Multi Gas Research Articles

Effects of intravenous xylazine versus dexmedetomidine premedication with ketamine-midazolam-isoflurane anaesthesia for castration in horses

The objectives of this research was to study the sedation and anaesthetic characteristics of intravenous xylazine and dexmedetomidine combined with ketamine-midazolam-isoflurane and to evaluate the cardiopulmonary effects during the anaesthetic period. Stallions were premedicated with xylazine (1.1 mg/kg IV) in Group 1 and dexmedetomidine (3.5 µg/kg IV) in Group 2. Sedation quality was evaluated and scored. General anaesthesia was achieved with ketamine (2.2 mg/kg IV) and midazolam (0.1 mg/kg IV) in both groups and anaesthesia was maintained with isoflurane inhalant in fresh oxygen gas flow (6-8 L/min). All the stallions underwent an orchiectomy by the half- closed method. Cardiovascular variables and pulmonary variables were recorded using multi gas vital sign monitor. Anaesthetic parameters, reflex status and quality of muscle relaxation were assessed. After the surgical procedure, recovery was monitored and scored on 6 point scale. Sedation score and quality was clinically better in Group 2. The difference in cardiopulmonary variables was statistically not significant. However, statistically significant changes were noticed between two groups with regard to some blood gas values during the intra-operative and at 15 min post anaesthetic period. Quality of muscle relaxation was better in group 2. Recovery was not significant. Overall quality of anaesthesia and recovery was almost similar in both the groups. In conclusion, both drug combinations produced satisfactory results for castration in the horses studied. In this study, dexmedetomidine at 3.5 µg/kg and xylazine at 1.1 mg/kg sedative doses did not result in much significant changes compared to one other.

Diagnostics and characterization of a novel multi gas layer RF atmospheric pressure plasma jet for polymer processing

The quest to employ cold plasma sources at atmospheric pressure in polymer processing has emerged as a potent driving force behind their development. Atmospheric pressure operation of plasma jets provides potential cost reductions as well as easier handling and maintenance. In addition, their unique advantage of remote operation allows the substrate to be placed outside the source boundaries. This latter feature makes it easier to process complex three-dimensional objects and to integrate plasma jets into existing production lines. Although conventional atmospheric pressure plasma jet (APPJ) sources have undergone significant advancements in their design and construction, they have reached their technical and technological thresholds in several domains, thereby also impeding further enhancements in material processing applications. To cope with this issue, this work introduces a promising APPJ (named MPPJ3) working in a three co-axial gas layer geometry, incorporating the capability of aerosol and shield gas introduction leading to a configuration rich in reactive plasma species with controllable size and suitable temperature for polymer processing. A parametric study on the novel MPPJ3 device is carried out and plasma characteristics, such as reactive plasma species and temperatures, are determined by means of optical emission spectroscopy (OES), laser scattering, and infrared (IR) camera imaging whereas the fluid dynamics are analyzed using computational fluid dynamics (CFDs) and Schlieren imaging. The obtained promising results clearly show the flexibility and adaptability of the MPPJ3 device for polymer processing applications.

Making Methane Gas from CO2 using Ni/Al2O3 Catalyst in a fixed bed reactor

CO2 emissions are a component of greenhouse gases, it is estimated that around 18.35 billion tons of CO2 are released each year (Sulistyono, 2012). This is the result of the global economic recovery from the COVID-19 pandemic. IEA data shows that industrial processes and energy combustion account for nearly 89% of the energy sector's greenhouse gas emissions by 2021, with greenhouse gas emissions from gas combustion of just 0.7%. Converting CO2 to chemicals, or hydrogenating CO2 to methane, is one way of reducing CO2 in the atmosphere. Many studies have been conducted on how CO2 turns into CH4 using various methods, catalysts and other variables. The aim of this research is to make a fixed reactor bed for CO2 methanation. In addition, this research will use a nickel catalyst with alumina support (Al2O3).The method used is in situ. In this study, CO₂ was used as a raw material with a Ni/Al2O3 catalyst. The NaOH concentration was adjusted with variations of 1M, 1.5M, 2M, 2.5M, 3M. The CO2 flow rate was adjusted with 0.1 L/Minute, 0.2 L /Minute, 3 L/Minute Operating Time 60 minutes at 55°C. For the analysis of the Methane (CH) gas produced, it will be analyzed using a Multi Gas Detector Analyzer.

