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1
Kornilova, A., S. Moukhtar, M. Saccon, L. Huang, W. Zhang, and J. Rudolph. "A method for stable carbon isotope ratio and concentration measurements of ambient aromatic hydrocarbons." Atmospheric Measurement Techniques Discussions 8, no. 1 (January 30, 2015): 1365–400. http://dx.doi.org/10.5194/amtd-8-1365-2015.
Повний текст джерелаАнотація:
Abstract. A technique for compound specific analysis of stable carbon isotope ratios and concentration of ambient volatile organic compounds (VOC) is presented. It is based on selective VOC sampling onto adsorbent filled cartridges by passing large volumes of air (up to 80 L) through the cartridge. The hydrocarbons are recovered by thermal desorption followed by two step cryogenic trapping and then are separated by gas chromatography in the laboratory. Once separated, individual VOC are subjected to online oxidation in a combustion interface and isotope ratio analysis by isotope ratio mass spectrometry. The method allows measurements of stable carbon isotope ratios of ambient aromatic VOC present in low pptV to ppbV levels with an accuracy of typically better than 0.5‰. The precision of concentration measurements is better than 10%. Examples of measurements conducted as part of a joint Environment Canada-York University (EC-YU) measurement campaign at a semi-rural location demonstrate that the ability to make accurate measurements in air with low VOC mixing ratios is important to avoid bias from an over-representation of samples that are strongly impacted by recent emissions.
2
Malley, C. S., C. F. Braban, P. Dumitrean, J. N. Cape, and M. R. Heal. "The impact of speciated VOCs on regional ozone increment derived from measurements at the UK EMEP supersites between 1999 and 2012." Atmospheric Chemistry and Physics Discussions 15, no. 5 (March 10, 2015): 7267–308. http://dx.doi.org/10.5194/acpd-15-7267-2015.
Повний текст джерелаАнотація:
Abstract. The impact of 27 volatile organic compounds (VOC) on the regional O3 increment was investigated using measurements made at the UK EMEP supersites Harwell (1999–2001 and 2010–2012) and Auchencorth (2012). Ozone at these sites is representative of rural O3 in south-east England and northern UK, respectively. Monthly-diurnal regional O3 increment was defined as the difference between the regional and hemispheric background O3 concentrations, respectively derived from oxidant vs. NOx correlation plots, and cluster analysis of back trajectories arriving at Mace Head, Ireland. At Harwell, which had substantially greater regional ozone increments than at Auchencorth, variation in the regional O3 increment mirrored afternoon depletion of VOCs due to photochemistry (after accounting for diurnal changes in boundary layer mixing depth, and weighting VOC concentrations according to their photochemical ozone creation potential). A positive regional O3 increment occurred consistently during the summer, during which time afternoon photochemical depletion was calculated for the majority of measured VOCs, and to the greatest extent for ethene and m + p-xylene. This indicates that, of the measured VOCs, ethene and m + p-xylene emissions reduction would be most effective in reducing the regional O3 increment, but that reductions in a larger number of VOCs would be required for further improvement. The VOC diurnal photochemical depletion was linked to the sources of the VOC emissions through the integration of gridded VOC emissions estimates over 96 h air-mass back trajectories. This demonstrated that the effectiveness of VOC gridded emissions for use in measurement and modelling studies is limited by the highly aggregated nature of the 11 SNAP source sectors in which they are reported, as monthly variation in speciated VOC trajectory emissions did not reflect monthly changes in individual VOC diurnal photochemical depletion. Additionally, the major VOC emission source sectors during elevated regional O3 increment at Harwell were more narrowly defined through disaggregation of the SNAP emissions to 91 NFR codes (i.e. sectors 3D2 (domestic solvent use), 3D3 (other product use) and 2D2 (food and drink)). However, spatial variation in the contribution of NFR sectors to parent SNAP emissions could only be accounted for at the country level. Hence, the future reporting of gridded VOC emissions in source sectors more highly disaggregated than currently (e.g. to NFR codes) would facilitate a more precise identification of those VOC sources most important for mitigation of the impact of VOCs on O3 formation. In summary, this work presents a clear methodology for achieving a coherent VOC regional-O3-impact chemical climate using measurement data and explores the effect of limited emission and measurement species on the understanding of the regional VOC contribution to O3 concentrations.
3
Hovánszki, Dóra, József Prokisch, and Zoltán Győri. "The study of headspace sampling for the measurement of Volatile Organic Compounds byGC-MS." Acta Agraria Debreceniensis, no. 23 (May 23, 2006): 35–38. http://dx.doi.org/10.34101/actaagrar/23/3203.
Повний текст джерелаАнотація:
Headspace sampling was studied for GC-MS measurements. A quick, direct method was developed for the measurement of petrol, gasoline and volatile organic solvent contamination of soil. According to our results this method is suitable for quick qualitative analysis of VOC contamination of soil, and helps to make decisions about further measurements. We concluded that an accurate quantitative measurement is not possible.
4
Szczurek, Andrzej, Marcin Przybyła, and Monika Maciejewska. "The Relationship between Elemental Carbon and Volatile Organic Compounds in the Air of an Underground Metal Mine." Atmosphere 13, no. 11 (November 21, 2022): 1935. http://dx.doi.org/10.3390/atmos13111935.
Повний текст джерелаАнотація:
Elemental carbon (EC) content in air is considered a proxy for the diesel exhaust impact at workplaces. This paper examines the possibility of estimating EC content in mine air on the basis of measurements of volatile organic compounds (VOC). The measurement study was carried out in an underground metal mine. Gas chromatography with mass spectrometry (GC/MS) was applied for VOC determination, and thermal-optical analysis (TOA) with an FID detector was utilized for EC measurements. A correlation was found between the measurements of EC and total VOC (TVOC) as well as the content of individual hydrocarbons C12–C14 in the air of an extraction zone in the mine. A regression model was developed which predicts EC based on C12, C13, and C14, considered individually, and the remaining VOCs detected with GC/MS taken in total. The model was statistically significant (p = 0.053), and it offered an EC prediction error of RMSE = 4.60 µg/sample. The obtained result confirms the possibility of using VOC measurements for the preliminary estimation of EC concentrations in mine air. This approach is feasible given the availability of portable GC/MS and offers easy and fast measurements providing qualitative and quantitative information.
5
Kato, Roberta Miyeko, Anne Nord, Erin McGuire, Daniel Gardner, Adam M. Bush, Jon Detterich, Michael Khoo, et al. "Changes in Regional Oxygenation At the Site of Sickle Cell Vaso-Occlusive Pain." Blood 120, no. 21 (November 16, 2012): 4773. http://dx.doi.org/10.1182/blood.v120.21.4773.4773.
Повний текст джерелаАнотація:
Abstract Abstract 4773 Background: The pathophysiology of sickle cell disease (SCD) is commonly thought to be in part a result of sickled red blood cells obstructing blood flow leading to hypoxic cellular injury. The most common SCD complication is painful vaso-occlusive crisis (VOC). However, the physiologic changes that occur at the site of VOC are poorly understood and there are no objective measurements of VOC. We hypothesized that regional oxygenation at the site of pain would be decreased from the patient's asymptomatic baseline and could be used as an objective measurement of the VOC process. Methods: Subjects were enrolled at the time of hospitalization for unilateral painful VOC. The subjects completed the adolescent pediatric pain tool (APPT) to assess the location, severity and quality of their pain. Regional oxygenation (RSO2) was measured by near infrared spectroscopy (NIRS) at the site that the subject identified as where they experienced the most severe VOC related pain. NIRS measurements were also made on the contralateral body site. NIRS measurements were made for 15 minutes with the subject in the supine position. Measurements were made in the first 24 hours of hospitalization. Blood pressure, heart rate, pulse oximetry, hematologic parameters and use of oxygen were determined. The subject returned 4 weeks after discharge for repeat testing to determine their physiologic post VOC RSO2 baseline. Mean values for the NIRS testing period were determined and the change in RSO2 during VOC from post VOC baseline were calculated. Results: 5 female subjects with SCD were studied, mean age 15.8±3.0years. There was an average pain score of 7.4/10+1.9. Pain occurred in the back of 2 subjects and the lower extremities in the others. The RSO2% in the painful and not painful sites was increased from baseline by an average of 10.6±4.0% and 16.6±5.6%, respectively. The painful site had a decreased RSO2% in comparison to the contralateral side in 2 of 5 subjects (see figure). The RSO2% VOC baseline at the painful site post was higher in 3 of 5 subjects. There was no difference from baseline in blood pressure, heart rate, or arterial oxygen saturations during VOC. There were changes in the hematologic parameters consistent with VOC and active hemolysis. Conclusions: The SCD subjects demonstrated increased regional oxygenation at both the painful and contralateral not painful sites during VOC compared to the post VOC baseline. During VOC there was no predictable difference in regional oxygenation at the site of VOC pain contrary to our original hypothesis. Disclosures: Wood: Ferrokin Biosciences: Consultancy; Shire: Consultancy; Apotex: Consultancy, Honoraria; Novartis: Honoraria, Research Funding. Coates:Novartis: Speakers Bureau; Apopharma: Consultancy.
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Malley, C. S., C. F. Braban, P. Dumitrean, J. N. Cape, and M. R. Heal. "The impact of speciated VOCs on regional ozone increment derived from measurements at the UK EMEP supersites between 1999 and 2012." Atmospheric Chemistry and Physics 15, no. 14 (July 28, 2015): 8361–80. http://dx.doi.org/10.5194/acp-15-8361-2015.
Повний текст джерелаАнотація:
Abstract. The impact of 27 volatile organic compounds (VOCs) on the regional O3 increment was investigated using measurements made at the UK EMEP supersites Harwell (1999–2001 and 2010–2012) and Auchencorth (2012). Ozone at these sites is representative of rural O3 in south-east England and northern UK, respectively. The monthly-diurnal regional O3 increment was defined as the difference between the regional and hemispheric background O3 concentrations, respectively, derived from oxidant vs. NOx correlation plots, and cluster analysis of back trajectories arriving at Mace Head, Ireland. At Harwell, which had substantially greater regional O3 increments than Auchencorth, variation in the regional O3 increment mirrored afternoon depletion of anthropogenic VOCs due to photochemistry (after accounting for diurnal changes in boundary layer mixing depth, and weighting VOC concentrations according to their photochemical ozone creation potential). A positive regional O3 increment occurred consistently during the summer, during which time afternoon photochemical depletion was calculated for the majority of measured VOCs, and to the greatest extent for ethene and m+p-xylene. This indicates that, of the measured VOCs, ethene and m+p-xylene emissions reduction would be most effective in reducing the regional O3 increment but that reductions in a larger number of VOCs would be required for further improvement. The VOC diurnal photochemical depletion was linked to anthropogenic sources of the VOC emissions through the integration of gridded anthropogenic VOC emission estimates over 96 h air-mass back trajectories. This demonstrated that one factor limiting the effectiveness of VOC gridded emissions for use in measurement and modelling studies is the highly aggregated nature of the 11 SNAP (Selected Nomenclature for Air Pollution) source sectors in which they are reported, as monthly variation in speciated VOC trajectory emissions did not reflect monthly changes in individual VOC diurnal photochemical depletion. Additionally, the major VOC emission source sectors during elevated regional O3 increment at Harwell were more narrowly defined through disaggregation of the SNAP emissions to 91 NFR (Nomenclature for Reporting) codes (i.e. sectors 3D2 (domestic solvent use), 3D3 (other product use) and 2D2 (food and drink)). However, spatial variation in the contribution of NFR sectors to parent SNAP emissions could only be accounted for at the country level. Hence, the future reporting of gridded VOC emissions in source sectors more highly disaggregated than currently (e.g. to NFR codes) would facilitate a more precise identification of those VOC sources most important for mitigation of the impact of VOCs on O3 formation. In summary, this work presents a clear methodology for achieving a coherent VOC, regional-O3-impact chemical climate using measurement data and explores the effect of limited emission and measurement species on the understanding of the regional VOC contribution to O3 concentrations.
