Source apportionment of atmospheric carbonaceous particulate matter based on the radiocarbon

A method was established to quantitatively estimate sources of atmospheric carbonaceous matter, using a combination of radiocarbon technology, linear regression of organic carbon (OC) -K⁺ and elemental carbon (EC) tracer method. Fractional contributions of fossil fuels, biomass burning, biogenic secondary organic carbon (BSOC) and soil dust to the atmospheric size-resolved carbonaceous matters in Shanghai suburb were estimated using this new method. The fossil carbon contributed most of the OC in particles smaller than 0.49 μm, and its fraction decreased with the increase of particle size. Biomass burning contributed 17–28 % to the OC. The BSOC contributed comparable proportions to the OC in particles smaller than 3.0 μm with the biomass burning, but larger in the particles lager than 3.0 μm. The soil dust contributed least fraction to the OC of each size with a proportion of 2–13 %. The biomass burning and fossil sources shared comparable fraction of the EC in all size range.     

Source apportionment of carbonaceous particulate matter during haze days in Shanghai based on the radiocarbon

To estimate the sources of carbonaceous particulate matter, ¹⁴C and biomass-burning marker (levoglucosan) were measured in the form of organic carbon (OC) and elemental carbon (EC) in PM_2.5 that was collected in five different functional districts of Shanghai during winter 2013. Spatial variations of the contemporary proportion among different districts were evident. The results of levoglucosan in Xujiahui (XH) and Chongming (CM) agreed well with those of ¹⁴C. The results indicate that environmental protection policies should vary for functional districts within the same city to account for their different sources of emissions.     

Measurement of the carbonaceous component in the Milan urban particulate matter

The carbonaceous component in the Milan urban particulate matter, i.e. the two components black carbon (BC) and organic carbon (OC), has been measured by means of a thermogravimetric analyzer combined with an infrared spectrophotometer (TGA/FT-IR). While black carbon may be considered a primary pollutant, organic carbon includes both primary emissions and secondary organic aerosols. Since carbonaceous aerosol (including a small quantity of inorganic carbon, too) makes up roughly from 25% to 50% of the average annual PM 2.5 mass concentration, a deeper understanding of this component is required. The TGA/FT-IR technique, employed for the first time to our knowledge for the quantification of the particulate matter carbonaceous component, allows, thought the results here presented are preliminary, to assess the two components BC and OC in a simple way especially if compared with the methods reported in the literature. The total carbon (TC) determinations performed by TGA/FT-IR on Milan urban particulate matter are in good agreement with the results obtained by a total organic carbon (TOC) analyzer operating directly on the solid sample.     

Assessment uncertainty associated to the analysis of organic compounds linked to particulate matter of atmospheric aerosols

Current work has evaluated uncertainty associated to quantification of several organic compounds present in particulate matter of atmospheric aerosols, setting out the stages of analytical procedure that contribute most to the global uncertainty. Several sources of uncertainty have been identified, which were clustered into five main contributions: sampling, extraction, clean-up, derivatization and analysis. A discussion of the main contributions to the overall uncertainty is reported, allowing authors to locate the largest ones and plan future improvements. Combined uncertainties ranged between 10-18% (alkanes), 12-16% (PAHs), 10-18% (alcohols) and 9-21% (acids). The analytical procedure was validated by analysing a standard reference material (SRM1649a, urban dust). Also, the proposed method was applied to the analysis of four samples of particulate matter.     

Chemical characterization of particulate matter (PM) and source apportionment study during winter and summer period for the city of Kozani,Greece

Eordaia basin located in northwest of Greece, comprises an area which is characterized by intense energy related activities, including coal burning at four power plants and the associated mining operations. Air samples of inhalable (PM10) and respirable particles (PM2.5) were collected in cold and warm periods in 2010 at an urban background site of Kozani, the major city and capital of the region which is located close to the power plants. Particulate matter concentration, particle-bound polycyclic aromatic hydrocarbons and anionic species concentrations were determined using gravimetric, GC-MS in SIM mode and Ion Chromatography analysis, respectively. For the cold period, the mean PM10 and PM2.5 mass concentration was found to be 19.62 and 14.68 µg m^?3, respectively. Correspondingly, for the warm period, the mean PM10 and PM2.5 values were 35.29 and 25.75 µg m^?3, respectively. In general, the results indicated that the major sources of air pollution in Kozani are traffic, combustion from agricultural activities and lignite power plants emissions, contributing by different percentages to each particle fraction.      

