Size-segregated measurements of particulate elemental carbon and aerosol light absorption at remote arctic locations

Size-segregated aerosol samples were taken during 2 winter pollution periods and in clean summer air at different remote locations in the European Arctic > 74°N. By means of a newly developed integrating sphere photometer these filter samples have been analysed for aerosol light absorption coefficients and particulate elemental carbon (PEC). The relatively high PEC concentrations in winter confirm other findings about the Arctic winter atmosphere having an aged continental aerosol burden. In summer very low light absorption coefficients of 4.5 × 10⁻⁸ m⁻¹ were measured, similar to upper tropospheric background values. For the climatically important months of March-May the key optical aerosol properties (extinction coefficient, single scattering albedo and absorption to backscatter ratio) were determined. Based on the approach of J.M. Mitchell (1971, in Man's Impact on Climate. MIT Press, Cambridge, MA) the Arctic haze aerosol is found to contribute to atmospheric heating, even in the summer. A first PEC size distribution was determined in a clean polar summer air. The results show systematic variations in the PEC size distribution from urban to remote locations and seasonal variations in the sink region which may be exploited to quantify aerosol removal process in long distance transport studies.     

Nitro-PAH in ambient particulate matter in the atmosphere of Athens

Nitrated polynuclear aromatic hydrocarbons (NPAH) with a molecular mass of 247 Daltons were found in soot collected in downtown Athens during a campaign performed in 1996. In particular, 2-nitrofluoranthene (2-NFa) and 2-nitropyrene (2-NPy), which are mainly related to photo-induced chemical processes occurring in the atmosphere, were more abundant than 1-nitropyrene (1-NPy) usually associated to motor vehicle exhaust.     

Alkyl sulfonic acids in the atmosphere

A gas Chromatographie technique, based on methylation with diazomethane and specific sulfur detection (FDP), is proposed for the on-filter speciation of add aerosol constituents. First results indicate, that apart from sulfuric acid (and/or acid sulfate) the atmospheric aerosol may contain sulfurous acid (and/or acid sulfite) and sulfonic acid. The latter are postulated to be products from the atmospheric oxidation of sulfides, disulfides and mercaptans.     

Horizontal inhomogeneities in the particulate carbon component of the Arctic haze

We present results obtained during the ‘AGASP 1983’ Arctic haze aircraft sampling experiment. During this program we operated the aethalometer, an instrument that responds to the aerosol graphitic (‘black’) carbon concentration in real time. Previous results showed strong vertical layering of this component of the Arctic haze. In this paper we present for the first time evidence of horizontal variations of aerosol black carbon concentration. Some of these variations correlate with meteorological parameters, but we also observed horizontal inhomogeneities with a characteristic scale of 50–100 km occurring in the absence of meteorological activity.     

Five years of air chemistry observations in the Canadian Arctic

Arctic air chemistry observations made in Canada between 1979 and 1984 are discussed. The weekly average concentration of 25 aerosol constituents has been measured routinely at three locations. Anthropogenic pollution typified by SO₄²⁻ and V has a persistent seasonal cycle. SO₄²⁻ concentrations are similar at all three locations, although they tend to be somewhat higher at Alert than at Mould Bay and Igloolik. The seasonal variation of an aerosol constituent depends on its source. There are four distinctive seasonal variations for:

• 1.(i) anthropogenic constituents Cr, Cu, Mn, Ni, Pb, Sr, V, Zn, H⁺, NH₄⁺, SO₄²⁻, NO₃⁻,
• 2.(ii) halogens (excepting Cl) Br, I, F,
• 3.(iii) sea salt elements Na, Mg, Cl and
• 4.(iv) soil constituents Al, Ba, Ca, Fe and Ti. In the Arctic winter, the mean concentrations of anthropogenic aerosol constituents, except SO₄²⁻, are 2–4 times lower than annual mean concentrations in southern Sweden near a major source region. SO₄²⁻ concentrations are only 30% lower mainly because of production from SO₂. Light scattering (b_scat) and SO₄²⁻ observations indicate that the SO₄²⁻ fraction of the fine particle mass fluctuates between 3 and 65% during the polluted winter months. Daily mean b_sact, at Mould Bay that exceeds 50 × 10⁻⁶m⁻¹ is associated with air originating from the northwest. The soluble major ion composition of aerosols during winter varies markedly with particle size. H⁺, NH₄⁺ and SO₄²⁻ dominate submicrometre particles while sea-salt ions Mg²⁺, Na⁺ and Cl⁻ predominate in supermicrometre particles. Winter SO₂ concentrations at Mould Bay and Igloolik ranged from 0.2 to 1.5 ppb
• 5.(v). The fraction of airborne S as SO₂ ranged from 20 to 90% and peaked in late December-early January. The concentration of total NO₃⁻ (0.025–0.090 ppb(v)) is much lower than that of SO₄²⁻ (0.3–1.2 ppb (v)).

