Characterisation of charred organic matter in micromorphological thin sections by means of Raman spectroscopy

AbstractBurned or charred organic matter in anthropogenic combustion features may provide important clues about past human activities related to fire. To interpret archaeological hearths, a correct identification of the organic source material is key. In the present work, Raman spectroscopy is applied to characterise the structural properties of char produced in laboratory heating- and open-fire experiments. This reference data set is compared to analyses of three different archaeological sites with Middle Palaeolithic combustion contexts. The results show that it is possible to determine whether a charred fragment is the product of burning animal-derived matter (e.g. meat) or plant-derived matter (e.g. wood) by plotting a few Raman spectral parameters (i.e. position of G and D bands, and intensity ratios HD/HG and HV/HG) against one another. The most effective parameters for discriminating animal- from plant-derived matter are the position of the G band and the HV/HG intensity ratio. This method can be applied on raw sample material and on uncovered micromorphological thin sections. The latter greatly compliments micromorphology by providing information about char fragments without any clear morphological characteristics. This study is the first of its kind and may provide archaeologists with a robust new method to distinguish animal- from plant-derived char in thin sections.

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Expressing Raman Spectral Details Through Raman Parameter Information Diagram (RAPID)

10.26434/chemrxiv.6845270.v1 ◽

2018 ◽

Author(s):

Rajesh Kumar

Keyword(s):

Raman Spectroscopy ◽

Raman Spectrum ◽

Raman Spectra ◽

Blue Shift ◽

Spectral Features ◽

Good Tool ◽

Spectral Parameters ◽

Raman Spectral ◽

Pictorial Form

A handy diagram with name RAPID (Raman parameter information diagram) is proposed here which can be used for listing spectral parameters associated with a Raman spectrum. It is demonstrated how by drawing simple shapes like lines, triangles etc, it becomes easy to express various nding in a Raman spectrum like red- (or blue-) shift, asymmetry, broadening, antiresonance etc. It will also be explained how by following certain protocols, conveying Raman spectral features becomes easier unambiguously in a pictorial form, proposed to be called as \RAPID" diagram. The proposed diagram will certainly prove to be a good tool in the eld of Raman spectroscopy. It will be noticed that, though it is proposed for Raman spectra, RAPID diagram can be used for representing features of any spectra.

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The Use of Raman Spectroscopy to Monitor the Removal of Humic Substances from Charcoal: Quality Control for 14C Dating of Charcoal

Radiocarbon ◽

10.1017/s0033822200064638 ◽

2002 ◽

Vol 44 (1) ◽

pp. 1-11 ◽

Cited By ~ 45

Author(s):

Dani Alon ◽

Genia Mintz ◽

Illit Cohen ◽

Steve Weiner ◽

Elisabetta Boaretto

Keyword(s):

Raman Spectroscopy ◽

Quality Control ◽

Humic Substances ◽

Quantitative Measure ◽

Sample Pretreatment ◽

Archaeological Sites ◽

14C Dating ◽

Carbon Dating ◽

Raman Spectral ◽

Raman Spectral Analysis

One of the largest sources of uncertainty in radiocarbon dating stems from the sample pretreatment procedures used to minimize contamination. A major source of carbon contamination in charcoal from archaeological sites is humic substances carried by groundwater. Here we present a method, independent of 14C dating itself, to evaluate the effectiveness of the cleaning procedure of charcoal. Raman spectra of mixtures of humic substances (HS) and laboratory prepared charcoal indicate that Raman spectroscopy can be used as a semi-quantitative measure of the amount of humic substances associated with archaeological charcoal. Raman spectral analysis of archaeological charcoal samples subjected to different cleaning regimes supports this contention. Such measurements can provide quality control for charcoal preparation procedures and may assist in the interpretation of carbon-dating results.

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Raman Spectroscopy as a potential strain gauge

10.5194/egusphere-egu21-11092 ◽

2021 ◽

Author(s):

Clare Bond ◽

Lauren Kedar ◽

David Muirhead

Keyword(s):

Raman Spectroscopy ◽

Strain Gauge ◽

Rock Sample ◽

Earth Science ◽

Spectral Response ◽

Carbonaceous Material ◽

Spectral Parameters ◽

Future Potential ◽

Raman Spectral ◽

Strained Material

Raman Spectroscopy is increasingly being used to better understand a range of Earth Science processes. Notable recently is the application of Raman Spectroscopy to carbonaceous material in strained rocks. Here we investigate the changes in Raman Spectral response in strained material relative to an unstrained equivalent, drawing on examples from the published literature and our own work. We consider inconsistencies in the relative changes in Raman Spectral parameters of strained material and their potential causes. In doing so we look at some of the current methods for determining Raman Spectral parameters in rocks and what they might tell us about the strain state of carbon in a single rock sample. Finally, we consider the implications for use of Raman Spectroscopy of carbonaceous material as a geothermometer as well as a future potential strain gauge.&#160;

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Expressing Raman Spectral Details Through Raman Parameter Information Diagram (RAPID)