Bioaugmentation Approach using Pseudomonas and Bacillus for Malodour Reduction in Poultry Feacal Waste Management

Introduction. A workable strategy is bioaugmentation, which involves introducing certain bacteria in sufficient quantities to promote biodegradation. This study focuses on isolating and utilizing malodor-reducing bacteria from fecal wastes obtained from a poultry farm in Ashi, Ibadan. Methods. Standard methods were employed to isolate and identify species of Pseudomonas and Bacillus. Quantitative detection of hydrogen sulfide gas and other relevant parameters was performed using MSA Orion and Multi Gas Detector. Hydrogen sulfide (H2S) release was quantitatively monitored during fermentation, considering varying loads of inocula. Results. The bacterial isolates comprised Pseudomonas aeruginosa, P. fluorescens, P. putida, Bacillus fastidiosus, B. licheniformis, B. megaterium, B. subtilis, B. sphaericus, and B. thuringiensis. Odor levels varied based on inocula load and fermentation duration. In batches with Pseudomonas, hydrogen sulfide was undetectable after two days, while Bacillus-inoculated batches required ten days. The formation of microbial mats and subsequent decrease in H2S content contributed to malodor reduction. Notably, fluorescent pseudomonas exhibited successful mineralization during the treatment of fecal waste. Conclusion. Pseudomonas isolates demonstrated superior effectiveness in odor reduction compared to Bacillus isolates.

Indicators of immunity in workers engaged in the processing of natural gas and condensate

Introduction. Despite the unique measures being taken at the Astrakhan Gas Processing Plant for personnel protection, the harmful exposure to the staff is not eliminated completely yet. Examination of the immune system is one of the methods of laboratory control over the gas-processing workers’ health and the system of measures for hygienic normalization of the working conditions. Materials and methods. The present study describes the working environment and evaluates the state of the immune system in workers with the use of the standard unified methods and approaches. A Brüel & Kjear 1302 multi gas monitor and a Tsvet-550 gas chromatograph were used to indicate pollutants. Examination involved one hundred sixty workers and 81 person from the control group (donors of Astrakhan Regional Blood Transfusion Center). The immune system was evaluated using the System 9000 Plus hematological analyser, Cyto FLEX LX flow cytometer, UNICO 2100UV specrophotometer, and KFK-3-03-ZOMZ photometer Results. The established set of the main unfavourable production factors includes air pollution of the work area with sulphur dioxide, nitrogen oxides, carbon, hydrogen sulphide, saturated and unsaturated hydrocarbons, and unfavourable microclimatic conditions. Occupational hazards cause in employees changes in the immune status including leukocytosis, lymphocytosis, changes in the composition of the lymphocyte population and T lymphocyte subpopulation, a decrease in the immunoglobulin content, lysozyme activity and phagocytosis index. Limitations. The study took into account only the effect of occupational hazards on the deviation of the immune status of workers engaged in natural gas and condensate processing. Conclusion. The authors consider the recorded changes to be adaptive. It suggests the possibility of normalization of the workers’ immune system functions with adequate rehabilitation measures.

