Elemental concentrations source samples

Receptor models are powerful tools for source apportionment of particulates because a vast amount of particulate species characterization data have been collected at many sampling sites worldwide, and because many aerosol species are primary pollutants. Most of the information available is for elemental concentrations, eg, lead, nickel, and alurninum, although more recent measurements have provided data on concentrations of ionic species and carbonaceous compounds. At a sampling (or receptor) site, the aerosol mass concentration of each species i is... 

This value characterizes the upper level of relative scattering of estimated elements concentration in all the considered snow samples, which is associated both with estimation errors in groups 1-3 and natural variation of the elements abundance in samples. Thus, the results of successive testing of ypotheses Ht -H3 allow us to conclude that the basic hypothesis Hb is true and only global source of chemical contamination exists on the territory of Karabash. 

The geochemical classification using major oxides shows that the samples used in this study plot in the litharenite field, and, implies that they are mineralogically submature. Major-element concentrations point to significant weathering effect in the source area of the sample set. Provenance analyses, based on major-and trace-element compositions suggest... 

Rare earth elements patterns show differences in Eu anomalies for the samples studied from Boca del Tordo (Fig. 5) that can be attributed to the mix of felsic and mafic sources. This variation can also be explained due to the impoverishment of feldspars due to weathering (Kasper-Zubillaga et al. 2008b). Also Boca del Tordo concentrates more rare earth elements especially in samples 16 and 18,... 

If we have determined m elements in n samples, we could display these results as n points in an m-dimensional space. However, because some of the elements are emitted by the same source of particles, their concentrations will be related. 

First, we analyzed samples for a large number of elements to Identify any elements, regardless of toxicity or typical concentration, that would provide signals for the presence of material from certain types of sources. Both ambient samples and particles from sources were analyzed by Instrumental neutron activation analysis (INAA), by which one can often measure about 35 elements In Individual samples (17), As the Important elements Pb, N1 and Cd are not consistently, If ever, observed by INAA, they were often measured by other methods. As INAA Is sensitive to very small amounts of obscure elements, we have obtained reliable data for elements such as Ga, Hf, Sc, In, W and many rare earths which pose no known health hazard at present levels and contribute Insignificant amounts of mass to TSP. However, as discussed below, many trace elements have already been shown to be Important In receptor... 

In a search for sources of alkaline materials in rural air and rain, we have sampled and performed multi-element analyses on ambient particulate matter and potential source materials. Ambient aerosols were sampled daily using single Nuclepore filters or Florida State University "streakers." Samples of soil and unpaved road materials were also collected and analyzed. The samples were analyzed by various multi-element methods, including ion-and proton-induced X-ray emission and X-ray fluorescence, as well as by atomic absorption spectrophotometry. Visual observations, as well as airborne elemental concentration distributions with wind direction and elemental abundances in aerosols and source materials, suggested that soil and road dust both contribute to airborne Ca. Factor analysis was able to identify only a "crustal" source, but a simple mass balance suggested that roads are the major source of Ca in rural central Illinois in summer. 

The results presented a variety of evidence for the identity of Ca sources near our rural sampling site. The distribution of mean crustal element concentrations as a function of wind direction in summer and fall, from the streaker data, suggest a combination of road and soil sources. This agrees with a comparison of crustal abundances in aerosols and source materials. The comparison showed that most of the elements examined had abundances in the aerosol that often fell between those characteristic of roads and soil. This was not the case for Si, but Si may be expected to be less abundant in aerosol samples than in bulk surficial materials because of the preponderance of quartz (Si02) in the larger particles. 

It is characteristic of such a laser ion source that the experimental conditions for LIMS can be optimized with respect to a stoichiometric evaporation and effective ionization of solid sample material by varying the laser power density as demonstrated in Figure 2.20. Under certain experimental conditions fractionation effects can be avoided. Stoichiometric laser evaporation and ionization of analyzed material is found at a laser power density between 109Wcm 2 and 1010Wcm-2. In this laser power density range, the relative sensitivity coefficients of the chemical elements (RSC = measured element concentration/true element concentration) are nearly one for all the... 

X-ray fluorescence is a rapid and low-cost method that can be performed on solid samples. However, the depth of penetration of X-rays in most solid samples is relatively shallow. High-precision XRF on geological samples such as obsidian requires preparation of homogeneous, powdered samples pressed into pellet form. If some loss of precision and accuracy due to irregular size, shape, and thickness of samples is acceptable, obsidian specimens can be analyzed non-destructively. Samples smaller than 1 cm in diameter or with element concentrations less than 5 ppm are generally not suitable for XRF. XRF can determine about 10-15 elements in obsidian (K, Ti, Mn, Fe, Zn, Ga, Rb, Sr, Y, Zr, Nb, Pb, and Th). Fortunately, many of the measurable elements are the incompatible elements which provide discrimination between sources. 

In atomic absorption spectrometry (AA) the sample is vaporized and the element of interest atomized at high temperatures. The element concentration is determined based on the attenuation or absorption by the analyte atoms, of a characteristic wavelength emitted from a light source. The light source is typically a hollow cathode lamp containing the element to be measured. Separate lamps are needed for each element. The detector is usually a photomultiplier tube. A monochromator is used to separate the element line and the light source is modulated to reduce the amount of unwanted radiation reaching the detector. 

Unlike elemental concentrations, isotopic compositions are only affected a little by chemical differentiation processes. Mass-dependent isotopic fractionations can arise in chemical partitioning (cf. Section 2.9), of course, but on the scale of interest in the present context, plausible fractionation effects are small, especially at the high temperatures prevalent in the mantle. We can thus be much more confident that a noble gas isotopic composition measured in a mantle-derived sample is indeed characteristic of its mantle source. Representative mantle ranges for selected isotopic ratios are presented in Table 6.2. 

In this study we have employed the simultaneous collection of atmospheric particles and gases followed by multielement analysis as an approach for the determination of source-receptor relationships. A number of particulate tracer elements have previously been linked to sources (e.g., V to identify oil-fired power plant emissions, Na for marine aerosols, and Pb for motor vehicle contribution). Receptor methods commonly used to assess the interregional impact of such emissions include chemical mass balances (CMBs) and factor analysis (FA), the latter often including wind trajectories. With CMBs, source-strengths are determined (1) from the relative concentrations of marker elements measured at emission sources. When enough sample analyses are available, correlation calculations from FA and knowledge of source-emission compositions may identify groups of species from a common source type and identify potential marker elements. The source composition patterns are not necessary as the elemental concentrations in each sample are normalized to the mean value of the element. Recently a hybrid receptor model was proposed by Lewis and Stevens (2) in which the dispersion, deposition, and conversion characteristics of sulfur species in power-plant emissions... 

Trace element concentration determinations at the part per million and lower levels with IDMS require rigorous attention to contamination of the sample Sources of contamination that comprise the analytical blank have been documented by Murphy (66) These are principally derived from chemical reagents ... 

Figure 12 Variability of trace element concentrations in MORE, expressed as 100 standard deviation/mean concentration. The data for Global MORE are from the PETDB compilation of (Su, 2002). All segments refers to 250 ridge segments from all oceans. Normal segments refers to 62 ridge segments that are considered not to represent any sort of anomalous ridges, because those might be affected by such factors as vicinity to mantle plumes or subduction of sediments (e.g., back-arc basins and the Southern Chile Ridge). The Atlantic MORE, 40-55° S, from which samples with less than 5% MgO have been removed (source le Roux et al., 2002).

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