Source Location and Characterization of Volatile Organic Compound Emissions at a Petrochemical Plant in Kaohsiung,Taiwan

Abstract

This paper elucidated a novel approach to locating volatile organic compound (VOC) emission sources and characterizing their VOCs by database and contour plotting. The target of this survey was a petrochemical plant in Linyan, Kaohsiung County, Taiwan. Samples were taken with canisters from 25 sites inside this plant, twice per season, and analyzed by gas chromatography–mass spectrometry. The survey covered 1 whole year. By consolidated into a database, the data could be readily retrieved, statistically analyzed, and clearly presented in both table and graph forms. It followed from the cross‐analysis of the database that the abundant types of VOCs were alkanes, alkenes/dienes, and aromatics, all of which accounted for 99% of total VOCs. By contour plotting, the emission sources for alkanes, aromatics, and alkenes/dienes were successfully located. Through statistical analysis, the database could provide the range and 90% confidence interval of each species from each emission source. Both alkanes and alkene/dienes came from tank farm and naphtha cracking units and were mainly composed of C₃–C₅ members. Regarding aromatics, benzene, toluene, and xylenes were the primary species; they were emitted from tank farm, aromatic units, and xylene units.     

Mapping and profile of emission sources for airborne volatile organic compounds from process regions at a petrochemical plant in Kaohsiung, Taiwan

This work surveyed five process regions inside a petrochemical plant in Taiwan to characterize the profiles of airborne volatile organic compounds (VOCs) and locate emission sources. Samples, taken with canisters, were analyzed with gas chromatography-mass spectrometry according to the TO-14 method. Each region was deployed with 24 sampling sites, sampled twice, and 240 samples in total were measured during the survey period. All of the data were consolidated into a database on Excel to facilitate retrieval, statistical analysis, and presentation in the form of a table or graph, and, subsequently, the profile of VOCs was elucidated. Emission sources were located by mapping the concentration distribution of either an individual or a type of species in terms of contour maps on Surfer. Through the cross-analysis of data, the abundant VOCs included alkenes, dienes, alkanes, and aromatics. A total of 19 emission sources were located from these five regions. The sources for alkanes stood inside first, third aromatic, and fourth naphtha cracking regions, whereas the ones for alkenes were inside two naphtha cracking regions. The sources for dienes were found inside the third naphtha cracking region alone; in contrast, the sources for aromatics were universally traced except inside the third naphtha cracking region. The measured intensity for sources mostly ranged from 1000 to 7000 ppb.     

Evaluation of non-enteric sources of non-methane volatile organic compound (NMVOC) emissions from dairies

Dairies are believed to be a major source of volatile organic compounds (VOC) in Central California, but few studies have characterized VOC emissions from these facilities. In this work, samples were collected from six sources of VOCs (Silage, Total Mixed Rations, Lagoons, Flushing Lanes, Open Lots and Bedding) at six dairies in Central California during 2006–2007 using emission isolation flux chambers and polished stainless steel canisters. Samples were analyzed by gas chromatography/mass spectrometry and gas chromatography/flame ionization detection. Forty-eight VOCs were identified and quantified in the samples, including alcohols, carbonyls, alkanes and aromatics. Silage and Total Mixed Rations are the dominant sources of VOCs tested, with ethanol as the major VOC present. Emissions from the remaining sources are two to three orders of magnitude smaller, with carbonyls and aromatics as the main components. The data suggest that animal feed rather than animal waste are the main source of non-enteric VOC emissions from dairies.     

Source profiles of volatile organic compounds associated with solvent use in Beijing,China

Compositions of volatile organic compound (VOC) emissions from painting applications and printing processes were sampled and measured by gas chromatography–mass spectrometry/flame ionization detection (GC–MS/FID) in Beijing. Toluene and C8 aromatics were the most abundant species, accounting for 76% of the total VOCs emitted from paint applications. The major species in printing emissions included heavier alkanes and aromatics, such as n-nonane, n-decane, n-undecane, toluene, and m/p-xylene. Measurements of VOCs obtained from furniture paint emissions in 2003 and 2007 suggest a quick decline in benzene levels associated with formulation changes in furniture paints during these years. A comparison of VOC source profiles for painting and printing between Beijing and other parts of the world showed significant region-specific discrepancies, probably because of different market demands and environmental standards. We conducted the evaluation of the source reactivities for various VOC emission sources. The ozone formation potential (OFP) for unit mass of VOCs source emissions is the highest for paint applications. Substituting solvent-based paints by water-based in Beijing will lead to an OFP reduction of 152,000 tons per year, which is more than 1/4 of the OFPs for VOCs emissions from vehicle exhaust in the city.     