7
Dunne, Erin, Ian E. Galbally, Min Cheng, Paul Selleck, Suzie B. Molloy, and Sarah J. Lawson. "Comparison of VOC measurements made by PTR-MS, adsorbent tubes–GC-FID-MS and DNPH derivatization–HPLC during the Sydney Particle Study, 2012: a contribution to the assessment of uncertainty in routine atmospheric VOC measurements." Atmospheric Measurement Techniques 11, no. 1 (January 10, 2018): 141–59. http://dx.doi.org/10.5194/amt-11-141-2018.
Повний текст джерелаАнотація:
Abstract. Understanding uncertainty is essential for utilizing atmospheric volatile organic compound (VOC) measurements in robust ways to develop atmospheric science. This study describes an inter-comparison of the VOC data, and the derived uncertainty estimates, measured with three independent techniques (PTR-MS, proton-transfer-reaction mass spectrometry; GC-FID-MS, gas chromatography with flame-ionization and mass spectrometric detection; and DNPH–HPLC, 2,4-dinitrophenylhydrazine derivatization followed by analysis by high-performance liquid chromatography) during routine monitoring as part of the Sydney Particle Study (SPS) campaign in 2012. Benzene, toluene, C8 aromatics, isoprene, formaldehyde and acetaldehyde were selected for the comparison, based on objective selection criteria from the available data. Bottom-up uncertainty analyses were undertaken for each compound and each measurement system. Top-down uncertainties were quantified via the inter-comparisons. In all seven comparisons, the correlations between independent measurement techniques were high with R2 values with a median of 0.92 (range 0.75–0.98) and small root mean square of the deviations (RMSD) of the observations from the regression line with a median of 0.11 (range 0.04–0.23 ppbv). These results give a high degree of confidence that for each comparison the response of the two independent techniques is dominated by the same constituents. The slope and intercept as determined by reduced major axis (RMA) regression gives a different story. The slopes varied considerably with a median of 1.25 and a range of 1.16–2.01. The intercepts varied with a median of 0.04 and a range of −0.03 to 0.31 ppbv. An ideal comparison would give a slope of 1.00 and an intercept of 0. Some sources of uncertainty that are poorly quantified by the bottom-up uncertainty analysis method were identified, including: contributions of non-target compounds to the measurement of the target compound for benzene, toluene and isoprene by PTR-MS as well as the under-reporting of formaldehyde, acetaldehyde and acetone by the DNPH technique. As well as these, this study has identified a specific interference of liquid water with acetone measurements by the DNPH technique. These relationships reported for Sydney 2012 were incorporated into a larger analysis with 61 similar published inter-comparison studies for the same compounds. Overall, for the light aromatics, isoprene and the C1–C3 carbonyls, the uncertainty in a set of measurements varies by a factor of between 1.5 and 2. These uncertainties (∼50 %) are significantly higher than uncertainties estimated using standard propagation of error methods, which in this case were ∼22 % or less, and are the result of the presence of poorly understood or neglected processes that affect the measurement and its uncertainty. The uncertainties in VOC measurements identified here should be considered when assessing the reliability of VOC measurements from routine monitoring with individual, stand-alone instruments; when utilizing VOC data to constrain and inform air quality and climate models; when using VOC observations for human exposure studies; and for comparison with satellite retrievals.
8
Bon, D. M., J. A. de Gouw, C. Warneke, W. C. Kuster, M. L. Alexander, A. Baker, A. Beyersdorf, et al. "Measurements of volatile organic compounds at a suburban ground site (T1) in Mexico City during the MILAGRO 2006 campaign: measurement comparison, emission ratios, and source attribution." Atmospheric Chemistry and Physics Discussions 10, no. 10 (October 8, 2010): 23229–86. http://dx.doi.org/10.5194/acpd-10-23229-2010.
Повний текст джерелаАнотація:
Abstract. Volatile organic compound (VOC) mixing ratios were measured with two different instruments at the T1 ground site in Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO) campaign in March of 2006. A gas chromatograph with flame ionization detector (GC-FID) quantified 18 light alkanes, alkenes and acetylene while a proton-transfer-reaction ion-trap mass spectrometer (PIT-MS) quantified 12 VOC species including oxygenated VOCs (OVOCs) and aromatics. A GC separation system was used in conjunction with the PIT-MS (GC-PIT-MS) to evaluate PIT-MS measurements and to aid in the identification of unknown VOCs. The VOC measurements are also compared to simultaneous canister samples and to two independent proton-transfer-reaction mass spectrometers (PTR-MS) deployed on a mobile and an airborne platform during MILAGRO. VOC diurnal cycles demonstrate the large influence of vehicle traffic and liquid propane gas (LPG) emissions during the night and photochemical processing during the afternoon. Emission ratios for VOCs and OVOCs are determined from early-morning enhancement ratios and compared to emission ratios calculated from the PMF results. Average emission ratios for non-oxygenated species relative to CO are on average a factor of 2 higher than measured for US cities. Emission ratios for OVOCs are estimated and compared to literature values the northeastern US and to tunnel studies in California. Positive matrix factorization analysis (PMF) is used to provide insight into VOC sources and processing and to estimate OVOC emission ratios. Three PMF factors were distinguished by the analysis including the emissions from vehicles, the use of liquid propane gas and the production of secondary VOCs + long-lived species. The total PIT-MS signal was summed to estimate the fraction of identified vs. unidentified VOC species.
9
Bon, D. M., I. M. Ulbrich, J. A. de Gouw, C. Warneke, W. C. Kuster, M. L. Alexander, A. Baker, et al. "Measurements of volatile organic compounds at a suburban ground site (T1) in Mexico City during the MILAGRO 2006 campaign: measurement comparison, emission ratios, and source attribution." Atmospheric Chemistry and Physics 11, no. 6 (March 16, 2011): 2399–421. http://dx.doi.org/10.5194/acp-11-2399-2011.
Повний текст джерелаАнотація:
Abstract. Volatile organic compound (VOC) mixing ratios were measured with two different instruments at the T1 ground site in Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO) campaign in March of 2006. A gas chromatograph with flame ionization detector (GC-FID) quantified 18 light alkanes, alkenes and acetylene while a proton-transfer-reaction ion-trap mass spectrometer (PIT-MS) quantified 12 VOC species including oxygenated VOCs (OVOCs) and aromatics. A GC separation system was used in conjunction with the PIT-MS (GC-PIT-MS) to evaluate PIT-MS measurements and to aid in the identification of unknown VOCs. The VOC measurements are also compared to simultaneous canister samples and to two independent proton-transfer-reaction mass spectrometers (PTR-MS) deployed on a mobile and an airborne platform during MILAGRO. VOC diurnal cycles demonstrate the large influence of vehicle traffic and liquid propane gas (LPG) emissions during the night and photochemical processing during the afternoon. Emission ratios for VOCs and OVOCs relative to CO are derived from early-morning measurements. Average emission ratios for non-oxygenated species relative to CO are on average a factor of ~2 higher than measured for US cities. Emission ratios for OVOCs are estimated and compared to literature values the northeastern US and to tunnel studies in California. Positive matrix factorization analysis (PMF) is used to provide insight into VOC sources and processing. Three PMF factors were distinguished by the analysis including the emissions from vehicles, the use of liquid propane gas and the production of secondary VOCs + long-lived species. Emission ratios to CO calculated from the results of PMF analysis are compared to emission ratios calculated directly from measurements. The total PIT-MS signal is summed to estimate the fraction of identified versus unidentified VOC species.
10
Zaini, Zaini, Dwi Mutiara Harfina, and Agung P. Iswar. "Real-Time SoC Estimation for Li-Ion Batteries using Kalman Filter based on SBC Raspberry-Pi." Andalas Journal of Electrical and Electronic Engineering Technology 1, no. 2 (December 10, 2021): 48–57. http://dx.doi.org/10.25077/ajeeet.v1i2.12.
Повний текст джерелаАнотація:
Measurement of electric charge on the battery in real-time cannot be separated from external noise and disturbances such as temperature and interference. An optimal State of Charge (SoC) estimator model is needed to make the estimation more accurate. To obtain the model, the battery was tested under room temperature conditions and at a temperature of 40oC to obtain a second-order RC model for the Li-Ion battery used. Based on the test data obtained, the data will be tested first using the Kalman Filter method to get an estimate of the State of Charge (SoC). Tests were carried out using MATLAB software. After the method was tested, the online SoC Estimator design began using the Raspberry Pi Single Board Computer (SBC). After that, the estimator will be tested first using data from offline measurements and then used in real-time (online) SoC estimation measurements. The Voc before the battery discharge test was 13.16 V and after the test, the measured Voc was 11.58 V. During the discharge the Voc was reduced by 1.58 V. While the discharge data from the battery manufacturer showed the reduced Voc during the discharge was 1.2V.
11
Zaini, Zaini, Dwi Mutiara Harfina, and Agung P. Iswar. "Real-Time SoC Estimation for Li-Ion Batteries using Kalman Filter based on SBC Raspberry-Pi." Andalas Journal of Electrical and Electronic Engineering Technology 1, no. 02 (December 10, 2021): 48–57. http://dx.doi.org/10.25077/ajeeet.v1i02.12.
Повний текст джерелаАнотація:
Measurement of electric charge on the battery in real-time cannot be separated from external noise and disturbances such as temperature and interference. An optimal State of Charge (SoC) estimator model is needed to make the estimation more accurate. To obtain the model, the battery was tested under room temperature conditions and at a temperature of 40oC to obtain a second-order RC model for the Li-Ion battery used. Based on the test data obtained, the data will be tested first using the Kalman Filter method to get an estimate of the State of Charge (SoC). Tests were carried out using MATLAB software. After the method was tested, the online SoC Estimator design began using the Raspberry Pi Single Board Computer (SBC). After that, the estimator will be tested first using data from offline measurements and then used in real-time (online) SoC estimation measurements. The Voc before the battery discharge test was 13.16 V and after the test, the measured Voc was 11.58 V. During the discharge the Voc was reduced by 1.58 V. While the discharge data from the battery manufacturer showed the reduced Voc during the discharge was 1.2V.
12
Rantala, Pekka, Leena Järvi, Risto Taipale, Terhi K. Laurila, Johanna Patokoski, Maija K. Kajos, Mona Kurppa, et al. "Anthropogenic and biogenic influence on VOC fluxes at an urban background site in Helsinki, Finland." Atmospheric Chemistry and Physics 16, no. 12 (July 1, 2016): 7981–8007. http://dx.doi.org/10.5194/acp-16-7981-2016.
Повний текст джерелаАнотація:
Abstract. We measured volatile organic compounds (VOCs), carbon dioxide (CO2) and carbon monoxide (CO) at an urban background site near the city centre of Helsinki, Finland, northern Europe. The VOC and CO2 measurements were obtained between January 2013 and September 2014 whereas for CO a shorter measurement campaign in April–May 2014 was conducted. Both anthropogenic and biogenic sources were identified for VOCs in the study. Strong correlations between VOC fluxes and CO fluxes and traffic rates indicated anthropogenic source of many VOCs. The VOC with the highest emission rate to the atmosphere was methanol, which originated mostly from traffic and other anthropogenic sources. The traffic was also a major source for aromatic compounds in all seasons whereas isoprene was mostly emitted from biogenic sources during summer. Some amount of traffic-related isoprene emissions were detected during other seasons but this might have also been an instrumental contamination from cycloalkane products. Generally, the observed VOC fluxes were found to be small in comparison with previous urban VOC flux studies. However, the differences were probably caused by lower anthropogenic activities as the CO2 fluxes were also relatively small at the site.
