scholarly journals Organic Geochemistry of Peat Deposits in southwest Rwanda

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Theophile Mugerwa ◽  
Francois Hategekimana ◽  
Olugbenga A. Ehinola ◽  
Ibrahim A. Oladosu ◽  
Digne Rwabuhungu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Geochemistry ◽  
Organic Matter Content ◽  
Cold Climate ◽  
Hydrocarbon Exploration ◽  
Adjacent Area ◽  
Methane Gas ◽  
Western Province ◽  
Area Of Interest ◽  
Peat Deposits

Rwanda hosts million tons of peat deposits and that of western province is of great importance as it close to Kivu Lake. The discovery of methane gas in Kivu Lake has attracted investors in methane gas utilization as source of power supply and Compressed Natural Gas (CNG). Researchers identified Kivu Lake and adjacent area as an area of interest for hydrocarbon exploration. However, organic geochemical prospecting for hydrocarbon and energy content assessment is inadequate for the identified areas. The study aimed at determining the organic geochemistry of peat deposits in southwest, Rwanda. Forty (40) subsurface peat samples (1 to 10 m depth) were collected, air-dried and pulverized and screened. Five (5) samples with high organic matter content were subjected to biomarkers analysis using GC-GCMS. The n-alkanes distribution comprised mainly n-C11 to n-C 37. The Pr/Ph ratios (3.3-10.4, the waxiness index (0.09-0.87), CPI (3.6-7.8), OEP (3.5-6.0), C29 steranes (63.0–100.0%), C28 (0.0–28.0%), C27 (0.0–18.0%) and C27/ C29 sterane ratios (0.0-0.28). The ββ/ (ββ + αα) and 20S/ (20S + 20R) are 0.5 and 0.46 respectively. The C30 -moretane/ C30 -hopane ratios ranged from 1.56 to 2.42, while the oleanane index ranged from 0.07 to 0.26. The Ts/ (Ts + Tm) ratios ranged from 0.13 to 1.05. The dominance of C-29 sterols and C29/C27 sterane ratio which ranged from 3.5 to 100 indicating derivation from terrigenous higher plant material. The Pr/Ph ratio (>3) reflect the oxic to sub-oxic environmental condition during peat deposition. The peat deposits in Western Province, Rwanda are very rich in organic matter of mainly terrestrial precursor deposited in dry and cold climate.

scholarly journals Organic Geochemistry Of The Middle To Upper Jurassic Source Rocks Succession In Balad-1 Well, Balad Oil Field, Central Iraq

2021 ◽  
Vol 71 ◽  
pp. 125-138
Author(s):  
Fawzi M.O. Albeyati ◽  
◽  
Rzger A. Abdula ◽  
Rushdy S. Othman ◽  
Keyword(s):  
Organic Matter ◽  
Organic Geochemistry ◽  
Equilibrium Phase ◽  
Organic Matter Content ◽  
Upper Jurassic ◽  
Matter Content ◽  
Oil Field ◽  
Source Rocks ◽  
Content Type ◽  
Depositional Setting

Thirty four cuttings samples from the Jurassic rock succession in well Balad-1 in the Balad Oil Field, Central Iraq have been collected. Using various organic geochemical techniques, the organic matter’s quantity, quality, maturity, and their source rock’s depositional setting were determined. The samples were evaluated to determine the amount of their organic matter content, type of organic matter, δ13C carbon isotopes abundance for both saturated and aromatic, and molecular properties. The results of organic geochemistry analysis show that Sargelu, Gotnia, and Chia Gara formations contain fair to decent amounts of organic matter. Naokelekan Formation encompasses fair to excellent organic matter, while Najmah Formation comprises very high to exceptional organic matter. The analyzed samples revealed the existence of kerogen types III and II/III mainly within oil window. Thermal maturity related biomarkers are in a good agreement with Rock-Eval parameters, but did not reach equilibrium phase. Source related biomarkers show that these rock units rich in organic matter were mainly deposited in an anoxic marine depositional setting which consists of carbonate influenced by terrestrial input.

scholarly journals Organic stratigraphy and its applications with examples from the North American Western Interior and Antarctica

1992 ◽  
Vol 6 ◽  
pp. 147-147
Author(s):  
Stephen R. Jacobson ◽  
Rosemary A. Askin
Keyword(s):  
Organic Matter ◽  
Sea Level ◽  
Organic Geochemistry ◽  
Sea Level Change ◽  
Molecular Data ◽  
Hydrocarbon Exploration ◽  
Level Change ◽  
The North ◽  
Global Sea Level ◽  
Age Relations

