Collection Of Gas Samples Research Articles

Quantification of Mutual Mass Transfer Coupled with Heat Transfer for CO2/C3H8-Heavy Oil Systems Under Reservoir Conditions

Summary Experimental and theoretical methods have been developed to quantitatively assess the heat and bidirectional mass transfer between a hot solvent (i.e., CO2 and C3H8) and heavy oil. Experimentally, we performed diffusion experiments for hot solvent-heavy oil systems at elevated pressures and temperatures using a pressure/volume/temperature (PVT) setup. The dynamic volume change of the oleic phase has been continuously measured and recorded throughout each experiment. At the conclusion of each test, gas chromatography (GC) analysis has been conducted on the collected gas samples. Theoretically, a diffusion model has been integrated with heat transfer to determine the mutual diffusivities for the hot CO2/C3H8-heavy oil systems by incorporating the volume-translated (VT) Peng-Robinson equation of state (PR EOS) together with the modified alpha functions and acentric factor redefined at Tr = 0.6. The mutual diffusivities can be determined once the computed parameters, including oil swelling factors and gas composition, match the measured ones. Due to solvent dissolution, heavy oil is found to swell faster initially as both heat and mass transfer contribute to the oil swelling. After the system temperature is stabilized, the volume of the diluted oil expands slowly as a result of the ongoing mass transfer. The extraction process was evident during the experiments with the presence of oil components in the collected gas samples, and it was found to be stronger at a higher temperature. The diffusivities determined using different alpha functions in the PR EOS are similar, but the newly defined acentric factor with the optimum alpha function minimizes the deviation between the measured and computed parameters. In addition to new experimental data, the bidirectional mass transfer between solvent and heavy oil has been quantified for the first time by coupling heat transfer.

Geochemical evidence for biodegradation in high-rank coals from Qinshui Basin, North China

Understanding the generation of secondary microbial methane (SMM) is important for the evaluation of natural gas resources and instructive for the stimulation of methane production. Coal seams are popular targets for extracting in situ preserved methane and studying microbe-stimulated methane yield. However, few studies have been done on overmature coals. Here we collected gas samples from coals varying from bituminous to meta-anthracite in the Qinshui Basin, North China, and analysed the molecular and stable isotopic compositions to systematically evaluate the influence of biodegradation in high-rank coals in geological settings. The stable isotope signatures (δ13C and δD) of methane are dominated by the thermal decomposition of organic matter in deep coals but inconsistent with the maturity rank of shallow burial coals. The decoupling of coal maturity with C1/C2+ ratios and δ13C-CH4 values, and positive δ13C-CO2 values (−9.2 to +24.4 ‰) suggest biodegradation of light wet gases (C2+ components) and CO2 reduction. Negative trends between δ13C-CO2 and CH4/CO2 in shallow burial coal seams reveal the mutual conversion of CH4 and CO2 and carbon isotope exchange, driven by microorganisms. The calculated isotopic temperatures (33–328 °C) based on the carbon isotope fractionation factors between CH4 and CO2 (1.024–1.069) demonstrate that carbon isotope exchange is prevalent in high-rank coals. It also reveals that the burial depth is an imperative factor in controlling microbial environments and thus the biodegradation process. This study implicates the potential of high-rank coals as the target for microbial-enhanced methane recovery and also implies that microorganisms are widely involved in reservoir carbon cycling.

Measurement and Evaluation of Greenhouse Gases with Cloud Based Logging

Abstract: Robust measurements of natural Greenhouse Gases emissions are vital for evaluating regional to global carbon budgets and for assessing climate feedbacks on natural emissions to improve climate models. To capture and analyze the high temporal variability of these fluxes in a well-defined footprint, we designed and developed an inexpensive device. In addition to automatically collect gas samples from footprint for subsequent various analyses in the laboratory, this device also utilizes a low cost carbon dioxide sensor, Temperature and Humidity Sensor, GPS sensor to measure Greenhouse Gases (GHG). Each of the devices modules were equipped with an ESP32 Wi-Fi, NodeMCU and Transceiver module to enable a local radio communication with the ground receiving Station for onward processing to cloud. This study shows the potential of a low cost and low instrument, open source software for devices development as automatic sensor network system to study GHG fluxes. Results obtained from research is shown as follows: CO2 (360 to 455 ppm), Temperature (26.9 OC to 30.9OC) and Humidity (35.5% to 36.5%) which is good for human health. However, this research proves human capacity building and promotion of open data access for research.

