Measurement Of Organic Carbon Content Research Articles

Evaluation method of oil saturation index OSI for shale oil reservoir based on well logging data

Oil saturation index (OSI) serves as an important indicator for potential movable hydrocarbons evaluation of shale oil reservoirs, which is mainly obtained through rock pyrolysis experiments. A new method is proposed to evaluate the OSI of shale quantitatively by NMR logging. The OSI value can be accurately obtained through the experimental measurement of organic carbon content (TOC) and rock pyrolysis of shale samples, which can identify the development of mobile hydrocarbons. Subsequently, the mobile fluid porosity can be obtained based on NMR logging. In order to establish the relationship between OSI value and mobile fluid porosity, it is important to determine the T2 cutoff value corresponding to the mobile fluid porosity. Take shale samples from the first member of the Qingshankou Formation (“Qing 1 Member”) as an example, based on 2D NMR experimental analysis in three different states (original, dried state at 105°C, saturated kerosene), the NMR T2 cutoff value of movable fluid porosity in the shale of Qing 1 Member is clarified as 8 ms. Integrating rock pyrolysis and 2D NMR experiments, it suggests that the NMR bin porosity with T2>8 ms has a good linear relationship with the OSI value obtained by pyrolysis analysis. The NMR bin porosity with T2> 8 ms reflects the OSI value of shale effectively. The larger the NMR bin porosity with T2>8 ms, the higher the mobile oil content of shale reservoir, which is consistent with the understanding of oil-bearing large pores in the Gulong Shale. The NMR bin porosity can continuously evaluate the vertical variation of the mobile hydrocarbon content. Compared with the traditional experimental measurement of finite depth points, this method has significant advantages, and can avoid the possibility of missing potentially movable oil layers.

Measurement of organic carbon content during the growth of soot particles in propane normal and inverse diffusion flames using a multi-wavelength light extinction method

This paper proposes a novel method for in situ determination of the organic carbon (OC) content in soot particles using a multi-wavelength light extinction method for propane normal diffusion flames (NDFs) and inverse diffusion flames (IDFs). Light extinction at wavelengths of 450–900 nm was measured using white light and a spectrometer. The light extinction coefficient plotted as a function of the reciprocal wavelength revealed the extinction characteristics of the soot particles. Additionally, the wavelength dependency of the OC content in soot was determined using the ratio of the slopes at short and long wavelengths. For the NDF, the slope ratio was higher near the flame center and upstream of the flame, whereas for the IDF, a constant of slope ratio was observed in all measurement positions. By comparing the slope ratio with the soot component analysis, a quantitative relationship was derived between the organic mass fraction (OMF) of the soot and the slope ratio. The OMF was 0.1–0.27 depending on the position in the NDF, and the IDF showed a similar OMF of 0.25–0.32 at all measurement positions. The results of transmission electron microscopy and electron energy loss spectroscopy also confirmed the validity of the OMF measurement.

Effect of hydrothermal conditions on microstructures of pure and doped CeO2 nanoparticles and their photo-catalytic activity: degradation mechanism and pathway of methylene blue dye

CeO2, Sm and Gd doped CeO2 were synthesized using the hydrothermal route. The influence of synthesis conditions on the crystal structure, particle size and microstructure was investigated. The prepared nanoparticles were characterized using X-ray powder diffraction, FT-Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. The photo-catalytic degradation of methylene blue was examined under UV light using the prepared nanoparticles at different conditions (pH, dye concentration, catalyst dosage). The photo-catalytic activity of CeO2 was kinetically enhanced by trivalent cations (Gd+3 and Sm+3) doping. The results displayed the excellent catalytic activity of the Gd doped CeO2 as compared to that Sm doped CeO2 and the undoped one. The degradation pathways of MB were followed using liquid chromatography/mass spectroscopy (LC/MS), it was found that MB was degraded completely into safe byproducts. The total organic carbon content measurements confirmed the results obtained by LC/MS.

Microwave synthesis of pure and doped cerium (IV) oxide (CeO2) nanoparticles for methylene blue degradation.

