Total Volatile Organic Compounds Concentrations Research Articles

Low Cost, Multi-Pollutant Sensing System Using Raspberry Pi for Indoor Air Quality Monitoring

Deteriorating levels of indoor air quality is a prominent environmental issue that results in long-lasting harmful effects on human health and wellbeing. A concurrent multi-parameter monitoring approach accounting for most crucial indoor pollutants is critical and essential. The challenges faced by existing conventional equipment in measuring multiple real-time pollutant concentrations include high cost, limited deployability, and detectability of only select pollutants. The aim of this paper is to present a comprehensive indoor air quality monitoring system using a low-cost Raspberry Pi-based air quality sensor module. The custom-built system measures 10 indoor environmental conditions including pollutants: temperature, relative humidity, Particulate Matter (PM)2.5, PM10, Nitrogen dioxide (NO2), Sulfur dioxide (SO2), Carbon monoxide (CO), Ozone (O3), Carbon dioxide (CO2), and Total Volatile Organic Compounds (TVOCs). A residential unit and an educational office building was selected and monitored over a span of seven days. The recorded mean PM2.5, and PM10 concentrations were significantly higher in the residential unit compared to the office building. The mean NO2, SO2, and TVOC concentrations were comparatively similar for both locations. Spearman rank-order analysis displayed a strong correlation between particulate matter and SO2 for both residential unit and the office building while the latter depicted strong temperature and humidity correlation with O3, SO2, PM2.5, and PM10 when compared to the former.

Long-term Trends of Volatile Organic Compounds over the Texas, USA in the Past Two Decades

Volatile organic compounds (VOCs) are organic compounds in the air that have low vapor pressure. VOCs can be emitted from a variety of sources including biogenic, anthropogenic and pyrogenic processes. VOCs are precursors of aerosols and tropospheric 03. which harm human health. However, the potential of VOCs forming secondary air pollutants varies by species. Here, we analyze the long-term trends of soiu'ce. concentration and reactivity of six classes of VOCs from 1995 to 2018 over Texas. USA. VOCs emission from petroleum and related companies in Texas kept increasing these years. Among the VOCs tracers of oil and gas companies, the concentration of ethane kept increasing until 2015. Despite the increase of oil and gas related VOCs. the concentration of total VOCs and reactivity-weighted VOCs have decreased in the past two decades. We further investigate the seasonality of VOC reactivities, which depend on both temperature and VOC concentration. We find that VOC reactivity generally is highest in fall and lowest in spring, and such seasonality does not change over the two decades.

Emissions from 3D Printers as Occupational Environmental Pollutants

Abstract While many people work remotely during the pandemic, three-dimensional (3D) printers are working to ensure the medical personnel and general public with the necessary specific materials. Ease of use, low cost, fast prototyping, and a wide range of materials are the advantages of 3D technology that can quickly adapt to specific needs in different application areas and result in increased popularity. The aim was to analyse the concentrations of particulate matter (PM) and volatile organic compounds (VOCs) emitted in 3D printing zone where printers are located throughout the room around the perimeter and where orthopaedics and designers develop models during their full shift. The average ultrafine particles (UFP) concentration level fluctuates from 4×103 to 26×103 particles/cm3 that exceed the background level (<3×103 particles/cm3) during 8 h-shift. Microclimate was evaluated as unsatisfied regarding permissible values for air quality at workplaces: air temperature exceeds permissible upper level +25 °C, relative humidity was 21.5 % and air velocity ≤0.05 m/s. The highest particles’ number concentrations in the nano-scale range (<0.1 μm) and significantly higher mass concentrations in the coarse particle range (>2.5 μm) were detected. The median diameters of particle number (0.019, 0.014, 0.015 μm) and mass concentrations (4.394, 4.433, and 4.677 μm) were similar in all observed premises. Total VOC concentration was increased and specific substances such as toluene and formaldehyde (0.56±0.1 and 0.23±0.034 mg/m3) were found at high concentration in comparison with indoor air quality recommendations.