NMOC,ozone, and organic aerosol in the southeastern United States, 1999–2007: 1. Spatial and temporal variations of NMOC concentrations and composition in Atlanta,Georgia

Volatile organic compounds (VOCs) are emitted from anthropogenic and natural (biogenic) sources into the atmosphere. Characterizing their ambient mixing ratios or concentrations is a challenge because VOCs comprise hundreds of species, and accurate measurements are difficult. Long-term hourly and daily-resolution data have been collected in the metropolitan area of Atlanta, Georgia, a major city dominated by motor vehicle emissions. A series of observations of daily, speciated C₂–C₁₀ non-methane organic compounds (NMOC) and oxygenated hydrocarbons (OVOC) in mid-town Atlanta (Jefferson Street, JST) are compared with data from three urban-suburban sites and a nearby non-urban site. Annual-average mixing ratios of NMOC and OVOC at JST declined from 1999 through 2007. Downward trends in NMOC, CO, and NO_y corroborate expected emission changes as reflected in emission inventories for Atlanta’s Fulton County. Comparison of the JST NMOC composition with data from roadside and tunnel sampling reveals similarities to motor vehicle dominated samples. The JST annual average VOC-OH reactivities from 1999 to 2007 were relatively constant compared with the decline in annual-average NMOC mixing ratios. Mean reactivity at JST, in terms of concentration*k_OH, was approximately 40% alkenes, 22% aromatics, 16% isoprene and 6% other biogenics, 13% C₇–C₁₀ alkanes and 3% C₂-C₆ alkanes, indicating that biogenic NMOCs are important but not dominant contributors to the urban reactive NMOC mix. In contrast, isoprene constituted ～50% of the VOC-OH reactivities at two non-urban sites. Ratios of 24-hour average CO/benzene, CO/isopentane, and CO/acetylene concentrations indicate that such species are relatively conserved, consistent with their low reactivity. Ratios of more-reactive to less-reactive species show diurnal variability largely consistent with expected emission patterns, transport and mixing of air, and chemical processing.     

Evaluation of the optimum volatile organic compounds control strategy considering the formation of ozone and secondary organic aerosol in Seoul, Korea

The characteristics of volatile organic compounds (VOCs) and their annual trends in Seoul, Korea were investigated, with their optimal control strategy suggested. The annual concentration of VOCs (96.2–121.1 ppbC) has shown a decreasing trend from 2004 to 2008, suggesting the control strategy via the “Special Measures for Metropolitan Air Quality Improvement,” which was implemented in 2005, has been successful. The contributions of individual VOC to the production of ambient ozone and secondary organic aerosol (SOA) are discussed to assess the adequacy of current control strategies. The contribution of aromatics (C6–C10) to the production of ozone accounted for 38.7–46.3 % of the total ozone production, followed by low carbon alkanes (C2–C6) (27.0–35.9 %). The total SOA formation potential of VOCs was found to range from 2.5 to 3.5 μg m^?3, mainly as a result of aromatics (C6–C10) (over 85 %). Considering the contributions from ozone and SOA production, it was concluded that solvent use was the most important emission source, followed by vehicle exhaust emissions. Thus, the current emission control strategy focused on these two emission sources is appropriate to reduce the VOCs related pollution level of the Seoul Metropolitan Region. Still, an additional control strategy, such as controlling the emissions from meat cooking, which is an emission source of high carbon alkanes (C7–C10), needs to be considered to further reduce the VOCs related pollution level in Seoul.     