Cerium (IV) oxide (CeO2), samarium (Sm) and gadolinium (Gd) doped CeO2 nanoparticles were prepared using microwave technique. The effect of microwave irradiation time, microwave power and pH of the starting solution on the structure and crystallite size were investigated. The prepared nanoparticles were characterized using X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscope. The photocatalytic activity of the as-prepared CeO2, Sm and Gd doped CeO2 toward degradation of methylene blue (MB) dye was investigated under UV light irradiation. The effect of pH, the amount of catalyst and the dye concentration on the degradation extent were studied. The photocatalytic activity of CeO2 was kinetically enhanced by trivalent cation (Gd and Sm) doping. The results revealed that Gd doped CeO2 nanoparticles exhibit the best catalytic degradation activity on MB under UV irradiation. For clarifying the environmental safety of the by products produced from the degradation process, the pathways of MB degradation were followed using liquid chromatography/mass spectroscopy (LC/MS). The total organic carbon content measurements confirmed the results obtained by LC/MS. Compared to the same nanoparticles prepared by another method, it was found that Gd doped CeO2 prepared by hydrothermal process was able to mineralize MB dye completely under UV light irradiation.

Метрологічне забезпечення вимірювання вмісту загального органічного вуглецюу мінеральних водах

Метрологічне забезпечення вимірювання вмісту загального органічного вуглецюу мінеральних водах

Accurate and Precise Measurement of Organic Carbon Content in Carbonate-Rich Soils

Accurate measurement of soil organic carbon (SOC) is dependent on precise and fast methods for the separation of organic and inorganic carbon. The widely used methods involving thermal decomposition of soil samples at a specific temperature in an automated carbon (C) analyzer are susceptible to interference by carbonates and overestimation of organic C, and thus removal of carbonates by acid pretreatment of samples is recommended. Two carbonate-removal pretreatments including hydrochloric (HCl) acid addition and HCl fumigation are compared using the calcium carbonate (CaCO3) standard and soil samples of varying SOC contents. Both pretreatment methods provided similar measurements of organic C, indicating that both methods are efficient in removal of carbonates present in the soil. However, the HCl fumigation method exhibited greater accuracy and precision compared to the HCl addition method. Hence, SOC measurement procedure involving HCl fumigation as a pretreatment for the removal of carbonates is recommended for carbonate-rich soils.

Radiation induced degradation of ketoprofen in dilute aqueous solution

The intermediates and final products of ketoprofen degradation were investigated in 0.4mmoldm−3 solution by pulse radiolysis and gamma radiolysis. For observation of final products UV−vis spectrophotometry and HPLC separation with diode array detection were used, and for identification MS was used. The reactions of •OH lead to hydroxycyclohexadienyl type radical intermediates, in their further reactions hydroxylated derivatives of ketoprofen form as final products. The hydrated electron is scavenged by the carbonyl oxygen and the electron adduct protonates to ketyl radical •OH is more effective in decomposing ketoprofen than hydrated electron. Chemical oxygen demand and total organic carbon content measurements on irradiated aerated solutions showed that using irradiation technology ketoprofen can be mineralised. The initial toxicity of the solution monitored by the Daphnia magna test steadily decreases with irradiation. Using 5kGy dose no toxicity of the solution was detected with this test.

Mineralization of aqueous phenolate solutions: A combination of irradiation treatment and wet oxidation

Wet oxidation (high-temperature, high-pressure oxidation of organic wastes in aqueous solution) and radiation technology were combined in γ-ray and electron beam induced oxidation of 4×10−4–1×10−2moldm−3 Na-phenolate solutions in a wide O2 concentration (1–20bar pressure) and absorbed dose (0–50kGy) range. Most experiments were made in stainless steel high pressure autoclave equipped with magnetic stirrer. The rate of oxidation was followed by chemical oxygen demand and total organic carbon content measurements. The rate was similar in γ-ray and pulsed electron beam irradiation and increased with O2 concentration in the liquid.