13
Pleil, Joachim D., and Andrew B. Lindstrom. "Exhaled human breath measurement method for assessing exposure to halogenated volatile organic compounds." Clinical Chemistry 43, no. 5 (May 1, 1997): 723–30. http://dx.doi.org/10.1093/clinchem/43.5.723.
Повний текст джерелаАнотація:
Abstract The organic constituents of exhaled human breath are representative of blood-borne concentrations through gas exchange in the blood/breath interface in the lungs. The presence of specific compounds can be an indicator of recent exposure or represent a biological response of the subject. For volatile organic compounds (VOCs), sampling and analysis of breath is preferred to direct measurement from blood samples because breath collection is noninvasive, potentially infectious waste is avoided, and the measurement of gas-phase analytes is much simpler in a gas matrix rather than in a complex biological tissue such as blood. To exploit these advantages, we have developed the “single breath canister” (SBC) technique, a simple direct collection method for individual alveolar breath samples, and adapted conventional gas chromatography–mass spectrometry analytical methods for trace-concentration VOC analysis. The focus of this paper is to describe briefly the techniques for making VOC measurements in breath, to present some specific applications for which these methods are relevant, and to demonstrate how to estimate exposure to example VOCs on the basis of breath elimination. We present data from three different exposure scenarios: (a) vinyl chloride and cis-1,2-dichloroethene from showering with contaminated water from a private well, (b) chloroform and bromodichloromethane from high-intensity swimming in chlorinated pool water, and (c) trichloroethene from a controlled exposure chamber experiment. In all cases, for all subjects, the experiment is the same: preexposure breath measurement, exposure to halogenated VOC, and a postexposure time-dependent series of breath measurements. Data are presented only to demonstrate the use of the method and how to interpret the analytical results.
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Wang, M., M. Shao, W. Chen, B. Yuan, S. Lu, Q. Zhang, L. Zeng, and Q. Wang. "A temporally and spatially resolved validation of emission inventories by measurements of ambient volatile organic compounds in Beijing, China." Atmospheric Chemistry and Physics 14, no. 12 (June 16, 2014): 5871–91. http://dx.doi.org/10.5194/acp-14-5871-2014.
Повний текст джерелаАнотація:
Abstract. Understanding the sources of volatile organic compounds (VOCs) is essential for ground-level ozone and secondary organic aerosol (SOA) abatement measures. We made VOC measurements at 27 sites and online observations at an urban site in Beijing from July 2009 to January 2012. Based on these measurement data, we determined the spatial and temporal distribution of VOCs, estimated their annual emission strengths based on their emission ratios relative to carbon monoxide (CO), and quantified the relative contributions of various sources using the chemical mass balance (CMB) model. These results from ambient measurements were compared with existing emission inventories to evaluate the spatial distribution, species-specific emissions, and source structure of VOCs in Beijing. The measured VOC distributions revealed a hotspot in the southern suburban area of Beijing, whereas current emission inventories suggested that VOC emissions were concentrated in downtown areas. Compared with results derived from ambient measurements, the annual inventoried emissions of oxygenated VOC (OVOC) species and C2–C4 alkanes may be underestimated, while the emissions of styrene and 1,3-butadiene may be overestimated by current inventories. Source apportionment using the CMB model identified vehicular exhaust as the most important VOC source, with the relative contribution of 49%, in good agreement with the 40–51% estimated by emission inventories. The relative contribution of paint and solvent utilization obtained from the CMB model was 14%, significantly lower than the value of 32% reported by one existing inventory. Meanwhile, the relative contribution of liquefied petroleum gas (LPG) usage calculated using the CMB model was 6%, whereas LPG usage contribution was not reported by current emission inventories. These results suggested that VOC emission strengths in southern suburban area of Beijing, annual emissions of C2–C4 alkanes, OVOCs and some alkenes, and the contributions of solvent and paint utilization and LPG usage in current inventories all require significant revisions.
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Kohl, Lukas, Markku Koskinen, Kaisa Rissanen, Iikka Haikarainen, Tatu Polvinen, Heidi Hellén, and Mari Pihlatie. "Technical note: Interferences of volatile organic compounds (VOCs) on methane concentration measurements." Biogeosciences 16, no. 17 (September 4, 2019): 3319–32. http://dx.doi.org/10.5194/bg-16-3319-2019.
Повний текст джерелаАнотація:
Abstract. Studies that quantify plant methane (CH4) emission rely on the accurate measurement of small changes in the mixing ratio of CH4 that coincide with much larger changes in the mixing ratio of volatile organic compounds (VOCs). Here, we assessed whether 11 commonly occurring VOCs (e.g. methanol, α- and β-pinene, Δ3-carene) interfered with the quantitation of CH4 by five laser-absorption spectroscopy and Fourier-transformed infrared spectroscopy (FTIR) based CH4 analysers, and quantified the interference of seven compounds on three instruments. Our results showed minimal interference with laser-based analysers and underlined the importance of identifying and compensating for interferences with FTIR instruments. When VOCs were not included in the spectral library, they exerted a strong bias on FTIR-based instruments (64–1800 ppbv apparent CH4 ppmv−1 VOC). Minor (0.7–126 ppbv ppmv−1) interference with FTIR-based measurements were also detected when the spectrum of the interfering VOC was included in the library. In contrast, we detected only minor (<20 ppbv ppmv−1) and transient (< 1 min) VOC interferences on laser-absorption spectroscopy-based analysers. Overall, our results demonstrate that VOC interferences have only minor effects on CH4 flux measurements in soil chambers, but may severely impact stem and shoot flux measurements. Laser-absorption-based instruments are better suited for quantifying CH4 fluxes from plant leaves and stems than FTIR-based instruments; however, significant interferences in shoot chamber measurements could not be excluded for any of the tested instruments. Our results furthermore showed that FTIR can precisely quantify VOC mixing ratios and could therefore provide a method complementary to proton-transfer-reaction mass spectrometry (PTR-MS).
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Xu, Dong Xia, Dong Bin Wang, and Yong Ping Lei. "Study of VOC-Free, No-Clean Flux for Lead-Free Soldering in Electronic Packaging." Advanced Materials Research 154-155 (October 2010): 1012–18. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.1012.
Повний текст джерелаАнотація:
Aiming at issues existed in lead-free electronic packaging, as well as the air pollution induced by volatile organic compounds (VOC) in conventional soldering fluxes, a new VOC-free no-clean flux was formulated specifically for lead-free wave soldering. Spread test and wetting balance test were carried out to evaluate the activity of the newly developed flux with Sn3.8Ag0.7Cu lead-free solder. Besides, influence of flux residues on corrosivity and reliability of printed circuit board (PCB) was investigated by measurement of surface insulation resistance (SIR). The results showed that VOC-free fluxes required a good preheat process to obtain better soldering performance. And, flux residues of new VOC-free 1 had higher corrosivity than VOC and VOC-free 2, so the flux formulations needed to be ameliorated for the future. Due to the benefits of eco-friendly and cost saving, it is promising to successful implementation of VOC-free fluxes if some process modification is done.
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Hurley, Michael D., Tai Y. Chang, Steven M. Japar, and Timothy J. Wallington. "Measurement of VOC Reactivities Using a Photochemical Flow Reactor." Environmental Science & Technology 32, no. 13 (July 1998): 1913–19. http://dx.doi.org/10.1021/es970844r.
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Sillman, S., and J. J. West. "Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models." Atmospheric Chemistry and Physics Discussions 8, no. 6 (December 9, 2008): 20501–36. http://dx.doi.org/10.5194/acpd-8-20501-2008.
Повний текст джерелаАнотація:
Abstract. We use results of a 3-D photochemistry/transport model for ozone formation in Mexico City during events in 1997 to investigate ambient concentrations of reactive nitrogen in relation to ozone-precursor sensitivity. Previous results from other locations suggest that ratios such as O3/NOy and H2O2/HNO3 might provide measurement-based indicators for NOx-sensitive or VOC-sensitive conditions. Mexico City presents a different environment due to its high concentrations of VOC and high level of pollutants in general. The model predicts a correlation between PAN and O3 with relatively high PAN/O3 (0.07), which is still lower than measured values. The model PAN is comparable with results from a model for Paris but much higher than were found in Nashville in both models and measurements. The difference can be explained by the lower temperature in Mexico City relative to Nashville. Model HNO3 in Mexico City is unusually low for an urban area and PAN/HNO3 is very high, probably due to the high ratio of reactivity-weighted VOC to NOx. The model predicts that VOC-sensitive chemistry in Mexico is associated with high NOx, NOy and NOx/NOy and with low O3/NOy and H2O2/HNO3, suggesting that these indicators work well for Mexico City. The relation between ozone-precursor sensitivity and either O3/NOz or O3/HNO3 is more ambiguous. VOC-sensitive conditions are associated with higher O3/HNO3 than would be found in NOx-sensitive conditions, but model O3/HNO3 associated with both NOx-sensitive and VOC-sensitive chemistry is higher in Mexico than in other cities. The model predicts mixed sensitivity to NOx and VOC in Mexico City, with a tendency towards VOC-sensitive chemistry in the morning and NOx-sensitive in the afternoon, in contrast to model results for more recent events that predicted strongly VOC-sensitive conditions. The difference in predicted ozone-precursor sensitivity is most likely due to changes in emission rates over time. The model with mixed sensitivity predicts much lower ambient NOx and NOx/NOy than the strongly VOC-sensitive model.
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Shi, Xue, Hua Zhang, Hanyang Ji, and Fanli Meng. "Dynamic Measurement of VOCs with Multiple Characteristic Peaks Based on Temperature Modulation of ZnO Gas Sensor." Chemosensors 10, no. 6 (June 15, 2022): 226. http://dx.doi.org/10.3390/chemosensors10060226.
Повний текст джерелаАнотація:
Volatile organic compounds (VOC) harm human health seriously in the air. Therefore, it is essential to recognize VOC gases qualitatively and quantitatively. The dynamic measurement method can improve the selectivity of metal oxide semiconductor (MOS) gas sensors to VOC, but there is a problem of the insufficient number of characteristic peaks. From the experimental point of view, the primary judgment basis for the correct qualitative and quantitative recognition of VOC gases by the dynamic measurement method is the characteristic peak of the dynamic response signal. However, the traditional dynamic measurement method generally only has two characteristic peaks. In this experiment, the voltage was changed at the time of the second characteristic peak by controlling the constant dynamic response period. Taking ethyl alcohol as an example, the experimental results show that the characteristic peak of the dynamic response signal does not increase when the voltage is constant. However, a new characteristic peak will appear based on a continuously rising heating voltage. The characteristic peaks of the dynamic response of n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol were also increased based on the rising heating voltage waveform. Based on the K-Nearest-Neighbors algorithm, the qualitative and quantitative recognition rate of the four alcohol homologue gases reached 100%.
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Wu, Shenglun, Hyung Joo Lee, Andrea Anderson, Shang Liu, Toshihiro Kuwayama, John H. Seinfeld, and Michael J. Kleeman. "Direct measurements of ozone response to emissions perturbations in California." Atmospheric Chemistry and Physics 22, no. 7 (April 14, 2022): 4929–49. http://dx.doi.org/10.5194/acp-22-4929-2022.