10.26434/chemrxiv.6845270 ◽

2018 ◽

Author(s):

Rajesh Kumar

Keyword(s):

Raman Spectroscopy ◽

Raman Spectrum ◽

Raman Spectra ◽

Blue Shift ◽

Spectral Features ◽

Good Tool ◽

Spectral Parameters ◽

Raman Spectral ◽

Pictorial Form

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Raman spectroscopy in thrust-stacked carbonates: an investigation of spectral parameters with implications for temperature calculations in strained samples

10.5194/se-2021-70 ◽

2021 ◽

Author(s):

Lauren Kedar ◽

Clare E. Bond ◽

David Muirhead

Keyword(s):

Raman Spectroscopy ◽

Raman Spectra ◽

Multiple Scales ◽

Raman Band ◽

Frictional Heating ◽

Shear Zones ◽

Spectral Parameters ◽

Thrust Belts ◽

Carbonate Sequence ◽

Raman Spectral

Abstract. Raman spectroscopy is commonly used to estimate peak temperatures in rocks containing organic carbon. In geological settings such as fold-thrust belts, temperature constraints are particularly important as complex burial and exhumation histories cannot easily be modelled. Many authors have developed equations to determine peak tempertaures from Raman spectral parameters, most recently to temperatures as low as 75 °C. However, recent work has shown that Raman spectra can be affected by strain as well as temperature. Fold-thrust systems are often highly deformed on multiple scales, with deformation characterised by faults and shear zones, and therefore temperatures derived from Raman spectra in these settings may be erroneous. In this study, we investigate how the four most common Raman spectral parameters and ratios change through a thrust-stacked carbonate sequence. By comparing samples from relatively low-strain localities to those on thrust planes and in shear zones, we show maximum differences of 0.16 for I[d]/I[g] and 0.11 for R2, while FWHM[d] and Raman Band Separation show no significant change between low and high strained samples. Plausible frictional heating temperatures of faulted samples suggest that the observed changes in Raman spectra are not the result of frictional heating. We apply three equations used to derive the peak temperatures from Raman spectra to our data to investigate the implications on predicted temperatures between strained and unstrained samples. All three equations produce different temperature gradients with depth in unstrained samples. We observe that individual equations exhibit apparently varying sensitivities to strain, but calculated temperatures can be up to 140 °C different for adjacent strained and unstrained samples using the same temperature equation. These results have implications for how temperatures are determined in strained rock samples from Raman spectra.

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Features of the Distribution of Spectral Parameters of Intermolecular Vibrations in Water Obtained by Raman Spectroscopy

Optics and Spectroscopy ◽

10.1134/s0030400x20020125 ◽

2020 ◽

Vol 128 (2) ◽

pp. 191-199

Author(s):

A. V. Kraiskii ◽

N. N. Mel’nik ◽

A. A. Kraiskii

Keyword(s):

Raman Spectroscopy ◽

Spectral Parameters ◽

Intermolecular Vibrations

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A rapid method for determining organic matter maturity using Raman spectroscopy: Application to Carboniferous organic-rich mudstones and coals

International Journal of Coal Geology ◽

10.1016/j.coal.2019.01.003 ◽

2019 ◽

Vol 203 ◽

pp. 87-98 ◽

Cited By ~ 18

Author(s):

D.G. Henry ◽

I. Jarvis ◽

G. Gillmore ◽

M. Stephenson

Keyword(s):

Raman Spectroscopy ◽

Organic Matter ◽

Rapid Method

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A generally applicable pedotransfer function that estimates field capacity and permanent wilting point from soil texture and bulk density

Canadian Journal of Soil Science ◽

10.4141/cjss07120 ◽

2008 ◽

Vol 88 (5) ◽

pp. 761-774 ◽

Cited By ~ 23

Author(s):

J. A. P. Pollacco

Keyword(s):

Organic Matter ◽

Soil Moisture ◽

Bulk Density ◽

Soil Texture ◽

The United States ◽

Pedotransfer Functions ◽

Pedotransfer Function ◽

Data Set ◽

Wide Range ◽

Fitting Parameters

Hydrological models require the determination of fitting parameters that are tedious and time consuming to acquire. A rapid alternative method of estimating the fitting parameters is to use pedotransfer functions. This paper proposes a reliable method to estimate soil moisture at -33 and -1500 kPa from soil texture and bulk density. This method reduces the saturated moisture content by multiplying it with two non-linear functions depending on sand and clay contents. The novel pedotransfer function has no restrictions on the range of the texture predictors and gives reasonable predictions for soils with bulk density that varies from 0.25 to 2.16 g cm-3. These pedotransfer functions require only five parameters for each pressure head. It is generally accepted that the introduction of organic matter as a predictor improves the outcomes; however it was found by using a porosity based pedotransfer model, using organic matter as a predictor only modestly improves the accuracy. The model was developed employing 18 559 samples from the IGBP-DIS soil data set for pedotransfer function development (Data and Information System of the International Geosphere Biosphere Programme) database that embodies all major soils across the United States of America. The function is reliable and performs well for a wide range of soils occurring in very dry to very wet climates. Climatical grouping of the IGBP-DIS soils was proposed (aquic, tropical, cryic, aridic), but the results show that only tropical soils require specific grouping. Among many other different non-climatical soil groups tested, only humic and vitric soils were found to require specific grouping. The reliability of the pedotransfer function was further demonstrated with an independent database from Northern Italy having heterogeneous soils, and was found to be comparable or better than the accuracy of other pedotransfer functions found in the literature. Key words: Pedotransfer functions, soil moisture, soil texture, bulk density, organic matter, grouping

