkyl glycerol, mono- and diethers, monoalkyl glycerol esters and small traces of 10-methyl branched C16 and C18 fatty acids and archaeol, indicative of intergrowths of cyanobacteria, Aquificales, and sulfate reducing bacteria and methanogenic archaea. In contrast, wavy laminated fabrics from abandoned meanders and palisade laminated fabrics from ponds differ in their branched fatty acids and the presence vs. absence of bacteriohopanetetrol, reflecting different cyanobacterial contributions. δ13C values of biomarkers range from −22.7 to −32.9‰, but their values in the wavy (pond) and bubble fabrics have much wider ranges than those of the wavy (meander), palisade, and vitreous fabrics, reflecting dissolved inorganic carbon (DIC) sources and a decrease in 13C downstream outflow channels, with heavier values closer to vents and depleted values in ponds.

scholarly journals Evaluating Dissolved Inorganic Carbon Cycling in a Forested Lake Watershed Using Carbon Isotopes

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 636-645 ◽  
Author(s):  
Ramon Aravena ◽  
S. L. Schiff ◽  
S. E. Trumbore ◽  
P. J. Dillon ◽  
Richard Elgood
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotopes ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Isotopic Composition ◽  
Isotopic Fractionation ◽  
Early Spring ◽  
Late Winter ◽  
Isotope Pattern ◽  
Carbon Isotopic

Dissolved inorganic carbon (DIC) is the main acid buffer in forested lake watersheds in Canada. We used carbon isotopes (13C, 14C) to evaluate the production and cycling of DIC in an acid-sensitive lake watershed of the Precambrian Shield. Soil CO2, groundwater and stream DIC were characterized chemically and isotopically. Soil CO2 concentration profiles reflect both changes in production and in losses due to diffusion. δ13C soil CO2 profiles (δ13C values of −23‰ in summer, slightly enriched during the fall and −25%‰ during the winter) are a reflection of the isotopic composition of the sources and changes in isotopic fractionation due to diffusion. Carbon isotopic composition (13C, 14C) of the groundwater and stream DIC clearly indicate that weathering of silicates by soil CO2 is the main source of DIC in these watersheds. 14C data show that, in addition to recent groundwater, an older groundwater component with depleted 14C activity is also present in the bedrock. The carbon isotope pattern in the groundwater also implies that, besides the main springtime recharge events, contributions to the groundwater may also occur during late winter/early spring.

Chemical and carbon isotopic composition of fatty acids in adipose tissue as indicators of dietary history in wild arctic foxes (A lopex lagopus) on Svalbard

1995 ◽  
Vol 236 (4) ◽  
pp. 611-623 ◽  
Author(s):  
Caroline M. Pond ◽  
Christine A. Mattacks ◽  
I. Gilmour ◽  
M. A. Johnston ◽  
C. T. Pillinger ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Isotopic Composition ◽  
Carbon Isotopic Composition ◽  
Dietary History ◽  
Carbon Isotopic ◽  
Arctic Foxes

scholarly journals Carbon isotopic composition of Frutexites in subseafloor ultramafic rocks

2021 ◽  
Author(s):  
Anna Neubeck ◽  
Magnus Ivarsson ◽  
Curt Broman ◽  
Jonathan Lima-Zaloumis ◽  
Wolfgang Bach ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Manganese Oxides ◽  
Hot Spring ◽  
Carbon Isotopic Composition ◽  
Ultramafic Rocks ◽  
Biological Origin ◽  
Carbon Isotopic ◽  
Carbonate Matrix ◽  
First Time ◽  
Secondary Ion

AbstractMicrometer sized stromatolitic structures called Frutexites are features observed in samples from the deep subsurface, and hot-spring environments. These structures are comprised of fine laminations, columnar morphology, and commonly consist of iron oxides, manganese oxides, and/or carbonates. Although a biological origin is commonly invoked, few reports have shown direct evidence of their association with microbial activity. Here, we report for the first time the occurrence of subsurface manganese-dominated Frutexites preserved within carbonate veins in ultramafic rocks. To determine the biogenicity of these putative biosignatures, we analyzed their chemical and isotopic composition using Raman spectroscopy and secondary ion mass spectroscopy (SIMS). These structures were found to contain macromolecular carbon signal and have a depleted 13C/12C carbon isotopic composition of – 35.4 ± 0.50‰ relative to the entombing carbonate matrix. These observations are consistent with a biological origin for the observed Frutexites structures.

scholarly journals Diel Variations in Carbon Metabolism by Green Nonsulfur-Like Bacteria in Alkaline Siliceous Hot Spring Microbial Mats from Yellowstone National Park