Fifteen years of nuclear techniques application to suspended particulate matter studies

Acute and chronic exposures to Airborne Particulate Matter (APM) have been linked, in epidemiological studies, to increased mortality and to a wide spectrum of respiratory and cardiovascular disorders. One factor that highly influences the toxicity of APM is its chemical composition. Nuclear Analytical Techniques (NATs) can be advantageously used in the determination of the particles element composition due to their multielement capability in association with low detection limits. Therefore, the characterization of APM by these techniques contributes to the identification of emission sources and, consequently, to the assessment of the effectiveness of the current air pollution abatement strategies. The main goal of this paper was to present the achievements obtained within 15 years of activities related with the use of NATs on the analysis of APM sampled in outdoor, indoor and industrial environments. The results presented in this work confirmed the relevance of NATs as efficient analytical techniques not only in the characterization of APM, but also in source apportionment, identification of long range transport and health assessment studies.     

Elemental concentrations and source identification of air particulate matter at a Nigerian site: A preliminary study

Air particulate matter collected between July and October 1990 at a site located close to an industrial estate in Lagos, Nigeria were analyzed for 18 elements by Wavelength Dispersive X-ray Fluorescence Spectroscopy (XRF) and Atomic Absorption Spectroscopy (AAS). Varimax rotated factor analysis was used for source identification of the coarse and fine fractions. For the coarse fraction, the major sources are: Re-entrained soil, Sea-salt, Industry, Regional sulphate and fresh automobile exhaust. For the fine fraction, the sources identified are Re-entrained soil, Vehicle exhaust, Sea-salt, and Industrial processes. Two other sources which are likely to be due to specific industrues come out in the fine fraction but they have not been clearly identified.     

The atmospheric chemistry of hydrogen peroxide: a review

This paper reviews the atmospheric chemistry of hydrogen peroxide, taking into account the formation processes of both gas-phase and aqueous H2O2, and the reactions involving hydrogen peroxide in the gas phase and in atmospheric hydrometeors. Gas-phase hydrogen peroxide mainly forms upon dismutation of the hydroperoxyl radical, a product of the reactions between atmospheric hydrocarbons, hydroxyl radicals, nitric oxide, and oxygen. Aqueous hydrogen peroxide originates from the dissolution of the gaseous one, the reduction of molecular oxygen, a series of reactions involving dissolved ozone, and the irradiation of anthraquinones, aromatic carbonyls, and semiconductor oxides. The reactions involving aqueous H2O2 are very important in the context of the chemistry of the atmosphere. They include oxidation of S(IV) to S(VI), photolysis, the Fenton reaction in the presence of Fe(II), and possibly the formation of peroxynitrous acid. Within this framework, the correlation of hydrogen peroxide with other atmospheric components and the time trends of hydrogen peroxide in the atmosphere are easily accounted for.     

CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: solving a lineshape paradox

Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4x10(19) spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S=1/2, and centres with S=0 ground state and thermally accessible triple state S=1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207-231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and (13)C nuclei indicates that IOM* centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H approximately 1.5+/-0.5x10(-2) of the order of values existing in interstellar medium.     

Determination of 23 polycyclic aromatic hydrocarbons in atmospheric particulate matter of the Paris area and photolysis by sunlight

Twenty-three polycyclic aromatic hydrocarbons (PAH) were determined in atmospheric particulate matter in 4 places of the Paris area at several times of the year. Fractionation was performed by reversed-phase high-pressure liquid chromatography. Determination was done by recording emission or excitation fluorescence spectra via a stopped-flow technique. Triphenylene was also extemporaneously determined by its phosphorescence spectrum at low temperature. Among the PAH determined dibenz(e,ghi)perylene has not been detected before in atmospheric particulate matter. The 10 more abundant PAH ranged from 0.1 to 40 ng/m3 of filtered air. Concentrations in August are from 14 to 250 times less than in January depending on the PAH. The reasons for this difference of behaviour among the PAH were investigated with regard to their photochemical and non-photochemical reactivity.     

Composition as a method for data reduction: application to carbon-13 NMR chemical shifts

The concept of composition as the counterpart to partition is introduced and advocated for the discussion of molecular properties. In the partition approach an observable (experimental) quantity is fragmented into contributions which are non-observable but which hopefully maintain constancy for fragments (bonds) in similar environments and thus facilitate comparison of data. With the composition as an approach the role of fragments and whole are reversed: one starts with a collection of observable fragment properties (e.g., atomic chemical shifts of NMR spectra) and then constructs an abstract non-observable quantity representing the collection of fragments as a whole. If a so-derived quantity for different molecules shows some regularity, the initial loss of information in condensation of independent fragment data is compensated by insight into novel structural correlations. The approach is illustrated first by ordering isomers (e.g., nonanes C₉H₂₀) with respect to their content of special graph invariants p ₂ and p ₃ (numbers of paths of length two and length three, respectively) and then showing that the constructed global quantity derived from individual carbon-13 NMR chemical shifts shows a regular variation with p ₂ and p ₃, very similar to isomeric variations of numerous thermodynamic properties of nonanes. Subsequently it is outlined how the difference (p ₂ p ₃) leads to a correlation for mean carbon-13 chemical shifts in octanes and nonanes, taken as an illustration for the approach. It is expected that the outlined approach opens new avenues for data reduction and the search for structure-property correlations.Dedicated to Professor J. Koutecký on the occasion of his 65th birthdayOperated by Iowa State University for the US Department of Energy under Contract No. W-7405-ENG-82. This work was supported in part by the Office of the Director     