Characterization of ambient volatile organic compounds at a landfill site in Guangzhou,South China

Ambient air monitoring was conducted at Datianshan landfill, Guangzhou, South China in 1998 to investigate the seasonal and horizontal variations of trace volatile organic compounds (VOCs). Twelve sampling points over the Datianshan landfill were selected and samples were collected simultaneously using Carbontrap(TM) adsorption tubes. Thirty eight VOCs were detected in the winter, whereas 60 were detected in the summer. The VOC levels measured in summer were alkanes, 0.5-6.5 microg/m(3); aromatics, 2.3-1667 microg/m(3); chlorinated species, 0.2-31 microg/m(3); terpines, 0.1-34 microg/m(3); carbonyl species, 0.3-5.6 microg/m(3) and naphthalene and its derivatives, 0.4-27 microg/m(3). Compared to the summer samples the VOC levels in winter were much lower (mostly 1-2 orders of magnitude lower). The aromatics are dominant VOCs in landfill air both in winter and summer. High levels of alkylbenzene and terpines such as methyl-isopropylbenzene (max 1667 microg/m(3)) and limonene (max 162 microg/m(3)) cause undesirable odor. The similar correlation coefficients of BTEX in summer and winter suggest VOCs emissions were from landfill site sources. The variation of BTEX ratio at landfill site is different from that in the urban area of Guangzhou. It shows that the ambient VOCs at landfill site were different from the urban areas.     

Speciation and quantification of vapor phases in soy biodiesel and waste cooking oil biodiesel

This study characterizes the compositions of two biodiesel vapors, soy biodiesel and waste cooking oil biodiesel, to provide a comprehensive understanding of biodiesels. Vapor phases were sampled by purging oil vapors through thermal desorption tubes which were then analyzed by the thermal desorption/GC/MS system. The results show that the compounds of biodiesel vapors can be divided into four groups. They include methyl esters (the main biodiesel components), oxygenated chemicals, alkanes and alkenes, and aromatics. The first two chemical groups are only found in biodiesel vapors, not in the diesel vapor emissions. The percentages of mean concentrations for methyl esters, oxygenated chemicals, alkanes and alkenes, and aromatics are 66.1%, 22.8%, 4.8% and 6.4%, respectively for soy biodiesel, and 35.8%, 35.9%, 27.9% and 0.3%, respectively for waste cooking oil biodiesel at a temperature of 25 ± 2 °C. These results show that biodiesels have fewer chemicals and lower concentrations in vapor phase than petroleum diesel, and the total emission rates are between one-sixteenth and one-sixth of that of diesel emission, corresponding to fuel evaporative emissions of loading losses of between 106 μg l⁻¹ and 283 μg l⁻¹. Although diesels generate more vapor phase emissions, biodiesels still generate considerable amount of vapor emissions, particularly the emissions from methyl esters and oxygenated chemicals. These two chemical groups are more reactive than alkanes and aromatics. Therefore, speciation and quantification of biodiesel vapor phases are important.     

A study of the atmospheric VOCs of Mount Tai in June 2006

Intensive field investigations were conducted at the summit of Mount Tai in June 2006 to understand the effects of the local and regional sources on atmospheric volatile organic compounds (VOCs) distributions. A total of 60 samples were collected and determined by quantitative analytical methods. The concentrations of the total VOCs (TVOCs) observed in the air of Mount Tai were 6.95 ± 5.71 ppb. Aromatic hydrocarbons provided the largest contribution to TVOCs, followed by alkanes and halocarbons. High levels of halocarbons accounted for 20% of TVOCs due to emission from a PVC plant located at the foot of Mount Tai. Alkenes and cycloalkanes contributed little to the total VOCs. The day-and-night differences and day-to-day variations in the concentrations of four selected species were investigated and the effects of several factors such as meteorological parameters, sources and transport characteristics on them were discussed in details. A back trajectory analysis showed that relatively higher levels of VOCs were related to long-range transport of pollutants from polluted areas. The vertical motions of air masses also had a large impact on the variations of the levels of VOCs. The result of the variability–lifetime relationships of VOCs, which is used to estimate the remoteness of the sampling location, showed that Mount Tai represents intermediate conditions between remote sites and sites in the vicinity of sources.     