Повний текст джерелаАнотація:
Abstract. A new technique was used to directly measure O3 response to changes in precursor NOx and volatile organic compound (VOC) concentrations in the atmosphere using three identical Teflon smog chambers equipped with UV lights. One chamber served as the baseline measurement for O3 formation, one chamber added NOx, and one chamber added surrogate VOCs (ethylene, m-xylene, n-hexane). Comparing the O3 formation between chambers over a 3-hour UV cycle provides a direct measurement of O3 sensitivity to precursor concentrations. Measurements made with this system at Sacramento, California, between April–December 2020 revealed that the atmospheric chemical regime followed a seasonal cycle. O3 formation was VOC-limited (NOx-rich) during the early spring, transitioned to NOx-limited during the summer due to increased concentrations of ambient VOCs with high O3 formation potential, and then returned to VOC-limited (NOx-rich) during the fall season as the concentrations of ambient VOCs decreased and NOx increased. This seasonal pattern of O3 sensitivity is consistent with the cycle of biogenic emissions in California. The direct chamber O3 sensitivity measurements matched semi-direct measurements of HCHO/NO2 ratios from the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor (Sentinel-5P) satellite. Furthermore, the satellite observations showed that the same seasonal cycle in O3 sensitivity occurred over most of the entire state of California, with only the urban cores of the very large cities remaining VOC-limited across all seasons. The O3-nonattainment days (MDA8 O3>70 ppb) have O3 sensitivity in the NOx-limited regime, suggesting that a NOx emissions control strategy would be most effective at reducing these peak O3 concentrations. In contrast, a large portion of the days with MDA8 O3 concentrations below 55 ppb were in the VOC-limited regime, suggesting that an emissions control strategy focusing on NOx reduction would increase O3 concentrations. This challenging situation suggests that emissions control programs that focus on NOx reductions will immediately lower peak O3 concentrations but slightly increase intermediate O3 concentrations until NOx levels fall far enough to re-enter the NOx-limited regime. The spatial pattern of increasing and decreasing O3 concentrations in response to a NOx emissions control strategy should be carefully mapped in order to fully understand the public health implications.
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Meisehen, T., F. Bühler, R. Koppmann, and M. Krebsbach. "An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds." Atmospheric Measurement Techniques Discussions 8, no. 7 (July 10, 2015): 7093–125. http://dx.doi.org/10.5194/amtd-8-7093-2015.
Повний текст джерелаАнотація:
Abstract. Stable isotope measurements in atmospheric volatile organic compounds (VOC) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOC in ambient air mainly focus on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOC. This system consisting of a GC-P-IRMS (Gas Chromatography Pyrolysis Isotope Ratio Mass Spectrometer) and a preconcentration system was thoroughly characterised using a working standard. A precision of better than 9 ‰ (in δD) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene, and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene, and n-octane. Above a compound specific minimum peak area the obtained δD values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3&plus; correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOC at ambient levels is demonstrated with measurements of outside air on five different days in February and March 2015. The measured hydrogen isotope ratios range from −136 to −105 ‰ for n-pentane, from −86 to −63 ‰ for toluene, from −39 to −15 ‰ for ethylbenzene, from −99 to −68 ‰ for m/p-xylene, and from −45 to −34 ‰ for o-xylene.
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Kim, Min-Gyu, Ji Yun Lee, Jeong Hun Kim, Hyo Eun Lee, Sung Hwan Cho, Jeong Ung Yu, Cheon Woong Kang, and Kyong Whan Moon. "Study of Chemical Substances Emitted during Paint Manufacturing through VOC Speciation." Atmosphere 13, no. 8 (August 5, 2022): 1245. http://dx.doi.org/10.3390/atmos13081245.
Повний текст джерелаАнотація:
Volatile organic compounds (VOCs) emitted from the paint manufacturing industry include substances that are highly volatile, such as toluene, and highly carcinogenic, such as benzene. In the Republic of Korea, the emission of volatile organic compounds is regulated under the Clean Air Conservation Act, but it is found that individual substances are systematically insufficient. Although the Pollutant Release and Transfer Register (PRTR) is maintained to report the expected emissions from each plant every year, actual measurements are not performed. This study measured and analyzed VOCs at the site fenceline boundary. The ratio of PRTR and VOCs speciation results for xylene and toluene was similar to that of xylene 29% and toluene 28%, but ethylbenzene accounted for 2% in PRTR. Still, the actual measurement result showed a big difference of 11%. Because it is a solvent that is treated in large quantities in the resin manufacturing process and the reactivity of ethylbenzene, it is vaporized at high temperature and high pressure, resulting in many measurements. This study classified a large amount of VOCs emitted through the fence line monitoring system in the paint manufacturing industry and confirmed which VOCs were emitted the most. We compared whether this produced similar results to the actual emission survey method conducted by the EPA. Some substances have produced similar results, but certain substances have significant differences. This indicates that priority VOCs should be selected for each location through continuous measurement.
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Eklund, Bart M., and Thomas P. Nelson. "Evaluation of VOC Emission Measurement Methods for Paint Spray Booths." Journal of the Air & Waste Management Association 45, no. 3 (March 1995): 196–205. http://dx.doi.org/10.1080/10473289.1995.10467360.
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Sillman, S., and J. J. West. "Reactive nitrogen in Mexico City and its relation to ozone-precursor sensitivity: results from photochemical models." Atmospheric Chemistry and Physics 9, no. 11 (June 2, 2009): 3477–89. http://dx.doi.org/10.5194/acp-9-3477-2009.
Повний текст джерелаАнотація:
Abstract. We use results of a 3-D photochemistry/transport model for ozone formation in Mexico City during events in 1997 to investigate ambient concentrations of reactive nitrogen in relation to ozone-precursor sensitivity. Previous results from other locations suggest that ratios such as O3/NOy and H2O2/HNO3 might provide measurement-based indicators for NOx-sensitive or VOC-sensitive conditions. Mexico City presents a different environment due to its high concentrations of VOC and high level of pollutants in general. The model predicts a correlation between PAN and O3 with relatively high PAN/O3 (0.07), which is still lower than measured values. The model PAN is comparable with results from a model for Paris but much higher than were found in Nashville in both models and measurements. The difference is due in part to the lower temperature in Mexico City relative to Nashville. Model HNO3 in Mexico City is unusually low for an urban area and PAN/HNO3 is very high, probably due to the high ratio of reactivity-weighted VOC to NOx. The model predicts that VOC-sensitive chemistry in Mexico is associated with high NOx, NOy and NOx/NOy and with low O3/NOy and H2O2/HNO3, suggesting that these indicators work well for Mexico City. The relation between ozone-precursor sensitivity and either O3/NOz or O3/HNO3 is more ambiguous. VOC-sensitive conditions are associated with higher O3/HNO3 than would be found in NOx-sensitive conditions, but model O3/HNO3 associated with both NOx-sensitive and VOC-sensitive chemistry is higher in Mexico than in other cities. The model predicts a mixed pattern of ozone-precursor sensitivity in Mexico City, with VOC-sensitive conditions in the morning and NOx-sensitive in the afternoon, in contrast to results from other models for more recent events that predicted strongly VOC- sensitive conditions throughout the day. The difference in predicted ozone-precursor sensitivity is most likely due to different emission rates and to changes in emissions over time. The model with mixed sensitivity predicts much lower ambient NOx and NOx/NOy than the strongly VOC-sensitive model.
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Kurt, Cem, Ilgen Sasmaz, Bulent Antmen, Yurdanur Kilinc, Sadi Kurdak, and Sedat Kuleci. "The Eveluation of Pulmonary Functions in Children with Sickle Cell Anemia." Blood 114, no. 22 (November 20, 2009): 4628. http://dx.doi.org/10.1182/blood.v114.22.4628.4628.
Повний текст джерелаАнотація:
Abstract Abstract 4628 Aim In this study we evaluated to pulmonary functions and determined relations of these findings with clinical parameters in children with sickle cell anemia (SCA) who were at follow up in our pediatric heamatology clinic. Materials and Methods 24 children with sickle cell anemia and 9 healthy children as control group include to the study. Complete blood count, hemoglobin electrophoresis and biochemical values were eveluated for both groups. At pulmonology department, the carbonmonoxide diffusion test performing for both groups. At the same day spirometric respiratory function evaluation and exercise test performed both groups at department of sports physiology. The data recieved are compared statistics. Results HbS, HbF, SGPT, ferritin, total bilirubine, direkt bilirubine and Fe++ values were high at patient group (p<0.05). Hemoglobin and hematocrit values were low at patient group according to control group as expected (p<0.05). The number of SCA patient who had one-three venoocclusive crises (VOC) were 14 (58.3%), patient who had three or more VOC were 7 (29.2%) and patient who had no VOC were 3 (12.5%). The number of patient who had acute chest syndrome (ACS) were 5 (20.9%) and 19 patients had no ACS (79.1%). Ýmpaired isole carbonmonoxide diffusion test was established at the 62.5% of the patient's. At patient group, spirometric FEV1 and MEF25 measurement were found lower than the control group (p<0.05). At exercise test VO2/HR rate were lower for patient group (p<0.05). VE/VO2 rate (p=0.023) and R (p=0.016) measurement were found higher. Conclusion Pulmonary gas transfer was found difficult in patients with SCA. Respiratory airways established obstructed in spirometric evaluation. Obstructive defficiensies have to be follow up. Oxygen pulse and respiratory exchange rates were determined low and more oxygen usage was observed for aerobic metabolic activity. With these results, ýt can be say that chronic inflamation process at lung due to oxygen radicals and hipoksemia in sickle cell patients, the aerobic respiratory load was increased. Disclosures: No relevant conflicts of interest to declare.
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Hebert, Nicolas, Rakotoson Marie Georgine, Gwellaouen Bodivit, Etienne Audureau, Nadia Oubaya, Sadaf Pakdaman, Mehdi Sakka, et al. "Fetal Hemoglobin Measurement per Red Blood Cell Provides Biological and Clinical Protective Thresholds." Blood 134, Supplement_1 (November 13, 2019): 1008. http://dx.doi.org/10.1182/blood-2019-126727.