Interpretation of atmospheric pollution phenomena in relationship with the vertical atmospheric remixing by means of natural radioactivity measurements (radon) of particulate matter

In this paper the results of seasonal monitoring campaign for primary (benzene and carbon monoxide) and secondary (nitrogen dioxide and ozone) pollutants and for the natural radioactivity of the particulate matter in the urban area of Rome, are reported to investigate acute atmospheric pollution episodes. Comparing the daily concentration trends of primary and secondary pollutants with those of the natural radioactivity, considered as index of the vertical diffusion in the low boundary layer, it has been evidenced that the acute pollution episodes in Rome occur in the winter period for the high atmospheric stability (primary pollution) and in the summer period for the strong diurnal atmospheric remixing (secondary pollution).     

Recent developments in assessment of bio-accessible trace metal fractions in airborne particulate matter: A review

In the last years a great deal of research has been focused on the determination of harmful trace metals such as Cd, Co, Cr, Cu, Ni or Pb in airborne particulate matter (APM). However, the commonly applied determination of total element concentrations in APM provides only an upper-end estimate of potential metal toxicity. For improved risk assessment it is important to determine bio-accessible concentrations instead of total metal contents. The present review gives an overview of analytical procedures reported for measurement of bio-accessible trace metal fractions in APM. The different approaches developed for extraction of soluble trace metals in APM are summarized. Furthermore the analytical techniques applied for accurate determination of dissolved trace metals in the presence of complex sample matrix are presented. Finally a compilation of published results for bio-accessible trace metals in APM is included.     

Critical review on the development of analytical techniques for the elemental analysis of airborne particulate matter

Among all environmental pollutants, particulate matter (PM) poses the major threat to our health. These tiny airborne particles vary in shape and composition, which is reflected in their hazardous potential. The particles are small enough to penetrate deep into the lungs and even enter the bloodstream, causing severe diseases. Therefore, their regular monitoring is required. Toxic metals and other elements are often measured by regulatory agencies as well as in research laboratories, either to compare ambient concentrations with prescribed limit values or to study provenance of air pollution sources in order to target PM pollution mitigation strategies. The most established method for the determination of regulated Pb, Cd, As, Ni and other elements in PM is microwave digestion inductively coupled plasma mass spectrometry (MW/ICPMS), whereas X-ray fluorescence (XRF) techniques have also often been used, especially in research. In this review paper we critically assess these two and three other analytical techniques (i.e., LA-ICPMS, PIXE and INAA) for element determination in PM deposited on filter media. All aspects from sample treatment to measurement range and limitations, costs and waste management are considered. In conclusion we identify XRF and LA-ICPMS as two promising surface techniques for the analysis of a PM deposit on a filter, which could replace the laborious wet MW/ICPMS method, which is – considering its wide use, very incriminating to the environment. In short, EDXRF is the cheapest, simplest for use and already customized for PM samples, whereas LA-ICPMS is promising, but still needs some development in the direction of autosamplers and matrix-matched standards for calibration.     

The micro-distribution of carbonaceous matter in the Murchison meteorite as investigated by Raman imaging

The carbonaceous Murchison chondrite is one of the most studied meteorites. It is considered to be an astrobiology standard for detection of extraterrestrial organic matter. Considerable work has been done to resolve the elemental composition of this meteorite. Raman spectroscopy is a very suitable technique for non-destructive rapid in situ analyses to establish the spatial distribution of carbonaceous matter. This report demonstrates that Raman cartography at a resolution of 1 microm2 can be performed. Two-dimensional distribution of graphitised carbon, amorphous carbonaceous matter and minerals were obtained on 100 microm2 maps. Maps of the surface of native stones and of a powdered sample are compared. Graphitic and amorphous carbonaceous domains are found to be highly overlapping in all tested areas at the surface of the meteorite and in its interior as well. Pyroxene, olivine and iron oxide grains are embedded into this mixed carbonaceous material. The results show that every mineral grain with a size of less than a few microm2 is encased in a thin carbonaceous matrix, which accounts for only 2.5 wt.%. This interstitial matter sticks together isolated mineral crystallites or concretions, including only very few individualized graphitised grains. Grinding separates the mineral particles but most of them retain their carbonaceous coating. This Raman study complements recent findings deduced from other spatial analyses performed by microprobe laser-desorption laser-ionisation mass spectrometry (microL2MS), transmission electron microscopy (TEM) and scanning transmission X-ray microscopy (STXM).     

