Multivariate Statistical Evaluation of the Chemical Composition of Fine Particles : A Case Study

Monitoring and assessment of the physical and chemical constituents of airborne pollutants are now common features of the efforts of Queensland Environmental Protection Agency (EPA) to protect the public from the adverse effects of ambient air pollution. This paper describes the evaluation of the profiles of the 21 chemical constituents of 24-hourly integrated fine particle samples collected by EPA at Rocklea from 1995 to 2003. Because of the multivariate nature of the data, they were subjected to the multi-criteria decision making method, Preference Ranking Organisation Method for Enrichment Evaluation (PROMETHEE) and Principal Component Analysis. The PROMETHEE results indicated that the quality of the fine particulate constituents at the site decreased in the order 1995 >1997 >1996 >1998 >2002 >2000 > 2003 > 2001 > 1999. The most important constituents influencing the ranking included the elemental carbon, sulfur, lead, bromine, vanadium, and chromium contents of the samples. Such multi-criteria ranking provides information that can assist the formulation and prioritization of mitigating measures. For example, the phasing out of leaded fuels contributed significantly to the lowering of Pb and Br in the samples. On the other hand, Principal Component Analysis showed that the major constituents clustered into groups with compositional profiles which suggested that the main sources of the particles were airborne soil, combustion activities (vehicular emission and vegetative burning), industrial emissions, secondary aerosols and sea salt. Correlation with other pollutants and meteorological data concurrently measured at the site provided further insights into the sources of the fine particles

Characterisation of Soluble Inorganic PM10 Aerosols in Brisbane

PM10 samples were collected from three sites in Brisbane over a period of 20 months. These samples were analysed for water soluble ionic species (Na+, K+, Mg2+, Ca2+, NH4+, Cl-,NO3-, SO42-, F-, Br-, NO2-, PO4-3) using Inductively coupled plasma optical emission spectrometer (ICP_OES )and Ion exchange chromatography (IC). Metallic species (Zn, Cu, Pb, Fe, Mn, Al) that are soluble in acid were also analysed using ICP-OES. Na+ and Cl- concentrations were high in all samples. Principal Components Analysis (PCA) was used to identify seasonal differences and weekend/weekday trends of the sample concentrations. This showed that seasonal variation played a major role in the soluble aerosol concentrations of the samples. PCA was also used to identify the sources of the samples and it could be concluded that sea salt is the major source of these aerosol samples

Raman Spectroscopic and SEM Analysis of Sodium-Zippeite

Raman at 298 and 77 K and infrared spectra of two samples of sodium-zippeite were studied and interpreted. U-O bond lengths in uranyl were calculated and compared with those inferred from the X-ray single crystal structure data of a synthetic sodium-zippeite analog. Hydrogen-bonding network in the studied samples is discussed. O-H…O bond lengths were calculated and compared with those predicted from the X-ray single crystal structure analysis

Polycyclic Aromatic Hydrocarbons in House Dust Samples : Source Identification and Apportionment

House dust is a heterogeneous matrix, consisting of a variety of inorganic, organic and biological materials. Once pollutants are adsorbed onto house dust particles, they either do not degrade at all or degrade at rates that are relatively slower than their ambient counterparts. Thus house dusts are useful reservoirs for chronic exposure to indoor pollutants. In this study, house dust samples from suburban houses in Brisbane, Australia were collected in summer 2004 and winter 2005. Given the growing need to understand the potential risks of indoor pollutants and to develop appropriate control strategies, the objective of the study was to use receptor-oriented models to estimate the number of sources, their compositions and the contribution of each source to the samples. Thus the polycyclic aromatic hydrocarbon (PAH) composition data were analyzed with advanced factor analysis models. Four factors were required to reproduce the summer data well and each factor had distinctive compositions that suggested that natural gas utilities, cooking, vehicle emissions and miscellaneous combustion processes are the main sources of PAHs in the samples. The implications of the results and of the observed correlation between the building characteristics and the PAH profiles on the quality of these indoor microenvironments and the development of control strategies are discussed

Chemical composition of outdoor airborne particles at urban schools and possible implications for the air quality in classrooms

Vehicle emissions are a significant source of fine particles (Dp < 2.5 µm) in an urban environment. These fine particles have been shown to have detrimental health effects, with children thought to be more susceptible. Vehicle emissions are mainly carbonaceous in nature, and carbonaceous aerosols can be defined as either elemental carbon (EC) or organic carbon (OC). EC is a soot-like material emitted from primary sources while OC fraction is a complex mixture of hundreds of organic compounds from either primary or secondary sources (Cao et al., 2006). Therefore the ratio of OC/EC can aid in the identification of source. The purpose of this paper is to use the concentration of OC and EC in fine particles to determine the levels of vehicle emissions in schools. It is expected that this will improve the understanding of the potential exposure of children in a school environment to vehicle emissions

Raman Spectroscopy of Uranopilite of Different Origins - Implications for Molecular Structure

