Applying Raman Spectroscopy to Modern and Palaeocharcoals Associated with Wildfire Activity

2020 ◽  
Author(s):  
Thomas Theurer ◽  
David Muirhead ◽  
David Jolley
Keyword(s):  
Raman Spectroscopy ◽  
Vitrinite Reflectance ◽  
Climatic Conditions ◽  
Thermal Maturity ◽  
Deep Time ◽  
New Approach ◽  
Composition And Structure ◽  
Determining Factors ◽  
Increasing Temperature ◽  
The Impact

<p>Evidence of wildfire activity in deep time is preserved in the rock record as fossilised charcoal. Modern wildfire temperature is often a function of fuel type, structure and availability. These three factors are reliant upon climatic conditions and offer a potential insight into palaeoenvironmental conditions through geothermometric analysis of preserved charcoals. Much like the analysis of vitrinite reflectance as an assessor of thermal maturity, similar methodology has been applied historically to charcoal in order to obtain palaeowildfire temperatures.  Raman spectroscopy has similarly been applied to organic material as an identifier of thermal maturity, via the analysis of carbon microstructure changes with increasing temperature – however very little palaeocharcoal has been analysed via Raman spectroscopy, with no apparent application to palaeowildfire geothermometry. Through the application of Raman spectroscopy, we present the first comparison of modern pyrolyzed plant material with spectra of early Danian palaeocharcoals, associated with wildfire activity. These results indicate that Raman spectroscopy of modern wildfire charcoal facilitates a correlation between charcoal microstructure change and temperature of formation. This in turn has enabled comparison with palaeocharcoal, and the generation of reliable wildfire geothermometry. With this new methodology, we intend to further the understanding of (1) changes in palaeowildfire regimes and intensity through time (2) the interaction between climate, plant community composition and structure, and palaeowildfires  (3) correlation and comparison with existing palaeowildfire interpretive approaches. Further analysis and experimentation is required to identify the impact of fire determining factors on observed spectra to target the new approach towards interpreting current and future wildfire behaviour under climatic stress. </p>

scholarly journals Evaluating Molecular Evolution of Kerogen by Raman Spectroscopy: Correlation with Optical Microscopy and Rock-Eval Pyrolysis

Energies ◽  
2018 ◽  
Vol 11 (6) ◽  
pp. 1406 ◽  
Author(s):  
Seyedalireza Khatibi ◽  
Mehdi Ostadhassan ◽  
David Tuschel ◽  
Thomas Gentzis ◽  
Humberto Carvajal-Ortiz
Keyword(s):  
Raman Spectroscopy ◽  
Organic Matter ◽  
Structural Information ◽  
Vitrinite Reflectance ◽  
Nondestructive Method ◽  
Thermal Maturity ◽  
Shale Formations ◽  
Reflectance Analysis ◽  
Rock Eval ◽  
Maturity Parameters

Vitrinite maturity and programmed pyrolysis are conventional methods to evaluate organic matter (OM) regarding its thermal maturity. Moreover, vitrinite reflectance analysis can be difficult if prepared samples have no primary vitrinite or dispersed widely. Raman spectroscopy is a nondestructive method that has been used in the last decade for maturity evaluation of organic matter by detecting structural transformations, however, it might suffer from fluorescence background in low mature samples. In this study, four samples of different maturities from both shale formations of Bakken (the upper and lower members) Formation were collected and analyzed with Rock-Eval (RE) and Raman spectroscopy. In the next step, portions of the same samples were then used for the isolation of kerogen and analyzed by Raman spectroscopy. Results showed that Raman spectroscopy, by detecting structural information of OM, could reflect thermal maturity parameters that were derived from programmed pyrolysis. Moreover, isolating kerogen will reduce the background noise (fluorescence) in the samples dramatically and yield a better spectrum. The study showed that thermal properties of OM could be precisely reflected in Raman signals.

