The distribution of particle-phase organic compounds in the atmosphere and their use for source apportionment during the Southern California Children''s Health Study

Atmospheric particulate matter (PM) samples from 12 sites in southern California, collected as part of the Southern California Children's Health Study (SCCHS), were analyzed using gas chromatography/mass spectrometry (GC/MS) techniques. Ninety-four organic compounds were quantified in these samples, including n-alkanes, fatty acids, polycyclic aromatic hydrocarbons (PAH), hopanes, steranes, aromatic diacids, aliphatic diacids, resin acids, methoxyphenols, and levoglucosan. Annual average concentrations of all detected compounds, as well as average concentrations for three seasonal periods, were determined at all 12 sites for the calendar year of 1995. These measurements provide important information about the seasonal and spatial distribution of particle-phase organic compounds in southern California. Also, co-located samples from one site were analyzed to assess precision of measurement. Excellent agreement was observed between annual average concentrations for the broad range of organic compounds measured in this study. Measured concentrations from the 12 sampling sites were used in a previously developed molecular-marker source apportionment model to quantify the primary source contributions to the PM10 organic carbon and mass concentrations at these 12 sites. Source contributions to atmospheric PM from six important air pollution sources were quantified: gasoline-powered motor vehicle exhaust, diesel vehicle exhaust, wood smoke, vegetative detritus, tire wear, and natural gas combustion. Important trends in the seasonal and spatial patterns of the impact of these six sources were observed. In addition, contributions from meat smoke were detected in selected samples.     

Occurrence and source of brominated organic compounds in surface waters

Monitoring of organic halogen compounds, measured as adsorbable organically bound bromine (AOBr), in an eutrophic lake, which is influenced by treated waste water, revealed repeatedly high concentrations of organobromine compounds in late summer, whereas five times lower values were measured during the rest of the year. It was possible to reproduce the in situ observed AOBr increase in the laboratory. Batch experiments were performed with lake water from two different lakes and an algae culture. It could be shown that the AOBr production is not limited to strong waste water influenced lakes. Furthermore, the AOBr formation requires light and the presence of algae, and thus is most probably biotic in nature. A low content of nutrients favours the formation of organic bromine compounds. To our knowledge this is the first report about the seasonally occurrence of naturally produced organic bromine compounds in lakes/surface waters.     

太湖水源地水体中半挥发性有机物的监测

太湖某水源地水样经C18柱富集、气相色谱-质谱法(GC-MS)分离,定性测定其中的有机物.在丰水期、平水期、枯水期分别采样,在检测到的近百种有机化合物中有40种出现频率很高,同时运用内标法对其进行相对含量的比较,结果表明脂肪族化合物、邻苯二甲酸酯、2,6-二叔丁基-4-甲基苯酚和异氰尿酸三甲酯的相对含量较高,值得引起关注.     

Gas- and particulate-phase specific tracer and toxic organic compounds in environmental tobacco smoke

Cigarette smoke constituents are worthy of concern and characterized as carcinogens. Different experiment conditions may affect the environmental tobacco smoke (ETS) constituents. A study was undertaken in a 75.5-m3 spare office to evaluate ETS constituents in a real environment. Thirty-four volatile organic compounds (VOCs) including three ETS tracers: nicotine, 2,5-dimethylfuran and 3-ethenylpyridine (3-EP), 19 carbonyl compounds, 54 semi-volatile compounds (24 polycyclic aromatic hydrocarbons (PAHs) and 30 alkanes) as well as CO and total particulate matter (TPM) from 15 leading commercial brands were determined. ETS constituents did not increase with increasing cigarette tar. ETS tracers nicotine and 3-EP were affected greatly due to more sorption and surface reactions in real world compared to other studies conducted in chamber, which resulted in 2-5 times lower. Benzene, toluene, ethylbenzene, xylenes, acrolein, 2-butanone and the high molecular weight compounds exhibited little affect. Pearson correlation analyses show that gas-phase and particulate-phase ETS tracers did not show significant correlation, but within each homologue many of compounds correlated significantly. Indole and cholesta-3,5-diene were also detected in ETS. These results may be useful in efforts to better understand the health effect of ETS exposure and source apportionment.     