     

Size-segregated particulate matter and its association with respiratory deposition doses among outdoor exercisers in Dhanbad City,India

Regular exercise improves physiological processes and yields positive health outcomes. However, it is relatively less known that particulate matter (PM) exposure during outdoor exercises may increase several respiratory health problems depending on PM levels. In this study, the respiratory deposition doses (RDDs) in head airway (HD), tracheobronchial (TB), and alveolar (AL) regions of various PM size fractions (<10, <2.5, and <1 μm; PM₁₀, PM_2.5, and PM₁) were estimated in healthy male and female exercisers in urban outdoors and within house premises. The highest RDDs were found for PM during morning hours in winter compared with remaining periods. RDDs in AL region for males and females, respectively, were 34.7 × 10^?2 and 28.8 × 10^?2 µg min^?1 for PM₁₀, 65.7 × 10^?2 and 56.9 × 10^?2 µg min^?1 for PM_2.5, and 76.5 × 10^?2 and 66.3 × 10^?2 µg min^?1 for PM₁. The RDD values in AL region were significantly higher in PM₁ (27%) compared with PM_2.5 (13%) and PM₁₀ (2%) during exercise in all periods. This result showed that the morning peak hours in winter are more harmful to urban outdoor exercisers compared with other periods. This study also showed that the AL region would have been the main affected zone through fine particle (PM₁) to all the exercisers.

Implications: Size-segregated particle concentrations in urban outdoors and within house premises were measured. The highest respiratory deposition doses (RDDs) were found for PM during morning hours in winter compared with remaining periods. During light exercise, the RDD values in alveolar (AL) region for PM₁₀, PM_2.5, and PM₁ for male exercisers were significantly higher, 20.4%, 15.5%, and 15.4%, respectively, compared with female exercisers during morning peak hours in winter.     

Size distributions and formation of dicarboxylic acids in atmospheric particles

The PM2.5 concentrations and the size distributions of dicarboxylic acids in Hong Kong were studied. Eleven sets of daily PM2.5 samples were obtained at a downtown sampling site during the period of 5–16 December 2000 using an R&P speciation PM2.5 sampler. About 6–12% of the total oxalic acid was found in the gas phase in some samples. A good correlation between succinate and sulfate (R²=0.88) and a moderate correlation between oxalate and sulfate (R²=0.74) were found. Sampling artifacts of oxalate, malonate and succinate were found to be negligible. A total of 18 sets of 48–96 h size distribution data on dicarboxylic acids, sulfate, nitrate and sodium at an urban site and a rural site from June 2000 to May 2001 were obtained using a Micro-Orifice Uniform Deposit Impactor. Data from both sites show similar size distribution characteristics of the dicarboxylic acids. The condensation mode of oxalate was usually observed at 0.177–0.32 μm. The location of the peak of the droplet mode of oxalate was associated with that of sulfate. When the peak of sulfate in the droplet mode appeared at 0.32–0.54 μm, the peak of oxalate sometimes appeared at 0.32–0.54 μm and sometimes shifted to 0.54–1.0 μm. When the peak of sulfate in the droplet mode appeared at 0.54–1.0 μm, the peak of oxalate sometimes appeared at 0.54–1.0 μm and sometimes shifted to 1.0–1.8 μm. Oxalate, succinate and sulfate found in the droplet mode were attributed to in-cloud formation. The slight shift of the oxalate peak from 0.32–0.54 to 0.54–1.0 μm or from 0.54–1.0 to 1.0–1.8 μm was ascribed to minor oxalate evaporation after in-cloud formation. The maximum peak of malonate sometimes appeared in the droplet mode and sometimes appeared at 3.1–6.2 μm. The formation of malonate is associated to the reactions between sea salt and malonic acid.     