Повний текст джерелаАнотація:
Introduction: Fetal hemoglobin (HbF) expression is a major modulator of sickle cell disease (SCD) severity by decreasing the HbS polymerization. However, the distribution of HbF in red blood cells (RBC) is heterogeneous in SCD patients. In the hypothesis of an HbF "threshold" in RBCs for inhibiting the HbS polymerization, accurate measurement of the HbF content in each red blood cell (HbF/RBC) is mandatory. To this purpose we developed a new and accurate method allowing the direct measurement of HbF content per RBC. Thanks to it, as a proof of concept, we analyzed HbF distribution and content in RBC from SCD patients before and after 6 months of treatment by hydroxyurea (HU). To determine if a threshold of HbF/RBC could modulate SCD, we analyzed the associations between the %RBC reaching different thresholds of HbF (in picograms), and biological parameters and the incidence of severe VOC. Methods: 14 SCD (βS/βS or βS/β0) patients were included to study HbF distribution during HU for a period of 6 months. RBCs were collected during each outpatient visit (Week 0, Week 2, Week 4, Week 12, and ≥ Week 24). HbF content was measured in RBCs using an anti-Human-HbF antibody by flow cytometry. Normalized RBC fluorescence intensity was then converted in picograms of HbF/RBC by using the linear association between mean HbF content and mean RBC fluorescence obtained from subjects presenting homogeneous HbF distribution (patients with hereditary persistence of HbF (HPFH), or β-Thalassemia or δβ-Thalassemia). Quantitative analysis were performed before and during HU treatment to characterize the response by comparing percentages of RBC classes based on different ranges of HbF/RBC during HU treatment. We therefore analyzed the associations between HbF/RBC thresholds (%RBC containing at least 2, 4, 6, 8, 10 or 20 pg HbF) and biological parameters before and ≥ 6 months of HU treatment. Finally HbF/RBC thresholds at Week 0 were compared to the incidence of hospitalized VOC within 3 years before W0, and HbF/RBC thresholds at Week 24 were compared to the incidence of hospitalized VOC within 3 years after W24 at a stable dose. Results: After 6 months of HU, mean %HbF, assessed by HPLC, raised from 6.16% (±3.5) to 15.2% (±8.7) (mean ± standard deviation). Quantitative analysis of HbF/RBC revealed a statistically significant decrease between D0 and ≥M6 of 24% of RBCs containing less than 2 pg (p = 0.0015) and a 2-fold increase of RBCs containing between 2 and 4 pg (p = 0.0025) (Friedman test). For biological parameters we observed an increase in mean %HbF, MCV and MCH and a decrease in RBC count significantly associated (p<0.001 - Spearman test) with %RBC containing ≥ 2 pg of HbF. The incidence of VOC within 3 years after HU treatment was not statistically significant than during the 3 years before (p = 0.4414 - Wilcoxon test). VOC incidence under treatment decreased in 6/14 patients, did not change in 4/14 and increased in 4/14. The incidence of VOC over 3 years was not associated with the %HbF assessed by HPCL (r = -0.0358; p = 0.8564 - Spearman test). We observed a statistically significant correlation between the incidence of VOC over 3 years and the HbF threshold of 4 pg (r = -0.5068; p = 0.0059). We therefore determined the percentage of RBCs by thresholds of HbF, associated to ≤ 1 VOC over 3 years (Table 1). For example, if more than 20% RBCs have ≥ 4 pg of HbF, we calculated a sensitivity and a specificity of 58.3% and 100% respectively, and a positive and a negative predictive value of 100.0% and 76.2% respectively, to have ≤ 1 VOC over 3 years. Conclusion: Our results strengthen the hypothesis that the percentage of RBC above a threshold of HbF is the important parameter to measure. These results need to be replicated in a larger cohort but they open up interesting prospects for analysis of new therapeutic efficacy, including gene therapy and HbF inducers. Disclosures Galactéros: Addmedica: Membership on an entity's Board of Directors or advisory committees. Bartolucci:Agios: Membership on an entity's Board of Directors or advisory committees; Global Blood Therapeutics: Membership on an entity's Board of Directors or advisory committees; HEMANEXT: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AddMedica: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.
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Cui, Long, Zhou Zhang, Yu Huang, Shun Cheng Lee, Donald Ray Blake, Kin Fai Ho, Bei Wang, Yuan Gao, Xin Ming Wang, and Peter Kwok Keung Louie. "Measuring OVOCs and VOCs by PTR-MS in an urban roadside microenvironment of Hong Kong: relative humidity and temperature dependence, and field intercomparisons." Atmospheric Measurement Techniques 9, no. 12 (December 1, 2016): 5763–79. http://dx.doi.org/10.5194/amt-9-5763-2016.
Повний текст джерелаАнотація:
Abstract. Volatile organic compound (VOC) control is an important issue of air quality management in Hong Kong because ozone formation is generally VOC limited. Several oxygenated volatile organic compound (OVOC) and VOC measurement techniques – namely, (1) offline 2,4-dinitrophenylhydrazine (DNPH) cartridge sampling followed by high-performance liquid chromatography (HPLC) analysis; (2) online gas chromatography (GC) with flame ionization detection (FID); and (3) offline canister sampling followed by GC with mass spectrometer detection (MSD), FID, and electron capture detection (ECD) – were applied during this study. For the first time, the proton transfer reaction–mass spectrometry (PTR-MS) technique was also introduced to measured OVOCs and VOCs in an urban roadside area of Hong Kong. The integrated effect of ambient relative humidity (RH) and temperature (T) on formaldehyde measurements by PTR-MS was explored in this study. A Poly 2-D regression was found to be the best nonlinear surface simulation (r = 0.97) of the experimental reaction rate coefficient ratio, ambient RH, and T for formaldehyde measurement. This correction method was found to be better than correcting formaldehyde concentrations directly via the absolute humidity of inlet sample, based on a 2-year field sampling campaign at Mong Kok (MK) in Hong Kong. For OVOC species, formaldehyde, acetaldehyde, acetone, and MEK showed good agreements between PTR-MS and DNPH-HPLC with slopes of 1.00, 1.10, 0.76, and 0.88, respectively, and correlation coefficients of 0.79, 0.75, 0.60, and 0.93, respectively. Overall, fair agreements were found between PTR-MS and online GC-FID for benzene (slope = 1.23, r = 0.95), toluene (slope = 1.01, r = 0.96) and C2-benzenes (slope = 1.02, r = 0.96) after correcting benzene and C2-benzenes levels which could be affected by fragments formed from ethylbenzene. For the intercomparisons between PTR-MS and offline canister measurements by GC-MSD/FID/ECD, benzene showed good agreement, with a slope of 1.05 (r = 0.62), though PTR-MS had lower values for toluene and C2-benzenes with slopes of 0.78 (r = 0.96) and 0.67 (r = 0.92), respectively. All in all, the PTR-MS instrument is suitable for OVOC and VOC measurements in urban roadside areas.
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Amoah, Papa K., Engelbert Redel, Helmut Baumgart, and Yaw Obeng. "Impact of Flushing Agents in Broadband Dielectric Spectroscopy (BDS) Study of Ethanol Detection By HKUST-1 Metal-Organic Frameworks." ECS Meeting Abstracts MA2022-01, no. 52 (July 7, 2022): 2133. http://dx.doi.org/10.1149/ma2022-01522133mtgabs.
Повний текст джерелаАнотація:
Traditional volatile organic compounds (VOC) detection with metal semiconductor oxide (MOS) sensing elements depends on chemical resistivity measurements which require electrical contact to the sensing materials [1]. These measurement contacts / probes are inadequate because they tend to introduce parasitic electrical errors which result in misleading reported resistivity values [2]. On the other hand, contactless broadband dielectric spectroscopy (BDS) is a potential alternative metrology [3]. In this paper, we will demonstrate that by using contactless broadband dielectric spectroscopy (BDS)-based metrology, in combination with a metal-organic framework (HKUST-1 SMOF) sensing element, we can avoid distortions in the reported resistivity values in gas monitoring, as well as develop new and unique mechanistic insights into the VOC detection. Specifically, we show that the experimental ambient influences the detection mechanism. The microwave insertion loss data (S21) shows that we lose resolution when N2 was used as the flushing agent, as compared to air, during the measurements. This suggests a possible competition between the ethanol and the N2 for the unsaturated copper centers inside the MOF. Therefore, we opted to use air as a flushing agent in the subsequent experiments. Additionally, the use of BDS enables stable VOC sensing in air at temperatures below 100 °C, which are well below the 200-300C normally used for VOC detection [1, 2]. 1) Huaping Wang et al 2021 J. Phys.: Condens. Matter 33 303001 2) Chem. Soc. Rev., 2020,49, 6364-6401, https://doi.org/10.1039/C9CS00778D 3) Papa K Amoah et al 2021 J. Phys. D: Appl. Phys. 54 135104
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Collier-Oxandale, Ashley M., Jacob Thorson, Hannah Halliday, Jana Milford, and Michael Hannigan. "Understanding the ability of low-cost MOx sensors to quantify ambient VOCs." Atmospheric Measurement Techniques 12, no. 3 (March 5, 2019): 1441–60. http://dx.doi.org/10.5194/amt-12-1441-2019.
Повний текст джерелаАнотація:
Abstract. Volatile organic compounds (VOCs) present a unique challenge in air quality research given their importance to human and environmental health, and their complexity to monitor resulting from the number of possible sources and mixtures. New technologies, such as low-cost air quality sensors, have the potential to support existing air quality measurement methods by providing data in high time and spatial resolution. These higher-resolution data could provide greater insight into specific events, sources, and local variability. Furthermore, given the potential for differences in selectivities for sensors, leveraging multiple sensors in an array format may even be able to provide insight into which VOCs or types of VOCs are present. During the FRAPPE and DISCOVER-AQ monitoring campaigns, our team was able to co-locate two sensor systems, using metal oxide (MOx) VOC sensors, with a proton-transfer-reaction quadrupole mass spectrometer (PTR-QMS) providing speciated VOC data. This dataset provided the opportunity to explore the ability of sensors to estimate specific VOCs and groups of VOCs in real-world conditions, e.g., dynamic temperature and humidity. Moreover, we were able to explore the impact of changing VOC compositions on sensor performance as well as the difference in selectivities of sensors in order to consider how this could be utilized. From this analysis, it seems that systems using multiple VOC sensors are able to provide VOC estimates at ambient levels for specific VOCs or groups of VOCs. It also seems that this performance is fairly robust in changing VOC mixtures, and it was confirmed that there are consistent and useful differences in selectivities between the two MOx sensors studied. While this study was fairly limited in scope, the results suggest that there is the potential for low-cost VOC sensors to support highly resolved ambient hydrocarbon measurements. The availability of this technology could enhance research and monitoring for public health and communities impacted by air toxics, which in turn could support a better understanding of exposure and actions to reduce harmful exposure.
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Kornilova, A., S. Moukhtar, M. Saccon, L. Huang, W. Zhang, and J. Rudolph. "A method for stable carbon isotope ratio and concentration measurements of ambient aromatic hydrocarbons." Atmospheric Measurement Techniques 8, no. 6 (June 4, 2015): 2301–13. http://dx.doi.org/10.5194/amt-8-2301-2015.
Повний текст джерелаАнотація:
Abstract. A technique for compound-specific analysis of stable carbon isotope ratios and concentration of ambient volatile organic compounds (VOCs) is presented. It is based on selective VOC sampling onto adsorbent-filled cartridges by passing large volumes of air (up to 80 L) through the cartridge. The hydrocarbons are recovered by thermal desorption followed by two-step cryogenic trapping and then are separated by gas chromatography in the laboratory. Once separated, individual VOCs are subjected to online oxidation in a combustion interface and isotope ratio analysis by isotope ratio mass spectrometry. The method allows measurements of stable carbon isotope ratios of ambient aromatic VOCs present in low pptV to ppbV levels with an accuracy of typically better than 0.5 ‰. The precision of concentration measurements is better than 10%. Examples of measurements conducted as part of a joint Environment Canada–York University (EC-YU) measurement campaign at a semi-rural location demonstrate that the ability to make accurate measurements in air with low VOC mixing ratios is important to avoid bias from an overrepresentation of samples that are strongly impacted by recent emissions.
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Journal, Baghdad Science. "Evaluation of Laser Doping of Si from MCLT Measurement." Baghdad Science Journal 1, no. 2 (June 6, 2004): 321–25. http://dx.doi.org/10.21123/bsj.1.2.321-325.
Повний текст джерелаАнотація:
The measurement of minority carrier lifetime (MCLT) ofp-n Si fabricated with aid of laser doping technique was reported. The measurement is achieved by using open circuit voltage decay (OCVD) technique. The experiment data confirms that the value of MCLT and proftle of Voc decay were very sensitive to the doping laser energy.
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Han, Yu, Tao Wang, Rui Li, Hongbo Fu, Yusen Duan, Song Gao, Liwu Zhang, and Jianmin Chen. "Measurement report: Volatile organic compound characteristics of the different land-use types in Shanghai: spatiotemporal variation, source apportionment and impact on secondary formations of ozone and aerosol." Atmospheric Chemistry and Physics 23, no. 4 (March 3, 2023): 2877–900. http://dx.doi.org/10.5194/acp-23-2877-2023.
