Food cooking can be a significant source of atmospheric particulate organic matter. In this study, the chemical composition of particulate organic matter (POM) in PM2.5 emitted from four different ...Chinese cooking styles were examined by gas chromotography−mass spectrometry (GC−MS). The identified species are consistent in the emissions from different Chinese cooking styles and the quantified compounds account for 5∼10% of total POM in PM2.5. The dominant homologue is fatty acids, constituting 73∼85% of the quantified compounds. The pattern of n-alkanes and the presence of β-sitosterol and levoglucosan indicate that vegetables are consumed during Chinese cooking operations. Furthermore, the emissions of different compounds are impacted significantly by the cooking ingredients. The candidates of organic tracers used to describe and distinguish emissions from Chinese cooking in Guangzhou are tetradecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid, levoglucosan, mannosan, galactosan, nonanal, and lactones. During the sampling period, the relative contribution of Chinese cooking to the mass concentration of atmospheric hexadecanoic acid should be less than 1.3% in Guangzhou.
Air pollution associated with atmospheric fine particulate matter (PM2.5, i.e., particles with an aerodynamic diameter of 2.5
μm or less) is a serious problem in Beijing, China. To provide a better ...understanding of the sources contributing to PM2.5, 24-h samples were collected at 6-day intervals in January, April, July, and October in 2000 at five locations in the Beijing metropolitan area. Both backward trajectory and elemental analyses identified two dust storm events; the distinctly low value of Ca:Si (<0.2) and high Al:Ca (>1.7) in Beijing PM2.5 appear indicative of contributions from dust storms. Positive matrix factorization (PMF) was used to apportion sources of PM2.5, and eight sources were identified: biomass burning (11%), secondary sulfates (17%), secondary nitrates (14%), coal combustion (19%), industry (6%), motor vehicles (6%), road dust (9%), and yellow dust. The lower organic carbon (OC), elemental carbon (EC), SO
4
2−, and Ca values of yellow dust enable it to be distinguished from road dust. The PMF method resolved 82% of PM2.5 mass concentrations and showed excellent agreement with a previous calculation using organic tracers in a chemical mass balance (CMB) model. The present study is the first reported comparison between a PMF source apportionment model and a molecular marker-based CMB in Beijing.
An instrument was developed for semi-continuous measurement of the size-distribution of submicron nitrate, ammonium, sulphate and chloride. Novel in the instrumentation is the size-classification, ...which is realised with a pre-separator that consists of a set of four parallel impactors. The cut-off diameters of the impactors are at 0.18, 0.32, 0.56 and 1.0
μm. Aerosols smaller than the associated cut-off size pass the respective impactor and arrive in the detector. The manifold with impactors contains two additional lines, one open line and one containing a filter that removes all aerosols. This latter line provides an on-line field-blank. The sample air-flow is automatically switched by wide-bore ball valves to one of the six sampling lines for a period of 20
min; a measuring cycle thus takes 2
h.
Down-stream of the pre-separator the sampling and automated on-line analysis of the transmitted aerosol is accomplished with a “MARGA”. In this instrument steam condensation is used to grow the aerosol. The droplets formed are collected in a cyclone that drains to wet-chemical analysis systems. A wet-denuder between pre-separator and collector removes interfering gases, like nitric acid and ammonia. This enables artefact-free and thus representative semi-continuous measurement of the size-distribution of the semi-volatile (ammonium) nitrate.
The novel MARGA-sizer was first used in a 1
week field-test. After modifications it was then deployed in a monitoring campaign of 2
months in the summer of 2002, at the top level of the meteo-tower of Cabauw in the centre of the Netherlands. The high location, 200
m, was chosen to obtain data on ammonium nitrate that are minimally affected by surface emissions of ammonia. The data coverage over the period was over 60%; failure of the instrumentation was mainly associated with spells of extreme solar heating of the tower and associated high temperatures inside.
The average concentration of nitrate was 2.6
μg
m
−3, which was very similar to the value interpolated from data in the national network. The mass concentration of submicron nitrate was 2.0
μg
m
−3, of which 46% was in particles smaller than 0.32
μm. To put this in perspective: the concentration of submicron sulphate was similar to that of nitrate, while 53% was in particles smaller than 0.32
μm. The ion balance showed that the compounds were present as the fully neutralised salts. Quite large diurnal variations were observed for nitrate, with a surprising maximum in the afternoon. The size-distribution of the semi-volatile nitrate was rather constant over a daily cycle.
The emissions from food cooking could be a significant contributor to atmospheric particulate organic matter (POM) and its chemical composition would vary with different cooking styles. In this ...study, the chemical composition of POM emitted from Western-style fast food cooking was investigated. A total of six PM
2.5 samples was collected from a commercial restaurant and determined by gas chromatography–mass spectrometry (GC–MS). It is found that the total amount of quantified compounds of per mg POM in Western-style fast food cooking is much higher than that in Chinese cooking. The predominant homologue is fatty acids, accounting for 78% of total quantified POM, with the predominant one being palmitic acid. Dicarboxylic acids display the second highest concentration in the quantified homologues with hexanedioic acid being predominant, followed by nonanedioic acid.
