Fenceline Monitoring at a Chemical Plant
Emissions of air pollutants such as benzene, sulfur dioxide, ammonia and particulate can be related to regulatory violations. In some instances, ambient concentrations of pollutants can raise public health concerns. To better understand the nature of these emissions and the risks to public health, the Air Enforcement Division (AED) operates a mobile remote sensing laboratory at facility fence lines, residential areas, and other off-site locations. The data helps inform the Agency during traditional regulatory investigations and can provide data for purposes of administrative or judicial orders under Clean Air Act section 303, Emergency powers.
AED's mobile laboratory includes an open-path ultra violet differential optical absorption spectrometer (UV DOAS), a real-time particulate matter monitor and sample collection system, and other measurement analyzers as required. Wind direction and wind speed data is also collected for purposes of data evaluation. The instrumentation provides highly time-resolved pollution data over relatively large areas, allowing for a variety of analyses for determining the source of emissions and their importance in terms of public health.
For example, UV DOAS has been used to measure benzene, a known human carcinogen, and other aromatic hydrocarbons in residential areas downwind of refineries, petrochemical plants, and other facilities suspected of violating benzene control requirements. Sulfur dioxide has also been measured downwind of combustion sources, including a coal-fired power plant in Ohio where residents and public health agencies were concerned about exposure to the plants' emissions. In a joint effort with the State of Missouri, Department of Natural Resources and public health agencies, the mobile laboratory was used to measure ammonia and particulate matter in the vicinity of a large-scale swine confined animal feeding operation (e.g., PSF/Continental Grain). In that case, the data helped to inform the need for ammonia controls and the potential impacts to public health.
Ambient measurements of source-related air pollutants has been a useful tool for identifying problem areas and determining the need for injunctive relief. AED plans to continue this program and to support EPA Regional offices and states in these special investigations.
Under a consent decree, a UV-DOAS system is being used for fence-line monitoring at the Westlake Petrochemicals facility in Westlake, Louisiana. The data generated from this system, which is measuring primarily monoaromatics are made available to the public on an Internet webpage. A special condition of the decree requires the company to provide data to any nearby resident requesting it by the next business day following the request.
Governments in Australia routinely use UV-DOAS to perform fenceline monitoring near facilities suspected of emitting excessive amounts of pollutants. For example, a DOAS system was installed and is operated at a grammar school located approximately 500 m from an oil refinery. The instrument, which has a 430 m open path, is monitored continuously. The results of the sampling indicated that benzene has exceeded action levels on several occasions, but in general, the concentrations were below levels of concern. The two exceedances occurred during light winds blowing from the direction of the refinery (EPA Victoria 2005, EPA South Australia 2003).
Schaefer et al. (2002) reports on using a mono-static DOAS system equipped with three retroreflectors to measure fugitive emissions from tanker loading operations at a river harbor. The effluent concentrations in the plume and meterological measurements were used to determine emission source strengths.
In cooperation with the Olin Corporation, EPA conducted a UV-DOAS survey at a chlor-alkali facility that used the mercury cell process to manufacture chlorine gas and sodium hydroxide. The system was deployed in a bi-static configuration on the roof of the plant's cell building. Measurements for mercury were taken across the roof vent. During the study period, approximately 472 gm/day of elemental mercury were being emitted from the vent (USEPA 2002).
Open Path Vehicle Emissions Monitoring
UV-DOAS equipment has been successfully deployed to detect vehicles that emit excessive amounts of pollutants through their mufflers. The system consists of a sending and receiving unit located on one side of a road and a retroreflector on the other. The ideal location is at a stop sign or stop light where vehicle engines will exert a high torque while accelerating from a stop thereby emitting the most pollutants. The equipment measures changes in gases as cars pass; and at the same time, a camera records the vehicle license plate. Those vehicles associated with elevated pollutant emissions are issued citations asking the owner to have the vehicle repaired and then inspected at an appropriate inspection station.