Повний текст джерелаАнотація:
Abstract. Volatile organic compounds (VOCs) have important impacts on air quality, atmospheric chemistry and human health. In order to identify the spatiotemporal variations, sources and ozone (O3) and secondary organic aerosol (SOA) formation potentials of the atmospheric VOCs, a concurrent multi-site observation campaign was performed at the supersites of Shanghai, East China, in the first three months of 2019. The sampling sites are located at the different land-use types, including an industrial district (the Jinshan site: JS), residential and commercial mixed districts (the Pudong site: PD) and a background district (the Qingpu site: QP) of Shanghai. During the observation period, the average VOC concentrations were sensitive to the land-use types in the order of the JS (21.88 ± 12.58 ppb) > PD (21.36 ± 8.58 ppb) > QP (11.93 ± 6.33 ppb) sites. The predominant VOC category was alkanes (49.32 %–71.48 %), followed by aromatics (10.70 %–21.00 %), alkenes (10.13 %–15.30 %) and alkynes (7.69 %–14.80 %) at the studied sites. There were distinct diurnal variations and “weekend effects” of VOCs at the sampling sites. The VOC concentrations increased by 27.15 %, 32.85 % and 22.42 % during the haze events relative to the clean days. Vehicle exhaust was determined as the predominant VOC source. The second-largest VOC contributor was identified as industrial production at the JS and PD sites, while it proved to be fuel production and evaporation at the QP site. The industrial emission and biomass burning showed slight contributions to VOC concentrations at the QP and JS/PD sites, respectively. This was consistent with the regional characteristics of anthropogenic activities dominated by land-use types. High potential source contribution function (PSCF) values primarily appeared in the northeastern and northern areas surrounding sampling sites, suggesting strong local emissions. The ozone formation potential (OFP) values of each land-use type were in the order of the JS (50.89 ± 2.63 ppb) > PD (33.94 ± 1.52 ppb) > QP (24.26 ± 1.43 ppb) sites, with alkenes and aromatics being the predominant contributors. Secondary organic aerosol formation potential (SOAFP), mainly contributed by the aromatics, was highest at the JS site (1.00 ± 2.03 µg m−3), followed by the PD (0.46 ± 0.88 µg m−3) and QP (0.41 ± 0.58 µg m−3) sites. The VOC–PM2.5 sensitivity analysis showed that VOCs at the QP site displayed a more rapid increment along with the increase in PM2.5 values relative to the other two sites. Alkenes and aromatics are both the key concerns in controlling the VOC-related pollution of O3 and SOA in Shanghai. These findings provide more information on accurate air-quality control at a city level in China. The results shown herein highlight that the simultaneous multi-site measurements with the different land-use types in a megacity or city cluster could be more appropriate for fully understanding the VOC characteristics relative to a single-site measurement performed normally.
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Choi, Jung-Min, Kye-Won Park, Jae-Gun Jeong, Yong-Kwon Lee, Gil-Nam Kim, Doo-Chan Choi, and Min-Hyuk Ko. "Experimental Study on the Availability of Fire Detection Using Gas Sensors for Air Quality Measurement." Fire Science and Engineering 35, no. 1 (February 28, 2021): 41–47. http://dx.doi.org/10.7731/kifse.0759bab4.
Повний текст джерелаАнотація:
This study tested gas sensors used to measure indoor air quality to explore the feasibility of using them as detection sensors in case of fire. A B-class fire environment was implemented in the compartment (ISO 9705 standard fire room), and four types of high- and low- accuracy and priced gas sensors (Carbon monoxide, carbon dioxide, methane, t-VOC) used for indoor air quality measurement were installed. From ignition of the fuel to alarming of the heat detector, the responses from the sensors were analyzed. The results revealed the following: 1) Among the four types of sensors, CO and t-VOC sensors were effective as fire detection sensors in terms of their concentration increase and response time. 2) Low-accuracy CO2 and CH4 sensors were not effective in fire detection as they responded late relatively to CO and t-VOC sensors. 3) It was confirmed that low-accuracy gas sensors are feasible for use for fire detection in that they showed valid increase in concentration before the heat detector alarms. However, as only liquid combustible (Heptane) was applied as a fire source, analysis in an environment where different types of combustibles are used will be necessary in the future.
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Kohl, Lukas, Markku Koskinen, Tatu Polvinen, Salla Tenhovirta, Kaisa Rissanen, Marjo Patama, Alessandro Zanetti, and Mari Pihlatie. "An automated system for trace gas flux measurements from plant foliage and other plant compartments." Atmospheric Measurement Techniques 14, no. 6 (June 17, 2021): 4445–60. http://dx.doi.org/10.5194/amt-14-4445-2021.
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Abstract. Plant shoots can act as sources or sinks of trace gases including methane and nitrous oxide. Accurate measurements of these trace gas fluxes require enclosing of shoots in closed non-steady-state chambers. Due to plant physiological activity, this type of enclosure, however, leads to CO2 depletion in the enclosed air volume, condensation of transpired water, and warming of the enclosures exposed to sunlight, all of which may bias the flux measurements. Here, we present ShoTGa-FluMS (SHOot Trace Gas FLUx Measurement System), a novel measurement system designed for continuous and automated measurements of trace gas and volatile organic compound (VOC) fluxes from plant shoots. The system uses transparent shoot enclosures equipped with Peltier cooling elements and automatically replaces fixated CO2 and removes transpired water from the enclosure. The system is designed for measuring trace gas fluxes over extended periods, capturing diurnal and seasonal variations, and linking trace gas exchange to plant physiological functioning and environmental drivers. Initial measurements show daytime CH4 emissions of two pine shoots of 0.056 and 0.089 nmol per gram of foliage dry weight (d.w.) per hour or 7.80 and 13.1 nmolm-2h-1. Simultaneously measured CO2 uptake rates were 9.2 and 7.6 mmolm-2h-1, and transpiration rates were 1.24 and 0.90 molm-2h-1. Concurrent measurement of VOC emissions demonstrated that potential effects of spectral interferences on CH4 flux measurements were at least 10-fold smaller than the measured CH4 fluxes. Overall, this new system solves multiple technical problems that have so far prevented automated plant shoot trace gas flux measurements and holds the potential for providing important new insights into the role of plant foliage in the global CH4 and N2O cycles.
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Mozaffar, Ahsan, Yan-Lin Zhang, Yu-Chi Lin, Feng Xie, Mei-Yi Fan, and Fang Cao. "Measurement report: High contributions of halocarbon and aromatic compounds to atmospheric volatile organic compounds in an industrial area." Atmospheric Chemistry and Physics 21, no. 23 (December 13, 2021): 18087–99. http://dx.doi.org/10.5194/acp-21-18087-2021.
Повний текст джерелаАнотація:
Abstract. Volatile organic compounds (VOCs) are key components of tropospheric chemistry. We investigated ambient VOCs in an industrial area in Nanjing, China, between July 2018 and May 2020. The sum of the suite of measured total VOC (TVOC) concentrations was 59.8 ± 28.6 ppbv (part per billion by volume) during the investigation period. About twice the TVOC concentrations were observed in the autumn (83 ± 20 ppbv) and winter (77.5 ± 16.8 ppbv) seasons compared to those in spring (39.6 ± 13.1 ppbv) and summer (38.8 ± 10.2 ppbv). In previous studies in Nanjing, oxygenated VOCs (OVOCs) and halocarbons were not measured, and the current TVOC concentration without halocarbons and OVOCs was similar to the previous investigation in the same study area. However, it was twofold higher than the one reported in the nonindustrial suburban area of Nanjing. Due to the industrial influence, the halocarbons VOC group (14.3 ± 7.3 ppbv, 24 %) was the second-largest contributor to the TVOCs after alkanes (21 ± 7 ppbv, 35 %), which is in contrast with the previous studies in Nanjing and also in almost all other regions in China. Relatively high proportions of halocarbons and aromatics were observed in autumn (25.7 % and 19.3 %, respectively) and winter (25.8 % and 17.6 %, respectively) compared to those in summer (20.4 % and 11.8 %, respectively) and spring (20.3 % and 13.6 %, respectively). According to the potential source contribution function (PSCF), short-distance transport from the surrounding industrial areas and cities was the main reason for the high VOC concentrations in the study area. According to positive matrix factorization (PMF) model results, vehicle-related emissions (33 %–48 %) contributed to the major portion of the ambient VOC concentrations. Aromatics, followed by alkenes, were the top contributors to the loss rate of OH radicals (LOH; 37 % and 32 %, respectively). According to the empirical kinetic modelling approach (EKMA) and relative incremental reactivity (RIR) analysis, the study area was in the VOC-sensitive regime for ozone (O3) formation during all measurement seasons. Therefore, alkenes and aromatics emissions from automobiles need to be decreased to reduce secondary air pollution formation in the study area.
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Bamberger, I., L. Hörtnagl, M. Walser, A. Hansel, and G. Wohlfahrt. "Gap-filling strategies for annual VOC flux data sets." Biogeosciences 11, no. 8 (April 30, 2014): 2429–42. http://dx.doi.org/10.5194/bg-11-2429-2014.
Повний текст джерелаАнотація:
Abstract. Up to now the limited knowledge about the exchange of volatile organic compounds (VOCs) between the biosphere and the atmosphere is one of the factors which hinders more accurate climate predictions. Complete long-term flux data sets of several VOCs to quantify the annual exchange and validate recent VOC models are basically not available. In combination with long-term VOC flux measurements the application of gap-filling routines is inevitable in order to replace missing data and make an important step towards a better understanding of the VOC ecosystem–atmosphere exchange on longer timescales. We performed VOC flux measurements above a mountain meadow in Austria during two complete growing seasons (from snowmelt in spring to snow reestablishment in late autumn) and used this data set to test the performance of four different gap-filling routines, mean diurnal variation (MDV), mean gliding window (MGW), look-up tables (LUT) and linear interpolation (LIP), in terms of their ability to replace missing flux data in order to obtain reliable VOC sums. According to our findings the MDV routine was outstanding with regard to the minimization of the gap-filling error for both years and all quantified VOCs. The other gap-filling routines, which performed gap-filling on 24 h average values, introduced considerably larger uncertainties. The error which was introduced by the application of the different filling routines increased linearly with the number of data gaps. Although average VOC fluxes measured during the winter period (complete snow coverage) were close to zero, these were highly variable and the filling of the winter period resulted in considerably higher uncertainties compared to the application of gap-filling during the measurement period. The annual patterns of the overall cumulative fluxes for the quantified VOCs showed a completely different behaviour in 2009, which was an exceptional year due to the occurrence of a severe hailstorm, compared to 2011. Methanol was the compound which, at 381.5 mg C m−2 and 449.9 mg C m−2, contributed most to the cumulative VOC carbon emissions in 2009 and 2011, respectively. In contrast to methanol emissions, however, considerable amounts of monoterpenes (−327.3 mg C m−2) were deposited onto the mountain meadow during 2009 caused by a hailstorm. Other quantified VOCs had considerably lower influences on the annual patterns.
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Bamberger, I., L. Hörtnagl, M. Walser, A. Hansel, and G. Wohlfahrt. "Gap-filling strategies for annual VOC flux data sets." Biogeosciences Discussions 10, no. 11 (November 15, 2013): 17785–818. http://dx.doi.org/10.5194/bgd-10-17785-2013.