Diurnal variation of particulate pollution of the atmosphere in an urban area

The diurnal evolution of the average particulate concentration in the atmosphere of the urban area of Jaén (Spain) has been studied for each of the established yearly periods—that of high emission during the autumn and winter months, and that of lower emission covering the remaining months of the year—using the densitometric analysis of the samples obtained with a dust impactor, during 1 yr.An absolute concentration peak has been determined between 6 and 9 a.m. (GMT) and a relative maximum between 6 and 9 p.m., the latter not appearing during the low-emission period.The results have enabled us to establish a clear relationship between the solar radiation and the diurnal evolution of the pollutant concentration.     

High abundance of gaseous and particulate 4-oxopentanal in the forestal atmosphere

Atmospheric concentrations of 4-oxopentanal (4-OPA) in both gas and particulate phase were measured at the experimental forest, 200 km north of Sapporo, Japan, from August 13 to 15, 2001. 4-OPA was collected using an annular denuder sampling system and measured with a gas chromatography employing benzylhydroxyl oxime derivatization. Its gas phase concentrations ranged from 180 ng m(-3) (44 pptv) to 1570 ng m(-3) (384 pptv), whereas those in the particulate phase were from below the detection limit (25 ng m(-3)) to 207 ng m(-3). The particulate 4-OPA accounted for 28% (particle/(gas+particle)) of the total concentration as the maximum at 06:00 on August 15th (average: 10%). The particulate concentrations of 4-OPA were found to be comparable to those of pinonic acid, indicating that 4-OPA is also an important constituent of organic aerosols in the forestal atmosphere. Here, we report, for the first time, the concentrations of 4-OPA in both gas and particulate phase and its diurnal variations in the forestal atmosphere.     

Source contributions to fine particulate matter in an urban atmosphere

This paper proposes a practical method for estimating source attribution by using a three-step methodology. The main objective of this study is to explore the use of the three-step methodology for quantifying the source impacts of 24-h PM2.5 particles at an urban site in Seoul, Korea. 12-h PM2.5 samples were collected and analyzed for their elemental composition by ICP-AES/ICP-MS/AAS to generate the source composition profiles. In order to assess the daily average PM2.5 source impacts, 24-h PM2.5 and polycyclic aromatic hydrocarbons (PAH) ambient samples were simultaneously collected at the same site. The PM2.5 particle samples were then analyzed for trace elements. Ionic and carbonaceous species concentrations were measured by ICP-AES/ICP-MS/AAS, IC, and a selective thermal MnO2 oxidation method. The 12-h PM2.5 chemical data was used to estimate possible source signatures using the principal component analysis (PCA) and the absolute principal component scores method followed by the multiple linear regression analysis. The 24-h PM2.5 source categories were extracted with a combination of PM2.5 and some PAH chemical data using the PCA, and their quantitative source contributions were estimated by chemical mass balance (CMB) receptor model using the estimated source profiles and those in the literature. The results of PM2.5 source apportionment using the 12-h derived source composition profiles show that the CMB performance indices; chi2, R2, and percent of mass accounted for are 2.3%, 0.97%, and 100.7%, which are within the target range specified. According to the average PM2.5 source contribution estimate results, motor vehicle exhaust was the major contributor at the sampling site, contributing 26% on average of measured PM2.5 mass (41.8 microg m-3), followed by secondary sulfate (23%) and nitrate (16%), refuse incineration (15%), soil dust (13%), field burning (4%), oil combustion (2.7%), and marine aerosol (1.3%). It can be concluded that quantitative source attribution to PM2.5 in an urban area where source profiles have not been developed can be estimated using the proposed three-step methodology approach.     

Multi-year measurements of polybrominated diphenyl ethers (PBDEs) in the Arctic atmosphere