CH4 and N2O Emissions of Undrained and Drained Nutrient-Rich Organic Forest Soil

The ability to accurately assess the impact of organic soil drainage on greenhouse gas emissions (GHG) is still limited. Methane (CH4) emissions are characterized by significant variations, and GHG emissions from nutrient-rich organic soil in the region have not been extensively studied. The aim of this study was to assess CH4 and nitrous oxide (N2O) emissions from nutrient-rich organic soil in hemiboreal forests to provide insights into their role in regional GHG balance. Over the course of one year, CH4 and N2O emissions, as well as their affecting factors, were monitored in 31 forest compartments in Latvia in both drained and undrained nutrient-rich organic soils. The sites were selected to include forests of different ages, dominated by silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karsten), and black alder (Alnus glutinosai (L.) Gärtner), as well as clearcuts. Soil GHG emissions were estimated by collecting gas samples using the closed manual chamber method and analyzing these samples with a gas chromatograph. In addition, soil temperature and groundwater level (GW) measurements were conducted during gas sample collection. The mean annual CH4 emissions from drained and undrained soil were −4.6 ± 1.3 and 134.1 ± 134.7 kg CH4 ha−1 year−1, respectively. N2O emissions from undrained soil (4.1 ± 1.4 kg N2O ha−1 year−1) were significantly higher compared to those from drained soil (1.7 ± 0.6 kg N2O ha−1 year−1). In most of the study sites, undrained soil acted as a CH4 sink, with the soil estimated as a mean source of CH4, which was determined by one site where an emission hotspot was evident. The undrained soil acted as a CH4 sink due to the characteristics of GW level fluctuations, during which the vegetation season GW level was below 20 cm.

Determination of mutual diffusivity of CO2/C3H8-heavy oil systems with consideration of natural convection under reservoir conditions

By performing dynamic volume analysis, we developed and applied an experimental and theoretical technique to determine mutual diffusivity (i.e., diffusivity of a gas component in an oil phase and that of the extracted oil components in the gas phase) of CO2/C3H8-heavy oil systems in the presence of natural convection under reservoir conditions. Experimentally, diffusion tests are conducted for CO2/C3H8-heavy oil systems at high pressures and elevated temperatures with a PVT setup, while swelling factors of the oil phase are measured and recorded continuously. We have collected gas and oil samples at end of the test for gas chromatography (GC) and oil compositional analysis. Theoretically, mutual diffusivity between a solvent and heavy oil can be determined once the discrepancies between the measured and calculated parameters, including swelling factors and gas compositions, have been minimized. The diffusivities of both solvents (i.e., CO2 and C3H8) and oil components are found to increase with pressure and temperature. Except for the dissolution of solvent(s) into heavy oil due to concentration difference, there exists an obvious extraction process from the oil to gas phases during each experiment at elevated temperatures as light-medium components (i.e., C1-C4 and C6-C8) have been detected in the collected gas samples at the end of the test, during which the oil swelling effect is diminished at its late period when the solvent-heavy oil system approaches its equilibrium state. Compared to the CO2-heavy oil systems, more light components have been detected for the C3H8-heavy oil systems, indicating that stronger extraction occurs when adding C3H8 to the heavy oil at elevated temperatures. Since natural convection has an opposite direction from molecular diffusion, separating the former from the latter results in larger diffusion coefficients of CO2 and C3H8. In addition to new experimental data, both diffusivity of a solvent/CO2 in heavy oil and that of the extracted oil components in the gas phase are quantified in a more complex solvent(s)/CO2-heavy oil system at high pressures and elevated temperatures, not only serving as the benchmark for future studies to consider the contribution of temperature and porous media, but also allowing us to evaluate and optimize the hybrid solvent-steam method in a heavy oil reservoir within a unified and consistent framework.