Upper Atmosphere Monitoring of Trace Gases and Pollutants
UV-DOAS instruments that operate in a passive open path mode and are housed in balloons or aircraft, have been used to investigate concentrations of pollutants in the atmosphere at various heights. For example, the THESEO2000 project measured O3, NO2, BrO, OClO, and H2O from a balloon-mounted UV-DOAS. Measurements were taken at various altitudes up to the float height of approximately 30 km using direct sun spectroscopy. The direct measurement data from these balloon experiments were used to test the predictions of 3-D photochemical transport models such as SLIMCAT (Chipperfield, 1999) and Reprobus (Lefevre, et al., 1994). For more information on this project, visit http://www.nilu.no/projects/theseo2000/.
The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), a passive UV/VIS/NIR instrument, was launched on ENVISAT on March 1, 2002. It measures wavelengths between 240 nm and 2,380 nm. By using the DOAS method, it is possible to retrieve the atmospheric absorptions of O3, NO2, BrO, OClO, SO2, HCHO, O2, O4, CO, CO2, CH4, and N2O on a global basis. Typical spatial resolution in nadir mode is 30 by 60 km, which can be improved to 30 by 15 km (Frankenberg et al. 2003).
Monitoring Ammonia Emissions from Animal Facilities
The U.S. EPA is concerned about ammonia emissions from confined animal (hog) feeding operations. Estimates show that each hog can produce up to 8 pounds of ammonia per year. At a large-scale feeding facility this could amount to over 1,000 pounds per day. Secrest (2001) reports on the use of open path FTIR and UV-DOAS for measuring ammonia concentrations downwind from two feeding facilities. The UV-DOAS had a detection limit of 4 ppb (100 m path) and a linear range up to 993 ppb. The actual path used for the monitoring was 150 m. The distance to the first facility was 800 m, and the distance to the second facility was 400 m. At 800 meters distance, concentrations of over 700 ppb were recorded. The continuous monitoring showed wide variations in concentrations during a 24-hour period. These variations were probably due to changes in temperature and wind speed. The author concludes that having continuous contaminant concentration data coupled with meteorological data provide a much better basis for estimating potential exposure and subsequent health effects than that which can be obtained with canister style point source monitoring.
Mount et al. (2002) are studying the release of ammonia gas at the Washington State University research dairy farm using a UV-DOAS system. They have found concentrations of ammonia in the tens of ppm in the barn and concrete yard area, 100s of ppb to low ppm over the slurry lagoon area, and low ppm after application of slurry onto pasture land. The DOAS system has a detection limit of around 1 ppb for ammonia.
Uses Suggested in Vendor Literature
Vendors that manufacture UV-DOAS equipment can be located through journal announcements and on the Internet. The following list contains applications in which the vendors claim their products have been successfully deployed:
- Urban air pollution monitoring
- Industrial fence-line monitoring
- Airport monitoring
- Traffic monitoring
- In-plant storage/process area monitoring
- Stratospheric pollutant monitoring
- Tropospheric pollutant monitoring
Allegheny County Health Department (ACHD). 2006. Air toxics studyï¿½first look at data. Eco-Currents, Volume 6, Issue 4, July-August, 4 pp. http://www.achd.net/airqual/pubs/pdf/ecojulaug2006.pdf
Arellano, S., M. Hall, and E. Ayala. 2006. Spectroscopic remote sensing of volcanic gases: The Ecuadorian case. ï¿½ptica Pura Y Aplicada ï¿½ Vol. 39, nï¿½m. 1 ï¿½ 2006 ï¿½ 3rd-Workshop LIDAR Measurements in Latin Amï¿½rica. http://www.sedoptica.es/revistas/pdfs/190.pdf
Bales R., J. Stutz, and S. Hurlock. 2006. Long term measurement of trace gases at GEOSummit using multi-axis differential optical absorption spectroscopy. January 2006. GEOSummit Meeting.