Contribution of Vehicular Emissions to Climate Change in Nigeria: A Closer Look

Climate change is fast becoming a global challenge, as most countries in the world have continue to increase their industrial capacities, resulting in increase in greenhouse gas emissions in the atmosphere. Also, the increase in human population in Nigeria has caused increase in motor vehicles, thereby resulting to release of more gaseous pollutants to the atmosphere. This study examined contributions of vehicular emissions to climate change in Port Harcourt, Nigeria. The concentration of air particulate matter and pollutants were monitored in three locations (Rumuokoro, Rumuola and Ada George) selected on the basis of traffic density. Air quality was monitored with MX6 Ibrid Multi gas monitors, MET ONE GT 321 for particulate matter, Davis Vantage Vue Weather Station for metrological parameters. Data on meteorological factors such as air temperature, wind speed, relative humidity were collected from the nearest weather station in Port Harcourt. Traffic records were taken at the designated locations using a close circuit television (Plate 5.1) in the morning, afternoon and evening respectively. All the parameters were monitored in each location, five days in a week every month for two years (2016-2017). The result of the analysis revealed that there was an increase in concentration of average air pollutants across the areas monitored between 2016 and 2017. The variation was attributed to increase in vehicular traffic volume and change in climatic conditions. This implies that emission rate from vehicles will continue to increase and contribute significantly to climate change, except measures are put in place to mitigate it.

Experimental Investigations on Control of Exhaust Emissions of a Semi-Adiabatic Diesel Engine with Plastic Oil

This paper concentrates on alternative fuel technology for diesel engine and environmental protection. The exhaust emissions from diesel engine cause severe health hazards when they are inhaled in.. They also cause environmental disorders. Hence control of these emissions is an immediate step. Vegetable oils and alcohols are important substitutes for diesel fuel, as they are renewable in nature. Though vegetable oils have comparable properties with diesel fuel, they have high viscosity and low volatility causing combustion problems in diesel engines. Alcohols have high volatility but low Cetane number (a measure of combustion quality in diesel engine). Plastic oil derived from waste plastic by the process of pyrolysis has equitant calorific value with diesel fuel. However, its viscosity is higher than diesel fuel calls for semi adiabatic diesel engine (SADE). The concept of semi adiabatic diesel engine is to reduce heat flow to the coolant there by providing hot combustion chamber used for burning high viscous fuels like plastic oil. Semi adiabatic engine consisted of air gap insulated piston with stainless steel crown and stainless steel gasket. The exhaust emissionsof particulate matter (PM), carbon monoxide (CO), nitrogen oxide levels (NOx ) and Un-burnt hydrocarbons (UBHC), with plastic oil were determined with conventional engine (CE) and SADE with varied injection timing at full load operation of the engine. Injection timing was varied with an electronic sensor. PM was determined by AVL Smoke meter, while NOx , CO and UBHC were measured by Netel Chromatograph multi gas analyzer at full load operation of the engine. Exhaust gas recirculation (EGR) at optimum value of 10% flow rate was provided to control the emissions. The data were compared with neat diesel operation on conventional engine with and without EGR.

Reduction of Pollutants of Insulated Diesel Engine with Plastic Oil with Supercharging

This paper aims at alternative fuel technology for diesel engine and environmental protection. The exhaust emissions from diesel engine are particulate matter (PM), nitrogen oxide (NOx ) levels, carbon mono oxide (CO) emissions and un-burnt hydro carbons (UBHC) and cause severe health hazards when they are inhaled in. They also cause environmental disorders like Global warming, Green-House effect, acid rain etc,. Hence control of these emissions is urgent and an immediate step. Vegetable oils and alcohols are important substitutes for diesel fuel, as they are renewable in nature. Though vegetable oils have comparable properties with diesel fuel, however, they have high viscosity and low volatility causing combustion problems in diesel engines. Alcohols have high volatility but low Cetane number (a measure of combustion quality in diesel engine). Plastic oil derived from waste plastic collected from debris by the process of pyrolysis has equitant calorific value with diesel fuel. However, its viscosity is higher than diesel fuel calls for low heat rejection (LHR) diesel engine. The concept of LHR diesel engine is to minimize the heat flow to the coolant there by increase of thermal efficiency. This LHR engine is useful for burning high viscous and low calorific value fuels. LHR engine consisted of ceramic coated cylinder head engine. The exhaust emissionsof PM, CO, NOx and UBHC with plastic oil were determined with conventional engine (CE) and LHR engine with varied injection timing at full load operation of the engine. Injection timing was varied with an electronic sensor. PM was determined by AVL Smoke meter, while NOx , CO and UBHC were measured by Netel Chromatograph multi gas analyzer at full load operation of the engine. The data was compared with neat diesel operation on conventional engine.

