scholarly journals Nano−porous pyrite and organic matter in 3.5-billion-year-old stromatolites record primordial life

Geology ◽  
2019 ◽  
Vol 47 (11) ◽  
pp. 1039-1043 ◽  
Author(s):  
Raphael J. Baumgartner ◽  
Martin J. Van Kranendonk ◽  
David Wacey ◽  
Marco L. Fiorentini ◽  
Martin Saunders ◽  
...  
Keyword(s):  
Organic Matter ◽  
High Resolution ◽  
Chemical Analysis ◽  
Microbial Communities ◽  
Convincing Evidence ◽  
Textural Features ◽  
Weathering Profile ◽  
Biological Matter ◽  
Primordial Life ◽  
Pilbara Craton

Abstract Stromatolites of the ∼3.5 billion-year-old Dresser Formation (Pilbara Craton, Western Australia) are considered to be some of Earth’s earliest convincing evidence of life. However, uniquely biogenic interpretations based on surface outcrops are precluded by weathering, which has altered primary mineralogy and inhibited the preservation of microbial remains. Here, we report on exceptionally preserved, strongly sulfidized stromatolites obtained by diamond drilling from below the weathering profile. These stromatolites lie within undeformed hydrothermal-sedimentary strata and show textural features that are indicative of biogenic origins, including upward-broadening and/or upward-branching digitate forms, wavy to wrinkly laminae, and finely laminated columns that show a thickening of laminae over flexure crests. High-resolution textural, mineralogical, and chemical analysis reveals that the stromatolites are dominated by petrographically earliest, nano-porous pyrite that contains thermally mature, N-bearing organic matter (OM). This nano-porous pyrite is consistent with a formation via sulfidization of an originally OM-dominated matrix. Evidence for its relationship with microbial communities are entombed OM strands and filaments, whose microtexture and chemistry are consistent with an origin as mineralized biofilm remains, and carbon isotope data of extracted OM (δ13COM = −29.6‰ ± 0.3‰ VPDB [Vienna Peedee belemnite]), which lie within the range of biological matter. Collectively, our findings provide exceptional evidence for the biogenicity of some of Earth’s oldest stromatolites through preservation of OM, including microbial remains, by sulfidization.

Cosmetology treatments on human hair: An SEM study

1996 ◽  
Vol 54 ◽  
pp. 940-941
Author(s):  
D.F. Bowling
Keyword(s):  
High School ◽  
High Resolution ◽  
Human Hair ◽  
Optical Microscope ◽  
Convincing Evidence ◽  
Brightness Contrast ◽  
Sem Study

High school cosmetology students study the methods and effects of various human hair treatments, including permanents, straightening, conditioning, coloring and cutting. Although they are provided with textbook examples of overtreatment and numerous hair disorders and diseases, a view of an individual hair at the high resolution offered by an SEM provides convincing evidence of the hair‘s altered structure. Magnifications up to 2000X provide dramatic differences in perspective. A good quality classroom optical microscope can be very informative at lower resolutions.Students in a cosmetology class are initially split into two groups. One group is taught basic controls on the SEM (focus, magnification, brightness, contrast, specimen X, Y, and Z axis movements). A healthy, untreated piece of hair is initially examined on the SEM The second group cements a piece of their own hair on a stub. The samples are dryed quickly using heat or vacuum while the groups trade places and activities.

Invasive plant-derived dissolved organic matter alters microbial communities and carbon cycling in soils

2021 ◽  
pp. 108191
Author(s):  
Morgan Luce McLeod ◽  
Lorinda Bullington ◽  
Cory C. Cleveland ◽  
Johannes Rousk ◽  
Ylva Lekberg
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microbial Communities ◽  
Carbon Cycling ◽  
Invasive Plant

A pedological study of phosphorus in 12 soils derived from granite

1961 ◽  
Vol 12 (2) ◽  
pp. 286 ◽  
Author(s):  
A Wild
Keyword(s):  
Organic Matter ◽  
Chemical Analysis ◽  
Soil Profiles ◽  
Rock Weathering ◽  
Simple Correlation ◽  
Methods Of Calculation ◽  
Parent Rocks