Повний текст джерелаАнотація:
Abstract. Up to now the limited knowledge about the exchange of volatile organic compounds (VOCs) between the biosphere and the atmosphere is one of the factors which hinders more accurate climate predictions. Complete long-term flux data sets of several VOCs to quantify the annual exchange and validate recent VOC models are basically not available. In combination with long-term VOC flux measurements the application of gap-filling routines is inevitable in order to replace missing data and make an important step towards a better understanding of the VOC ecosystem-atmosphere exchange on longer time scales. We performed VOC flux measurements above a mountain meadow in Austria during two complete growing seasons (from snowmelt in spring to snow reestablishment in late autumn) and used this data set to test the performance of four different gap-filling routines, mean diurnal variation (MDV), mean gliding window (MGW), look up tables (LUT) and linear interpolation (LIP), in terms of their ability to replace missing flux data in order to obtain reliable VOC sums. According to our findings the MDV routine was outstanding with regard to the minimization of the gap-filling error for both years and all quantified VOCs. The other gap-filling routines, which performed gap-filling on 24 h average values, introduced considerably larger uncertainties. The error which was introduced by the application of the different filling routines increased linearly with the number of data gaps. Although average VOC fluxes measured during the winter period (complete snow coverage) were close to zero, these were highly variable and the filling of the winter period resulted in considerably higher uncertainties compared to the application of gap-filling during the measurement period. The annual patterns of the overall cumulative fluxes for the quantified VOCs showed a completely different behavior in 2009, which was an exceptional year due to the occurrence of a severe hailstorm, compared to 2011. Methanol was the compound which contributed with 381.5 mg C m–2 and 449.9 mg C m–2 most to the cumulative VOC carbon emissions in 2009 and 2011, respectively. In contrast to methanol emissions, however, considerable amounts of monoterpenes (−327.3 mg C m–2) were deposited to the mountain meadow in consequence to the hailstorm in 2009. Other quantified VOCs had considerably lower influences on the annual patterns.
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Li, Mingai, Luca Cappellin, Jia Xu, Franco Biasioli, and Claudio Varotto. "High-throughput screening for in planta characterization of VOC biosynthetic genes by PTR-ToF-MS." Journal of Plant Research 133, no. 1 (November 7, 2019): 123–31. http://dx.doi.org/10.1007/s10265-019-01149-z.
Повний текст джерелаАнотація:
Abstract Functional characterization of plant volatile organic compound (VOC) biosynthetic genes and elucidation of the biological function of their products often involve the screening of large numbers of plants from either independent transformation events or mapping populations. The low time resolution of standard gas chromatographic methods, however, represents a major bottleneck for in planta genetic characterization of VOC biosynthetic genes. Here we present a fast and highly-sensitive method for the high-throughput characterization of VOC emission levels/patterns by coupling a Proton Transfer Reaction Time-of-Flight Mass Spectrometer to an autosampler for automation of sample measurement. With this system more than 700 samples per day can be screened, detecting for each sample hundreds of spectrometric peaks in the m/z 15–300 range. As a case study, we report the characterization of VOC emissions from 116 independent Arabidopsis thaliana lines transformed with a putative isoprene synthase gene, confirming its function also when fused to a C-terminal 3×FLAG tag. We demonstrate that the method is more reliable than conventional characterization of transgene expression for the identification of the most highly isoprene-emitting lines. The throughput of this VOC screening method exceeds that of existing alternatives, potentially allowing its application to reverse and forward genetic screenings of genes contributing to VOC emission, constituting a powerful tool for the functional characterization of VOC biosynthetic genes and elucidation of the biological functions of their products directly in planta.
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Karl, T. "Eddy covariance measurement of biogenic oxygenated VOC emissions from hay harvesting." Atmospheric Environment 35, no. 3 (2001): 491–95. http://dx.doi.org/10.1016/s1352-2310(00)00405-2.
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Yu, C. W. F., and D. R. Crump. "Small Chamber Tests for Measurement of VOC Emissions from Flooring Adhesives." Indoor and Built Environment 12, no. 5 (October 2003): 299–310. http://dx.doi.org/10.1177/142032603035502.
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Healy, Robert M., Uwayemi M. Sofowote, Jonathan M. Wang, Qingfeng Chen, and Aaron Todd. "Spatially Resolved Source Apportionment of Industrial VOCs Using a Mobile Monitoring Platform." Atmosphere 13, no. 10 (October 20, 2022): 1722. http://dx.doi.org/10.3390/atmos13101722.
Повний текст джерелаАнотація:
Industrial emissions of volatile organic compounds (VOCs) directly impact air quality downwind of facilities and contribute to regional ozone and secondary organic aerosol production. Positive matrix factorization (PMF) is often used to apportion VOCs to their respective sources using measurement data collected at fixed sites, for example air quality monitoring stations. Here, we apply PMF analysis to high time-resolution VOC measurement data collected both while stationary and while moving using a mobile monitoring platform. The stationary monitoring periods facilitated the extraction of representative industrial VOC source profiles while the mobile monitoring periods were critical for the spatial identification of VOC hotspots. Data were collected over five days in a heavily industrialized region of southwestern Ontario containing several refineries, petrochemical production facilities and a chemical waste disposal facility. Factors associated with petroleum, chemical waste and rubber production were identified and ambient mixing ratios of selected aromatic, unsaturated and oxygenated VOCs were apportioned to local and background sources. Fugitive emissions of benzene, highly localized and predominantly associated with storage, were found to be the dominant local contributor to ambient benzene mixing ratios measured while mobile. Toluene and substituted aromatics were predominantly associated with refining and traffic, while methyl ethyl ketone was linked to chemical waste handling. The approach described here facilitates the apportionment of VOCs to their respective local industrial sources at high spatial and temporal resolution. This information can be used to identify problematic source locations and to inform VOC emission abatement strategies.
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Li, Shao-Meng, Amy Leithead, Samar G. Moussa, John Liggio, Michael D. Moran, Daniel Wang, Katherine Hayden, et al. "Differences between measured and reported volatile organic compound emissions from oil sands facilities in Alberta, Canada." Proceedings of the National Academy of Sciences 114, no. 19 (April 24, 2017): E3756—E3765. http://dx.doi.org/10.1073/pnas.1617862114.
Повний текст джерелаАнотація:
Large-scale oil production from oil sands deposits in Alberta, Canada has raised concerns about environmental impacts, such as the magnitude of air pollution emissions. This paper reports compound emission rates (E) for 69–89 nonbiogenic volatile organic compounds (VOCs) for each of four surface mining facilities, determined with a top-down approach using aircraft measurements in the summer of 2013. The aggregate emission rate (aE) of the nonbiogenic VOCs ranged from 50 ± 14 to 70 ± 22 t/d depending on the facility. In comparison, equivalent VOC emission rates reported to the Canadian National Pollutant Release Inventory (NPRI) using accepted estimation methods were lower than the aE values by factors of 2.0 ± 0.6, 3.1 ± 1.1, 4.5 ± 1.5, and 4.1 ± 1.6 for the four facilities, indicating underestimation in the reported VOC emissions. For 11 of the combined 93 VOC species reported by all four facilities, the reported emission rate and E were similar; but for the other 82 species, the reported emission rate was lower than E. The median ratio of E to that reported for all species by a facility ranged from 4.5 to 375 depending on the facility. Moreover, between 9 and 53 VOCs, for which there are existing reporting requirements to the NPRI, were not included in the facility emission reports. The comparisons between the emission reports and measurement-based emission rates indicate that improvements to VOC emission estimation methods would enhance the accuracy and completeness of emission estimates and their applicability to environmental impact assessments of oil sands developments.
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Ryan, Robert G., Jeremy D. Silver, Richard Querel, Dan Smale, Steve Rhodes, Matt Tully, Nicholas Jones, and Robyn Schofield. "Comparison of formaldehyde tropospheric columns in Australia and New Zealand using MAX-DOAS, FTIR and TROPOMI." Atmospheric Measurement Techniques 13, no. 12 (December 4, 2020): 6501–19. http://dx.doi.org/10.5194/amt-13-6501-2020.
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Abstract. South-eastern Australia has been identified by modelling studies as a hotspot of biogenic volatile organic compound (VOC) emissions; however, long-term observational VOC studies are lacking in this region. Here, 2.5 years of multi-axis differential optical absorption spectroscopy (MAX-DOAS) formaldehyde (HCHO) measurements in Australasia are presented, from Broadmeadows, in northern Melbourne, Australia, and from Lauder, a rural site in the South Island of New Zealand. Across the measurement period from December 2016 to November 2019, the mean formaldehyde columns measured by the MAX-DOAS were 2.50±0.61×1015 molec. cm−2 at Lauder and 5.40±1.59×1015 molec. cm−2 at Broadmeadows. In both locations, the seasonal cycle showed a pronounced peak in Austral summer (December–January–February) consistent with temperature-dependent formaldehyde production from biogenic precursor gases. The amplitude of the seasonal cycle was 0.7×1015 molec. cm−2 at Lauder, and it was 2.0×1015 molec. cm−2 at Broadmeadows. The Lauder MAX-DOAS HCHO measurements are compared with 27 months of co-located Fourier transform infrared (FTIR) observations. The seasonal variation of Lauder MAX-DOAS HCHO, smoothed by the FTIR averaging kernels, showed good agreement with the FTIR measurements, with a linear regression slope of 1.03 and an R2 of 0.66 for monthly averaged formaldehyde partial columns (0–4 km). In addition to ground-based observations, a clear way to address the VOC measurement gap in areas such as Australasia is with satellite measurements. Here, we demonstrate that the TROPOspheric Monitoring Instrument (TROPOMI) can be used to distinguish formaldehyde hotspots in forested and agricultural regions of south-eastern Australia. The MAX-DOAS measurements are also compared to TROPOMI HCHO vertical columns at Lauder and Melbourne; very strong monthly average agreement is found for Melbourne (regression slope of 0.61 and R2 of 0.95) and a strong agreement is found at Lauder (regression slope of 0.73 and R2 of 0.61) for MAX-DOAS vs. TROPOMI between May 2018 and November 2019. This study, the first long-term satellite comparison study using MAX-DOAS in the Southern Hemisphere, highlights the improvement offered by TROPOMI's high resolution over previous satellite products and provides the groundwork for future studies using ground-based and satellite DOAS for studying VOCs in Australasia.
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Cui, Lulu, Di Wu, Shuxiao Wang, Qingcheng Xu, Ruolan Hu, and Jiming Hao. "Measurement report: Ambient volatile organic compound (VOC) pollution in urban Beijing: characteristics, sources, and implications for pollution control." Atmospheric Chemistry and Physics 22, no. 18 (September 15, 2022): 11931–44. http://dx.doi.org/10.5194/acp-22-11931-2022.
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Abstract. The increasing ozone (O3) pollution and high fraction of secondary organic aerosols (SOA) in fine particle mass has highlighted the importance of volatile organic compounds (VOCs) in air pollution control. In this work, four intensive field measurements of VOCs during winter of 2018 (from 1 December 2018 to 17 January 2019), spring (15 April to 27 May), summer (17 June to 13 July), and autumn (22 September to 27 November) of 2019 were conducted at an urban site in Beijing to characterize VOC sources and their contributions to air pollution. The total mixing ratio of the 95 quantified VOCs (TVOC) observed in this study ranged from 5.5–118.7 ppbv with the mean value of 34.9 ppbv. Alkanes, OVOCs, and halocarbons were the dominant chemical groups, accounting for 75 %–81 % of the TVOC across the sampling months. The molar ratios of VOCs to NOx indicated that O3 formation was limited by VOCs during the whole sampling period. Positive matrix factorization (PMF) analysis showed that diesel vehicle exhaust, gasoline vehicle exhaust, and industrial emissions were the main VOC sources during both the O3-polluted and PM2.5-polluted months. On the basis of O3 formation impact, VOCs from fuel evaporation and diesel exhaust, particularly toluene, xylenes, trans-2-butene, acrolein, methyl methacrylate, vinyl acetate, 1-butene, and 1-hexene, were the main contributors, illustrating the necessity of conducting emission controls on these pollution sources and species to alleviate O3 pollution. Instead, VOCs from diesel exhaust as well as coal and biomass combustion were found to be the dominant contributors to secondary organic aerosol formation potential (SOAFP), particularly the VOC species of toluene, 1-hexene, xylenes, ethylbenzene, and styrene, and top priority should be given to these for the alleviation of haze pollution. This study provides insights for the government to formulate effective VOC control measures for air pollution in Beijing.