Addition of internal standards to particulate sample matrices for routine trace analyses of semivolatile organic compounds: A source of systematical and random errors

This article is a criticism of the strategy of adding (isotope labelled) internal standards of semi volatile hydrophobic organic compounds directly on the surface of particulate samples matrix such as sediment, soil and fly ash, etc. in a small aliquot (mL) of solvent, before trace level analysis. The use of the internal standard is intended to compensate for incomplete extractions, clean-up losses, dilution errors and instrument variations. However, direct addition of internal standards to sample matrices creates two possibilities for inaccurate results by processes only affecting the internal standard: First, evaporation losses of standard from the sample matrix during evaporation of the carrier solvent. Second, the native analyte and internal standard sorb to the sample matrix with differing force. Both processes can introduce systematic and random error to the result. A systematic error of 74% due to evaporation losses of tetra chlorinated dibenzo-p-dioxins is observed, while the corresponding error for octa chlorinated dioxin is 0%. The associated random error is 45% for tetra down to 1–4% relative standard deviations for hepta and octa chlorinated dioxins. For laboratory staff the evaporation losses of standard (and native) compounds causes, besides dust, an additional risk of inhalation exposure. The internal standard should instead be added to the extraction solvent after the extraction. Smaller systematical errors (10–20%) and associated random errors due to irreversible sorption are discussed.     

Addition of internal standards to particulate sample matrices for routine trace analyses of semivolatile organic compounds: A source of systematical and random errors

This article is a criticism of the strategy of adding (isotope labelled) internal standards of semi volatile hydrophobic organic compounds directly on the surface of particulate samples matrix such as sediment, soil and fly ash, etc. in a small aliquot (mL) of solvent, before trace level analysis. The use of the internal standard is intended to compensate for incomplete extractions, clean-up losses, dilution errors and instrument variations. However, direct addition of internal standards to sample matrices creates two possibilities for inaccurate results by processes only affecting the internal standard: First, evaporation losses of standard from the sample matrix during evaporation of the carrier solvent. Second, the native analyte and internal standard sorb to the sample matrix with differing force. Both processes can introduce systematic and random error to the result. A systematic error of 74% due to evaporation losses of tetra chlorinated dibenzo-p-dioxins is observed, while the corresponding error for octa chlorinated dioxin is 0%. The associated random error is 45% for tetra down to 1–4% relative standard deviations for hepta and octa chlorinated dioxins. For laboratory staff the evaporation losses of standard (and native) compounds causes, besides dust, an additional risk of inhalation exposure. The internal standard should instead be added to the extraction solvent after the extraction. Smaller systematical errors (10–20%) and associated random errors due to irreversible sorption are discussed. Received: 4 September 1997 / Revised: 26 January 1998 / Accepted: 31 January 1998     

Selenium speciation from food source to metabolites: a critical review

Especially in the last decade, a vast number of papers on Se and its role in health issues have been published. This review gives a brief, critical overview of the main analytical findings reported in these papers. Of particular interest is the Se content in different food sources worldwide and the extent to which their consumption is reflected in the Se content of human tissues and body fluids. Several food sources, both natural (Brazil nuts, garlic, Brassica juncea) and Se-enriched (yeast-based supplements), are discussed as to origin, characteristics, Se metabolism and impact of their consumption on the human body. The continuous development of new and improvement of existing analytical techniques has provided different powerful tools to unravel the Se species and their function. An up-to-date literature study on Se speciation analysis is given, illustrating how analytical chemistry in its different facets aids in the identification of Se compounds and provides insight into the complete metabolic pathway of Se throughout the human body. This review includes a detailed image of the current state-of-the-art of Se speciation analysis in these food sources and in human tissues and body fluids.     

The determination of benzo[a]pyrene in the total particulate matter of cigarette smoke

A procedure for the isolation and determination of benzo[a]pyrene in the total particulate matter of cigarette smoke is described. Two high-pressure liquid chromatographic (HPLC) techniques are employed: a normal-phase, mu Bondapak-NH2, amino column is used for isolation of the benzo[a]pyrene fraction and a reversed-phase, Vydac 201TP54, polymeric octadecyl silane column is used for quantitation. Fluorescence detection is used in both modes of chromatography. The wavelengths of excitation and emission are evaluated for analytical detection. Extraction media and various isolation techniques are compared for their extraction efficiency and isolation from interferences, respectively. The procedure is efficient, reproducible, sensitive (3 pg), and gives results that compare favorably with other techniques reported in the literature for the B[a]P content of reference cigarettes, 1R1 and 1R4F.