Monitoring Kualitas Udara dan Kontrol Air Purifier Honeywell HHT-080

Air is very important for the survival of living things, air quality will affect the state of human health. At present air quality is only monitored by KLH (Ministry of Environment) of Riau Province, with monitoring points only 1-3 points per city / regency in Riau. The frequent occurrence of forest fires in Riau, causing air quality to deteriorate rapidly so it requires a tool that can monitor air quality and improve air quality to maintain human health. Therefore, the authors conducted research and design of tools to be able to monitor air quality (CO gas levels) and improve air quality in the room. The workings of this monitoring device are MQ-7 gas sensors measuring CO (carbon monoxide) gas levels, where the data is then processed and sent through a wi-fi network using ESP8266 and the data is also used as a reference for control the air purifier in the room. The results of this monitoring are shared using Google Spreadsheets by e-mail to the people whom concerned. The MQ-7 sensor works best in the range of 50-150 ppm carbon monoxide gas with a deviation of 14 ppm from a calibrated multi gas detector.

Elevated CO2 Emissions during Magmatic-Hydrothermal Degassing at Awu Volcano, Sangihe Arc, Indonesia

Awu is a remote and little known active volcano of Indonesia located in the northern part of Molucca Sea. It is the northernmost active volcano of the Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of 11,048. Two of these eruptions were classified with a Volcanic Explosivity Index (VEI) of 4. Since 2004, a lava dome has occupied the centre of Awu crater, channelling the fumarolic gas output along the crater wall. A combined Differential Optical Absorption Spectroscopy (DOAS) and Multi-component Gas Analyzer System (Multi-GAS) study highlight a relatively small SO2 flux (13 t/d) sustained by mixed magmatic–hydrothermal emissions made-up of 82 mol.% H2O, 15 mol.% CO2, 2.55 mol.% total S (ST) and 0.02 mol.% H2. The CO2 emission budget, as observed during a short observation period in 2015, corresponds to a daily contribution to the atmosphere of 2600 t/d, representing 1% of the global CO2 emission budget from volcanoes. The gas CO2/ST ratio of 3.7 to 7.9 is at the upper limit of the Indonesian gas range, which is ascribed to (i) some extent of S loss during hydrothermal processing, and perhaps (ii) a C-rich signature of the feeding magmatic gas phase. The source of this high CO2 signature and flux is yet to be fully understood; however, given the peculiar geodynamic context of the region, dominated by the arc-to-arc collision, this may result from either the prolonged heating of the slab and consequent production of carbon-rich fluids, or the recycling of crustal carbon.

First In-Situ Measurements of Plume Chemistry at Mount Garet Volcano, Island of Gaua (Vanuatu)

Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 ± 11.6, 1.8 ± 0.5, 2.0 ± 0.01, 0.26 ± 0.02 and 0.06 ± 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d−1 for Mt. Garet, we estimate a total volatile output of about 6482 t d−1 (CO2 ~259 t d−1; H2O ~5758 t d−1; H2S ~30 t d−1; H2 ~0.5 t d−1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.

Miniaturised Infrared Spectrophotometer for Low Power Consumption Multi-Gas Sensing.

Concept, design and practical implementation of a miniaturized spectrophotometer, utilized as a mid-infrared-based multi gas sensor is described. The sensor covers an infrared absorption wavelength range of 2.9 to 4.8 um, providing detection capabilities for carbon dioxide, carbon monoxide, nitrous oxide, sulphur dioxide, ammonia and methane. A lead selenide photo-detector array and customized MEMS-based micro-hotplate are used as the detector and broadband infrared source, respectively. The spectrophotometer optics are based on an injection moulded Schwarzschild configuration incorporating optical pass band filters for the spectral discrimination. This work explores the effects of using both fixed-line pass band and linear variable optical filters. We report the effectiveness of this low-power-consumption miniaturized spectrophotometer as a stand-alone single and multi-gas sensor, usage of a distinct reference channel during gas measurements, development of ideal optical filters and spectral control of the source and detector. Results also demonstrate the use of short-time pulsed inputs as an effective and efficient way of operating the sensor in a low-power-consumption mode. We describe performance of the spectrometer as a multi-gas sensor, optimizing individual component performances, power consumption, temperature sensitivity and gas properties using modelling and customized experimental procedures.