Both insoluble (particulate) and soluble (molecular) sedimentary organic matter carry signatures of physical, chemical, and biological processes. These signatures may reflect (a) primary age-diagnostic, organism-specific, and environmentally-sensitive processes; (b) secondary factors related to mode of transportation, deposition, and preservation; and (c) tertiary agents that indicate post-burial alteration of the organic matter. Application of any or all organic matter data recorded in rocks can be used to solve geologic problems.Organic stratigraphy may be applied to hydrocarbon exploration. Our example uses both particulate and molecular data to reconstruct the age relations of Cretaceous-Lower Tertiary sediments in Wyoming, to determine the age of thrust fault motion, and to demonstrate constraints on the timing of upward petroleum migration to available trapped reservoirs.Another perspective helps establish chronostratigraphic frameworks for correlations of global sea-level change. Our example from Antarctic sediments that span the Cretaceous-Tertiary boundary reflects perturbations in relative sea-level and the consequential changes in the distribution of organic particulates from marine and terrestrial regimes. These data can be compared to age-equivalent data from other parts of the world, and test global sea-level change.Both of these applications demonstrate the versatility of organic matter in solving geologic problems. Data from contemporaneous land plants, freshwater and marine organic-walled micro-organisms provide clues on their lifestyle and subsequent afterlife alteration. Organic stratigraphy represents a long anticipated integration of several paleontological disciplines. It combines aspects of palynology, organic geochemistry, paleobotany, and coal petrography into a coherent science, with an enhanced capability to provide significant applications in the future.

scholarly journals Strategies for the Development of Spectral Models for Soil Organic Matter Estimation

2021 ◽  
Vol 13 (7) ◽  
pp. 1376
Author(s):  
Everson Cezar ◽  
Marcos Rafael Nanni ◽  
Luís Guilherme Teixeira Crusiol ◽  
Liang Sun ◽  
Mônica Sacioto Chicati ◽  
...  
Keyword(s):  
Organic Matter ◽  
Prediction Models ◽  
Organic Matter Content ◽  
Soil Samples ◽  
The State ◽  
State Model ◽  
Target Area ◽  
Spectral Curves ◽  
Area Of Interest ◽  
Spectral Models

Visible (V), Near Infrared (NIR) and Short Waves Infrared (SWIR) spectroscopy has been indicated as a promising tool in soil studies, especially in the last decade. However, in order to apply this method, it is necessary to develop prediction models with the capacity to capture the intrinsic differences between agricultural areas and incorporate them in the modeling process. High quality estimates are generally obtained when these models are applied to soil samples displaying characteristics similar to the samples used in their construction. However, low quality predictions are noted when applied to samples from new areas presenting different characteristics. One way to solve this problem is by recalibrating the models using selected samples from the area of interest. Based on this premise, the aim of this study was to use the spiking technique and spiking associated with hybridization to expand prediction models and estimate organic matter content in a target area undergoing different uses and management. A total of 425 soil samples were used for the generation of the state model, as well as 200 samples from a target area to select the subsets (10 samples) used for model recalibration. The spectral readings of the samples were obtained in the laboratory using the ASD FieldSpec 3 Jr. Sensor from 350 to 2500 nm. The spectral curves of the samples were then associated to the soil attributes by means of a partial least squares regression (PLSR). The state model obtained better results when recalibrated with samples selected through a cluster analysis. The use of hybrid spectral curves did not generate significant improvements, presenting estimates, in most cases, lower than the state model applied without recalibration. The use of the isolated spiking technique was more effective in comparison with the spiked and hybridized state models, reaching r2, square root of mean prediction error (RMSEP) and ratio of performance to deviation (RPD) values of 0.43, 4.4 g dm−3, and 1.36, respectively.

scholarly journals Distribution of organic matter and evaluation of brittleness index of the Lower Silurian shales of west Lithuania based on interpretation of well logs

Baltica ◽  
2020 ◽  
Vol 33 (2) ◽  
pp. 146-165
Author(s):  
Saulius Šliaupa ◽  
Jurga Lazauskienė ◽  
Saulius Lozovskis ◽  
Rasa Šliaupienė
Keyword(s):  
Organic Matter ◽  
Gamma Ray ◽  
Organic Matter Content ◽  
Matter Content ◽  
Black Shales ◽  
Well Logs ◽  
Brittleness Index ◽  
Lower Silurian ◽  
Combined Application ◽  
Area Of Interest