"군부대 생활공간의 포름알데히드(HCHO)와 총휘발성유기화합물(TVOCS) 농도 수준 "

"군부대 생활공간의 포름알데히드(HCHO)와 총휘발성유기화합물(TVOCS) 농도 수준 "

Sources and components of volatile organic compounds in breast surgery operating rooms

ObjectivesThe composition and concentration distribution of volatile organic compounds (VOCs) in surgical smoke had seldomly been reported. This study aimed to investigate the profile of VOCs and their concentration in surgical smoke from breast surgery during electrocautery in different tissues, electrosurgical units, and electrocautery powers. MethodsThirty-eight surgical smoke samples from 23 patients performed breast surgery were collected using evacuated stainless steel canisters. The concentrations of 87 VOCs in surgical smoke samples were analyzed by gas chromatography-mass spectrometry. The human tissues, electrosurgical units, and electrocautery power were recorded. ResultsThe median level of total VOCs concentrations in surgical smoke samples from mammary glands (total VOCs: 9953.5 ppb; benzene: 222.7 ppb; 1,3-butadiene: 856.2 ppb; vinyl chloride: 3.1 ppb) using conventional electrosurgical knives were significantly higher than that from other tissues (total VOCs: 365.7–4266.8 ppb, P < 0.05; benzene: 26.4–112 ppb, P < 0.05; 1,3-butadiene: 15.6–384 ppb, P < 0.05; vinyl chloride: 0.6–1.8 ppb, P < 0.05) using different electrosurgical units. A high methanol concentration was found in surgical smoke generated during breast surgery (641.4–4452.5 ppb) using different electrosurgical units. An electrocautery power of ≥ 27.5 watts used for skin tissues produced a higher VOCs concentration (2905.8 ppb). ConclusionsThe surgical smoke samples collected from mammary glands using conventional electrosurgical knives had high VOCs concentrations. The carcinogens (including benzene, 1,3-butadiene, and vinyl chloride) and methanol were found in the surgical smoke samples from different electrosurgical units. The type of electrosurgical unit and electrocautery power used affected VOCs concentrations in surgical smoke.

Profiles and Source Apportionment of Nonmethane Volatile Organic Compounds in Winter and Summer in Xi’an, China, based on the Hybrid Environmental Receptor Model

Summer and winter campaigns for the chemical compositions and sources of nonmethane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (OVOCs) were conducted in Xi’an. Data from 57 photochemical assessment monitoring stations for NMHCs and 20 OVOC species were analyzed. Significant seasonal differences were noted for total VOC (TVOC, NMHCs and OVOCs) concentrations and compositions. The campaign-average TVOC concentrations in winter (85.3 ± 60.6 ppbv) were almost twice those in summer (47.2 ± 31.6 ppbv). Alkanes and OVOCs were the most abundant category in winter and summer, respectively. NMHCs, but not OVOCs, had significantly higher levels on weekends than on weekdays. Total ozone formation potential was higher in summer than in winter (by 50%) because of the high concentrations of alkenes (particularly isoprene), high temperature, and high solar radiation levels in summer. The Hybrid Environmental Receptor Model (HERM) was used to conduct source apportionment for atmospheric TVOCs in winter and summer, with excellent accuracy. HERM demonstrated its suitability in a situation where only partial source profile data were available. The HERM results indicated significantly different seasonal source contributions to TVOCs in Xi’an. In particular, coal and biomass burning had contributions greater than half in winter (53.4%), whereas traffic sources were prevalent in summer (53.1%). This study’s results highlight the need for targeted and adjustable VOC control measures that account for seasonal differences in Xi’an; such measures should target not only the severe problem with VOC pollution but also the problem of consequent secondary pollution (e.g., from ozone and secondary organic aerosols).