Spatial gradients and source apportionment of volatile organic compounds near roadways

Concentrations of 55 volatile organic compounds (VOCs) (C₂–C₁₂) are reported near a highway in Raleigh, NC. Thirty-minute samples were collected at eight locations, ranging from approximately 10–100 m perpendicular from the roadway. The highest concentrations of VOCs were generally measured closest to the roadway, and concentrations decreased exponentially with increasing distance from the roadway. The highest mean concentration for individual VOCs were for ethylene (3.10 ppbv) (mean concentration at x = 13 m), propane (2.27 ppbv), ethane (1.91 ppbv), isopentane (1.54 ppbv), toluene (0.95 ppbv), and n-butane (0.89 ppbv). Concentrations at the nearest roadway location (x = 13 m) were generally between 2.0 and 1.5 times those from the farthest roadway location (x = 92 m). The data were apportioned into four source categories using the EPA Chemical Mass Balance Model (CMB8.2): motor vehicle exhaust, compressed natural gas, propane gas, and evaporative gasoline. The majority of the VOCs resulted from motor vehicle exhaust (67 ± 12%) (% of total VOC at x = 13 m ± S.D.). Compressed natural gas, propane gas, and evaporative gasoline accounted for approximately 15%, 7% and 1% of the total VOC emissions, respectively, at x = 13 m.     

沈阳市固定燃烧源挥发性有机化合物2007年排放清单研究

挥发性有机化合物(VOCs)与.OH的反应是对流层臭氧形成的重要化学过程,是导致城市光化学烟雾的根本原因。为建立沈阳市固定燃烧源VOCs排放清单,选取了电力热力行业、钢铁行业和秸秆燃烧3个主要排放源进行研究。结果表明:(1)2007年,沈阳市固定燃烧源VOCs排放总量为8 544.539 t,其中排放量最大的是秸秆燃烧,为6 317.115 t;其次是电力热力行业,为2 225.780 t;最小的是钢铁行业,为1.644 t。(2)沈阳市各区县固定燃烧源VOCs排放量由大到小排序依次为新民市、法库县、东陵区、康平县、辽中县、于洪区、苏家屯区、大东区、沈北新区、铁西区、沈河区、皇姑区、和平区;VOCs排放强度由大到小排序依次为大东区、沈河区、铁西区、东陵区、皇姑区、和平区、于洪区、苏家屯区、法库县、康平县、辽中县、沈北新区、新民市。     

Vertical and diurnal characterization of volatile organic compounds in ambient air in urban areas

More than half of the world's population lives in cities, and their populations are rapidly increasing. Information on vertical and diurnal characterizations of volatile organic compounds (VOCs) in urban areas with heavy ambient air pollution can help further understand the impact of ambient VOCs on the local urban environment. This study characterized vertical and diurnal variations in VOCs at 2, 13, 32, 58, and 111 m during four daily time periods (7:00 to 9:00 a.m., 12:00 to 2:00 p.m., 5:00 to 7:00 p.m., and 11:00 p.m. to 1:00 a.m.) at the upwind of a high-rise building in downtown, Kaohsiung City, Taiwan. The study used gas chromatography-mass spectrometry to analyze air samples collected by silica-coated canisters. The vertical distributions of ambient VOC profiles showed that VOCs tended to decrease at greater heights. However, VOC levels were found to be higher at 13 m than at ground level at midnight from 11:00 p.m. to 1:00 a.m. and higher at 32 than 13 m between 7:00 and 9:00 a.m. These observations suggest that vertical dispersion and dilution of airborne pollutants could be jointly affected by local meteorological conditions and the proximity of pollution sources. The maximum concentration of VOCs was recorded during the morning rush hours from 7:00 to 9:00 a.m., followed by rush hours from 5:00 to 7:00 p.m., hours from 12:00 to 2:00 p.m., and hours from 11:00 p.m. to 1:00 a.m., indicating that the most VOC compounds in urban air originate from traffic and transportation emissions. The benzene-toluene-ethyl benzene-xylene (BTEX) source analysis shows that BTEX at all heights were mostly associated with vehicle transportation activities on the ground.     

Hourly and daily patterns of particle-phase organic and elemental carbon concentrations in the urban atmosphere

Two semicontinuous elemental and organic carbon analyzers along with daily integrated samplers, which were used for laboratory elemental and organic carbon analysis, were operated to measure PM2.5 organic carbon (OC) and elemental carbon (EC) for the entire year of 2002 at the St. Louis Midwest Supersite. The annual-average denuded OC and EC concentrations were 3.88 and 0.7 microg/m3, respectively. A comparison of the 24-hr average denuded and undenuded OC measurements showed a positive bias for the undenuded OC measurement that was best represented by a positive intercept of 0.34 +/- 0.1 microg/m3 and a slope of 1.06 +/- 0.02, with an R2 of 0.91. The full year of daily EC and OC measurements was used to demonstrate that a one-in-six-day sampling strategy at this site accurately represents the annual average concentrations. Although fine particle OC concentrations did not correlate with day of the week, EC concentrations showed a significant weekly pattern, with the highest concentration during the middle of the workweek and the lowest concentration on Sundays. Hourly EC and OC measurements yielded average diurnal patterns for the EC to OC ratio that peaked during morning rush hour traffic on weekdays but not on weekends.     