Thermal maturity of the accretionary wedge

2020 ◽  
Author(s):  
Utsav Mannu ◽  
David Fernández-Blanco ◽  
Ayumu Miyakawa ◽  
Taras Gerya ◽  
Masataka Kinoshita
Keyword(s):  
Thermal Conductivity ◽  
Phase Transitions ◽  
Vitrinite Reflectance ◽  
Geothermal Gradient ◽  
Accretionary Wedge ◽  
Thermal Maturity ◽  
Thermomechanical Model ◽  
Borehole Data ◽  
Different Temperatures ◽  
The Impact

<p>Records of thermal maturities in boreholes have led to a better understanding of the formation of geological structures, especially the duration of thrusting during the evolution of accretionary wedges. The temporal extent of thrusting is controlled by a host of factors such as the nature of sedimentation, the topography of the incoming plate and so on. As a result, estimating the peak heating through the thermal maturity of organic material can help elucidate which mechanism has played a prominent role in wedge evolution. However, the thermal maturity value expressed as the distribution of vitrinite reflectance is the combined effect of two factors: the geothermal gradient and the time the sediments were exposed to different temperatures. Thus, the distribution of vitrinite reflectance in accretionary wedges does not necessarily reveal the deformational pathway of individual thrusts. Moreover, since the conductivity of the sediments close to the surface (<10 km) is most accessible in borehole data and predominantly controlled by porosity, models of accretionary wedge simulating thermal maturity ought to incorporate the impact of porosity on thermal conductivity. Additionally, phase transitions of the sediments in the wedge, such as smectite-illite transition and the formation of zeolite facies, that lead to increased thermal conductivity and internal angle of friction for sediments at structurally deeper locations within the wedge, must be accounted for in modeling studies. Therefore, we use a 2D thermomechanical model of subduction with empirical porosity values form the Nankai subduction margin and incorporate the effect of phase transitions to simulate the formation of the accretionary wedge under several sedimentary conditions and track the evolution of the vitrinite reflectance. As a result, we gain a holistic picture of deformation in accretionary wedges exploring different scenarios using geodynamic modeling alongside field data.</p>

scholarly journals Backtracking to Parent Maceral from Produced Bitumen with Raman Spectroscopy

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 679
Author(s):  
Seyedalireza Khatibi ◽  
Arash Abarghani ◽  
Kouqi Liu ◽  
Alexandra Guedes ◽  
Bruno Valentim ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Thermal Maturity ◽  
Maturity Level ◽  
Production Potential ◽  
Hydrocarbon Production ◽  
Solid Bitumen ◽  
Rock Eval ◽  
Oil Gas

In order to assess a source rock for economical exploitation purposes, many parameters should be considered; regarding the geochemical aspects, the most important ones are the amount of organic matter (OM) and its quality. Quality refers to the thermal maturity level and the type of OM from which it was formed. The origin of the OM affects the ability of the deposited OM between sediments to generate oil, gas, or both with particular potential after going through thermal maturation. Vitrinite reflectance and programmed pyrolysis (for instance, Rock-Eval) are common methods for evaluating the thermal maturity of the OM and its potential to generate petroleum, but they do not provide us with answers to what extent solid bitumen is oil-prone or gas-prone, as they are bulk geochemical methods. In the present study, Raman spectroscopy (RS), as a powerful tool for studying carbonaceous materials and organic matter, was conducted on shale and coal samples and their individual macerals to show the potential of this technique in kerogen typing and to reveal the parent maceral of the examined bitumen. The proposed methodology, by exhibiting the chemical structure of different organic matters as a major secondary product in unconventional reservoirs, can also detect the behavior of solid bitumen and its hydrocarbon production potential for more accurate petroleum system evaluation.

scholarly journals Thermal maturity evaluation using Raman spectroscopy for oil shale samples of USA: comparisons with vitrinite reflectance and pyrolysis methods

2020 ◽  
Vol 17 (3) ◽  
pp. 567-581 ◽  
Author(s):  
Md. Golam Kibria ◽  
Souvik Das ◽  
Qin-Hong Hu ◽  
Asish R. Basu ◽  
Wen-Xuan Hu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Oil Shale ◽  
Vitrinite Reflectance ◽  
Thermal Maturity ◽  
Maturity Evaluation

Effects of thermal maturity and chemical composition of kerogen on its dielectric constant

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. D53-D64
Author(s):  
Archana Jagadisan ◽  
Zoya Heidari
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Thermal Maturity ◽  
Formation Evaluation ◽  
Heat Treated ◽  
Composition And Structure ◽  
Physical And Chemical ◽  
The Impact