Significant contribution of spring northwest transport to volatile organic compounds in Beijing

High values of ozone (O3) occur frequently in the dry spring season; thus, understanding the evolution characteristics of volatile organic compounds (VOCs) in spring is of great significance for preventing O3 pollution. In this study, a total of 101 VOCs from April 16 to May 21, 2019, were quantified using an online gas chromatography mass spectrometer/flame ionization detector (GCMS/FID). The results indicated that the observed concentration of total VOCs (TVOCs) was 30.4 ± 17.0 ppbv, and it was dominated by alkanes (44.3%), followed by oxygenated VOCs (OVOCs) (17.4%), halocarbons (12.7%), aromatics (9.5%), alkenes (8.2%), acetylene (5.3%) and carbon disulfide (2.5%). The average mixing ratio of VOCs showed obvious diurnal variation (high at night, low during daytime). We conducted a source apportionment study based on 32 major VOCs using positive matrix factorization (PMF), and coal + biomass burning (25.2%), diesel exhaust (16.0%), gasoline exhaust + evaporation (17.4%), secondary + long-lived species (16.7%), biogenic sources (4.3%), industrial emissions (9.3%) and solvent use (11.2%) were identified as major sources of VOCs. In addition to local emissions, most of the atmospheric VOCs were derived from long-distance air masses (65.7%), and the average mixing ratio of VOCs in the northwest direction was 29.4 ppbv. Combined with the results of the potential source contribution function (PSCF) indicate that research should focus on the local emissions of combustion, transportation sources and solvents usage to control atmospheric VOCs. Additionally, transmission of the northwest air mass is an important component that cannot be ignored during spring in Beijing.

Characteristics of wintertime VOCs in urban Beijing: Composition and source apportionment

Abstract Characteristics and sources of volatile organic compounds (VOCs) were investigated with highly time-resolved measurements by a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) at an urban site in Beijing in winter 2017. During the measurement period, high mixing ratios of VOCs (48.9 ppbv) and trace gases were observed, with alternating episodes of strong haze pollution and clean air. Ten VOC families showed clear dependence on the VOC concentration. Aromatics increased the most during haze, with significantly elevated benzene concentration at high VOC concentration, while CxHyO3 and CxHy increased the least. The positive matrix factorization (PMF) receptor model was applied to the VOC mass spectra, yielding four major VOC factors: traffic emissions (21.0%), solid fuel combustion (SFC, 24.4%), and two oxygenated VOC (OVOC) factors (32.3% and 22.3%). Traffic and solid fuel combustion were dominant during the periods of high total VOC concentration, while the OVOC1 fraction was reduced. Comparisons with organic aerosol (OA) sources showed increased oxygenated organic aerosol (OOA) concentration during high VOC concentration periods, indicating the importance of OVOCs to secondary organic aerosol formation. Furthermore, trajectory analysis showed that most of the clean days were associated with northerly winds with high ratios of OVOC1. In contrast, the haze periods were not only due to high primary emissions under stagnant conditions, but also influenced by air masses from a more regional scale.

Spatial Distribution, Source Apportionment, Ozone Formation Potential, and Health Risks of Volatile Organic Compounds over a Typical Central Plain City in China

The profiles, contributions to ozone formation, and associated health risks of 56 volatile organic compounds (VOCs) species were investigated using high time resolution observations from photochemical assessment monitoring stations (PAMs) in Luoyang, China. The daily averaged concentration of total VOCs (TVOCs) was 21.66 ± 10.34 ppbv in urban areas, 14.45 ± 7.40 ppbv in suburbs, and 37.58 ± 13.99 ppbv in an industrial zone. Overall, the VOCs levels in these nine sites followed a decreasing sequence of alkanes &gt; aromatics &gt; alkenes &gt; alkyne. Diurnal variations in VOCs exhibited two peaks at 8:00–9:00 and 19:00–20:00, with one valley at 23:00–24:00. Source apportionment indicated that vehicle and industrial emissions were the dominant sources of VOCs in urban and suburban sites. The industrial site displayed extreme levels, with contributions from petrochemical-related sources of up to 38.3%. Alkenes and aromatics displayed the highest ozone formation potentials because of their high photochemical reactivity. Cancer and noncancer risks in the industrial site were higher than those in the urban and suburban areas, and USEPA possible risk thresholds were reached in the industrial site, indicating PAMs VOC–related health problems cannot be ignored. Therefore, vehicle and industrial emissions should be prioritized when considering VOCs and O3 control strategies in Luoyang.

