| 1. |
- Akselsson, Roland, et al.
(author)
-
Application of Proton Induced X-Ray Emission Analysis to the St. Louis Regional Air Pollution Study
- 1975
-
In: Advances in X-Ray Analysis. ; 18, s. 588-597
-
Journal article (peer-reviewed)abstract
- The St Louis aerosol was sampled during the period 16-22 August 1973 simultaneously at two locations using cascade impactors for sequential 12-hour samples. The six particle size fractions of each sampling were individually analyzed using PIXE for elements from S to Br and beyond and for heavy elements including Pb which permitted time variations of concentrations and particle size distributions to be followed and related to meteorological changes during the sampling period. In addition, the data were compared with average levels of the elements in coastal north Florida and maritime Bermuda as well as at a third St. Louis site. From this it appeared that some of the concentrations in St. Louis were at natural levels whereas others appeared to be higher and linked to air pollution sources. These relationships and others in this study may lead to criteria for distinguishing between pollutants and natural background in urban aerosols.
|
|
| 2. |
- Akselsson, Roland, et al.
(author)
-
X-Ray Techniques for Aerosol Sulfur Baseline Assessment Along an Urban Freeway
- 1976
-
In: Advances in X-Ray Analysis. ; 19, s. 415-425
-
Journal article (peer-reviewed)abstract
- Atmospheric aerosol particles have been sampled near a Los Angeles freeway and analyzed by proton-induced X-ray emission, PIXE, as a sulfur baseline study in September 1974 before 1975-model automobiles, equipped with catalytic emission control devices, appeared in large numbers. The sampling plan was optimized according to the requirements of X-ray analysis techniques, fluctuations in air flow across the freeway, and the time and particle size resolution of the aerosol sampling equipment. During five selected two-hour intervals with cross wind conditions, particles were collected as a function of size by six cascade impactors operating simultaneously on three towers at 2 and 7 meters above road level 35 meters upwind and 35 meters downwind of the traffic lanes. Particles as a function of time were sampled continuously, for the 100-hour duration of the experiment, from the tree 7-meter heights using time series streaker filter samplers with two-hour time resolution. Precise analysis of S, Cl, K, Ca, Fe, Br, and Pb established relationships which permit estimates to be made of future increases in particulate sulfur as a consequence of increased sulfate emissions from catalytic automobiles
|
|
| 3. |
- Nelson, J William, et al.
(author)
-
Automatic Time Sequence Filter Sampling of Aerosols for Rapid Multi-Element Analysis by Proton-Induced X-Ray Emission
- 1976
-
In: Advances in X-Ray Analysis. ; 19, s. 403-413
-
Journal article (peer-reviewed)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.
|
|
| 4. |
- Van Grieken, René E., et al.
(author)
-
Geophysical Applicability of Aerosol Size Distribution Measurements Using Cascade Impactors and Proton Induced X-Ray Emission
- 1976
-
In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 0004-6981. ; 10:8, s. 571-576
-
Journal article (peer-reviewed)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.
|
|