Development of a Nondestructive Moldy Coffee Beans Detection System Based on Electronic Nose

Coffee drinks prepared from moldy coffee beans can adversely affect human health. No convenient screening method for detecting the smell of stale coffee beans exists. Accordingly, this study developed an electronic nose (E-nose) system for detecting the smell of coffee beans. This system comprises an environmental control system, a sensor array, and a data signal readout system. The system can distinguish various degrees of mold on coffee beans through the recognition of the smell of the coffee beans. In this study, we established a standard operating procedure to collect gas samples from coffee beans in a temperature- and humidity-controlled environment and recorded changes in the signals by using the sensor array after introducing the target gas. Features were first extracted from the collected data, then dimensionality reduction methods such as principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to these features. Thus, their complexity was reduced, and the noise was eliminated. K-nearest neighbor (KNN) and support vector machine (SVM) were adopted as classification algorithms, and the classification accuracy of the proposed system reached 91.77%.

CAGE13-5 Cruise Report: Investigation of glacial geomorphology in the Storfjordrenna.

The course GEO‐8144/3144 Marine geology and geophysics cruise, taught at the University of Tromsø, is part of the obligatory courses to be completed by PhD students affiliated with the AMGG research school and yields 5 credits (ECTS). Participants include scientific staff and students.
 This cruise was conducted within the framework of
 
 the Norwegian Science Council (NFR) project Glaciations in the Barents Sea area (GlaciBar) and
 the trainee school in Arctic Marine Geology and Geophysics (AMGG) financed by the University of Tromsø. The cruise was funded by AMGG.
 
 The main target areas are the Storfjordbanken and Storfjordrenna south of Svalbard. The cruise addressed marine glacigenic processes of the areas, with a focus on the last glacial-interglacial cycle in order to reconstruct in a more detail way the retreat of the Barents Sea–Svalbard Ice Sheet.
 To collect data have been used different methods and instruments, which will be described in a more detailed way in chapter 3. Below here there is only an overview:
 
 Multibeam echo sounder: Sound-wave beams are transmitted in a fan perpendicular to the ship track from a hull-mounted echo sounder. Produces high-resolution seafloor bathymetry.
 Chirp: High-resolution acoustic profiling.
 CTD (Conductivity, Temperature, Depth): Sensors installed in a frame measure CTD properties of the water column. Generally used for oceanographic studies, but here mainly to calibrate the multibeam data from calculated velocities.
 2D seismic: GI airguns and hydrophone cable (streamer).
 Sediment coring: Gravity coring.
 Gas sample collection.
 
 The targeted study area is under-explored compared to similar areas (Bjørnøyrenna) in the SW Barents Sea. The study areas in the Storfjordrenna and Stordfjorbanken are shown. Several different features have been identified on the seafloor, like MSGLs, grounding zone wedges, flares, pockmarks and ploughmarks. All these features will be described in detail in chapter 4.
 In addition, 9 gravity cores were acquired in areas likely to provide information on the timing of the formation of the sediment accumulation. The specific core locations were chosen based on information from multibeam swath bathymetry and chirp data. Furthermore, gas samples were collected from the cores from pockmarks and will be analyzed later.
 The new results add new detailed data regarding the deglaciation of the Storfjorden trough. Glacial geomorphologic features similar to the ones in Bjørnøyrenna were discovered. The observation of gas flares were the first such discovery in the northern Barents Sea. The discovery of flares and pockmarks might have a big impact on future petroleum exploration activities in the region.
 The cruise may be known as: HH_2013_GEO_8144_3144

Agreement between arterial and venous blood gas measurements in patients with sepsis and septic shock