Radiological and hyperfine characterization of soils from the Northeastern region of the Province of Buenos Aires, Argentina

The activity concentrations of both natural (238U and 232Th chains and 40K) and anthropogenic (137Cs) radionuclides down along the soil profile have been determined in soil samples collected from inland and coastal areas of the La Plata River, located in the Northeastern region of the Province of Buenos Aires, Argentina. These studies were complemented with 57Fe Mossbauer spectroscopy characterization, pH, texture and organic carbon content measurements. From Mossbauer results, the sample compositions differ from one area to the other. Spectra from both soil samples are dominated by the Fe3+ paramagnetic signal. For soil samples from the coastal area, the α-Fe2O3 contribution is lower, Fe3O4 was not detected, and the relative areas of each spectral contribution are nearly constant with depth. For samples from the inland area, the Fe3+ paramagnetic fraction increases up to 82%, mainly at the expense of the magnetically ordered phase. The main observed activity originates from the decay of 40K (540–750 Bq/kg), followed by 238U (60–92 Bq/kg) and 232Th (37–46 Bq/kg) chains. The activity of 235U was in all the cases lower than the detection limit (LD = 0.02 Bq/kg). The only determined anthropogenic nuclide was 137Cs, arising from the fallout of the Southern Hemisphere nuclear weapon tests. Three of the observed differences in the depth distributions can be described by the dispersion-convection model. A correlation between the natural nuclide activities and the Mossbauer relative fractions was found, whereas no correlation was found between the 137Cs profile and the relative fraction of Fe3O4 or with other iron species.

The Role of Ozonation and Activated Carbon Filtration in the Natural Organic Matter Removal from Drinking Water

Aquatic natural organic matter is one of the most important problems in the drinking water treatment process design and development. In this study, the removal of the natural organic matter was followed both in the full-scale drinking water treatment process and in the pilot-scale studies. The full-scale process consisted of coagulation, flocculation and flotation, sand filtration, ozonation, activated carbon filtration and disinfection. The aim of the pilot study was to investigate the influence of the dose and contact time of ozonation, and also the impact of activated carbon filtration, on the removal efficiency of organic matter. Several methods, including high-performance size-exclusion chromatography, total organic carbon content and assimilable organic carbon content measurements were used to characterize the behaviour of organic matter and its removal efficiency. On the full-scale process, total organic carbon was removed by over 90 %. According to size-exclusion measurements, chemical coagulation removed the high molar mass organic matter with an efficiency of 98 %. The ozonation further removed the smaller molar mass fraction compounds by about 27%, while residual higher molar mass matter remained quite unaltered. Activated carbon filtration removed primarily intermediate and low molar mass organic matter. In the pilot-tests, conducted with sand filtered water from the full-scale process, it was noticed, that the ozonation removed primarily smaller organic compounds. The amount of assimilable organic carbon increased with increasing ozone dose, up to 0.4 mg l−1 with the highest ozone dose of 4.0 mg l-1. The activated carbon filtration removed the assimilable organic carbon. Total organic carbon content was not reduced in ozonation.

Photo-assisted Fenton type processes for the degradation of phenol: A kinetic study

In this study the application of advanced oxidation processes (AOPs), dark Fenton and photo-assisted Fenton type processes; Fe 2+/H 2O 2, Fe 3+/H 2O 2, Fe 0/H 2O 2, UV/Fe 2+/H 2O 2, UV/Fe 3+/H 2O 2 and UV/Fe 0/H 2O 2, for degradation of phenol as a model organic pollutant in the wastewater was investigated. A detail kinetic modeling which describes the degradation of phenol was performed. Mathematical models which predict phenol decomposition and formation of primary oxidation by-products: catechol, hydroquinone and benzoquinone, by applied processes were developed. The study also consist the modeling of mineralization kinetic of the phenol solution by applied AOPs. This part, besides well known reactions of Fenton and photo-Fenton chemistry, involves additional reactions which describe removal of iron from catalytic cycle through formation of ferric complexes and its regeneration induced by UV radiation. Phenol decomposition kinetic was monitored by HPLC analysis and total organic carbon content measurements (TOC). Complete phenol removal was obtained by all applied processes. Residual TOC by applied Fenton type processes ranged between 60.2 and 44.7%, while the efficiency of those processes was significantly enhanced in the presence of UV light, where residual TOC ranged between 15.2 and 2.4%.