There is little known of the basic parameters of the Lower Silurian graptolitic black shales that are considered the most prospective unconventional gas reservoir in west Lithuania, situated in the deep central part of the Baltic sedimentary basin. Hundreds of deep oil exploration wells have been drilled in the area of interest, owing to extensive exploration of oil fields. The lower and middle Llandovery interval was mainly drilled with coring, while most of the section was covered by only logging. Therefore, the knowledge of major parameters of the Lower Silurian shales is rather obscure and is based on scarce rock sample data. The gamma-ray, electrical resistivity and sonic logs were utilised, together with mineralogical studies of rock samples to document vertical and lateral distribution of organic matter. Also, the brittleness index was defined to characterise the whole Lower Silurian section. Some unexpected trends were identified that may redirect exploration strategy in west Lithuania. The combined application of mineralogical studies and well logs indicate a much higher exploitation quality of the Lower Silurian shales than previously believed. A higher organic matter content and brittleness were derived from logging data in the Lower Silurian shales.

Gas seepage pockmark microbiomes suggest the presence of sedimentary coal seams in the Öxarfjörður graben of northeastern Iceland

2020 ◽  
Vol 66 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Guðný Vala Þorsteinsdóttir ◽  
Anett Blischke ◽  
M. Auður Sigurbjörnsdóttir ◽  
Finnbogi Òskarsson ◽  
Þórarinn Sveinn Arnarson ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Organic Matter Content ◽  
Matter Content ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Bacterial Phyla ◽  
Methane Gas ◽  
Gas Seepage

Natural gas seepage pockmarks are found off- and onshore in the Öxarfjörður graben, Iceland. The bacterial communities of two onshore seepage sites were analysed by 16S rRNA gene amplicon sequencing; the geochemical characteristics, hydrocarbon content, and the carbon isotope composition of the sites were also determined. While one site was found to be characterised by biogenic origin of methane gas, with a carbon isotope ratio (δ13C (‰)) of −63.2, high contents of organic matter and complex hydrocarbons, the other site showed a mixed origin of the methane gas (δ13C (‰) = −26.6) with geothermal characteristics and lower organic matter content. While both sites harboured Proteobacteria as the most abundant bacterial phyla, the Deltaproteobacteria were more abundant at the geothermal site and the Alphaproteobacteria at the biogenic site. The Dehalococcoidia class of phylum Chloroflexi was abundant at the geothermal site while the Anaerolineae class was more abundant at the biogenic site. Bacterial strains from the seepage pockmarks were isolated on a variety of selective media targeting bacteria with bioremediation potential. A total of 106 strains were isolated and characterised, including representatives from the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. This article describes the first microbial study on gas seepage pockmarks in Iceland.

scholarly journals Gas seepage pockmark microbiomes suggest the presence of sedimentary coal seams in the Öxarfjörður graben of NE-Iceland

2018 ◽  
Author(s):  
Guðný Vala Þorsteinsdóttir ◽  
Anett Blischke ◽  
M. Auður Sigurbjörnsdóttir ◽  
Finnbogi Óskarsson ◽  
Þórarinn Sveinn Arnarson ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Organic Matter Content ◽  
Carbon Isotope Ratio ◽  
Matter Content ◽  
Bacterial Strains ◽  
Bacterial Phyla ◽  
Methane Gas ◽  
Gas Seepage

AbstractNatural gas seepage pockmarks are found off and onshore in the Öxarfjörður graben, NE Iceland. The bacterial communities of two onshore seepage sites were analysed by amplicon sequencing of 16S rDNA, along with determining the geochemical characteristics, hydrocarbon content and the carbon isotope composition of the sites.While one site was found to be characterised by biogenic origin of methane gas, with carbon isotope ratio δ13C [‰] = −63.2, high content of organic matter and complex hydrocarbons, the other site showed a mixed origin of the methane gas (δ13C [‰] = −26.6) with geothermal characteristics and lower organic matter content. While both sites harbouredProteobacteriaas the most abundant bacterial phyla, theDeltaproteobacteriawere more abundant at the geothermal site, and theAlphaproteobacteriaat the biogenic site. TheDehalococcoidiaclass of theChloroflexiphylum was abundant at the geothermal site while theAnaerolineaeclass was more abundant at the biogenic site. Bacterial strains from the seepage pockmarks were isolated on a variety of selective media targeting bacteria with bioremediation potential. A total of 106 strains were isolated and characterised, including representatives from the phylaProteobacteria, Bacterioidetes, Firmicutes, andActinobacteria. This article describes the first microbial study on gas seepage pockmarks in Iceland.