Perspectives of Biological Analysis in Latin America Using Multi and Comprehensive Two-Dimensional Gas Chromatography: A Mini-review

Multi and comprehensive two-dimensional gas chromatography application have been increasingly mentioned in different countries. This technique increases the efficiency of peak separation in chromatographic analysis, minimizing problems due to the presence of interfering compounds in the analysis, especially in complex matrices. In Latin America, it has been applied to different areas of study. However, biological samples have been reported in a small number of applications. This mini-review addresses studies where the multi and comprehensive two-dimensional gas chromatography technique have been applied to biological samples’ analyses. Biological matrices are generally complex, and sample preparation usually requires a large number of steps to minimize potential interferences. The main areas of study described were related to doping control analysis and biomarker analysis. The urine sample was the main type of biological sample used in the studies. Studies have shown that results obtained by two-dimensional gas chromatography or supported or not by mathematical tools allow high efficiency in solving problems such as coelution. However, the small number of works published with the participation of Latin American researchers indicate that equipment price, especially when mass spectrometry is used as a detector, has a limiting factor in its wide application.

Multi gas sensors using one nanomaterial, temperature gradient, and machine learning algorithms for discrimination of gases and their concentration

In this work, four identical micro sensors on the same chip with noble metal decorated tin oxide nanowires as gas sensing material were located at different distances from an integrated heater to work at different temperatures. Their responses are combined in highly informative 4D points that can qualitatively (gas recognition) and quantitatively (concentration estimate) discriminate all the tested gases. Two identical chips were fabricated with tin oxide (SnO2) nanowires decorated with different metal nanoparticles: one decorated with Ag nanoparticles and one with Pt nanoparticles. Support Vector Machine was used as the “brain” of the sensing system. The results show that the systems using these multisensor chips were capable of achieving perfect classification (100%) and good estimation of the concentration of tested gases (errors in the range 8–28%). The Ag decorated sensors did not have a preferential gas, while Pt decorated sensors showed a lower error towards acetone, hydrogen and ammonia. Combination of the two sensor chips improved the overall estimation of gas concentrations, but the individual sensor chips were better for some specific target gases.

Ammonia emission from a manure-belt laying hen facility equipped with an external manure drying tunnel

Ammonia is the main pollutant associated to laying hen facilities. Best Available Techniques such as manure drying tunnels have been implemented to minimise ammonia losses. However, scarce information is available about their performance as a cleaner technology. Ammonia emission from a manure-belt laying hen building and the annexed external manure drying tunnel were measured from July 2015 to October 2016 under Continental Mediterranean climate conditions. Ammonia emission from the building and manure drying tunnel were continuously measured by a photoacoustic multi gas analyser. Temperature and relative humidity were monitored. The uncertainty of ammonia emission calculation was examined. Nitrogen mass balance was also used to estimate ammonia losses from the building. Results showed that the annual mean ammonia emission from the building was 93.8 mg ammonia d−1 hen−1. Mean ammonia emission uncertainty in the building was 9.7% throughout the sampling period. Ventilation rate was identified as the main factor affecting uncertainty due to the variability of fans operation. Concerning the manure drying tunnel, mean ammonia emission was 209.3 mg NH3 d−1 hen−1. Ammonia losses were affected by the atmospheric temperature and relative humidity, and manure dry matter content in both systems. Manure ammonia emission should be researched in following steps of the manure continuum to state the manure drying tunnel as a cleaner production technology. Ammonia emission estimation by nitrogen mass balance method was 98.4 mg NH3 d−1 hen−1. It was demonstrated to be a good indicator of the ammonia emission over the year although it did not reflect the variations between shorter time periods.