2005 ◽  
Vol 71 (7) ◽  
pp. 3978-3986 ◽  
Author(s):  
Marcel T. J. van der Meer ◽  
Stefan Schouten ◽  
Mary M. Bateson ◽  
Ulrich Nübel ◽  
Andrea Wieland ◽  
...  
Keyword(s):  
Carbon Metabolism ◽  
Inorganic Carbon ◽  
Microbial Mats ◽  
Hot Spring ◽  
Carbon Sources ◽  
Carbon Isotopic Composition ◽  
Specific Lipids ◽  
Carbon Isotopic ◽  
Bicarbonate Uptake

ABSTRACT Green nonsulfur-like bacteria (GNSLB) in hot spring microbial mats are thought to be mainly photoheterotrophic, using cyanobacterial metabolites as carbon sources. However, the stable carbon isotopic composition of typical Chloroflexus and Roseiflexus lipids suggests photoautotrophic metabolism of GNSLB. One possible explanation for this apparent discrepancy might be that GNSLB fix inorganic carbon only during certain times of the day. In order to study temporal variability in carbon metabolism by GNSLB, labeling experiments with [13C]bicarbonate, [14C]bicarbonate, and [13C]acetate were performed during different times of the day. [14C]bicarbonate labeling indicated that during the morning, incorporation of label was light dependent and that both cyanobacteria and GNSLB were involved in bicarbonate uptake. 13C-labeling experiments indicated that during the morning, GNSLB incorporated labeled bicarbonate at least to the same degree as cyanobacteria. The incorporation of [13C]bicarbonate into specific lipids could be stimulated by the addition of sulfide or hydrogen, which both were present in the morning photic zone. The results suggest that GNSLB have the potential for photoautotrophic metabolism during low-light periods. In high-light periods, inorganic carbon was incorporated primarily into Cyanobacteria-specific lipids. The results of a pulse-labeling experiment were consistent with overnight transfer of label to GNSLB, which could be interrupted by the addition of unlabeled acetate and glycolate. In addition, we observed direct incorporation of [13C]acetate into GNSLB lipids in the morning. This suggests that GNSLB also have a potential for photoheterotrophy in situ.

scholarly journals Differences in metabolic rate between two Atlantic cod (Gadus morhua) populations estimated with carbon isotopic composition in otoliths

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0248711
Author(s):  
Szymon Smoliński ◽  
Côme Denechaud ◽  
Gotje von Leesen ◽  
Audrey J. Geffen ◽  
Peter Grønkjær ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Gadus Morhua ◽  
Inorganic Carbon ◽  
Atlantic Cod ◽  
Dissolved Inorganic Carbon ◽  
Physiological State ◽  
Carbon Isotopic Composition ◽  
Physiological Basis ◽  
Carbon Isotopic ◽  
Growth Increments

The isotopic composition of inorganic carbon in otoliths (δ13Coto) can be a useful tracer of metabolic rates and a method to study ecophysiology in wild fish. We evaluated environmental and physiological sources of δ13Coto variation in Icelandic and Northeast Arctic (NEA) cod (Gadus morhua) over the years 1914–2013. Individual annual growth increments of otoliths formed at age 3 and 8 were micromilled and measured by isotope-ratio mass spectrometry. Simultaneously, all annual increment widths of the otoliths were measured providing a proxy of fish somatic growth. We hypothesized that changes in the physiological state of the organism, reflected by the isotopic composition of otoliths, can affect the growth rate. Using univariate and multivariate mixed-effects models we estimated conditional correlations between carbon isotopic composition and growth of fish at different levels (within individuals, between individuals, and between years), controlling for intrinsic and extrinsic effects on both otolith measurements. δ13Coto was correlated with growth within individuals and between years, which was attributed to the intrinsic effects (fish age or total length). There was no significant correlation between δ13Coto and growth between individuals, which suggests that caution is needed when interpreting δ13Coto signals. We found a significant decrease in δ13Coto through the century which was explained by the oceanic Suess effect-admixture of isotopically light carbon from fossil fuel. We calculated the proportion of the respired carbon in otolith carbonate (Cresp) using carbon isotopic composition in diet and dissolved inorganic carbon of the seawater. This approach allowed us to correct the values for each stock in relation to these two environmental baselines. Cresp was on average 0.275 and 0.295 in Icelandic and NEA stock, respectively. Our results provide an insight into the physiological basis for differences in growth characteristics between these two cod stocks, and how that may vary over time.

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