Uranopilite, \[(UO2)6(SO4)O2(OH)6(H2O)6](H2O)8, the composition of which may vary, can be understood as a complex hydrated uranyl oxy hydroxy sulfate. The structure of uranopilite of different localities has been studied by Raman spectroscopy at 298 and 77 K. A single intense band at 1009 cm-1 assigned to the ￮1 (SO4)2- symmetric stretching mode shifts to higher wavenumbers at 77 K. Three low intensity bands are observed at 1143, 1117 and 1097 cm-1. These bands are attributed to the (SO4)2- ν3 antisymmetric stretching modes. Multiple bands provide evidence that the symmetry of the sulphate anion in the uranopilite structure is lowered. Three bands are observed at 843 to 816 cm-1 in both 298 and 77 K spectra and are attributed to the ν1 symmetric stretching modes of the (UO2)2+ units. Multiple bands prove the symmetry reduction of the UO2 ion. Multiple OH stretching modes prove a complex arrangement of OH groupings and hydrogen bonding in the crystal structure. A series of infrared bands not observed in the Raman spectra are found at 1559, 1540, 1526 and 1511 cm-1 attributed to ￤ UOH bending modes. U-O bond lengths in uranyl and O-H…O bond lengths are calculated and compared with X-ray single crystal structure analysis. Raman spectra of uranopilites of different origin show subtle differences in spectra proving the spectra are origin and sample dependent. Hydrogen-bonding network and its arrangement in the crystal structure play an important role in the origin and stability of uranopilite

Characterization of particle number concentrations and PM2.5 in a school: influence of outdoor air pollution on indoor air

Background, Aim and Scope The impact of air pollution on school children’s health is currently one of the key foci of international and national agencies. Of particular concern are ultrafine particles which are emitted in large quantities, contain large concentrations of toxins and are deposited deeply in the respiratory tract. Materials and methods In this study, an intensive sampling campaign of indoor and outdoor airborne particulate matter was carried out in a primary school in February 2006 to investigate indoor and outdoor particle number (PN) and mass concentrations (PM2.5), and particle size distribution, and to evaluate the influence of outdoor air pollution on the indoor air. Results For outdoor PN and PM2.5, early morning and late afternoon peaks were observed on weekdays, which are consistent with traffic rush hours, indicating the predominant effect of vehicular emissions. However, the temporal variations of outdoor PM2.5 and PN concentrations occasionally showed extremely high peaks, mainly due to human activities such as cigarette smoking and the operation of mower near the sampling site. The indoor PM2.5 level was mainly affected by the outdoor PM2.5 (r = 0.68, p<0.01), whereas the indoor PN concentration had some association with outdoor PN values (r = 0.66, p<0.01) even though the indoor PN concentration was occasionally influenced by indoor sources, such as cooking, cleaning and floor polishing activities. Correlation analysis indicated that the outdoor PM2.5 was inversely correlated with the indoor to outdoor PM2.5 ratio (I/O ratio) (r = -0.49, p<0.01), while the indoor PN had a weak correlation with the I/O ratio for PN (r = 0.34, p<0.01). Discussion and Conclusions The results showed that occupancy did not cause any major changes to the modal structure of particle number and size distribution, even though the I/O ratio was different for different size classes. The I/O curves had a maximum value for particles with diameters of 100 – 400 nm under both occupied and unoccupied scenarios, whereas no significant difference in I/O ratio for PM2.5 was observed between occupied and unoccupied conditions. Inspection of the size-resolved I/O ratios in the preschool centre and the classroom suggested that the I/O ratio in the preschool centre was the highest for accumulation mode particles at 600 nm after school hours, whereas the average I/O ratios of both nucleation mode and accumulation mode particles in the classroom were much lower than those of Aitken mode particles. Recommendations and Perspectives The findings obtained in this study are useful for epidemiological studies to estimate the total personal exposure of children, and to develop appropriate control strategies for minimizing the adverse health effects on school children

Porous Graphene Materials for Energy Storage and Conversion Applications

Porous graphene materials possess a unique structure with interconnected networks, high surface area, and high pore volume. Because of the combination of its remarkable architecture and intrinsic properties, such as high mechanical strength, excellent electrical conductivity, and good thermal stability, porous graphene has attracted tremendous attention in many fields, such as nanocomposites, lithium batteries, supercapacitors, and dye-sensitized solar cells. This chapter reviews synthesis methods, properties, and several key applications of porous graphene materials

On the influence of biodiesel feedstock on compression ignition particulate emissions

Particulate emissions from compression ignition engines are a major health concern, especially in underground mine environments where limited ventilation during the operation of diesel powered equipment can exacerbate the problem. Clearly strategies are required to address the diesel particulate matter problem, with alternative fuels, such as biodiesel, having been recently considered to ameliorate the problem. This study considers a physico-chemical characterisation of particulate emissions from an underground coal mine compression ignition engine to determine the effect of using 3 biodiesel feedstocks at 4 different blend percentages. Particle physical properties measured included particle number size distributions and the lung deposited surface area, and particle chemical properties measured included particle and vapour phase polycyclic aromatic hydrocarbons (PAHs) and also the measurement of reactive oxygen species (ROS), which are believed to play an important role in the human body’s inflammatory response after exposure to diesel emissions. The particle number size distributions showed strong dependency on both feedstock and the blend percentage employed, with the canola feedstock yielding higher particle number emissions than diesel (followed by tallow), whereas the soy feedstock showed significant particle number reductions. Both particle and vapour phase PAHs were generally reduced with biodiesel, although the results did not exhibit dependence on blend percentage. The ROS concentrations increased monotonically with biodiesel blend percentage but the data did not suggest strong feedstock dependency. It was also shown that ROS emissions correlate quite well with the organic volume percentage of particles which was calculated using unheated and heated particle volume distributions. Whilst biodiesel fuels might be effective at reducing particle mass emissions, some feedstocks increase the number of particles emitted, and all feedstocks increase the oxidative capacity of particles and also emit particles that have a much smaller median diameter than ultra-low sulphur diesel