Weekly high-volume air samples have been collected in the Canadian High Arctic (Alert, Nunavut) since 1992. Fifteen polybrominated diphenyl ethers (PBDEs) are quantified in 104 samples over the time period of 2002–2004. To our knowledge, this study reports the first continuous multi-year measurements of PBDEs in Arctic air. Average air concentrations (in pg m⁻³) were 7.7 (0.40–47) and 1.6 (0.091–9.8) for 14 PBDEs (excluding BDE-209) and BDE-209, respectively, over the entire sampling period. BDE-28/33, 47, 99, 100, 153, 154, and 209 accounted for 90% (72–97%, n=104) of the 15 PBDEs. Occurrence of BDE-47, 99, and 209 suggests that PBDEs in Alert air were likely associated with the usage of “penta-BDE” and “deca-BDE” technical mixtures worldwide. Natural logarithm of concentrations for less brominated PBDEs correlated significantly with ambient temperatures in the summertime, suggesting importance of volatilization emissions in a local and/or regional scale. On the other hand, episodically elevated concentrations of the less brominated PBDEs in the wintertime and lack of seasonality for the non-volatile BDE-209 indicate potential inputs of particle-bound PBDEs through long-range transport (LRT), especially during the Arctic haze season. Inter-annual trend data further show that concentrations of the eight PBDEs increased inter-annually in 2002–2004 with doubling times of 2–6 years, which were similar to growth rates found in Arctic biotic samples. The results of this study and previous measurements suggest that potential sources of PBDEs in Arctic air include both volatilization emissions and LRT inputs.     

Polycyclic aromatic hydrocarbons and total extractable particulate organic matter in the Arctic aerosol

Samples of total suspended paniculate matter were collected in March and August 1979 at Barrow, Alaska, a remote site in the Arctic. Ambient concentrations of extractable paniculate organic matter (POM), of polycyclic aromatic hydrocarbons (PAH) and of ²¹⁰Pb were determined. The samples were also examined by optical and scanning electron microscopy. Average concentrations of POM and PAH were similar to those reported for other remote sites in the northern hemisphere, but the concentrations were considerably higher in March than in August. The presence of fly ash in the samples collected during the March sampling period, as well as seasonal differences in the concentrations of the organic species and ²¹⁰Pb and in meteorology indicate that the principal source of POM and PAH was fossil fuel combustion in the mid-latitudes during the March sampling period.     

The relationship between dimethyl sulfide and particulate sulfate in the mid-atlantic ocean atmosphere

Dimethyl sulfide (DMS) and atmospheric aerosols were sampled simultaneously over the Atlantic Ocean in the vicinity of Bermuda using the NOAA King Air research aircraft. Total and fine (50% cutoff at 2 μm diameter) aerosol fractions were sampled using two independent systems. The average nonsea-salt (nss)SO₄²⁻ concentrations were 1.9 and 1.0 μg m⁻³ (as SO₄²⁻) for the total and the fine fractions in the boundary layer (BL) and 0.53 and 0.27 μg m⁻³ in the free troposphere (FT). Non-sea-salt SO₄²⁻ in the two aerosol fractions were highly correlated (r = 0.90), however a smaller percentage (55%) was found in the fine aerosol near Bermuda relative to that (90%) near the North American continent. The BL SO₄²⁻ concentrations measured in this study were higher than those measured by others at remote marine locations despite the fact that the 7-day air mass back trajectories indicated little or no continental contact at altitudes of 700 mb and below; the trajectories were over subtropical oceanic areas that are expected to be rich in DMS. DMS concentrations were higher near the ocean surface and decreased with increasing altitude within the BL; the average DMS concentration was 0.13 μg m⁻³. Trace levels of DMS were also measured in the FT (0.01 μg m⁻³). Computer simultation of the oxidation and removal of DMS in the marine atmosphere suggests that <50% of the SO₄²⁻ observed could be related to the natural S cycle.     

Anthropogenic pollutants in the Russian Arctic atmosphere: sources and sinks in spring and summer

The 5-day forward and backward trajectories of air mass transport to three Russian Arctic points for each day in April and July over a 10-year period from 1986 to 1995 have been analyzed. The important features and seasonal differences in air exchange processes in various areas of the Arctic have been investigated. Taking into account seasonal variations in aerosol scavenging mechanisms and velocities, the average contributions of large highly industrialized regions of the Russian Arctic air pollution were estimated for April and July. Reasonable correspondence between the calculated mean concentrations for six anthropogenic chemical elements (As, Ni, Pb, V, Zn, Cd) and experimentally determined values have been obtained. The atmospheric pollution transport from the Arctic was studied as yet another way of cleaning the Arctic atmosphere, in addition to the traditionally considered wet and dry depositions onto the surface. The average apportionment of conservative contaminants after passing the observation points was estimated for spring and summer. The air masses passing through the observation points in spring may take about 20–40% of pollutants out of the Arctic. In summer, however, more than 90% of pollutants transported into the Russian Arctic deposit within 5 days onto the surface inside the Arctic region. The monthly average fluxes of six anthropogenic elements onto the surface in the Russian Arctic were estimated for April and July.