Soil Biological Activities in Monitoring the Bioremediation of Diesel Oil-Contaminated Soil

The effects of two different biological treatments on hydrocarbon degradation and on soil biological activities were determined during a 100-d incubation period. An evaluation of soil biological activities as a monitoring instrument for the decontamination process of diesel-oil contaminated soil was made using measurements of organic carbon content, soil microbial respiration, soil ATP and dehydrogenase, β-glucosidase, lipase enzyme activities. Five samples were used: S (control, uncontaminated soil), CS (contaminated soil), SCS (sterilized contaminated soil), CFS (contaminated soil plus N and P), CCS (contaminated soil plus compost). The relationships between soil parameters and the levels of total petroleum hydrocarbons (TPH) residues were investigated. Results showed that inorganic nutrients NP and compost stimulated hydrocarbon biodegradation but not all biological activities to a significant extent. The residual hydrocarbon trend was positively related with that of the organic C content, microbial respiration and with β-glucosydase activity, while both soil lipase and dehydrogenase activities were negatively related with the hydrocarbon trend. Lipase activity was found to be the most useful parameter for testing hydrocarbon degradation in soil.

Paleoceanographic significance of sediment color on western North Atlantic drifts: I. Origin of color

Reflectance spectra collected during ODP Leg 172 were used in concert with solid phase iron chemistry, carbonate content, and organic carbon content measurements to evaluate the agents responsible for setting the color in sediments. Factor analysis has proved a valuable and rapid technique to detect the local and regional primary factors that influence sediment color. On the western North Atlantic drifts, sediment color is the result of primary mineralogy as well as diagenetic changes. Sediment lightness is controlled by the carbonate content while the hue is primarily due to the presence of hematite and Fe 2+/Fe 3+ changes in clay minerals. Hematite, most likely derived from the Permo-Carboniferous red beds of the Canadian Maritimes, is differentially preserved at various sites due to differences in reductive diagenesis and dilution by other sedimentary components. Various intensities for diagenesis result from changes in organic carbon content, sedimentation rates, and H 2S production via anaerobic methane oxidation. Iron monosulfides occur extensively at all high sedimentation sites especially in glacial periods suggesting increased high terrigenous flux and/or increased reactive iron flux in glacials.

A sediment and organic carbon budget for the Canadian Beaufort Shelf

The Arctic Ocean accounts for 20% of the world's continental shelves. Because the Arctic is sensitive to global change, budgets of organic carbon for its shelves are of immediate interest. The Mackenzie Shelf of the Canadian Beaufort Sea is the best North American proxy for the enormous Eurasian Shelves (large area, large river input), and the only site for which a complete organic carbon budget can be attempted, due to an extensive data base. A mass balance for the Mackenzie Shelf has been constructed for sediments, terrestrial organic carbon, and primary produced carbon. We have considered allochthonous inputs from the Mackenzie River, from coastal erosion, from smaller rivers, from groundwater, from the atmosphere and import by ice. The Mackenzie River dominates the supply to the Beaufort shelf of inorganic sediment (127 Mt a −1) and paniculate and dissolved terrestrial carbon (2.1 Mt a −1 POC, 1.3 Mt a −1 DOC). The combined input from all other sources contributes only about 5% of the Mackenzie load. Using sediment accumulation data we estimate that about half of the sediment supply is trapped in the delta, about 40% on the shelf and the remainder escapes the shelf edge by various processes. Autochthonous primary production in the delta and on the shelf adds a further 3.3 Mt a −1 of particulate organic carbon. A box model has been constructed to account for sediment, terrestrial organic carbon and primary produced carbon. Whereas about 60% of the terrestrial POC is preserved in delta and shelf sediments, it appears that most (97%) of the primary produced carbon is recycled and not preserved in sediments. Confidence in the budget should be improved by focusing future research on the determination of modern sedimentation rates on the delta and shelf, measurement of organic carbon content of deltaic sediments, determination of primary production on the shelf, and determination of the relative proportions of terrestrial and marine organic carbon preserved in sediments.