Characteristics and Source Apportionment of VOCs and O3 in Shijiazhuang

To study the composition characteristics and sources of volatile organic compounds (VOCs) in Shijiazhuang City, three national control points were selected to conduct VOCs sampling and analysis from March 2017 to January 2018. The correlation of VOCs through combination with meteorological and ground-level O3 data, and the sources of VOCs were analyzed by positive matrix factorization (PMF). To quantify the pollution period of O3 in summer, its temporal sequence characteristics were studied by wavelet analysis. During the sampling period, the average concentration of ambient total VOCs (TVOCs) was (137.23±64.62) μg·m-3. Haloalkanes were the most dominant VOC compounds, accounting for 31.77% of total VOCs mass, followed by aromatic (30.97%) and oxygenated VOCs (OVOCs, 23.76%). The seasonal variation in VOC concentration followed the trend in winter (187.7 μg·m-3) > autumn (146.8 μg·m-3) > spring (133.24 μg·m-3) > summer (107.1 μg·m-3); the concentration of VOCs shows a trend of increasing gradient from west to east. The O3 concentration correlated negatively with VOCs and NO2, and positively with temperature, sunshine duration, wind speed, and visibility. Changes in meteorological elements were concerned before the occurrence of ozone pollution in summer, especially in 4-5 days in June and 7-8 days during July to August after the occurrence of increasing temperature. Finally six potential sources of VOCs were quantified by the PMF model, including from gasoline emissions (24.78%), diesel vehicle emissions (24.69%), solvent usage (18.64%), the chemical industry (11.87%), regional background (10.84%), and the pharmaceutical industry (9.17%). Ozone formation potential (OFP) contribution of emission sources of gasoline and diesel vehicles (54.98%) was over half of the total contribution. Meanwhile, these findings illustrated that control of vehicle emissions and industrial sources would be an important way to reduce VOCs concentrations and improve air quality in Shijiazhuang.

Characteristics and Sources of Atmospheric Volatile Organic Compounds Pollution in Summer in Chengdu

In the research, volatile organic compounds (VOCs) were observed online in urban areas of Chengdu to study VOC concentration level, change characteristics, ozone generation contribution (OFP), and source contribution from June to September 2019. The results showed that the average concentration of TVOCs (total volatile organic compounds) was 112.66 μg·m-3, with alkanes (29.51%) and halogenated hydrocarbons (23.23%) forming the main components. The diurnal peak in VOCs mainly occurred from 10:00 am to 11:00 am, which is affected by urban motor vehicles, oil or gas volatilization, and industrial emissions. For OFP contribution of VOCs in summer, the contribution rate of aromatic hydrocarbons (42.7%) was the highest, followed by alkenes (27.4%). The key active species were m/p-xylene, ethylene, propylene, o-xylene, isopentane, cyclopentane, and acrolein. According to the source analysis by the PMF model, mobile sources are the main contributors of VOCs in summer in Chengdu, contributing 34% to TVOCs, followed by industrial sources (17%), volatile oil and gas (14%), and solvent use and natural sources contributing 11% and 13%. Therefore, motor vehicle and industrial emissions are the key control sources of VOCs in Chengdu, although control of pollution sources such as solvent use and oil or gas volatilization cannot be ignored.

Measurement report: Important contributions of oxygenated compounds to emissions and chemistry of volatile organic compounds in urban air