Biogenic volatile organic compounds as a potential stimulator for organic contaminant degradation by soil microorganisms

The effects of monoterpenes on the degradation of ¹⁴C-2,4-dichlorophenol (DCP) were investigated in soils collected from areas surrounding monoterpene and non-monoterpene-emitting vegetation. Indigenous microorganisms degraded ¹⁴C-2,4-DCP to ¹⁴CO₂, after 1 d contact time. Degradation was enhanced by prior exposure of the soils to 2,4-DCP for 32 d, increasing extents of mineralisation up to 60%. Monoterpene amendments further enhanced 2,4-DCP degradation, but only following pre-exposure to both 2,4-DCP and monoterpene, with total 2,4-DCP mineralisation extents of up to 71%. Degradation was greatest at the higher monoterpene concentrations (≥1 μg kg⁻¹). Total mineralisation extents were similar between concentrations, but higher than the control and the 0.1 μg kg⁻¹ amendment, indicating that increases in monoterpene concentration has a diminishing enhancing effect. We suggest that monoterpenes can stimulate the biodegradation of 2,4-DCP by indigenous soil microorganisms and that monoterpene amendment in soils is an effective strategy for removing organic contaminants.     

Levels and source apportionment of volatile organic compounds in southwestern area of Mexico City

Thirteen volatile organic compounds (VOCs) were quantified at three sites in southwestern Mexico City from July 2000 to February 2001. High concentrations of different VOCs were found at a Gasoline refueling station (GS), a Condominium area (CA), and at the University Center for Atmospheric Sciences (CAS). The most abundant VOCs at CA and CAS were propane, n-butane, toluene, acetylene and pentane. In comparison, at GS the most abundant were toluene, pentane, propane, n-butane, and acetylene. Benzene, a known carcinogenic compound had average levels of 28, 35 and 250 ppbC at CAS, CA, and GS respectively. The main contributing sources of the measured VOCs at CA and CAS were the handling and management of LP (Liquid Propane) gas, vehicle exhaust, asphalt works, and use of solvents. At GS almost all of the VOCs came from vehicle exhaust and fuel evaporation, although components of LP gas were also present. Based on the overall results possible abatement strategies are discussed.     

Sorption of organic gases in residential rooms

Experiments were conducted to characterize organic gas sorption in residential rooms studied “as-is” with furnishings and material surfaces unaltered and in a furnished chamber designed to simulate a residential room. Results are presented for 10 rooms (five bedrooms, two bathrooms, a home office, and two multi-function spaces) and the chamber. Exposed materials were characterized and areas quantified. A mixture of volatile organic compounds (VOCs) was rapidly volatilized within each room as it was closed and sealed for a 5-h Adsorb phase; this was followed by 30-min Flush and 2-h closed-room Desorb phases. Included were alkane, aromatic, and oxygenated VOCs representing a range of ambient and indoor air pollutants. Three organophosphorus compounds served as surrogates for Sarin-like nerve agents. Measured gas-phase concentrations were fit to three variations of a mathematical model that considers sorption occurring at a surface sink and potentially a second, embedded sink. The 3-parameter sink–diffusion model provided acceptable fits for most compounds and the 4-parameter two-sink model provided acceptable fits for the others. Initial adsorption rates and sorptive partitioning increased with decreasing vapor pressure for the alkanes, aromatics and oxygenated VOCs. Best-fit sorption parameters obtained from experimental data from the chamber produced best-fit sorption parameters similar to those obtained from the residential rooms.     