Direct measurement of organic carbon content in soils by the Leco CR‐12 carbon analyzer

A straightforward procedure is described for soil organic carbon (C) measurement in soil samples that may contain carbonates by using the Leco CR‐12 Carbon Analyzer. At a temperature of 840°C, a measured oxygen flow of 3.6 L min‐1, lancing flow of 1.0 L min‐1, soil organic C content can be directly measured on 0.20 to 0.40 g of samples, which have previously been ground to pass 40‐mesh sieve, for most medium‐ and fine‐textured soils. The organic C is combusted and measured within 2 min. A larger sample size of up to 2.5 g is suggested for sandy soils of low organic C content.

Transports fluviaux de carbone organique par la Garonne à l'entrée de l'estuaire de la Gironde. / Fluvial transport of organic carbon by the Garonne river into the Gironde estuary

In order to draw a reliable budget of the organic matter fluxes arriving in the Gironde estuary, weekly measurements of organic carbon content in particulate and dissolved phases over three successive annual hydrological cycles were carried out in the Garonne river water, at the boundary of the estuarine system. As the sampling period presented an important hydrological deficit (about 40%). the estimated carbon budgets are much lower than those previously proposed from data of poorer quality. Nevertheless, this study allowed us to determine precisely the relationships between water discharge, suspended matter concentration and organic carbon content, to better define the origins of organic matter (its phytoplanctonic and pedological components) and to highlight effects of dryness (dissolved organic carbon contents ; impact of a flood following a long period of low discharge). Finally, by applying the different models developed for the study period cycles to an average year (mean annual river discharge of 650 m³.s⁻¹). it is proposed mean carbon fluxes entering the estuary. It appears that, by comparing these fluxes to those exported into the ocean at the mouth of the Gironde estuary. about 55% of the particulate organic carbon input disappear in the estuary after mineralization. This biogeochemical process is confirmed by different studies on the high CO₂ emission into these continent-ocean interfaces.