Basaldud, R. and M. Grutter. 2006. Remote sensing of SO2 and NO2 emissions from industrial sources in Mexico by passive DOAS. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Bobrowski, N., et al. 2006. Measurements of sulfur dioxide and halogen oxides in volcanic plumes. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Bruns, M., S. A. Buehler, J. P. Burrows, K.-P. Heue, U. Platt, I. Pundt, A. Richter, A. Rozanov, T. Wagner and P. Wang. 2004. Retrieval of profile information from airborne multi axis UV/visible skylight absorption measurements. Appl. Opt., 43(22), 4415-4426. http://www.sat.ltu.se/members/sab/publications/doas/doas_retrieval_paper.pdf
Bunton,B., P. Oï¿½Shaughnessy, S. Fitzsimmons, J. Gering, S. Hoff, M. Lyngbye, P. Thorne, J. Wasson, and M. Werner. 2006. Monitoring and Modeling of Emissions from Concentrated Animal Feeding Operations: Overview of Methods. Environmental Health Perspectives, VOL 115 No 2 February 2007, pp 303-307.
Cheng A. and M. Chan. 2004. Acousto-optic differential optical absorption spectroscopy for atmospheric measurement of nitrogen dioxide in Hong Kong. Appl Spectrosc. 2004 Dec;58(12):1462-8. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15606960&dopt=Abstract
Chipperfield, M.P. 1999. Multiannual simulations with a 3-D chemical transport model. Journal of Geophysical Research, Vol 104, pp 1781-1805. http://www.cluin.org/programs/21m2/lit_show.cfm?id=981
Dils, B. et al. 2005. Comparisons between SCIAMACHY and ground-based FTIR data for total columns of CO, CH4, CO2 and N2O. Atmospheric Chemistry and Physics Discussions, Vol. 5, pp 2677-2717, 3-5.
Dunlea, E. et al. 2006. Technical note: Evaluation of standard ultraviolet absorption ozone monitors in a polluted urban environment. Atmos. Chem. Phys., 6, 3163ï¿½3180. http://www.atmos-chem-phys.net/6/3163/2006/
EPA South Australia. 2003. Air Quality Monitoring Hot Spot No 4 near the Castalloy Foundry, North Plympton, 36 pp.
EPA Victoria. 2005. Benzene Air Monitoring in Corio 2003ï¿½2005. Environmental Report Publication 999. 8 pp. http://epanote2.epa.vic.gov.au/EPA/publications.nsf/d85500a0d7f5f07b4a2565d1002268f3/cedcb7ec217f5842ca256ffe00818bab/$FILE/999.pdf
Frankenberg, C. et al. 2003. Potential of SCIAMACHY near infrared measurements for investigating global tropospheric trace gas distributions. EXPORT-E2, European Export of Particulates and Ozone by Long- Range Transport: A Study in EUROTRAC-2 Final Report, Report 13, 6 pp.
Friedeburg, C., I. Pundt, K.-U. Mettendorf, T. Wagner, and U. Platt. 2005. Multi-axis-DOAS measurements of NO2 during the BAB II motorway emission campaign. Atmospheric Environment 39 (2005) pp 977ï¿½985. http://www.imk.uni-karlsruhe.de/download/BAB-Friedeburg.pdf
Frieï¿½, U., P. Monks, J. Remedios, T. Wagner, A. Rozanov, and U. Platt. 2006. Inverse modelling of multi-axis DOAS measurements: a new technique to derive information on atmospheric aerosols. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Fuqi , S., J. Liu, P. Xie, and Y. Zhang. 2006. Correlation study between suspended particulate matter and DOAS data. Advances in Atmospheric Sciences, Vol. 23, No. 3, pp 461ï¿½467.