Abstract. Volatile organic compounds (VOCs) play important roles in the tropospheric atmosphere. In this study, VOCs were measured at an urban site in Guangzhou, one of the megacities in the Pearl River Delta (PRD), using a gas chromatograph–mass spectrometer/flame ionization detection (GC–MS/FID) and a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). Diurnal profile analyses show that stronger chemical removal by OH radicals for more reactive hydrocarbons occurs during the daytime, which is used to estimate the daytime average OH radical concentration. In comparison, diurnal profiles of oxygenated volatile organic compounds (OVOCs) indicate evidence of contributions from secondary formation. Detailed source analyses of OVOCs, using a photochemical age-based parameterization method, suggest important contributions from both primary emissions and secondary formation for measured OVOCs. During the campaign, around 1700 ions were detected in PTR-ToF-MS mass spectra, among which there were 462 ions with noticeable concentrations. VOC signals from these ions are quantified based on the sensitivities of available VOC species. OVOC-related ions dominated PTR-ToF-MS mass spectra, with an average contribution of 73 % ± 9 %. Combining measurements from PTR-ToF-MS and GC–MS/FID, OVOCs contribute 57 % ± 10 % to the total concentration of VOCs. Using concurrent measurements of OH reactivity, OVOCs measured by PTR-ToF-MS contribute greatly to the OH reactivity (19 % ± 10 %). In comparison, hydrocarbons account for 21 % ± 11 % of OH reactivity. Adding up the contributions from inorganic gases (48 % ± 15 %), ∼ 11 % (range of 0 %–19 %) of the OH reactivity remains `missing”, which is well within the combined uncertainties between the measured and calculated OH reactivity. Our results demonstrate the important roles of OVOCs in the emission and evolution budget of VOCs in the urban atmosphere.

Rapid Profiling of the Volatilome of Cooked Meat by PTR-ToF-MS: Characterization of Chicken, Turkey, Pork, Veal and Beef Meat.

This study aimed to compare the volatile organic compound (VOC) profiles of cooked meat from different species. Four burgers were prepared and cooked from each of 100 meat samples obtained from 100 animals of five species/categories (chicken, turkey, pork, veal and beef) sourced from five supermarkets and five local butchers. Two burgers were cooked in a water bath and two were grilled. Direct proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS) analysis of the sample headspace yielded 129 mass peaks, 64 of which were tentatively identified. The results showed that turkey and chicken had the largest and the smallest total concentrations of all VOCs, respectively. Of the mammalian meats, veal and beef had greater total VOC concentrations than pork. The proportions of the amounts of all the individual VOCs differed significantly according to species. Additionally, 14 of 17 independent latent explanatory factors (LEFs) identified by multivariate analysis exhibited significant differences between meat species/categories, and therefore helped to characterize them. PTR-ToF-MS has been used for the first time for the rapid and non-invasive profiling of cooked meat of different species/categories. Knowledge of specific VOC profiles paves new avenues for research aimed at characterizing species through sensory description, at authenticating species or at identifying abnormalities or fraud.

Implementation of the Indoor Environmental Quality (IEQ) Model for the Assessment of a Retrofitted Historical Masonry Building

Achieving a satisfactory level for indoor environments of historical buildings is an ongoing problem that needs to be solved due to a large demand for deep retrofits in the whole of Europe. The implementation of the indoor environmental quality index (IEQ) to predict an occupant’s satisfaction in thermo-modernized historical buildings is a new concept which is a response to existing needs. In this article, a relevant study is provided with the intention to evaluate the indoor environmental performance of retrofitting effects in historical buildings dating back to the years 1873–1878. Considering the historical character of the buildings, some of the cellar spaces were fitted out with an innovative internal insulation system of mineral sheets based on calcium silicate to prevent water vapor condensation and effectively limit mold growth. The IEQ methodology was applied for retrofitted and non-retrofitted spaces as a comparison. Four essential components of indoor quality are investigated: thermal comfort, indoor air quality, acoustic comfort, and visual quality. The results of sub-component indexes are calculated based on the measured indoor parameters and the specific sensory functions. This paper discusses the results of an indoor environmental analysis including a mycological air quality assessment with the newly developed IAQindex (fungal air contamination index), total volatile organic compound concentration (TVOC), CO2, and formaldehyde (HCHO) assessment, the evaluation energy-related thermal comfort, acoustic, and visual quality, of modernized spaces. A questionnaire survey study was additionally carried out among a building’s users intentioned to compare the accounts of satisfaction before and after the retrofitting process and also to compare “subjective” results with the one’s based on in situ tests. The retrofitting approach was proven to be effective in limiting the presence of molds and a significant difference in indoor environmental quality between thermally insulated and uninsulated spaces was observed and discussed.

Source, temporal variation and health risk of volatile organic compounds (VOCs) from urban traffic in harbin, China.