An alternative approach to photochemical ozone creation potentials applied under European conditions

Photochemical ozone creation potential (POCP) values for 83 different volatile organic compounds (VOCs), including CO and CH4, were calculated under different environmental conditions representative for Europe. These calculations show that variations in POCP values are large between different types of chemical environments and that POCP values for VOCs should be presented as ranges instead of single values. POCP ranges are based on the extremes of the POCP values and are defined with the intention to include all POCP values an individual VOC will obtain in any European environment where O3 formation is of environmental concern. The POCP ranges indicate large differences in O3 production between individual VOCs, which justifies the use of this ranking scale instead of treating all VOCs as a homogeneous group of species in abatement strategies. Both the average O3 production over 96 hr and the maximum contribution to the O3 concentration were studied. The most efficient O3 producers were found to be isoprene, 2-methyl-2-butene, and acrolein. As a group, the alkenes are the most potent O3 producers, followed by higher alkanes and then the aromatics. The calculated values show a good agreement with previously calculated POCP values under northern European conditions.     

Characterization of hydrocarbons, halocarbons and carbonyls in the atmosphere of Hong Kong

Ambient air quality measurements of 156 species including 39 alkanes, 32 alkenes, 2 alkynes, 24 aromatic hydrocarbons, 43 halocarbons and 16 carbonyls, were carried out for 120 air samples collected at two sampling stations (CW and TW) in 2001 throughout Hong Kong. Spatial variations of volatile organic compounds (VOCs) in the atmosphere were investigated. Levels of most alkanes and alkenes at TW site were higher than that at the CW site, while the BTEX concentrations at the two sites were close. The BTEX ratios at CW and TW were 1.6:10.1:1.0:1.6 and 2.1:10.8:1.0:2.0, respectively. For major halogenated hydrocarbons, the mean concentrations of chloromethane, CFCs 12 and 22 did not show spatial variations at the two sites. However, site-specific differences were observed for trichloroethene and tetrachloroethene. Furthermore, there were no significant differences for carbonyls such as formaldehyde, acetaldehyde and acetone between the two sites. The levels of selected hydrocarbons in winter were 1-5 times that in summer. There were no common seasonal trends for carbonyls in Hong Kong. The ambient level of formaldehyde, the most abundant carbonyl, was higher in summer. However, levels of acetaldehyde, acetone and benzaldehyde in winter were 1.6-3.8 times that in summer. The levels of CFCs 11 and 12, and chloromethane in summer were higher than that in winter. Strong correlation of most hydrocarbons with propene and n-butane suggested that the primary contributors of hydrocarbons were vehicular emissions in Hong Kong. In addition, gasoline evaporation, use of solvents, leakage of liquefied petroleum gas (LPG), natural gas leakage and other industrial emissions, and even biogenic emissions affected the ambient levels of hydrocarbons. The sources of halocarbons were mainly materials used in industrial processes and as solvents. Correlation analysis suggested that photochemical reactions made significant contributions to the ambient levels of carbonyls in summer whereas in winter motor vehicle emissions would be the major sources of the carbonyls. The photochemical reactivity of selected VOCs was estimated in this study. The largest contributors to ozone formation were formaldehyde, toluene, propene, m,p-xylene, acetaldehyde, 1-butene/i-butene, isoprene and n-butane, suggesting that motor vehicles, gasoline evaporation, use of solvents, leakage of LPG, photochemical processes and biogenic emission are sources in the production of ozone. On the other hand, VOCs from vehicles and gasoline evaporation were predominant with respect to reactions with OH radical.     