C
max of
n-alkanes occurs at C25, but they still appear relative higher concentrations at C29 and C31. In addition, both levoglucosan and cholesterol are quantified. The relationship of concentrations of unsaturated fatty acids (C16 and C18) with a double bond at C9 position and C9 acids indicates the reduction of the unsaturated fatty acids in the emissions could form the C9 acids. Moreover, the nonlinear fit indicates that other C9 species or other compounds are also produced, except for the C9 acids. The potential candidates of tracers for the emissions from Western-fast food cooking could be: tetradecanoic acid, hexadecanoic acid, octadecanoic acid, 9-octadecenoic acid, nonanal, lactones, levoglucosan, hexanedioic acid and nonanedioic acid.
Size-resolved chemical composition of aerosol was investigated during the PRIDE intensive field campaign in October 2004 at Xinken, at Pearl River Delta (PRD), China. Xinken is a rural/coastal site ...located south of Guangzhou. Size-segregated particles were sampled using Micro-Orifice Uniform Deposit Impactors (MOUDI) in order to characterize regional aerosol pollution. The meteorological conditions during the measurements were stable with low wind speed, high temperature and high RH, leading to high concentrations of fine particles, especially due to secondary components. The average concentrations of PM
1.8 and PM
10 were 51±19 and 84±27
μg
m
−3, respectively, with a ratio of PM
1.8/PM
10 0.64±0.09, which indicates that fine particles dominated in PM
10. Sulfate, nitrate and ammonium were major ionic components. Aerosol mass size distributions showed either two or three modes. Land–sea circulation brought back aged aerosols to the sampling site leading to an increase of the concentrations of sodium and chloride in aerosols. The “condensation mode” of sulfate, which was formed by gas-to-particle conversion, was in the size range of 0.32–0.56
μm, and the “droplet mode” of sulfate was observed in the size range of 0.56–1.0 or 1.0–1.8
μm. Nitrate was distributed evenly over fine and coarse particles. The analysis of measured and calculated equilibrium constant of NH
4NO
3 indicates that dissociation of NH
4NO
3 in daytime is favored, but that at night ammonium nitrate is stable and constitutes the fine mode nitrate, while the coarse mode nitrate may be formed by the reaction of HNO
3 and sea-salt or soil components. Chemical mass closures showed reasonable agreement.
During recent years, it has become clear that ammonia is an important gas in relation to different environmental issues, such as acidification, eutrophication, human health and climate change ...(through particle formation). Therefore, there is a growing need to develop and apply instrumentation suitable for research into emission, dispersion, conversion and deposition of ammonia and ammonium. Recently, several instruments were developed suitable for measuring concentrations in ambient conditions even at very low levels, such as ammonia sensors suitable for monitoring and research, deposition measuring systems and aerosol samplers for on-line measurement of aerosol composition. These instruments have been tested and applied in a number of field studies. These studies include dry deposition measurements, ammonium nitrate studies in relation to the (in)direct aerosol effect, emission studies and policy evaluation with concentration and deposition monitoring data. The policy evaluation study showed that the measures to reduce ammonia emissions were not as successful as projected beforehand by statistical studies.
Emissions caused by the use of coal and by traffic have caused serious photochemical smog and aerosol pollution with unique characteristics in most Chinese cities. This report gives an overview of ...aerosol concentrations in China based on data obtained from both the literature and recent research by the authors. The results show that TSP (total suspended particulate) and PM-10 (particles with aerodynamic diameter 10 µm) concentrations frequently exceed the National Ambient Air Quality Standard and that ambient aerosol concentrations constitute a serious air pollution problem. PM-2.5 concentrations are also high and account for 60 % of the PM-10 mass. Organic carbon and sulfate are the most abundant components of PM-2.5, while crustal elements represent a minor portion.Nitrate concentrations are almost the same as sulfate in summertime, which implies that NO
control is very important in lowering fine particle concentrations and in improving air visibility. The chemical mass balance (CMB) method was applied in Beijing to identify the sources of PM-2.5. The main sources include fugitive dust, coal burning/industrial processes, traffic emissions, and secondary aerosol produced by atmospheric chemical conversion.
Two different measurement methods for atmospheric nitric and nitrous acid during the Atlanta Supersite study are described and compared. Both approaches combined wet denuder collection coupled to ion ...chromatographic analysis. One of these utilized a rotating wet annular denuder maintained indoor with a very dilute Na
2CO
3 solution as an absorber, operated by the Energieonderzoek Centrum Nederland (ECN), ion chromatography (IC) being conducted with a carbonate eluent system. Data from this instrument was available for a 15
min sample every hour. The other wet denuder was of the parallel plate design and was deployed on the roof of the measurement shelter. This device used dilute H
2O
2 solution as an absorber and was coupled to an IC operated with a hydroxide eluent. Operated by Texas Tech University (TTU), this instrument provided data with 10
min time resolution. When both instruments were seemingly operating properly, data from TTU and ECN instruments were well correlated, although the peak HNO
3 values during high NO
2/NO
y
periods were lower for the TTU instrument. Daily peaks in HNO
3, typically ranging in magnitude between 3 and 6
ppbv (7.8
ppbv registered by the ECN instrument on the highest NO
y
day) were observed. HONO results from both TTU and ECN instruments exhibited strong diurnal variations with nighttime peaks up to ∼5
ppbv. Data from the middle of the study period for the two instruments were correlated with a
r
2 value of 0.78. The relationship was not statistically distinguishable from a 1:1 correspondence. A similar correlation of
r
2=0.76 was observed for the HNO
3 data; in this case the peak concentrations occurring in day time.
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