| 51. |
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| 52. |
- Malmqvist, Klas, et al.
(författare)
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Determination of Heavy Metals and Fluorine in Airborne Particulate Matter in an Indoor Environment by Simultaneous Use of PIXE and γ-Ray Detection
- 1978
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Ingår i: Proc. Analyt. Div. Chem. Soc.. ; 15, s. 13-16
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Konferensbidrag (refereegranskat)abstract
- The current rapid development within work-environment research has created a considerable demand among industrial hygienists for suitable analytical methods. PIXE (particle-induced X-ray emission analysis), which was introduced in Lund in 1970, has been shown to be a feasible method for use in studying the elemental composition of aerosols. However, in some work environments, fluorine, an element not suitable for PIXE analysis, is hygienically of considerable interest. This paper discusses the possibility of combining PIXE with a nuclear method for the simultaneous quantitative determination of fluorine.
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| 53. |
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| 54. |
- Nelson, J William, et al.
(författare)
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Automatic Time Sequence Filter Sampling of Aerosols for Rapid Multi-Element Analysis by Proton-Induced X-Ray Emission
- 1976
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Ingår i: Advances in X-Ray Analysis. ; 19, s. 403-413
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Tidskriftsartikel (refereegranskat)abstract
- An automatic time sequence filter sampler has been developed for atmospheric aerosol particle sampling of ambient air and subsequent analysis for elemental composition using the proton beam of a Van de Graaff accelerator. Some features of the operation of the sampler are given, the retention of particles by the filter material are discussed, examples of the type of data obtained are presented, and some approaches to the numerical analysis of data for environmental interpretation are considered. Lines for further development and improvement in this type of sampler are indicated.
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| 55. |
- Orsini, Celso Q, et al.
(författare)
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Variation of Elemental Composition with Particle Size in the St. Louis Aerosol
- 1977
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 142:1-2, s. 91-96
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Tidskriftsartikel (refereegranskat)abstract
- Detailed particle size distribution of elemental constituents have been determined in the St. Louis aerosol by sampling with cascade impactors for particles >0.25 μm aerodynamic diameter and by analyzing using proton-induced X-ray emission, PIXE, for S, Cl, K, Ca, Ti, Mn, Fe, Zn, Br, and Pb. Two rooftop sites were selected for intensive sampling in industrial and residential locations in St. Louis during February 1974, every 12 h for a 7 d period which included clear, rainy, and snowy weather regimes. The data could be compared with the results of a similar study of the St. Louis aerosol during August 1973 when the weather was generally warm and without rain. Both data sets could also be compared with results of studies of Tallahassee, situated in coastal north Florida, and the north Atlantic marine atmosphere of Bermuda. Although variation in elemental concentrations and their size distributions were observed which could be associated with local weather conditions during the February sampling period, the data set was sufficiently large for meaningful average characteristics to be computed. As examples, two elements of pollution importance, sulfur and iron, show the following comparison between St. Louis and the Florida and Atlantic locations: Sulfur in all data sets was most abundant in the smallest particle size classes. Winter and summer concentration in St. Louis air were the same within a factor of two but generally exceeded north Florida concentrations. Bermuda concentrations were intermediate between St. Louis and north Florida, except for largest particles where sea spray derived material was present. The results reflect the importance of gas phase conversion to particulate forms of sulfur, e.g. sulfate, in all three locations. Iron concentrations in St. Louis generally exceeded those in north Florida for smallest particles and to a lesser extent for larger sizes. Concentrations in Bermuda were about 10-fold lower than in St. Louis for all particle sizes. The results reflect the terrestrial dust origin of iron and also suggest that iron is partially pollution-derived in the St. Louis atmosphere, especially in smaller size ranges.
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| 56. |
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| 57. |
- Sheline, Jonathan, et al.
(författare)
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Trace Element Similarity Groups in North Florida Spanish Moss
- 1976
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Ingår i: Journal of Geophysical Research. - 2156-2202. ; 81:6, s. 1047-1050
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Tidskriftsartikel (refereegranskat)abstract
- The elemental composition of 10 samples of Spanish moss Tillandsia usneoides L. collected mainly in forested areas near Tallahassee, Florida, has been compared to the composition of the ambient aerosol particle background in the forest measured as a function of particle size. For forest samples, moss composition is similar to the composition of aerosol particles greater than about 0.5-μm diameter for the elements S, Cl, Ti, V, Fe, Ni, Zn, Br, Pb, and possibly Cu. Elements relatively enriched in the moss fall into two groups, K, Rb, Zr and Ca, Sr, Mn, based on detailed association patterns. No evidence is found for an enrichment, relative to the ambient aerosol, of pollution-derived elements Pb, Br, V, and Ni, although those elements are found at higher concentrations in moss samples from locations nearer roadways or oil-fired power plants. The moss appears to have potential value as an indicator of time average aerosol composition for particles of ≥0.5 μm, except for the enriched elements, which may have longer biological retention times.
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| 58. |
- Van Grieken, René E., et al.
(författare)
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Geophysical Applicability of Aerosol Size Distribution Measurements Using Cascade Impactors and Proton Induced X-Ray Emission
- 1976
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 0004-6981. ; 10:8, s. 571-576
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Tidskriftsartikel (refereegranskat)abstract
- Proton Induced X-ray Emission, (PIXE), is capable of high precision analysis for trace element components of aerosol particle size fractions sampled by cascade impactor. A statistical evaluation of data quality has been carried out in order to distinguish between analytical uncertainties in the PIXE procedure, errors caused by cascade impactor performance and by other factors in the sampling procedure, and geophysical causes of differences in composition and particle size distributions of the elements in aerosols. Replicate analyses and simultaneous samplings taken in north Florida and St. Louis have been used for the data evaluation. In addition to the analytical error the sampling procedure contributes an error of ~ 10% to be added quadratically. The resulting precision is sufficient to evaluate the data in geophysical terms. This is illustrated by means of sample sets taken simultaneously in an urban, forest and coastal environment of the same region.
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