Global comparison of VOC and CO observations in urban areas

Speciated volatile organic compound (VOC) and carbon monoxide (CO) measurements from the Marylebone Road site in central London from 1998 through 2008 are presented. Long-term trends show statistically significant decreases for all the VOCs considered, ranging from ?3% to ?26% per year. Carbon monoxide decreased by ?12% per year over the measurement period. The VOC trends observed at the kerbside site in London showed greater rates of decline relative to trends from monitoring sites in rural England (Harwell) and a remote high-altitude site (Hohenpeissenberg), which showed decreases for individual VOCs from ?2% to ?13% per year. Over the same 1998 through 2008 period VOC to CO ratios for London remained steady, an indication that emissions reduction measures affected the measured compounds equally. Relative trends comparing VOC to CO ratios between Marylebone Road and Hohenpeissenberg showed greater similarities than absolute trends, indicating that emissions reductions measures in urban areas are reflected by regional background locations. A comparison of VOC mixing ratios and VOC to CO ratios was undertaken for London and other global cities. Carbon monoxide and VOCs (alkanes greater than C₅, alkenes, and aromatics) were found to be strongly correlated (>0.8) in the Annex I countries, whereas only ethene and ethyne were strongly correlated with CO in the non-Annex I countries. The correlation results indicate significant emissions from traffic-related sources in Annex I countries, and a much larger influence of other sources, such as industry and LPG-related sources in non-Annex I countries. Yearly benzene to ethyne ratios for London from 2000 to 2008 ranged from 0.17 to 0.29 and compared well with previous results from US cities and three global megacities.     

Characteristics and source apportionment of VOCs measured in Shanghai,China

Volatile organic compounds (VOCs) were measured from 2007 to 2010 at the center of Shanghai, China. Because VOCs are important precursors for ozone photochemical formation, detailed information of VOC sources needs to be investigated. The results show that the measured VOC concentrations in Shanghai are dominated by alkanes (43%) and aromatics (30%), following by halo-hydrocarbons (14%) and alkenes (6%). Based on the measured VOC concentrations, a receptor model (PMF; positive matrix factorization) coupled with the information related to VOC sources (the distribution of major industrial complex, meteorological conditions, etc.) is applied to identify the major VOC sources in Shanghai. The result shows that seven major VOC sources are identified by the PMF method, including (1) vehicle related source which contributes to 25% of the measured VOC concentrations, (2) solvent based industrial source to 17%, (3) fuel evaporation to 15%, (4) paint solvent usage to 15%, (5) steel related industrial production to 12%, (6) biomass/biofuel burning to 9%, and (7) coal burning to 7%. Furthermore, ozone formation potential related to VOC sources is calculated by the MIR (maximum incremental reactivity) technique. The most significant VOC source for ozone formation potential is solvent based industrial sources (27%), paint solvent usage (24%), vehicle related emissions (17%), steel related industrial productions (14%), fuel evaporations (9%), coal burning (6%), and biomass/biofuel burning (3%). The weekend effect on the VOC concentrations shows that VOC concentrations are generally higher in the weekdays than in the weekends at the sampling site, suggesting that traffic conditions and human activities have important impacts on the VOC emissions in Shanghai.     

C2–C10 nonmethane hydrocarbons measured in Dallas,USA—Seasonal trends and diurnal characteristics

Nonmethane hydrocarbons (NMHCs) are important precursors of ozone and other photo oxidants. We presented continuous hourly average concentrations of 45 C₂–C₁₀ NMHCs measured in urban area of Dallas, USA from 1996 to 2004. Most of the selected compounds are good variables with less noise. The top 10 species with high ozone-generating potential were identified according to their concentrations and reactivities. The ambient concentrations of abundant anthropogenic emission hydrocarbons measured in Dallas were about 2–4 times of the background values measured in the remote areas with adjacent latitude. The time series for anthropogenic emission hydrocarbons showed an obvious seasonal cycle with relatively high concentration in winter and low concentration in summer. The sinusoidal function with a linearly decreasing factor could well fit the time series of NMHCs. The phase of seasonal cycle for the aromatic hydrocarbons of toluene, m/p xylene and o-xylene that might come from both vehicle emission and solvent utilities evaporation was about 1 month earlier than that for alkanes and alkenes that mainly came from vehicle emission. Ambient NMHCs in Dallas decreased with a stable rate during 1996–2004. For most of compounds with high ozone-generating potential, the rate of ambient concentration decrease was higher or much higher than the rate of volatile organic compounds (VOCs) source emission reduction estimated by EPA's National Emission Inventory. On weekdays, the morning hydrocarbon concentration peak was coincident with morning traffic rush time in Dallas. Another concentration peak was delayed to afternoon traffic rush time. The characteristics of VOCs sources, photochemical removal processes and atmospheric dilution could be interpreted by the diurnal variations of benzene/ethylbenzene (B/E), toluene/ethylbenzene (T/E) and xylene/ethylbenzene (X/E). The ratio of VOC/NO_x measured in Dallas was substantially smaller than that calculated for USA cities. Ozone formation in Dallas was VOC sensitive.     