<p>Background and Objective: Acid–base status is mandatory for clinical assessment of patients with septic shock and severe sepsis. Generally, venous blood gas sample collection is easier, however, the data regarding this approach are lesser defined in our population as a substitute for arterial blood gas (ABG) sample. The present study aimed to determine and compare the pH, pCO2, and bicarbonate levels in VBG and ABG samples in patients with sepsis and septic shock.</p>
 <p>Method: A cross sectional comparative study was conducted on 350 patients with sepsis and/or septic shock admitted to the medical emergency of Jinnah Hospital, Lahore, Pakistan. Both ABG and VBG samples were collected and pH, pCO2, and bicarbonate levels were determined by standard methods. Data were analyzed using Pearson correlation and the Bland–Altman method for bias.</p>
 <p>Results: An interclass correlation (r = 0.995, r = 0.929 and r = 0.946) was found for pH, pCO2, and bicarbonate between ABG and VBG samples, respectively. The Bland–Altman method showed a high degree of agreement for two sets of measurements; pH (bias ± SD, 0.089 ± 0.00472) and pCO2 (bias ± SD, -1.1096 ± 1.0089) with a clinically acceptable difference whereas the difference in bicarbonate measurement was found slightly higher (bias ± SD, 1.124 ± 0.674) revealing, however, a good degree of agreement with clinically acceptable bias.</p>
 <p>Conclusion: Use of a venous blood sample in patients with sepsis or septic shock is a clinically acceptable substituent for ABG measurement in evaluating acid-base status of these patients for further management.</p>

Guía de práctica clínica para toma de muestra de gases en sangre en México

In order to promote preanalytic blood gas sample quality and to standardize sample collection, transport, and preservation protocols, a multidisciplinary experts group developed Guía de práctica clínica para toma de muestra de gases en México (Clinical practice guidelines for blood gas sample collection in Mexico). It includes recommendations for request, identification and patient´s preparation, sampling indications, contraindications, simple type selection, anatomical site, use and selection of the optimal sampling materials, operating room sampling, complications, handling, transport, and simple rejection criteria.

Understanding the flux of nitrous oxide from the eucalypt soil in monoculture and Integrated Crop–Livestock–Forest systems

The Brazilian agricultural sector is largely responsible for nitrous oxide (N2O) soil emissions, mainly due to beef cattle and the use of synthetic nitrogen fertilizers. Therefore, Brazil is looking for measures, such as integrated crop–livestock– forest (ICLF), to increase productivity and reduce greenhouse gas emissions in this sector. The forest component within this system plays a positive role in the context of climate change, soil conservation, carbon dioxide (CO2) sequestration, and biodiversity protection. The aim of this study was to evaluate the effect of management and rainfall on N2O emissions in eucalypt monoculture soils and eucalypt soils in ICLF systems. Manual static chambers were used to collect gas samples, from November 2013 to October 2014, in four treatments, i.e., one eucalypt monoculture (F) and three modalities of ICLF (livestock–forest [LF], livestock–crop–forest [LCF], and integrated crop–livestock–forest [ICLF]). A gas chromatograph with an electron capture detector was used to measure the N2O concentrations. The results showed that rainfall considerably affected N2O fluxes across all the treatments, indicating that rainfall is the main factor in increasing emissions. During the wet season, the N2O levels ranged from 0.158 to 0.482 kg N-N2O ha-1 across all treatments. During the dry season, all treatments behaved like sinks of N2O. Moreover, N2O flux did not differ between the soils in the eucalypt monoculture and ICLF systems. This indicates that the forestry component in the ICLF systems did not affect N2O soil fluxes.

Sheep grazing as a strategy to manage cover crops in Mediterranean vineyards: Short-term effects on soil C, N and greenhouse gas (N2O, CH4, CO2) emissions