Bottom sediment as a source of organic contaminants in Lake Mead, Nevada, USA

Treated wastewater effluent from Las Vegas, Nevada and surrounding communities’ flow through Las Vegas Wash (LVW) into the Lake Mead National Recreational Area at Las Vegas Bay (LVB). Lake sediment is a likely sink for many hydrophobic synthetic organic compounds (SOCs); however, partitioning between the sediment and the overlying water could result in the sediment acting as a secondary contaminant source. Locating the chemical plumes may be important to understanding possible chemical stressors to aquatic organisms. Passive sampling devices (SPMDs and POCIS) were suspended in LVB at depths of 3.0, 4.7, and 6.7 (lake bottom) meters in June of 2008 to determine the vertical distribution of SOCs in the water column. A custom sediment probe was used to also bury the samplers in the sediment at depths of 0-10, 10-20, and 20-30 cm. The greatest number of detections in samplers buried in the sediment was at the 0-10 cm depth. Concentrations of many hydrophobic SOCs were twice as high at the sediment-water interface than in the mid and upper water column. Many SOCs related to wastewater effluents, including fragrances, insect repellants, sun block agents, and phosphate flame retardants, were found at highest concentrations in the middle and upper water column. There was evidence to suggest that the water infiltrated into the sediment had a different chemical composition than the rest of the water column and could be a potential risk exposure to bottom-dwelling aquatic organisms.     

Comparison of receptor models for source apportionment of volatile organic compounds in Beijing, China

Identifying the sources of volatile organic compounds (VOCs) is key to reducing ground-level ozone and secondary organic aerosols (SOAs). Several receptor models have been developed to apportion sources, but an intercomparison of these models had not been performed for VOCs in China. In the present study, we compared VOC sources based on chemical mass balance (CMB), UNMIX, and positive matrix factorization (PMF) models. Gasoline-related sources, petrochemical production, and liquefied petroleum gas (LPG) were identified by all three models as the major contributors, with UNMIX and PMF producing quite similar results. The contributions of gasoline-related sources and LPG estimated by the CMB model were higher, and petrochemical emissions were lower than in the UNMIX and PMF results, possibly because the VOC profiles used in the CMB model were for fresh emissions and the profiles extracted from ambient measurements by the two-factor analysis models were "aged".     

Seasonal variation and source estimation of organic compounds in urban aerosol of Augsburg, Germany

This study reports a general assessment of the organic composition of the PM_2.5 samples collected in the city of Augsburg, Germany in a summer (August-September 2007) and a winter (February-March 2008) campaign of 36 and 30 days, respectively. The samples were directly submitted to in-situ derivatisation thermal desorption gas chromatography coupled with time of flight mass spectrometry (IDTD-GC-TOFMS) to simultaneously determine the concentrations of many classes of molecular markers, such as n-alkanes, iso- and anteiso-alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, n-alkanoic acids, alcohols, saccharides and others.The PCA analysis of the data identified the contributions of three emission sources, i.e., combustion sources, including fossil fuel emissions and biomass burning, vegetative detritus, and oxidized PAHs. The PM chemical composition shows seasonal trend: winter is characterized by high contribution of petroleum/wood combustion while the vegetative component and atmospheric photochemical reactions are predominant in the hot season.     

Wood smoke contribution to winter aerosol in Fresno, CA

In an effort to better quantify wintertime particulate matter (PM) and the contribution of wood smoke to air pollution events in Fresno, CA, a field campaign was conducted in winter 2003-2004. Coarse and fine daily PM samples were collected at five locations in Fresno, including residential, urban, and industrial areas. Measurements of collected samples included gravimetric mass determination, organic and elemental carbon analysis, and trace organic compound analysis by gas chromatograph mass spectrometry (GC/MS). The wood smoke tracer levoglucosan was also measured in aqueous aerosol extracts using high-performance anion exchange chromatography coupled with pulsed amperometric detection. Sample preparation and analysis by this technique is much simpler and less expensive than derivatized levoglucosan analysis by GC/MS, permitting analysis of daily PM samples from all five of the measurement locations. Analyses revealed low spatial variability and similar temporal patterns of PM2.5 mass, organic carbon (OC), and levoglucosan. Daily mass concentrations appear to have been strongly influenced by meteorological conditions, including precipitation, wind, and fog events. Fine PM (PM2.5) concentrations are uncommonly low during the study period, reflecting frequent precipitation events. During the first portion of the study, levoglucosan had a strong relationship to the concentrations of PM2.5 and OC. In the later portion of the study, there was a significant reduction in levoglucosan relative to PM2.5 and OC. This may indicate a change in particle removal processes, perhaps because of fog events, which were more common in the latter period. Combined, the emissions from wood smoke, meat cooking, and motor vehicles appear to contribute approximately 65-80% to measured OC, with wood smoke, on average, accounting for approximately 41% of OC and approximately 18% of PM2.5 mass. Two residential sites exhibit somewhat higher contributions of wood smoke to OC than other locations.     