An Alternative Approach to Photochemical Ozone Creation Potentials Applied under European Conditions

ABSTRACT

Photochemical ozone creation potential (POCP) values for 83 different volatile organic compounds (VOCs), including CO and CH₄, were calculated under different environmental conditions representative for Europe. These calculations show that variations in POCP values are large between different types of chemical environments and that POCP values for VOCs should be presented as ranges instead of single values. POCP ranges are based on the extremes of the POCP values and are defined with the intention to include all POCP values an individual VOC will obtain in any European environment where O₃ formation is of environmental concern. The POCP ranges indicate large differences in O₃ production between individual VOCs, which justifies the use of this ranking scale instead of treating all VOCs as a homogeneous group of species in abatement strategies.

Both the average O₃ production over 96 hr and the maximum contribution to the O₃ concentration were studied. The most efficient O₃ producers were found to be iso-prene, 2-methyl-2-butene, and acrolein. As a group, the alkenes are the most potent O₃ producers, followed by higher alkanes and then the aromatics. The calculated values show a good agreement with previously calculated POCP values under northern European conditions.     

The indoor volatile organic compound (VOC) characteristics and source identification in a new university campus in Tianjin,China

This study investigates the volatile organic compounds (VOCs) constituents and concentration levels on a new university campus, where all of the buildings including classrooms and student dormitories were newly built and decorated within 1 year. Investigated indoor environments include dormitories, classrooms, and the library. About 30 dormitory buildings with different furniture loading ratios were measured. The characteristics of the indoor VOCs species are analyzed and possible sources are identified. The VOCs were analyzed with gas chromatography–mass spectroscopy (GC-MS). It was found that the average total VOC (TVOC) concentration can reach 2.44 mg/m³. Alkenes were the most abundant VOCs in dormitory rooms, contributing up to 86.5% of the total VOCs concentration. The concentration of α-pinene is the highest among the alkenes. Unlike the dormitory rooms, there is almost no room with TVOC concentration above 0.6 mg/m³ in classroom and library buildings. Formaldehyde concentration in the dormitory rooms increased about 23.7% after the installation of furniture, and the highest level reached 0.068 mg/m³. Ammonia released from the building antifreeze material results in an average indoor concentration of 0.28 mg/m³, which is 100% over the threshold and should be seriously considered. Further experiments were conducted to analyze the source of the α-pinene and some alkanes in dormitory rooms. The results showed that the α-pinene mainly comes from the bed boards, while the wardrobes are the main sources of alkanes. The contribution of the pinewood bed boards to the α-pinene and TVOC concentration can reach up to above 90%. The same type rooms were sampled 1 year later and the decay rate of α-pinene is quite high, close to 100%, so that it almost cannot be detected in the sampled rooms.

Implications: Analysis of indoor volatile organic compounds (VOCs) in newly built campus buildings in China identified the specific constituents of indoor VOCs contaminants exposed to Chinese college students. The main detected substances α-pinene, β-pinene, and 3-carene originated from solid wood bed boards and should be seriously considered. In addition, the contribution rates of building structure materials and furniture to specific VOCs constituents are quantitative calculated. Also, the decay rates of these specific constituents within 1 year are also quantitative calculated in this paper. This study can help us to better understand the sources and concentration levels of VOC contaminants in campus buildings, and to help select appropriate materials in buildings.     