Sheep grazing is increasingly being considered by winegrape growers to manage cover crop growth in Mediterranean vineyards, a practice that could contribute to reducing fertilizer inputs, coupling the cycles of C and N and increasing soil health. Nevertheless, short-term increases in available soil C and N could trigger the emission of greenhouse gases (GHG). We carried out a field experiment in a Mediterranean vineyard of the Central Coast of California to investigate the short-term effects of grazing in combination with tillage on soil C, N and GHG emissions. Tillage and grazing treatments were combined in a full factorial design with 16 plots. Gas samples were collected using static chambers during the main management events from the tractor row and the soil under the vines within each plot. Gas samples were collected through two years, including two wet and two dry seasons and analyzed to assess daily fluxes and cumulative seasonal emisions of N2O, CH4 and CO2. In spring each year we collected soil samples from 0 to 15 and 15–30 cm depths of the vine and tractor rows of each plot, and from 0 to 15 cm depth at the time of gas sample collection. We observed that sheep grazing did not produce an increase in available soil N and C, but resulted in sporadic and localized peaks in daily N2O, CH4 and CO2 emissions. Nevertheless emissions were not significantly larger than non-grazed soils when extrapolated to the cumulative emissions of the whole season. The combination of tillage and grazing increased N2O emissions from the soil under the vine potentially due to increased nitrification rates. Sheep grazing and tillage did not have a significant effect on the yield and quality of the grapes during the two years of the study.

Effects of plantain in pasture on nitrous oxide emissions from cattle urine patches, as affected by urine deposition timing and soil type

ABSTRACT Two lysimeter experiments were conducted to quantify the effect of including plantain in pasture on nitrous oxide (N2O) emissions from cattle urine patches, as affected by urine deposition timing and soil type. In experiment one, two pasture types were tested: (i) perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) (PRG/WC), and (ii) perennial ryegrass/white clover/plantain (Plantago lanceolata) (PRG/WC/P) pastures, under four urine application dates (late summer, early autumn, mid-autumn, and late autumn). In experiment two, two pasture types were tested: (i) PRG/WC and (ii) PRG/WC/P on two soil types (Balmoral shallow stony silt loam and Templeton deep stone-less silt loam). Both experiments applied cow urine (700 kg N ha−1) and collected gas samples using a closed chamber method. In experiment one and two, the addition of plantain to pasture had no significant effect on N2O-N emissions. Soil type had no significant effect on N2O-N emissions. However, urine application timing had a significant effect, with February having the highest average N2O-N emissions (9.0 kg N2O-N ha−1), followed by March (3.0 kg N2O-N ha−1), April (2.7 kg N2O-N ha−1) and May (1.7 kg N2O-N ha−1). This change in N2O-N emissions is attributed to cooler conditions reducing microbial activity, subsequently reducing nitrification and denitrification rates.

Plants are a natural source of nitrous oxide even in field conditions as explained by 15N site preference

Plants are either recognized to produce nitrous oxide (N2O) or considered as a medium to transport soil-produced N2O. To date, it is not clear whether in their habitat plants conduit N2O produced in soil or are a natural source. We aimed to understand role of plants in N2O emissions in field conditions. Therefore, rubber plants (Ficus elastica) were planted in the field; then plant and soil chambers were deployed simultaneously to collect gas samples, and 15N site preference (SP) of N2O was evaluated. The mean SP values of plant and soil emitted N2O were −20.85 ± 2.8‰ and −8.85 ± 1.08‰, respectively, and were significantly different (p < 0.0001); while bulk 15N of plant and soil emitted N2O were −10.83 ± 3.33‰ and −22.56 ± 3.37‰, respectively and were similar (p = 0.06). In the current study, soil always acted as a source of N2O, while plants were both source and sink. Plant and soil N2O fluxes had significant positive exponential relationship with both soil and air temperature. Soil water-filled pore space (WFPS) had significant negative linear relationship with only soil N2O fluxes. Plant N2O fluxes had significant positive linear relationship with plant respiration rates and negative linear relationship with plant surface areas. Based on the relationship between plant respiration rates and N2O fluxes, we suggest that mitochondria are the possible sites of N2O formation in plant cells while the relationship between plant surface areas and N2O fluxes suggests that roots are the parts of its formation in natural and field conditions. Our results suggest that plants are a natural source of N2O even at field conditions and challenge a view that plants are a medium to transport soil-produced N2O into the atmosphere.