The Impact of Microclimate Parameters on Odour Emissions from Pig Production in Spring

Abstract The aim of this study was to examine the impact of inside temperature and relative humidity, ventilation rate and gas concentrations (NH3, N2O, CO2) on odour emissions from deep-litter piggery. The studied facility had temperature-controlled mechanical ventilation. The measurements were conducted from March to June 2014. During the research, selected microclimate parameters, as well as number and mass of animals were monitored and air samples were collected (two samples of air in each series of measurements). Temperature and relative humidity were measured using Testo 435-4 multifunctional measuring instrument. To measurements of gas concentrations was used the photo-acoustic spectrometer Multi Gas Monitor Model 1312. The concentration of odours in the air samples was determined by dynamic olfactometry with the TO 8 olfactometer, according to PN-EN 13725:2007. The odour concentration ranged from 450 to 2004 ouE · m–3 (mean 1048 ouE · m–3) and the mean odour emission factor was from 5.76 to 46.79 ouE · (s · pig)−1 (mean 20.93 ouE· (s · pig)−1.The statistical analysis showed that the inside temperature explained most of the variability of the odour concentration and the relationship was described by equation: cod = 5634 – 197 Tinside (R 2 = 0.82, p ≤ 0.05). For odour emission factor, two parameters: the inside temperature and ventilation rate, explained most of the variability, according to the equation: EFod = 108 + 1939 VR – 5.5 Tinside (R 2 = 0.81, p ≤ 0.05).

Radar Path Delay Effects in Volcanic Gas Plumes: The Case of Láscar Volcano, Northern Chile

Modern volcano monitoring commonly involves Interferometric Synthetic Aperture Radar (InSAR) measurements to identify ground motions caused by volcanic activity. However, InSAR is largely affected by changes in atmospheric refractivity, in particular by changes which can be attributed to the distribution of water (H2O) vapor in the atmospheric column. Gas emissions from continuously degassing volcanoes contain abundant water vapor and thus produce variations in the atmospheric water vapor content above and downwind of the volcano, which are notably well captured by short-wavelength X-band SAR systems. These variations may in turn cause differential phase errors in volcano deformation estimates due to excess radar path delay effects within the volcanic gas plume. Inversely, if these radar path delay effects are better understood, they may be even used for monitoring degassing activity, by means of the precipitable water vapor (PWV) content in the plume at the time of SAR acquisitions, which may provide essential information on gas plume dispersion and the state of volcanic and hydrothermal activity. In this work we investigate the radar path delays that were generated by water vapor contained in the volcanic gas plume of the persistently degassing Láscar volcano, which is located in the dry Atacama Desert of Northern Chile. We estimate water vapor contents based on sulfur dioxide (SO2) emission measurements from a scanning UV spectrometer (Mini-DOAS) station installed at Láscar volcano, which were scaled by H2O/SO2 molar mixing ratios obtained during a multi-component Gas Analyzer System (Multi-GAS) survey on the crater rim of the volcano. To calculate the water vapor content in the downwind portion of the plume, where an increase of water vapor is expected, we further applied a correction involving estimation of potential evaporation rates of water droplets governed by turbulent mixing of the condensed volcanic plume with the dry atmosphere. Based on these estimates we obtain daily average PWV contents inside the volcanic gas plume of 0.2–2.5 mm equivalent water column, which translates to a slant wet delay (SWD) in DInSAR data of 1.6–20 mm. We used these estimates in combination with our high resolution TerraSAR-X DInSAR observations at Láscar volcano, in order to demonstrate the occurrence of repeated atmospheric delay patterns that were generated by volcanic gas emissions. We show that gas plume related refractivity changes are significant and detectable in DInSAR measurements. Implications are two-fold: X-band satellite radar observations also contain information on the degassing state of a volcano, while deformation signals need to be interpreted with care, which has relevance for volcano observations at Láscar and for other sites worldwide.