The main of this work investigated the levels, emission sources, and associated health risks of ambient volatile organic compounds (VOCs) closed urban traffic trunk from June 2017 to November 2018. The seasonal variation trend for total VOCs (TVOCs) concentrations was autumn>winter>summer>spring. During the daily fluctuations in summer, the TVOC concentrations appeared to be the highest at midnight and the lowest at 14:00. In spring, autumn, and winter, the concentrations of TVOCs reached the highest levels at 06:00 and dropped to the lowest levels at 14:00 to 15:00; then, the levels increased after 20:00. Aromatics were the most important types of ambient VOCs for the formation of secondary organic aerosols (SOAs). The Positive Matrix Factorization (PMF) source analysis indicated that the traffic emission accounted for 28.9% of TVOCs, followed by combustion (24.7%), industrial (21.3%), gasoline volatilization (12.4%), and solvent (11.7%) sources. Carcinogenic and non-carcinogenic risks via inhalation exposure to the selected 10 toxic VOCs may be of more concern for residents nearby traffic trunk in Harbin in autumn.

Potential of Passive Sampling and Plant Absorption to Quantify Inhalation Exposure to Volatile Organic Compounds

Emission of volatile organic compounds (VOCs) from photocopiers was investigated to assess the potential health impacts on inhalation exposure to VOCs. VOCs samples were collected during working hours using SKC VOCs 575 series passive sample. Twenty-one quantified VOCs were measured and analyzed by GC-MS/MS. The results showed that the total VOCs concentration emitted in the photocopy centers A and B were 2.29×104 and 2.32×104 µg/m3, respectively. The highest detected chemical was trans-1,2-Dichloroethene at about 2.18×104 (photocopy center A) and 2.15×104 µg/m3 (photocopy center B (The results reveal that the non-carcinogenic risk for inhalation exposure to m-Xylene, p-Xylene, and trans-1,2-Dichloroethene were in the range 0.94-1.53 and 1.19-1.79 and 51.54-52.23, respectively, resulting in the hazard index (HI) of non-carcinogenic VOCs in total being greater than 1.0. This indicated that the cumulative effects of inhalation exposure to VOCs at low concentrations should be of concern, even though it does not exceed the occupational exposure limits and Threshold Limit Values-Time Weighted Average for the mixtures (TLV-TWAmix). Plants display a greener solution to reduce indoor air pollution. The bio-concentration levels of total VOCs in Epipremnum aureum were noted as 74.71 to 174.42, signifying that E. aureum is effective for removal of VOCs naturally and sustainably.

Removal of indoor odors via phytoremediation: interaction between aromatic hydrocarbon odorants decreases toluene removal

The composition of volatile organic compounds (VOCs) in the air of homes and offices is often complex and can have a significant effect on the health of individuals exposed. Certain plant species and their associated microorganisms are known to remove VOCs from the air; however, the rate of removal of one VOC may be influenced by the presence of others. We investigated the effect of VOCs on toluene phytoremediation rate by comparing the interaction of toluene, xylene, and benzene, common indoor odorants. Golden pothos (Epipremnum aureum (L.) Engl.) and Cornstalk (Dracaena fragrans (L.) Ker Gawl.) were exposed to different concentrations of one or more gases in a sealed chamber. The removal of 0.9 μL L−1 toluene was little affected by the addition of 0.9 μL L−1 xylene until the concentration was ≥ 1.8 μL L−1. At 1.8 and 2.7 μL L−1 xylene, there was a progressive decline in toluene removal. Similarly, at 1 μL L−1 toluene, 1 μL L−1 of xylene did not have a significant effect on phytoremediation; however, with the addition of 1.0 μL L−1 benzene, removal of toluene declined an average of 50% in both plant species. The addition of xylene reduced toluene removal by 39% and with xylene + benzene 58% when the total VOC concentration remained constant, but total VOC removal by the plants was similar. Since homes and offices generally have a much more diverse VOC composition than described in this study, VOC interaction effects on phytoremediation are probably more complex in real-world situations.