Formation and emission characteristics of VOCs from a coal-fired power plant

Abstract On-site measurements of volatile organic compounds (VOCs) in different streams of flue gas were carried out on a real coal-fired power plant using sampling bags and SUMMA canisters to collect gas samples, filters to collect particle samples. Gas chromatography-flame ionization detector/mass spectrometry and gas chromatography-mass spectrometry was the offline analysis method. We found that the total mass concentration of the tested 102 VOC species at the outlet of wet flue gas desulfuration device was (13456 ± 47) µg·m−3, which contained aliphatic hydrocarbons (57.9%), aromatic hydrocarbons (26.8%), halogen-containing species (14.5%), and a small amount of oxygen-containing and nitrogen-containing species. The most abundant species were 1-hexene, n-hexane and 2-methylpentane. The top ten species in terms of mass fraction (with a total mass fraction of 75.3%) were mainly hydrocarbons with a carbon number of 6 or higher and halogenated hydrocarbons with a lower carbon number. The mass concentration of VOC species in the particle phase was significantly lower than that in the gas phase. The change of VOC mass concentrations along the air pollution control devices indicates that conventional pollutant control equipment had a limited effect on VOC reduction. Ozone formation potential calculations showed that aromatic hydrocarbons contributed the highest ozone formation (46.4%) due to their relatively high mass concentrations and MIR (maximum increment reactivity) values.

Technical note: Greenhouse gas flux studies: an automated online system for gas emission measurements in aquatic environments

Abstract. Aquatic ecosystems are major sources of greenhouse gases (GHGs). Robust measurements of natural GHG emissions are vital for evaluating regional to global carbon budgets and for assessing climate feedbacks of natural emissions to improve climate models. Diffusive and ebullitive (bubble) transport are two major pathways of gas release from surface waters. To capture the high temporal variability of these fluxes in a well-defined footprint, we designed and built an inexpensive device that includes an easily mobile diffusive flux chamber and a bubble counter all in one. In addition to automatically collecting gas samples for subsequent various analyses in the laboratory, this device also utilized a low-cost carbon dioxide (CO2) sensor (SenseAir, Sweden) and methane (CH4) sensor (Figaro, Japan) to measure GHG fluxes. Each of the devices was equipped with an XBee module to enable local radio communication (DigiMesh network) for time synchronization and data readout at a server controller station on the lakeshore. The software of this server controller was operated on a low-cost computer (Raspberry Pi), which has a 3G connection for remote control and monitor functions from anywhere in the world. This study shows the potential of a low-cost automatic sensor network system for studying GHG fluxes on lakes in remote locations.

Low Cost, Energy Efficient Production of Bio-Methane from Landfill Gas

As the world is currently moving fast towards globalization, industrial and technological advancement; sufficient generation and utilization of energy sources have become important issues. Presently, the main energy source is fossil fuel which is non-renewable. However, Renewable energy sources (RES) supply about 14% of the total world energy demand. The aim of this research work is to generate and study the quality of gases produced from municipal solid waste. Landfill simulating vessels, with associated piping, fitting and treatment unit, were to generate the required gas samples for the study. The test rig is intended to receive, treat and convert bio-degradable non-hazardous solid waste into pure bio-methane which is a useful renewable energy resource. The objectives of this study are to;(1) To ensure maintenance of high sanitary standards for the disposal of waste in Niger Delta University and its environs;(2) To develop waste prevention scheme via recycling and conversion of waste into bio-methane;(3) To reduce cost for the disposal of waste. A total of three gas samples were simulated; one gas sample in each of the three vessels and subjected to five different treatment resulting to fifteen gas samples (5 treatment by 3 replication experiment =15 samples) which were collected using 0.5L capacity Swagelok gas bottles and stored in large plastic coolers containing iced blocks so as to retain the quality &amp; composition of gas samples, while in transit to laboratory for analysis. The experimental gas samples were designated as samples; A1, A2, A3, A4, A5, B1, B2, B3, B4, B5, C1, C2, C3, C4 and C5 respectively. Analysis of collected gas samples was carried out at Niger Delta University central Research laboratory with support from Geospectra Engineering services &amp; consultancy laboratory, using gas chromatograph and other hi-tech equipment. Results show that; sample A1 had the highest methane content of 78.87 %. The methane contents got here are higher than those reported in some past researches. For example Polprasert (1996), reported that landfills gas is basically composed of methane (CH4, 55 to 65%). While, Larry (2011), Reported in his research on landfills gas that he recorded Methane content of between 45 – 60%. Sample A5 had the highest amount of carbon dioxide of 10.53%. While sample C2 yielded the smallest amount of CO2 of 3.94% out of the 15 gas samples that were used for this experiment. Sample A1 had the lowest moisture content of 0.5 ppm. Sample A1 also yielded the highest Gross heating value of 48.67 KJ/kg and Net heating value of 44.16 KJ/kg. From the findings of this research the following recommendations were made; That the renewable energy solutions got in this research should be commercialized by the Niger Delta University management, the federal government of Nigeria and agencies of government like; Petroleum Technology Development Fund, Tertiary Education Trust fund &amp; Nigeria content Development Board.