Chemical analysis of 12 soil profiles on granite showed that all except two had lost phosphate by leaching. The loss of phosphorus from each profile is calculated in grams per sq centimetre of profile surface, and as a percentage of the amount originally present. Three methods of calculation are used, each being based on one of the following assumptions as to the changes which take place on rock weathering: that there is (a) no change in weight, (b) no change in volume, (c) no loss of zirconium. The three methods are generally consistent in showing which soils are the most leached and which are the least leached. The estimated loss of phosphorus from each profile depends on which assumption is made. There is no simple correlation between the loss of phosphorus and the present rainfall. Reasons which are suggested are that the soils differ in age, in level of organic matter, and possibly in the rates of weathering of the parent rocks. Up to two-thirds of the phosphorus retained in the soil is chemically bound by the free oxides of iron and aluminium.

Metabolic and structural response of hyporheic microbial communities to variations in supply of dissolved organic matter

2003 ◽  
Vol 48 (4) ◽  
pp. 1608-1617 ◽  
Author(s):  
Stuart E. G. Findlay ◽  
Robert L. Sinsabaugh ◽  
William V. Sobczak ◽  
M. Hoostal
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Microbial Communities ◽  
Structural Response

scholarly journals SEDIMENTOLOGIA DE LAGUNAS COSTERAS: CIENAGA GRANDE DE SANTA MARTA Y CIENAGA DE PAJARALES

2016 ◽  
Vol 25 ◽  
Author(s):  
Gladys Bernal ◽  
Julliet Betancur
Keyword(s):  
Grain Size ◽  
Organic Matter ◽  
Chemical Analysis ◽  
X Ray Diffraction ◽  
Caribbean Coast ◽  
X Ray ◽  
Deltaic Plain ◽  
Magdalena River

Ciénaga Grande de Santa Marta and Ciénaga de Pajarales are the two main lagoons of the marginal lagunar system at the deltaic floodplain of Magdalena river, Caribbean coast of Colombia. A systematic surficial sampling was carried out in such lagoons and Salamanca coast. A sporadic sampling was done in other places of the deltaic plain. This paper presents results about grain size, mineralogy, organic matter contents, CaCOa contents, X ray diffraction and chemical analysis of salts for sediments. Sedimentologic charts, distribution schemes and provenience notes are presented.

scholarly journals Agricultural constraints on microbial resource use and niche breadth in drainage ditches

2017 ◽  
Author(s):  
Ellard R Hunting ◽  
Henrik Barmentlo ◽  
Maarten Schrama ◽  
Peter van Bodegom ◽  
Yujia Zhai ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Resource Utilization ◽  
Agricultural Land ◽  
Niche Breadth ◽  
Niche Differentiation ◽  
Drainage Ditches ◽  
Substrate Quality ◽  
Degradation Rates ◽  
Natural Communities

Background. Microorganisms govern important ecosystems processes, in particular the degradation of organic matter (OM). However, microorganisms are rarely considered in efforts to monitor ecosystem health and functioning. Evidence suggests that environmental perturbations can adversely affect microbial communities and and their ability to use available substrates. However, whether impacted microbial efficiencies in extracting and utilizing the available resources (resource niche breadth) translate to changes in organic matter (OM) degradation in natural systems remains poorly understood. Methods. Here we evaluated effects of differences in organic matter (OM) related to agricultural land use (OM derived from ditches adjacent to grasslands, bulb fields and a pristine dune area) on microbial functioning. We specifically assessed 1) resource niche breadths of microbial communities during initial community assembly in laboratory microcosms and already established natural communities, and 2) how changes in community resource niche breadth translates to the degradation of natural OM. Results. A disparity existed between microbial resource niche breadth in laboratory incubations and natural microbial communities. Resource utilization and niche breadth of natural microbial communities was observed to be constrained in drainage ditches adjacent to agricultural fields. This outcome coincides with retarded degradation of natural OM collected from ditches adjacent to hyacinth bulb fields. Microbial communities in bulb field ditches further showed functional redundancy when offered grassland OM of seemingly higher substrate quality. Discussion. Results presented in this study suggest that agricultural practices can impose constraints on microbial functional diversity by reducing OM resource quality, which can subsequently translate to confined microbial resource niche differentiation and reduced organic matter degradation rates. This hints that assessments of actual microbial resource utilization and niche differentiation could potentially be used to assess the ecological health and functioning of natural communities.