Gas emissions and crustal deformation from the Krýsuvík high temperature geothermal system, Iceland

The Krýsuvík volcanic system is located on the oblique spreading Reykjanes Peninsula, SW Iceland. Since early 2009 the region has been undergoing episodes of localized ground uplift and subsidence. From April–November 2013, we operated near-real time monitoring of gas emissions in Krýsuvík, using a Multi-component Gas Analyzer System (Multi-GAS), collecting data on gas composition from a fumarole (H2O, CO2, SO2, H2S). The dataset in this study, comprises a near-continuous gas composition time series, the quantification of diffuse CO2 gas flux, analytical results for direct samples of dry gas, seismic records, and GPS data. Gas emissions from the Krýsuvík geothermal system were examined and compared with crustal deformation and seismicity.The gas emissions from the Krýsuvík system are H2O-dominated, with CO2 as the most abundant dry gas species, followed by smaller concentrations of H2S. The average subsurface equilibrium temperature was calculated as 278 °C. This is consistent with previous observations made through sporadic spot sampling campaigns. In addition, the semi-continuous Multi-GAS dataset reveals higher variations in gas composition than previously reported by spot sampling.The diffuse soil CO2 flux is found to be variable between the three studied degassing areas in Krýsuvík, ranging from 10.9–70.9 T/day, with the highest flux in Hveradalir where the Multi-GAS station is located. The total flux is estimated as 101 T/day.Comparison between Multi-GAS and geophysical data shows that peaks of H2O-rich emissions appears to follow crustal movements. Coinciding with the H2O-rich peaks, SO2 is detected in minor amounts (~0.6 ppmv), allowing for calculations of H2O/SO2, CO2/SO2 and H2S/SO2 ratios. This is the first time SO2 has been detected in the Krýsuvík area.The large variations in H2O/CO2 and H2O/H2S ratios are considered to reflect variable degassing activity in the fumarole. The activity of the fumarole appears less intense during intervals of low or no recorded seismic events. The H2O/CO2 and H2O/H2S ratios are lower, presumably due to H2O condensation affecting the steam jet before reaching the Multi-GAS inlet tube.

Detection of multi absorption lines for CH4 using broadband laser beam modulation

In this work we implemented a setup to modulate wavelength of a broad band beam of low laser power to detect multi absorption lines of multi gas species simultaneously, using long absorption path and monochromator. This setup consists mainly of tunable diode Laser built with an External Cavity designed by Littrow configuration, typical Herriott multipass cell with absorption path length of 30 m, monochromator with photomultiplier tube as detector, function generator, digital oscilloscope, and a photodiode. The proposed setup gives us ability to apply two techniques: direct absorption and wavelength modulation, in addition to changing some parameters for tuning diode laser. Using the proposed setup with low laser power we were able to detect multi absorption lines of a small concentration of CH4 simultaneously, based on spectroscopic databases we believe these detected lines belong to weak absorption NIR region of CH4. Most of the detected lines were listed recently in HITRAN 2012 but some of them are not listed, which merits further theoretical and experimental study which we are currently perusing.

Highly Sensitive Surface‐Enhanced Raman Scattering (SERS)‐ Based Multi Gas Sensor : Au Nanoparticles Decorated on Partially Embedded 2D Colloidal Crystals into Elastomer

AbstractAdvent of surface‐enhanced Raman spectroscopy (SERS) has engendered, the attention to exploit a facile, cost effective, 2D self‐assembly based architecture for sensing. Here, Au nanoparticles are decorated on controlled morphology of 2D polystyrene colloidal crystals (PSCCs), partially embedded into flexible polydimethylsiloxane elastomer. Self‐assembled flexible hexagonally close‐packed PSCCs form the 75 and 25 nm voids in the 500 and 200 nm, PSCCs monolayers and act as an effective plasmonic propagator for SERS sensors signal. Optical and sensing response investigates with UV‐Vis and Raman spectroscopy after the exposure of Au NP/2D PS CC/PDMS to NH3, H2O2, N2O and H2S gases environment. The increase in the SERS intensity at 491 cm−1 for the 200 nm, CCs based sensors as compared to 500 nm, indicates that the sensing response, strongly dependent on the CCs size. The red‐shift in the UV‐Vis spectra and enhancement in intensity of SERS designate that H2S forms the maximum Au NPs aggregates over the all tested gases. The chemisorptions on the phenyl ring, due to B2 symmetric modes of the PSCCs with orthogonal polarizability of Au NPs, act as a hot spot for higher sensing response for the detection of gaseous precursors with higher SERS sensitivity and reliability.