Explosion mechanism analysis during tunnel construction in the Zengwen Reservoir

The objective of this paper is to investigate the accident cause and uses CFD model to simulate the impact of an explosion occurred in Zengwen Reservoir. An explosion occurred during a tunnel construction at Zengwen Reservoir, which caused a cement mixer parked at the tunnel entrance to fly 10 m out, while also killing two workers inside the tunnel. In the past, it was difficult to carry out quantitative analysis for such explosions. This research conducted field investigation on the scene after the explosion to investigate the cause, while collecting gas samples within and near the tunnel entrance for GC–MS analysis. By comparing samples from different sections of the diversion tunnel, a methane concentration of 94.86% was discovered near the area of ignition. The tunnel model was built using FLACS v10.4 to simulate the explosion scenarios. Under 1.1 kg/s leakage rate (5.47% methane concentration), overpressure caused by the explosion could not reach the tunnel entrance. An increase to 1.3 kg/s leakage rate would yield an explosion overpressure of 0.44 bar, which is close to the force needed to overturn a vehicle. Other higher concentrations of methane caused overpressures exceeding that value, but were less indicative of the scenario at that time. This research showed the use of GC–MS during investigation was crucial in identification of substance composition. In addition, this case study showed FLACS software could predict and perform numerical quantification of the gas leakage and diffusion conditions, while it could also aid in the evaluation of gas explosion scenarios in accident investigations.

Deuteron Plasmas Driven to Neutrality and 4He

This paper discusses Radio Frequency (RF) applied to cavitating D2O, resulting in jet plasma implantation of charged separated electrons and a deuteron-compressed plasma pulse; these interactions involved hot charged particles at an effective temperature of 104 K in a sub-picosecond time frame A. Free electrons were focused on clustered deuterons that compressed the deuterons like a spherical piston, squeezing a Meso-Cluster (MC) of deuterons. The compressed clusters were different from the deuterium clusters used by A. Takahashi. A reaction pathway similar to muon fusion was observed. The RF applied at a deuteron resonance, produced charge neutrality in the plasma’s electromagnetic (EM) pathway where alpha production was observed. Each MC consisted of 2– 100 deuterons. Here we will use 10 deuterons to describe the MC and its alpha production, within time frame A. The changing MC density, pressure, and temperature were critical to alpha production, within time frame A. The MC volume was about 10−39 m3 and compression force was continuously applied to the MC located at the target foil (TF) surface. The heat transport was fast, and MCs were confined by electromagnetic fields (EM) tangent to the MC interface and motion of the neutralizing electrons. It is conjectured in this paper that the neutralizing plasma in time frame A produced a shockwave (SW) using a single electron to form a D atom that fused two deuterons in the MC to create an alpha. Before the fusion reaction, the surface target foil atoms were cavitating for an active period of 100 ns duration with each RF cavitation resonance cycle (see the main text in Fig 4). The physical basis for the conjectured deuteron fusion reaction consisted of a preliminary compression cycle due to the electromagnetic field applied to the deuteron MC for a few hundred femtoseconds, followed by a rapid expansion. The compression cycle produced an effective temperature sufficient to create an alpha particle from the compression of two deuterons. The expansion cycle produced a slight temperature drop, allowing a deuterium ion to recombine with a low energy electron. This produced an orbital electron capture in the MC, forming a deuterium atom that jumped a distance 60,000 times larger than the deuteron’s ionic radius. It is conjectured that this impulse fused two deuterons in the MC into an alpha particle. The Mass Spectrometer (MS) measurements of collected gas samples produced by RF MHz cavitation in Ar-saturated H2O or D2O in a target foil lattice supported this conjecture. This conjecture was only a model, as other reaction pathways likely exist. Malcolm Fowler of McFarland Instrumentation Service (AIM) performed the MS analysis for He4 in the gas-phase RF reaction products. The analysis for tritium was done by Tom Claytor of High Mesa Tech (HMT). Pd TF were checked for any 4He retained in the Pd lattice. Electron mobility and target foil crystal types (face centered or body centered) may play an important role in the location of 4He in the lattice structure.

