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| 2. |
- Axelsson, H, et al.
(författare)
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Measurement of Aromatic-hydrocarbons With the DOAS Technique
- 1995
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 49:9, s. 1254-1260
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Tidskriftsartikel (refereegranskat)abstract
- Long-path DOAS (differential optical absorption spectroscopy) in the ultraviolet spectral region has been shown to be applicable for low-concentration measurements of light aromatic hydrocarbons. However, because of spectral interferences among different aromatics as well as with oxygen, ozone, and sulfur dioxide, the application of the DOAS technique for this group of components is not without problems. This project includes a study of the differential absorption characteristics, between 250 and 280 nm, of twelve light aromatic hydrocarbons representing major constituents in technical solvents used in the automobile industry. Spectral overlapping between the different species, including oxygen, ozone, and sulfur dioxide, has been investigated and related to the chemical structure of the different aromatics. Interference effects in the DOAS application due to spectral overlapping have been investigated both in quantitative and in qualitative terms, with data from a field campaign at a major automobile manufacturing plant.
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| 3. |
- Edner, Hans, et al.
(författare)
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Industrial Emission Control Using Lidar Techniques
- 1995
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 29:2, s. 330-337
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Tidskriftsartikel (refereegranskat)abstract
- A mobile DIAL (differential absorption lidar) remote sensing system has been employed in the monitoring of industrial pollutant emissions. Measurements of sulfur dioxide and mercury vapor were performed at nine different Swedish industrial plants within the framework of a control program commissioned by the Swedish Environmental Protection Agency. Total atmospheric fluxes of these species could be determined by combining wind data with a mapping of the concentration distribution downwind from the sources. The emission values obtained were compared with in situ measurements made by the companies themselves. The values from single point sources correlate well, whereas the DIAL system normally measures a higher total flux from several distributed sources including diffuse emissions. The results are used to discuss the applicability and limitation of the DIAL technique for remote surveillance of industrial emissions.
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| 4. |
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| 5. |
- Holst, Ulla, et al.
(författare)
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Locally weighted least squares kernel regression and statistical evaluation of LIDAR measurements
- 1996
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Ingår i: Environmetrics. - 1099-095X. ; 7:4, s. 401-416
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Tidskriftsartikel (refereegranskat)abstract
- The LIDAR technique is an efficient tool in monitoring the distribution of atmospheric species of importance. We study the concentration of atmospheric atomic mercury in an Italian geothermal field and discuss the possibility of using recent results from local polynomial kernel regression theory for the evaluation of the derivative of the DIAL curve. A MISE-optimal bandwidth selector, which takes account of the heteroscedasticity in the regression is suggested. Further, we estimate the integrated amount of mercury in a certain area.
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| 6. |
- Milton, M. J. T, et al.
(författare)
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Raman-shifted laser sources suitable for differential-absorption lidar measurements of ozone in the troposphere
- 1998
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171. ; 66:1, s. 105-113
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Tidskriftsartikel (refereegranskat)abstract
- Measurements have been performed at eight laboratories on Raman-shifted radiation from frequency-quadrupled Nd:YAG and KrF lasers. Each of these sources is a possible candidate for making differential-absorption lidar measurements of ozone in the free troposphere. The spectral purity, efficiency and divergence of the different sources are compared and explained using a simplified model of the Raman interaction. Particular attention has been given to the use of buffer gases to optimize the Raman gain and divergence. The experimental results show that the operating conditions required to optimize the output energy of each of these types of laser source can be quite different. In the case of the KrF laser, it has been shown that high energies can be generated at low active gas pressures, and that increasing the pressure increases the beam quality, but decreases the energy.
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| 7. |
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| 8. |
- Sandsten, J, et al.
(författare)
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Gas imaging by infrared gas-correlation spectrometry
- 1996
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Ingår i: Optics Letters. - 0146-9592. ; 21:23, s. 1945-1947
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Tidskriftsartikel (refereegranskat)abstract
- We describe a new method for visualization of gas flows based on infrared absorption and gas-correlation techniques. This result is a gray-scale or false color-coded image showing the distribution of a specific gas in the area studied. A sequence of images showing the workplace test setup with a turbulent flowing gas is presented.
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| 9. |
- Swietlicki, Erik, et al.
(författare)
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Urban air pollution source apportionment using a combination of aerosol and gas monitoring techniques
- 1996
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 30:15, s. 2795-2809
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Tidskriftsartikel (refereegranskat)abstract
- The dominating local and regional sources of gaseous and particulate air pollution in the city of Lund (69,000 inhabitants) in southern Sweden were characterized using a combination of aerosol and gas-phase monitoring techniques. Twelve-hour samples were taken at two stations of both fine and coarse fraction urban aerosols with a stacked filter unit during the four-week measurement campaign in March/April 1993. The aerosol samples were analysed with PIXE for 14 major and trace elements. In addition, gaseous species (SO2, NO2, O-3) were measured simultaneously with the DOAS technique over two stretches, crossing each other only 300 m from the downtown aerosol sampling site. The combined results obtained by the analytical techniques PIXE and DOAS for aerosol and gas measurements, respectively, were used in an absolute receptor model in order to identify the major sources affecting the measurement sites and to apportion the measured air pollutants to the identified sources. The gases (SO2, NO2, O-3) could also be attributed to specific sources by combining the trace elemental concentration data for the fine fraction aerosol with that of the gaseous species in the receptor model. According to the absolute principal component analysis (APCA) model, the dominant sources for the measured species were resuspended road dust, automobile and diesel emissions, combustion of oil and coal, ferrous and non-ferrous smelters and sea spray. Of these, the sources related to traffic are mainly local in character while the others constitute a regional background. For a small city in southern Scandinavia like Lund with only light industry, the long-range transported air pollutants make up a significant part of the fine fraction aerosol. (C) 1996 Elsevier Science Ltd
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| 10. |
- Wallinder, E, et al.
(författare)
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Vertically sounding ozone lidar system based on a KrF excimer laser
- 1997
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Ingår i: Physica Scripta. Topical Issues. - : IOP Publishing. - 0281-1847. ; 55:6, s. 714-718
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Tidskriftsartikel (refereegranskat)abstract
- A differential absorption (DIAL) lidar system based on a Raman shifted KrF excimer laser was constructed and employed for vertically sounding measurements of tropospheric ozone, This system is described, including a presentation of measurements of Raman shifting efficiencies in hydrogen and deuterium. The performance of the new system was evaluated in measurement campaigns involving two further optical remote-sensing systems: A Nd:YAG/dye laser based lidar and a long-path differential optical absorption spectroscopy (DOAS) system, utilising a high-pressure xenon lamp.
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