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A Systematic Study on DNA Barcoding of Medicinally Important Genus Epimedium L. (Berberidaceae)

Genes ◽

10.3390/genes9120637 ◽

2018 ◽

Vol 9 (12) ◽

pp. 637 ◽

Cited By ~ 9

Author(s):

Mengyue Guo ◽

Yanqin Xu ◽

Li Ren ◽

Shunzhi He ◽

and Xiaohui Pang

Keyword(s):

Dna Barcode ◽

Morphological Characteristics ◽

Identification Accuracy ◽

Dna Barcodes ◽

Success Rates ◽

Data Set ◽

Herba Epimedii ◽

Potential Risks ◽

Medicinal Properties ◽

Species Being

Genus Epimedium consists of approximately 50 species in China, and more than half of them possess medicinal properties. The high similarity of species’ morphological characteristics complicates the identification accuracy, leading to potential risks in herbal efficacy and medical safety. In this study, we tested the applicability of four single loci, namely, rbcL, psbA-trnH, internal transcribed spacer (ITS), and ITS2, and their combinations as DNA barcodes to identify 37 Epimedium species on the basis of the analyses, including the success rates of PCR amplifications and sequencing, specific genetic divergence, distance-based method, and character-based method. Among them, character-based method showed the best applicability for identifying Epimedium species. As for the DNA barcodes, psbA-trnH showed the best performance among the four single loci with nine species being correctly differentiated. Moreover, psbA-trnH + ITS and psbA-trnH + ITS + rbcL exhibited the highest identification ability among all the multilocus combinations, and 17 species, of which 12 are medicinally used, could be efficiently discriminated. The DNA barcode data set developed in our study contributes valuable information to Chinese resources of Epimedium. It provides a new means for discrimination of the species within this medicinally important genus, thus guaranteeing correct and safe usage of Herba Epimedii.

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Spatial control of carbon dynamics in soil by microbial decomposer communities

10.5194/egusphere-egu2020-13107 ◽

2020 ◽

Author(s):

Holger Pagel ◽

Björn Kriesche ◽

Marie Uksa ◽

Christian Poll ◽

Ellen Kandeler ◽

...

Keyword(s):

Organic Matter ◽

Spatial Distribution ◽

Soil Organic Matter ◽

Distribution Patterns ◽

Microbial Succession ◽

Thin Sections ◽

Spatial Control ◽

Soil Organic Matter Turnover ◽

Microbial Decomposer ◽

Modelling Approach

Trait-based models have improved the understanding and prediction of soil organic matter dynamics in terrestrial ecosystems. Microscopic observations and pore scale models are now increasingly used to quantify and elucidate the effects of soil heterogeneity on microbial processes. Combining both approaches provides a promising way to accurately capture spatial microbial-physicochemical interactions and to predict overall system behavior. The present study aims to quantify controls on carbon (C) turnover in soil due to the mm-scale spatial distribution of microbial decomposer communities in soil. A new spatially explicit trait-based model (SpatC) has been developed that captures the combined dynamics of microbes and soil organic matter (SOM) by taking into account microbial life-history traits and SOM accessibility. Samples of spatial distributions of microbes at &#181;m-scale resolution were generated using a spatial statistical model based on Log Gaussian Cox Processes which was originally used to analyze distributions of bacterial cells in soil thin sections. These &#181;m-scale distribution patterns were then aggregated to derive distributions of microorganisms at mm-scale. We performed Monte-Carlo simulations with microbial distributions that differ in mm-scale spatial heterogeneity and functional community composition (oligotrophs, copiotrophs and copiotrophic cheaters). Our modelling approach revealed that the spatial distribution of soil microorganisms triggers spatiotemporal patterns of C utilization and microbial succession. Only strong spatial clustering of decomposer communities induces a diffusion limitation of the substrate supply on the microhabitat scale, which significantly reduces the total decomposition of C compounds and the overall microbial growth. However, decomposer communities act as functionally redundant microbial guilds with only slight changes in C utilization. The combined statistical and process-based modelling approach derives distribution patterns of microorganisms at the mm-scale from microbial biogeography at microhabitat scale (&#181;m) and quantifies the emergent macroscopic (cm) microbial and C dynamics. Thus, it effectively links observable process dynamics to the spatial control by microbial communities. Our study highlights a powerful approach that can provide further insights into the biological control of soil organic matter turnover.

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