Temporal variation and impact of wood smoke pollution on a residential area in southern Germany

This paper is a continuation of our previous publication (Bari, M.A., Baumbach, G., Kuch, B., Scheffknecht, G., 2009. Wood smoke as a source of particle-phase organic compounds in residential areas. Atmospheric Environment 43, 4722–4732) and describes a detailed characterisation of different particle-phase wood smoke tracer compounds in order to find out the impact of wood-fired heating on ambient PM₁₀ pollution in a residential area near Stuttgart in southern Germany. The results from previous flue gas measurements help distinguishing different tracer compounds in ambient PM₁₀ samples. In the residential area, significant amounts of hardwood markers (syringaldehyde, acetosyringone, propionylsyringol, sinapylaldehyde) and low concentrations of softwood markers (vanillin, acetovanillone, coniferyldehyde, dehydroabietic acid, retene) were found in the ambient air. The general wood combustion markers Levoglucosan, mannosan and galactosan were detected in high concentrations in all particle-phase PM₁₀ samples. To find out the size distribution of ambient particles, cascade impactor measurements were carried out. It was found that more than 70% of particulate matter was in the particle diameter of less than 1 μm. Using emission ratio of levoglucosan to PM₁₀, it can be demonstrated that during winter months 59% of ambient PM₁₀ pollution could be attributed to residential wood-fired heating.     

Volatile organic sulfur compounds in a stratified lake

Three volatile organic sulfur compounds (VOSCs), dimethyl sulfide (DMS), carbon disulfide (CS(2)), and dimethyl disulfide (DMDS), were detected in the stratified water column of a lake (Linsley Pond) in Connecticut. The compounds DMS and DMDS appeared in both the oxic and the anoxic portions of the water column, CS(2) was primarily found in anoxic hypolimnion. Algal metabolism and/or bacterial degradation of sulfur-containing amino acids or other organic materials are potential sources of VOSCs in the oxic lake water. Reactions of hydrogen sulfide with organic compounds and microbial degradation of organic matter may be responsible for the production of VOSCs in the anoxic lake water. The vertical distribution patterns of these three VOSCs varied from month to month in the summer, but the daily profiles obtained in one 5-day period in the summer displayed consistency. No clear diurnal pattern for any of the three VOSCs was observed. Based on observation that these VOSCs were not present in surface and near surface waters of Linsley Pond, freshwater inputs of reduced sulfur compounds to the atmosphere may be insignificant.     

Aqueous-phase reactive uptake of dicarbonyls as a source of organic aerosol over eastern North America

We use a global 3-D atmospheric chemistry model (GEOS-Chem) to simulate surface and aircraft measurements of organic carbon (OC) aerosol over eastern North America during summer 2004 (ICARTT aircraft campaign), with the goal of evaluating the potential importance of a new secondary organic aerosol (SOA) formation pathway via irreversible uptake of dicarbonyl gases (glyoxal and methylglyoxal) by aqueous particles. Both dicarbonyls are predominantly produced in the atmosphere by isoprene, with minor contributions from other biogenic and anthropogenic precursors. Dicarbonyl SOA formation is represented by a reactive uptake coefficient γ = 2.9 × 10^?3 and takes place mainly in clouds. Surface measurements of OC aerosol at the IMPROVE network in the eastern U.S. average 2.2 ± 0.7 μg C m^?3 for July–August 2004 with little regional structure. The corresponding model concentration is 2.8 ± 0.8 μg C m^?3, also with little regional structure due to compensating spatial patterns of biogenic, anthropogenic, and fire contributions. Aircraft measurements of water-soluble organic carbon (WSOC) aerosol average 2.2 ± 1.2 μg C m^?3 in the boundary layer (<2 km) and 0.9 ± 0.8 μg C m^?3 in the free troposphere (2–6 km), consistent with the model (2.0 ± 1.2 μg C m^?3 in the boundary layer and 1.1 ± 1.0 μg C m^?3 in the free troposphere). Source attribution for the WSOC aerosol in the model boundary layer is 27% anthropogenic, 18% fire, 28% semi-volatile SOA, and 27% dicarbonyl SOA. In the free troposphere it is 13% anthropogenic, 37% fire, 23% semi-volatile SOA, and 27% dicarbonyl SOA. Inclusion of dicarbonyl SOA doubles the SOA contribution to WSOC aerosol at all altitudes. Observed and simulated correlations of WSOC aerosol with other chemical variables measured aboard the aircraft suggest a major SOA source in the free troposphere compatible with the dicarbonyl mechanism.     

Source apportionment of airborne particulate matter using organic compounds as tracers

A chemical mass balance receptor model based on organic compounds has been developed that relates source contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.