Reliable formation evaluation using borehole geophysical measurements in organic-rich mudrocks requires knowledge about the physical properties of kerogen. For instance, estimates of water-filled pore volume are significantly affected by the assumptions made for dielectric permittivity of kerogen, which can be influenced by thermal maturity. However, the impact of thermal maturity of pure kerogen on its dielectric properties is not yet thoroughly understood. We quantify the dielectric constant of kerogen samples extracted from three formations, with different levels of natural thermal maturity, and we identify the impact of thermal maturity on their dielectric properties. We first isolate kerogen from mudrock samples using physical and chemical treatments. We then synthetically mature the samples in a controlled environment and measure their dielectric constant (at 1 GHz) using a microwave resonator. X-ray photoelectron spectroscopy (XPS) monitors the variation in chemical composition of kerogen. The dielectric constant of the kerogen samples varied significantly in the range of 1.89–3.2 upon being heat treated from 25°C to 650°C. The variation in the dielectric constant is explained by the alteration in the chemical composition and structure of kerogen as a result of thermal maturation. XPS measurements also showed an increase in aromatic carbon content in the kerogen samples as the thermal maturity increased. The documented results enable the integration of the kerogen geochemistry to the interpretation of dielectric measurements, which contributes to improved interpretation of dielectric logs in organic-rich mudrocks, and result in enhanced formation evaluation of these reservoirs.

scholarly journals The Effect of Climate Variability on Maize Production in the Ejura-Sekyedumase Municipality, Ghana

Climate ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 145
Author(s):  
Godwin P. Cudjoe ◽  
Phillip Antwi-Agyei ◽  
Benjamin A. Gyampoh
Keyword(s):  
Climate Variability ◽  
Maize Yield ◽  
Climatic Conditions ◽  
Chi Square ◽  
Maize Production ◽  
Change Dynamics ◽  
The Right ◽  
Increasing Temperature ◽  
The Impact ◽  
The Relationship

Agriculture is one of the sectors most susceptible to changes in climatic conditions. The impact is even stronger in Africa, where rain-fed agriculture is vital for daily subsistence, but where adaptive capacity is low. It is therefore crucial to increase the understanding of the actual climate change dynamics on agricultural productivity. This study examined the effects of changes in climatic variables such as rainfall and temperature on maize production in the Ejura-Sekyedumase Municipality, Ghana. Regression, chi-square and trend analyses were used to establish the relationship between climate variables (rainfall and temperature) and maize yield in the study area. This was supplemented with participatory household interviews with 120 farmers to understand the perception of farmers on rainfall and temperature patterns. The results from the study respondents and trend analysis show that rainfall is shorter in terms of duration and less predictable, whilst temperature has increased. The findings suggest that the general relationship between rainfall, temperature and maize yield is such that maize yield increased with increasing rainfall of the right amount and distribution pattern and decreased with increasing temperature. The study concludes that climate variability and/or change is evident in the study area and its effect on maize yield is severe.

scholarly journals A New Approach to Measuring Tax Effort

Economies ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 77
Author(s):  
Basil Dalamagas ◽  
Panagiotis Palaios ◽  
Stefanos Tantos
Keyword(s):  
Utility Maximization ◽  
Optimal Level ◽  
Tax Revenue ◽  
Productive Capacity ◽  
New Approach ◽  
Tax Effort ◽  
Optimal Tax ◽  
Determining Factors ◽  
Macroeconomic Determinants ◽  
The Impact

This paper attempts to extend the theoretical and empirical methodology employed in previous literature, by proposing a utility maximization process to estimate the optimal tax revenue from a sample of 30 countries. It is shown that an optimal tax system is defined solely by two crucial determining factors: The productive capacity of the country (GDP) and consumers’ preferences (consumption spending). All the other variables can be disregarded, as macroeconomic determinants (GDP, consumption) tend to capture the impact of all the remaining factors on tax revenue. It is also shown that our utility maximization method generates tax-effort indices which do not differ significantly from those of IMF and World Bank studies. The actual tax burden for most of the sample countries is shown to be below its optimal level. As expected, the tax-effort performance of each of the sample countries appears to be affected by the variety of approaches employed throughout the text.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