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Bechara, J., A. Borbon, C. Jambert, A. Colomb, and P. E. Perros. "Evidence of the impact of deep convection on reactive Volatile Organic Compounds in the upper tropical troposphere during the AMMA experiment in West Africa." Atmospheric Chemistry and Physics 10, no. 21 (November 4, 2010): 10321–34. http://dx.doi.org/10.5194/acp-10-10321-2010.
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Abstract. A large dataset of reactive trace gases was collected for the first time over West Africa during the African Monsoon Multidisciplinary Analysis (AMMA) field experiment in August 2006. Volatile Organic Compounds (VOC from C5–C9) were measured onboard the two French aircrafts the ATR-42 and the Falcon-20 by a new instrument AMOVOC (Airborne Measurement Of Volatile Organic Compounds). The goal of this study is (i) to characterize VOC distribution in the tropical region of West Africa (ii) to determine the impact of deep convection on VOC distribution and chemistry in the tropical upper troposphere (UT) and (iii) to characterize its spatial and temporal extensions. Experimental strategy consisted in sampling at altitudes between 0 and 12 km downwind of Mesoscale Convective Systems (MCS) and at cloud base. Biogenic and anthropogenic VOC distribution in West Africa is clearly affected by North to South emission gradient. Isoprene, the most abundant VOC, is at maximum level over the forest (1.26 ppb) while benzene reaches its maximum over the urban areas (0.11 ppb). First, a multiple physical and chemical tracers approach using CO, O3 and relative humidity was implemented to distinguish between convective and non-convective air masses. Then, additional tools based on VOC observations (tracer ratios, proxy of emissions and photochemical clocks) were adapted to characterize deep convection on a chemical, spatial and temporal basis. VOC vertical profiles show a "C-shaped" trend indicating that VOC-rich air masses are transported from the surface to the UT by deep convective systems. VOC mixing ratios in convective outflow are up to two times higher than background levels even for reactive and short-lived VOC (e.g. isoprene up to 0.19 ppb at 12 km-altitude) and are dependent on surface emission type. As a consequence, UT air mass reactivity increases from 0.52 s−1 in non-convective conditions to 0.95 s−1 in convective conditions. Fractions of boundary layer air contained in convective outflow are estimated to be 40 ± 15%. Vertical transport timescale is calculated to be 25 ± 10 min between 0 to 12 km altitude. These results characterize deep convection occurring over West Africa and provide relevant information for tropical convection parameterization in regional/global models.
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Saarikoski, Sanna, Heidi Hellén, Arnaud P. Praplan, Simon Schallhart, Petri Clusius, Jarkko V. Niemi, Anu Kousa, et al. "Characterization of volatile organic compounds and submicron organic aerosol in a traffic environment." Atmospheric Chemistry and Physics 23, no. 5 (March 6, 2023): 2963–82. http://dx.doi.org/10.5194/acp-23-2963-2023.
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Abstract. Urban air consists of a complex mixture of gaseous and particulate species from anthropogenic and biogenic sources that are further processed in the atmosphere. This study investigated the characteristics and sources of volatile organic compounds (VOCs) and submicron organic aerosol (OA) in a traffic environment in Helsinki, Finland, in late summer. The anthropogenic VOCs (aVOCs; aromatic hydrocarbons) and biogenic VOCs (bVOCs; terpenoids) relevant for secondary-organic-aerosol formation were analyzed with an online gas chromatograph mass spectrometer, whereas the composition and size distribution of submicron particles was measured with a soot particle aerosol mass spectrometer. This study showed that aVOC concentrations were significantly higher than bVOC concentrations in the traffic environment. The largest aVOC concentrations were measured for toluene (campaign average of 1630 ng m−3) and p/m xylene (campaign average of 1070 ng m−3), while the dominating bVOC was α-pinene (campaign average of 200 ng m−3). For particle-phase organics, the campaign-average OA concentration was 2.4 µg m−3. The source apportionment analysis extracted six factors for OA. Three OA factors were related to primary OA sources – traffic (24 % of OA, two OA types) and a coffee roastery (7 % of OA) – whereas the largest fraction of OA (69 %) consisted of oxygenated OA (OOA). OOA was divided into less oxidized semi-volatile OA (SV-OOA; 40 % of OA) and two types of low-volatility OA (LV-OOA; 30 %). The focus of this research was also on the oxidation potential of the measured VOCs and the association between VOCs and OA in ambient air. Production rates of the oxidized compounds (OxPR) from the VOC reactions revealed that the main local sources of the oxidation products were O3 oxidation of bVOCs (66 % of total OxPR) and OH radical oxidation of aVOCs and bVOCs (25 % of total OxPR). Overall, aVOCs produced a much smaller portion of the oxidation products (18 %) than bVOCs (82 %). In terms of OA factors, SV-OOA was likely to originate from biogenic sources since it correlated with an oxidation product of monoterpene, nopinone. LV-OOA consisted of highly oxygenated long-range or regionally transported OA that had no correlation with local oxidant concentrations as it had already spent several days in the atmosphere before reaching the measurement site. In general, the main sources were different for VOCs and OA in the traffic environment. Vehicle emissions impacted both VOC and OA concentrations. Due to the specific VOCs attributed to biogenic emissions, the influence of biogenic emissions was more clearly detected in the VOC concentrations than in OA. In contrast, the emissions from the local coffee roastery had a distinctive mass spectrum for OA, but they could not be seen in the VOC measurements due to the measurement limitations for the large VOC compounds. Long-range transport increased the OA concentration and oxidation state considerably, while its effect was observed less clearly in the VOC measurements due to the oxidation of most VOC in the atmosphere during the transport. Overall, this study revealed that in order to properly characterize the impact of different emission sources on air quality, health, and climate, it is of importance to describe both gaseous and particulate emissions and understand how they interact as well as their phase transfers in the atmosphere during the aging process.
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Sonderfeld, Hannah, Iain R. White, Iain C. A. Goodall, James R. Hopkins, Alastair C. Lewis, Ralf Koppmann, and Paul S. Monks. "What effect does VOC sampling time have on derived OH reactivity?" Atmospheric Chemistry and Physics 16, no. 10 (May 24, 2016): 6303–18. http://dx.doi.org/10.5194/acp-16-6303-2016.
Повний текст джерелаАнотація:
Abstract. State-of-the-art techniques allow for rapid measurements of total OH reactivity. Unknown sinks of OH and oxidation processes in the atmosphere have been attributed to what has been termed “missing” OH reactivity. Often overlooked are the differences in timescales over which the diverse measurement techniques operate. Volatile organic compounds (VOCs) acting as sinks of OH are often measured by gas chromatography (GC) methods which provide low-frequency measurements on a timescale of hours, while sampling times are generally only a few minutes. Here, the effect of the sampling time and thus the contribution of unmeasured VOC variability on OH reactivity is investigated. Measurements of VOC mixing ratios by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) conducted during two field campaigns (ClearfLo and PARADE) in an urban and a semi-rural environment were used to calculate OH reactivity. VOCs were selected to represent variability for different compound classes. Data were averaged over different time intervals to simulate lower time resolutions and were then compared to the mean hourly OH reactivity. The results show deviations in the range of 1 to 25 %. The observed impact of VOC variability is found to be greater for the semi-rural site.The selected compounds were scaled by the contribution of their compound class to the total OH reactivity from VOCs based on concurrent gas chromatography measurements conducted during the ClearfLo campaign. Prior to being scaled, the variable signal of aromatic compounds results in larger deviations in OH reactivity for short sampling intervals compared to oxygenated VOCs (OVOCs). However, once scaled with their lower share during the ClearfLo campaign, this effect was reduced. No seasonal effect on the OH reactivity distribution across different VOCs was observed at the urban site.
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Brito, J., and A. Zahn. "An unheated permeation device for calibrating atmospheric VOC measurements." Atmospheric Measurement Techniques Discussions 4, no. 3 (May 17, 2011): 2931–63. http://dx.doi.org/10.5194/amtd-4-2931-2011.
Повний текст джерелаАнотація:
Abstract. The development of an unpowered permeation device for continuous calibration of in-situ instruments measuring atmospheric volatile organic compounds (VOCs) is described. Being lightweight and compact, and containing only negligible amounts of chemicals, the device is especially suited for field use such as onboard aircraft. Its speciality is to maintain the permeation process in thermal equilibrium, i.e. the instantaneous permeation rate can be ascribed via a simple temperature measurement. This equilibrium state is maintained by a combination of three features: (i) a thin PTFE membrane as permeation medium which guarantees short stabilization times, (ii) a water bath as heat buffer, and (iii) a vacuum-panel based insulation, in which features (ii) and (iii) minimize temperature drifts. The uncertainty of the permeation rate due to thermal non-equilibrium is kept below 1 %. An extensive theory part details the major permeation processes of gases through porous polymers, being Fick's diffusion, Knudsen flow, and viscous flow. Both the measured stabilization time and the measured temperature dependence of the permeation rate independently indicate that the permeation can be described by a viscous flow model, where diffusion of the gas molecules in large pores (having a diameter of >0.05 μm) dominates.
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Stroud, Craig A., Paul A. Makar, Junhua Zhang, Michael D. Moran, Ayodeji Akingunola, Shao-Meng Li, Amy Leithead, Katherine Hayden, and May Siu. "Improving air quality model predictions of organic species using measurement-derived organic gaseous and particle emissions in a petrochemical-dominated region." Atmospheric Chemistry and Physics 18, no. 18 (September 25, 2018): 13531–45. http://dx.doi.org/10.5194/acp-18-13531-2018.
Повний текст джерелаАнотація:
Abstract. This study assesses the impact of revised volatile organic compound (VOC) and organic aerosol (OA) emissions estimates in the GEM-MACH (Global Environmental Multiscale–Modelling Air Quality and CHemistry) chemical transport model (CTM) on air quality model predictions of organic species for the Athabasca oil sands (OS) region in Northern Alberta, Canada. The first emissions data set that was evaluated (base-case run) makes use of regulatory-reported VOC and particulate matter emissions data for the large oil sands mining facilities. The second emissions data set (sensitivity run) uses total facility emissions and speciation profiles derived from box-flight aircraft observations around specific facilities. Large increases in some VOC and OA emissions in the revised-emissions data set for four large oil sands mining facilities and decreases for others were found to improve the modeled VOC and OA concentration maxima in facility plumes, as shown with the 99th percentile statistic and illustrated by case studies. The results show that the VOC emission speciation profile from each oil sand facility is unique and different from standard petrochemical-refinery emission speciation profiles used for other regions in North America. A significant increase in the correlation coefficient is reported for the long-chain alkane predictions against observations when using the revised emissions based on aircraft observations. For some facilities, larger long-chain alkane emissions resulted in higher secondary organic aerosol (SOA) production, which improved OA predictions in those plumes. Overall, the use of the revised-emissions data resulted in an improvement of the model mean OA bias; however, a decrease in the OA correlation coefficient and a remaining negative bias suggests the need for further improvements to model OA emissions and formation processes. The weight of evidence suggests that the top-down emission estimation technique helps to better constrain the fugitive organic emissions in the oil sands region, which are a challenge to estimate given the size and complexity of the oil sands operations and the number of steps in the process chain from bitumen extraction to refined oil product. This work shows that the top-down emissions estimation technique may help to constrain bottom-up emission inventories in other industrial regions of the world with large sources of VOCs and OA.
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Priddle, M. W., and R. E. Jackson. "Laboratory Column Measurement of VOC Retardation Factors and Comparison with Field Values." Ground Water 29, no. 2 (March 1991): 260–66. http://dx.doi.org/10.1111/j.1745-6584.1991.tb00518.x.
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