Enzymatically catalyzed CO2 -H2 O equilibration for oxygen isotope analyses of aqueous samples.

The classic CO2 -H2 O equilibration method is a very popular technique for the measurement of the oxygen isotope composition of aqueous samples in stable isotope geochemistry. This study examined whether enzymatically controlled CO2 -H2 O equilibration by carbonic anhydrase (CA) could reduce the time for oxygen isotope equilibrium between CO2 and H2 O at 25°C. Four types of aqueous samples containing CA were equilibrated with CO2 gases using a continuous flow isotope ratio mass spectrometer equipped with an automated gas sample collection device. We examined the effect of CA concentration in an aqueous sample, the influence of drying technique for the preparation of sample vials containing dried CA, the age of CA stock solution, and the ionic strength and the oxygen isotope composition of aqueous samples. CA rapidly catalyzed the oxygen isotope exchange between CO2 and H2 O and was unaffected by drying technique or stock solution age. Compared with aqueous samples with no CA or 0.2 μmolal CA, samples containing 4μmolal CA significantly reduced the CO2 -H2 O equilibration time for deionized water and artificial seawater (ionic strength = ~0.6) from ~19 h and ~23 h to ~0.30 h and ~0.77 h, respectively at 25°C. This enzymatically catalyzed CO2 -H2 O equilibration method is time-efficient, cost-effective, requires no additional data correction procedure, and can be used for most commercially available CO2 -H2 O equilibration devices without any modification.

Sediment geochemical study of hydrocarbon seeps in Isfjorden and Mohnbukta: a comparison between western and eastern Spitsbergen, Svalbard

Methane is the most widespread volatile hydrocarbon and one of the most potent greenhouse gases. Marine sediments form the largest methane reservoir, from where large quantities of methane from gas-saturated sediments are released into the sea water and into the shallow shelf seas, through the water column almost unaltered into the atmosphere. Craters on the sea floor known as pockmarks are often related to seepage of methane-rich fluids originating either from shallow (microbial) or deep (thermogenic) sources. This paper presents the geochemical characteristics of migrating hydrocarbon gas from selected pockmarks and surrounding seabed in Isfjorden and Mohnbukta in western and eastern Spitsbergen, respectively. Collected gas samples, including wet gas fraction, were analyzed for methane concentration and methane carbon stable isotope ratio. Mixtures of microbial and thermogenic methane, together with higher homologies were found in the pockmarks as well as in the adjacent undisturbed seafloor, suggesting that the seepage activity in both areas is currently on the same level. Although the methane concentration profiles and methane stable carbon isotope ratios in Isfjorden and Mohnbukta show signs of biological oxidation and elevated concentrations of ethane/propane indicate input from deeper thermogenic sources. The gas composition and methane carbon stable isotope ratio from Isfjorden and Mohnbukta areas show similar trends, most likely due to originating in the same Mesozoic organic-rich marine mudstone.