A Predictive Model of the Impact of the Skidding System on Forest Soil in Severe Climatic Conditions

2020 ◽  
pp. 131-144
Author(s):  
S.E. Rudov ◽  
◽  
V.Ya. Shapiro ◽  
O.I. Grigoreva ◽  
I.V. Grigorev ◽  
...  
Keyword(s):  
Forest Soil ◽  
Warm Season ◽  
Climatic Conditions ◽  
Soil Freezing ◽  
Class Iii ◽  
Freezing And Thawing ◽  
Metal Structures ◽  
Rapid Adjustment ◽  
Soil Freezing And Thawing ◽  
The Impact

In the Russian Federation logging operations are traditionally carried out in winter. This is due to the predominance of areas with swamped and water-logged (class III and IV) soils in the forest fund, where work of forestry equipment is difficult, and sometimes impossible in the warm season. The work of logging companies in the forests of the cryolithozone, characterized by a sharply continental climate, with severe frosts in winter, is hampered by the fact that forest machines are not recommended to operate at temperatures below –40 °C due to the high probability of breaking of metal structures and hydraulic system. At the same time, in the warm season, most of the cutting areas on cryosolic soils become difficult to pass for heavy forest machines. It turns out that the convenient period for logging in the forests of the cryolithozone is quite small. This results in the need of work in the so-called off-season period, when the air temperature becomes positive, and the thawing processes of the soil top layer begin. The same applies to the logging companies not operating in the conditions of cryosolic soils, for instance, in the Leningrad, Novgorod, Pskov, Vologda regions, etc. The observed climate warming has led to a significant reduction in the sustained period of winter logging. Frequent temperature transitions around 0 °C in winter, autumn and spring necessitate to work during the off-season too, while cutting areas thaw. In bad seasonal and climatic conditions, which primarily include off-season periods in general and permafrost in particular, it is very difficult to take into account in mathematical models features of soil freezing and thawing and their effect on the destruction nature. The article shows that the development of long-term predictive models of indicators of cyclic interaction between the skidding system and forest soil in adverse climatic conditions of off-season logging operations in order to improve their reliability requires rapid adjustment of the calculated parameters based on the actual experimental data at a given step of the cycles.

scholarly journals Conventional and Organic Honeys as a Source of Water- and Ethanol Soluble Molecules with Nutritional and Antioxidant Characteristics

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3746
Author(s):  
Magdalena Polak-Śliwińska ◽  
Małgorzata Tańska
Keyword(s):  
Antioxidant Activity ◽  
Immune System ◽  
Vitamin C ◽  
Geographical Area ◽  
Production Method ◽  
Climatic Conditions ◽  
Organic Production ◽  
Organoleptic Characteristics ◽  
Nutritional Characteristics ◽  
The Impact

The benefits of natural honeybee products (e.g., honey, royal jelly, beeswax, propolis, beevenom and pollen) to the immune system are remarkable, and many of them are involved in the induction of antibody production, maturation of immune cells and stimulation of the immune system. The type of plants in the geographical area, climatic conditions and production method have a significantly influence on the nutritional quality of honey. However, this variability can influence consumer liking by the sensory attributes of the product. The aim of this work was to compare the most popular honeys from Poland in terms of nutritional value, organoleptic properties and antioxidant activity. In the study, five varieties of honey (honeydew, forest, buckwheat, linden and dandelion) from conventional and organic production methods were tested. The nutritional characteristics of honey samples included acidity, content of water, sugars, vitamin C, HMF and phenolics (total and flavonoids), while honey color, taste, aroma and consistency were investigated in the organoleptic characteristics. The antioxidant activity was determined in water- and ethanol-soluble honey extracts using DPPH and ORAC tests. The results showed that organoleptic and nutritional characteristics of popular Polish honeys differ significantly in relation to plant source and production method. The significant effect of honey variety on the content of HMF, saccharose and phenolics, as well as acidity and antioxidant capacity were noted. The impact of variety and variety × production method interaction was significant in the case of the content of vitamin C, glucose and fructose. A visible difference of buckwheat and forest honeys from other samples was observed. The highest content of total phenolics with antioxidant activity based on the SET mechanism was found in buckwheat honeys, while forest honeys were richer in flavonoids.

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