Petroleum Source Beds: Environment of Deposition and Stratigraphy: ABSTRACT

Measurement of organic carbon content, alone, is insufficient to identify potential oil source beds because terrestrial OM (Organic Matter), oxidixzed planktonic OM, or reworked OM from a previous sedimentary cycle can create misleadingly high levels of organic carbon in marine sediments. Consequently, the presence of an organic facies, as identified End_Page 2465------------------------------ by kerogen typing, is essential to establish oil source rock character. Kerogen is mainly dependent on the origin of the precursor plant remains (whether planktonic or terrestrial) and on the oxidizing (oxic) or reducing (anoxic) character of the early depositional environment. Oxygen depletion, sufficient to arrest or minimize bioturbation at the benthic boundary, enhances oil source bed deposition, because it leads to almost entirely anaerobic microbial reworking of planktonic remains. This of bacterial reworking favors the preservation and concentration of lipids in the residual OM, leading to the formation of oil-prone koergens (types I and II). Marine oil source bed deposition and occurrence are controlled mainly by factors relevant to qualitative organic matter preservation during early sedimentation, rather than by planktonic productivity in the shallow euphotic zone. Many areas of high planktonic productivity, today, do not correspond with zones of high organic enrichment in bottom sediments (e.g., Grand Banks of Newfoundland, Antarctica, Australia, Northwest Shelf, Northeast Brazilian Shelf) because of oxic conditions, commonly in combination with low sedimentation rates. Conversely, whenever zones of high productivity, such as those present in some coastal upwellings, are underlain by anoxic water layers, then prolific oil source bed deposition does occur. Zones where deep ventilation and thus oxic conditions prevail at sea bottom are much more common than zones of oxygen depletion. Persistent oxic conditions at the benthic boundary lead to deposition of gas-prone, type III, to non-source, type IV organic facies, depending on sedimentation rate and amount of terrestrial organic matter input. Such unfavorable organic facies, resulting from past oxic conditions, have been commonly recognized as stratigraphically widespread under continental margins and in cratonic basins, regardless of past water depth. Thus, prolific oil source beds, in terms of relative rock volumes, are the exception in most sedimentary basins. These observations are compatible with the functioning of the carbon cycle: efficient organic matter recycling through mineralization, rather than enhanced preservation, is the most common and most probable fate of dead organic matter in the environment. Geochemical-sedimentologic evidence suggests that potential oil source beds are and have been deposited in the geologic past in four main anoxic settings as follows: 1. Large anoxic lakes: Permanent stratification promotes development of anoxic bottom water, particularly in large lakes which are not subject to seasonal overturn, such as Lake Tanganyika. Warm equable climatic conditions favor lacustrine anoxia and nonmarine oil source bed deposition. 2. Anoxic silled basins: Only those landlocked silled basins with positive water balance tend to become anoxic. The Baltic and Black Seas are examples. In arid-region seas (Red and Mediterranean Seas), evaporation exceeds river inflow, causing negative water balance and well-oxygenated bottom waters. Silled basins should be prone to oil source bed deposition at times of worldwide transgression, at high and low paleolatitudes. Silled-basin geometry, however, does not automatically imply the presence of oil source beds. 3. Anoxic layers caused by upwelling: These develop only when the oxygen supply in deep water cannot match demand owing to high surface biologic productivity. Examples are the Benguela Current and Peru coastal upwelling. No systematic correlation exists between upwelling and anoxic conditions because deep oxygen supply is commonly sufficient to match strongest demand. Oil source beds and phosphorites resulting from upwelling are present preferentially at low paleolatitudes and at times of worldwide transgression. 4. Open-ocean anoxic layers: These are present in the oxygen-minimum layers of the northeastern Pacific and northern Indian Oceans, far from deep, oxygenated polar water sources. They are analogous, on a smaller scale, to worldwide anoxic events which occurred at global climatic warmups and major transgressions, as in Late Jurassic and middle Cretaceous times. Known marine oil source bed systems are not randomly distributed in time but tend to coincide with periods of worldwide transgression and oceanic anoxia. Recognition of the proposed anoxic models in ancient sedimentary basins helps in regional stratigraphic mapping of oil shale and oil source beds. Furthermore, explanation and prediction of the most favorable zones for widespread and prolific oil source bed occurrence can be achieved by paleogeographic reconstructions (plate tectonics, paleoclimate, and paleo-oceanography) conducted in conjunction with seismic stratigraphy and regional geochemical studies. End_of_Article - Last_Page 2466------------

Organic matter fluxes from sediment traps in the equatorial Atlantic Ocean

The vertical flux of particulate organic matter to the ocean floor is controlled by complex remineralization and transport processes. Rapidly sinking, large (>32 µm) particles may account for most of the vertical mass flux1–3. Experiments involving collection of sedimenting particles in traps deployed at varying depths in the water column provide a way of assessing these processes directly2–12. Measurement of organic carbon content of trap material may lead to a general understanding of the flux of particulate organic matter to the sea floor3,8–10. However, details of the transport and transformation phenomena involving sinking particulate organic material can be elucidated only by determining distributions of specific organic compounds associated with the particles11,12. We report here direct flux measurements and composition of lipids obtained by organic geochemical studies of particulate material collected in a deep-sea moored sediment trap experiment in the equatorial Atlantic Ocean.

STUDIES WITH WASTE SULPHITE LIQUOR: II. WASTE SULPHITE LIQUOR AS A SOIL AGGREGATING AGENT

Ammonium-base waste sulphite liquor (solids) (W.S.L.S.) was added to three soils and incubated for 7 weeks. Weekly measurements of organic carbon content and aggregation showed an increase in aggregation to a maximum at 3 weeks, followed by a decline and then by a second increase at 6 weeks. This increase and decline in aggregation paralleled very closely the corresponding biological activity as indicated by loss of organic carbon. Results suggest that decomposition of sugars is responsible for the⁁ development of aggregation in the early stages of incubation and that the ligninsulphonates may have an effect after further incubation.The aggregating effect of W.S.L.S. was compared with that of two synthetic conditioners HPAN and VAMA. The effect of all materials varied considerably with the clay content of the soil. Results indicate that W.S.L.S. is about 1/16 as effective as HPAN and about 1/36 as effective as VAMA.