High-Resolution Dynamics of Microbial Communities during Dissimilatory Selenate Reduction in Anoxic Soil

2015 ◽  
Vol 49 (13) ◽  
pp. 7684-7691 ◽  
Author(s):  
Ronald R. Navarro ◽  
Tomo Aoyagi ◽  
Makoto Kimura ◽  
Hideomi Itoh ◽  
Yuya Sato ◽  
...  
Keyword(s):  
High Resolution ◽  
Microbial Communities

Onset of Oceanic Anoxic Event 2 in the Lower Saxony Basin – Insights fromhigh-resolution stable isotope stratigraphy and geochemical modelling

2021 ◽  
Author(s):  
Pia Müller ◽  
Ulrich Heimhofer ◽  
Christian Ostertag-Henning
Keyword(s):  
Organic Matter ◽  
High Resolution ◽  
Stable Isotope ◽  
Carbon Cycle ◽  
Geochemical Modelling ◽  
Positive Anomaly ◽  
Lower Saxony ◽  
Data Set ◽  
Oceanic Anoxic Event ◽  
Anoxic Event

<p>The Oceanic Anoxic Event (OAE) 2 spanning the Cenomanian-Turonian boundary (93.5 Ma)<br>represents a major perturbation of the global carbon cycle and is marked by organic-rich<br>sediments deposited under oxygen-depleted conditions. In many studies the eruption of the<br>Caribbean LIP is considered to be the cause for rapidly increasing CO2 concentrations and<br>resulting global warming accompanied by widespread oceanic anoxia. In the Lower Saxony<br>Basin of northern Germany, the deposits of the OAE 2 are exposed in several industry drill<br>cores. In this study, the lower part of the OAE 2 has been studied in the HOLCIM 2011-3 drill<br>core. Sedimentary rocks are composed of limestones, marly limestones, marls and black<br>shales and have been analysed with a high-resolution stable isotope approach<br>(approximately one sample every 2 cm) combined with geochemical modelling. Using stable<br>carbon isotopes, bulk rock parameters and petrographic analysis, the onset of OAE 2 has<br>been investigated in detail. The high-resolution δ<sup>13</sup>C curve exhibits overall stable values<br>around 3 ‰ before the onset of the Plenus event. This background level is interrupted by<br>three short-lived and small but significant negative carbon isotope excursions (CIEs) down to<br>δ<sup>13</sup>C values of 2.5 ‰, 2.7 ‰ and 1.9 ‰. Immediately before the main rise in the Plenus bed,<br>a longer-lasting negative CIE down to 2.8 ‰ is observed, preceding the large positive CIE of<br>the OAE 2 to values of 5.2 ‰ over 33 ka. Thereafter, the δ<sup>13</sup>C values decrease to 3.5 ‰ over<br>a period of approximately 130 ka. The results can be correlated with the lower-resolution<br>data set of Voigt et al. (2008) but enable a more accurate characterization of the subtle<br>features of the CIE and hence events before and during this time interval. Carbon cycle<br>modelling with the modelling software SIMILE using a model based on Kump & Arthur (1999)<br>reveals that the negative excursion before the Plenus bed can be explained by a massive<br>volcanic pulse releasing of 0.95*10<sup>18</sup> mol CO2 within 14 ka. This amount corresponds to only<br>81 % of the calculated volume of CO<sub>2</sub> release during emplacement of the Caribbean LIP by<br>Joo et al. (2020). In the model the volcanic exhalation increases atmospheric CO<sub>2</sub><br>concentrations. This will increase global temperatures, intensify the hydrological cycle and<br>thus increase nutrient input into the ocean, resulting in an expansion of the oxygen minimum<br>zone, the development of anoxic conditions and an increase in the preservation potential for<br>organic material. In the model enhanced primary productivity and organic matter preservation<br>can be controlled by the implemented riverine phosphate input and the preservation factor for<br>organic matter. For the positive anomaly, the riverine phosphate input must be nearly<br>doubled (from 0.01 μmol/kg PO<sub>4 </sub>to 0.019 μmol/kg) for the period of the increasing δ<sup>13</sup>C<br>values (app. 33 ka), with a concomitant rise of the preservation factor from 1 % to 2 %. This<br>model scenario accurately reproduces the major features of the new high-resolution δ<sup>13</sup>C<br>record over the onset of the OAE 2 CIE.</p>

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