HEAVY METAL SPECIATION IN BOTTOM SEDIMENTS OF THE VYSHNEVOLOTSKY RESERVOIR

2018 ◽  
pp. 46-54
Author(s):  
O. A. Lipatnikova
Keyword(s):  
Heavy Metal ◽  
Organic Matter ◽  
Bottom Sediments ◽  
Metal Speciation ◽  
Organic Matter Content ◽  
Water Reservoir ◽  
Matter Content ◽  
Heavy Metal Speciation ◽  
Mobile Forms ◽  
Manganese Hydroxides

The study of heavy metal speciation in bottom sediments of the Vyshnevolotsky water reservoir is presented in this paper. Sequential selective procedure was used to determine the heavy metal speciation in bottom sediments and thermodynamic calculation — to determine ones in interstitial water. It has been shown that Mn are mainly presented in exchangeable and carbonate forms; for Fe, Zn, Pb и Co the forms are related to iron and manganese hydroxides is played an important role; and Cu and Ni are mainly associated with organic matter. In interstitial waters the main forms of heavy metal speciation are free ions for Zn, Ni, Co and Cd, carbonate complexes for Pb, fulvate complexes for Cu. Effects of particle size and organic matter content in sediments on distribution of mobile and potentially mobile forms of toxic elements have been revealed.

Physico-Chemical Properties of Soil Collected from Chandrabhaga River in Kalmeshwar, Nagpur, Maharashtra

2020 ◽  
Vol 07 (02) ◽  
pp. 1-3
Author(s):  
Amita M Watkar ◽  
Keyword(s):  
Organic Matter ◽  
Soil Quality ◽  
Agricultural Land ◽  
Organic Matter Content ◽  
Chemical Properties ◽  
Matter Content ◽  
Soil Attributes ◽  
Essential Components ◽  
Agricultural Land Management ◽  
Physical And Chemical

Soil, itself means Soul of Infinite Life. Soil is the naturally occurring unconsolidated or loose covering on the earth’s surface. Physical properties depend upon the amount, size, shape, arrangement, and mineral composition of soil particles. It also depends on the organic matter content and pore spaces. Chemical properties depend on the Inorganic and organic matter present in the soil. Soils are the essential components of the environment and foundation resources for nearly all types of land use, besides being the most important component of sustainable agriculture. Therefore, assessment of soil quality and its direction of change with time is an ideal and primary indicator of sustainable agricultural land management. Soil quality indicators refer to measurable soil attributes that influence the capacity of a soil to function, within the limits imposed by the ecosystem, to preserve biological productivity and environmental quality and promote plant, animal and human health. The present study is to assess these soil attributes such as physical and chemical properties season-wise.

Behaviour of the fecal pollution indicators in a soil irrigated with treated wastewater under onsurface and subsurface drip irrigation

2000 ◽  
Vol 42 (1-2) ◽  
pp. 75-79 ◽  
Author(s):  
C. Campos ◽  
G. Oron ◽  
M. Salgot ◽  
L. Gillerman
Keyword(s):  
Organic Matter ◽  
Drip Irrigation ◽  
Organic Matter Content ◽  
Fecal Pollution ◽  
Fecal Coliforms ◽  
Subsurface Drip Irrigation ◽  
Treated Wastewater ◽  
Reclaimed Wastewater ◽  
Pollution Indicators ◽  
Subsurface Drip

A critical objective for any wastewater reuse programme is to minimise health and environmental hazard. When applying wastewater to soil–plant systems, it is to be noted that the passage of water through the soil considerably reduces the number of microorganisms carried by the reclaimed wastewater. Factors that affect survival include number and type of microorganisms, soil organic matter content, temperature, moisture, pH, rainfall, sunlight, protection provided by foliage and antagonism by soil microflora. The purpose of this work was to examine the behaviour of fecal pollution indicators in a soil irrigated with treated wastewater under onsurface and subsurface drip irrigation. The experiment was conducted in a vineyard located at a commercial farm near the City of Arad (Israel). Wastewater and soil samples were monitored during the irrigation period and examined for fecal coliforms, somatic and F+ coliphages and helminth eggs. Physico-chemical parameters were controlled in order to determine their relationship with removal of microorganisms. The results showed high reduction of the concentration of microorganisms when wastewater moves through the soil; and a good correlation between the reduction of fecal pollution indicators and moisture content, organic matter concentration and pH. The application of secondary treated domestic wastewater in this specific soil and under these irrigation systems affect the survival of microorganisms, thus reducing the health and environmental risk.

Sign in / Sign up

Export Citation Format

Share Document