机动车尾气VOCs排放特征及减排措施研究

分析了机动车尾气挥发性有机物(VOCs)的排放特征,发现尾气VOCs排放具有明显的日变化和季节变化特征。不同区域不同车型机动车尾气VOCs成分谱略有差异,轻型汽油车尾气VOCs中芳香烃和烷烃含量较高,柴油车烷烃含量较高。尾气排放受机动车保有量、行驶里程、维护保养水平、行驶速度和燃油标准、排放标准等因素影响。从优先控制汽油车、加快机动车更新、采取本地化减排措施、加强多元管理措施、提高科研水平等方面提出了针对性的减排措施。     

Components and dispersion characteristics of organic and inorganic odorous gases in a large-scale dairy farm

The rapid development of large-scale livestock husbandry has caused serious air pollution problems (e.g., The Tuzuoqi demonstration farm belonging to the Yili Group. The farm is located in the suburb of Hohhot City in northern China). In this study, the gases in typical areas of a large-scale dairy farm were sampled and measured for volatile organic compounds (VOCs), hydrogen sulfide, and ammonia concentrations. Fifty-two species of VOCs were identified. The VOCs emitted from the cowshed mainly consisted of halogenated hydrocarbons (16,960 µg/m³), ketones (15,700 µg/m³), esters (9889 µg/m³), and sulfur compounds (3677 µg/m³). The VOCs from the oxidation pond were mainly composed of halogenated hydrocarbons (21,940 µg/m³) and ketones (3589 µg/m³). The VOCs from the solid–liquid separation tank comprised halogenated hydrocarbons (32,010 µg/m³), ketones (7169 µg/m³), and sulfur compounds (1003 µg/m³). The highest concentrations of ammonia and hydrogen sulfide were obtained from the milking parlor and solid–liquid separation tank, respectively. The ammonia concentration declined gradually due to the superposition of ammonia emitted from the cowshed and milking parlor. Analysis results of the influences of distance and meteorological factors on the dispersion of ammonia and hydrogen sulfide suggested that the dilution factors decreased with increasing distance from the emission source. Within distance ranges of 0–10 and 10–25 m, the concentration dilution factors were positively correlated with wind speed and temperature but negatively correlated with humidity and atmospheric pressure. The results of our work can provide a theoretical basis for the prevention and control of odorous gases in large-scale livestock farms.

Implications: Gases in typical areas of a large-scale dairy farm were sampled, and a total of 52 species of VOCs were identified. The highest concentrations of ketones, sulfur compounds, and esters were obtained at the cowshed (15,700, 3677, and 9889 µg/m³, respectively). Within the distance ranges of 0–10 and 10–25 m, the concentration dilution factors were positively correlated with wind speed and temperature.     

Characteristics of ambient C2–C11 non-methane hydrocarbons in metropolitan Nagoya,Japan

To understand the characteristics of non-methane hydrocarbon (NMHC) abundance in an urban air of Nagoya, one of the metropolitan areas of Japan, 48 species of C₂–C₁₁ NMHCs were measured with a measurement system, developed in this study, by using gas chromatography with flame ionization detection (GC/FID) continuously for one year from December 2003 to November 2004.Annual mean concentration of NMHCs in normal and propylene equivalent (PE) in Nagoya was compared with those in four urban areas of Seoul, London, Lille, and Dallas to extract characteristics of urban air. While the absolute values of the normal and PE concentrations of alkanes, alkenes, alkyne, and aromatics were significantly different among these urban areas, the proportions of each chemical group to the total NMHC were not so different.In Nagoya, the total normal concentration was high from November to February and low from June to August. The pattern of the seasonal variation was influenced mainly by that of alkanes. On the other hand, the total PE concentration was high from July to December and low from January to June. The pattern of the seasonal variation was influenced mainly by those of alkenes and aromatics. Particularly the normal concentration of isoprene was high from May to September because of large emission associated with activity of plants. As the results, in summer, the PE concentration of isoprene was especially high, and its contribution to the total NMHCs measured in this study was approximately 40%. The total PE concentrations were high in summer when the concentration of OH radicals is also high, suggesting that the productions of ozone and secondary organic aerosol (SOA) are likely to be promoted in summer of Nagoya.