Scalable and stable silica-coated silver nanoparticles, produced by electron beam evaporation and rapid thermal annealing, for plasmon-enhanced photocatalysis

This study demonstrates an easy, scalable way to fabricate stable plasmonic photocatalysts for gas-phase photocatalysis. Silver nanoparticles, coated with silica for improved stability, were fabricated via electron beam evaporation and rapid thermal annealing, modeled via finite difference time domain simulations, and characterized. Catalytic performance was evaluated by monitoring total volatile organic compound concentration from toluene degradation in a gas-phase recirculating batch reactor. Results of cycled experiments demonstrate 5-fold increase in apparent quantum yield and 18% increase in reaction rate constant over TiO2. This approach may enable plasmonic photocatalysis by offering a simple, scalable fabrication method more reliable than colloidal synthesis.

Investigation of the influencing factors in odor emission from wet-end white water

Emission of malodorous gases, such as volatile organic compounds (VOCs), hydrogen sulfide (H2S), and ammonia (NH3) during pulping and papermaking has caused certain harm to the air environment and human health. This paper investigated the influencing factors of odor emission from wet-end white water during the pro-duction of bobbin paper in a papermaking mill using old corrugated containers (OCC) as raw material. The concentration of malodorous gases emitted from wet-end white water was determined with pump-suction gas detectors. The results indicated that low temperature could limit the release of malodorous gases from white water. Specifically, no total volatile organic compounds (TVOC), H2S, and NH3 was detected at a temperature of 15°C. The concentrations of malodorous gases were slightly increased when temperature increased to 25°C. When temperature was 55°C, the released concentrations of TVOC, H2S, and NH3 were 22.3 mg/m3, 5.91 mg/m3, and 2.78 mg/m3, respectively. Therefore, the content of malodorous gases significantly increased with the temperature increase. The stirring of white water accelerated the release of malodorous gases, and the release rate sped up as the stirring speed increased. However, the total amount of malodorous gases released were basically the same as the static state. Furthermore, the higher the concentration of white water, the greater the amount of malodorous gases released. The pH had little influence on the TVOC release, whereas it significantly affected the release of H2S and NH3. With the increase of pH value, the released amount of H2S and NH3 gradually decreased. When pH reached 9.0, the release amount of H2S and NH3 was almost zero, proving that an alkaline condition inhibits the release of H2S and NH3.

Concentration monitoring of volatile organic compounds and ozone in Xi'an based on PTR-TOF-MS and differential absorption lidar

Ozone has become a severe ambient pollutant. As the critical precursors of the formation of ozone, volatile organic compounds (VOCs) can adversely affect the atmospheric environment. In order to obtain reliable data on the sources and pollution characteristics of VOCs and ozone in the city for precise emission reduction, the concentrations of VOCs and ozone in Xi'an city were monitored by navigation observation using both a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and differential absorption lidar. Three different functional areas were selected, including a residential area (RA), a commercial district (CD), and an industrial park (IP). The PTR-TOF-MS measurement results found total concentrations of VOCs (TVOCs) with mean values of 136 ppb, 175 ppb, and 267 ppb at RA, CD, and IP sites, respectively. The dominant category of VOCs was oxygenated VOCs (OVOCs) at all three sites, accounting for 86%, 81%, and 75% of TVOCs at the RA, CD, and IP sites, respectively. Among OVOCs and aromatic hydrocarbons (AHs), acetone and toluene were the predominant chemical species, accounting for 51% and 58% at the IP site, respectively. Propylene was the most abundant aliphatic hydrocarbon (ALH) at the RA and CD sites, accounting for 42% and 48% of the TVOCs, respectively. The average ozone formation potentials (OFP) of the measured VOCs were 546 μg/m3, 574 μg/m3, and 772 μg/m3 at the RA, CD, and IP sites, respectively; OVOCs were the dominant contributors to OFP at all three sites. Ozone concentrations were measured by differential absorption lidar, with mean values of 82 μg/m3, 92 μg/m3, and 117 μg/m3 at the RA, CD, and IP sites, respectively. Ozone concentration was correlated to VOCs concentration. Local meteorological conditions including wind speed and air pressure influenced VOCs and ozone concentrations. The assessment of the measurement results of local environmental protection departments indicated that forming relevant VOCs and ozone control policies and priority strategies should be considered in order to reduce the adverse effects of these pollutants.