Grutter, M. and E. Flores. 2004. Air pollution monitoring with two optical remote sensing techniques in Mexico City. Remote Sensing of Clouds and the Atmosphere IX, ed. K. Schï¿½fer, A. Camerï¿½n, M. Carleer, R. Picard, and N. Sifakis, Proceedings of SPIE Vol. 5571, Bellingham, WA, 2004. http://www.atmosfera.unam.mx/fqa/grutter/papers/Grutter_2004_SPIE_5571.pdf
Halla, J., D. Majonis, and R. McLaren. 2006. Trace gas measurements using MAX-DOAS in a polluted marine environment. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Heckel, A., A. Richter, T. Tarsu, F. Wittrock, C. Hak, I. Pundt, W. Junkermann, and J. P. Burrows. 2005. MAX-DOAS measurements of formaldehyde in the Po-Valley. Atmos. Chem. Phys., 5, 909ï¿½918.
Hendrick, F., et al. 2005 Intercomparison exercise between different radiative transfer models used for the interpretation of ground-based zenith-sky and multi-axis DOAS observations. Atmos. Chem. Phys. Discuss., 5, 7929ï¿½7964.
Hoenninger, G., C. von Friedeburg, and U. Platt. 2004. Multi axis differential optical absorption spectroscopy (MAX-DOAS). Atmos. Chem. Phys., 4, 231ï¿½254. http://www.atmos-chem-phys.net/4/231/2004/acp-4-231-2004.pdf
Ibrahim, O., T. Stein, T. Wagner, and U. Platt. 2006. Auto-MAX DOAS: A new measurement platform. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Jimï¿½nez, R., A. Martilli, I. Balin, H. van den Bergh, B. Calpini, B.R. Larsen, G. Favaro, and D. Kita. 2000a. Measurement of formaldehyde (HCHO) by DOAS: Intercomparison to DNPH measurements and interpretation from Eulerian model calculations. Proceedings of A&WMA 93rd Annual Conference & Exhibition, Salt Lake City (UT), June 18-22. Paper #829, 15 pp, 2000. http://www.cluin.org/programs/21m2/lit_show.cfm?id=901
Jimï¿½nez, R., T. Iannone, H. van den Bergh, B. Calpini; and D. Kita. 2000. Investigation of the emission of monocyclic aromatic hydrocarbons from a wastewater treatment plant at Lausanne (Switzerland) by differential optical absorption spectroscopy (DOAS). Proceedings of A&WMA 93rd Annual Conference & Exhibition, 18-22 June 2000, Salt Lake City, Utah. Paper #830, 17 pp, 2000. http://www.cluin.org/programs/21m2/lit_show.cfm?id=886
Kern, C., S. Trick, J. Zingler, D. Pedersen, B. Rippel, and U. Platt. 2006. Applicability of light-emitting diodes as light sources for active DOAS measurements. Third International DOAS Workshop, University of Bremen, March 20-26, 2006. http://troposat.iup.uni-heidelberg.de/AT2/DOAS_workshop/kern_christoph_o105.pdf
Kim, K.-H. 2004. Comparison of BTX measurements using a differential optical absorption spectroscopy and an on-line gas chromatography system. Environmental Engineering Science, Mar 2004, Vol. 21, No. 2: pp 181-194. http://www.liebertonline.com/doi/abs/10.1089/109287504773087354?cookieSet=1&journalCode=ees
Laepple, T., V. Knab, K.-U. Mettendorf, and I. Pundt. 2004. Longpath DOAS tomography on a motorway exhaust gas plume: Numerical studies and application to data from the BAB II campaign.
Langford, A., R.Schofield, M. Melamed, J.S. Daniel, R.W. Portmann, and S. Solomon. 2006. Measurements of the ring effect in the near ultraviolet. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Lee J, K. Kim, Y. Kim, and J. Lee. 2007. Application of a long-path differential optical absorption spectrometer (LP-DOAS) on the measurements of NO(2), SO(2), O(3), and HNO(2) in Gwangju, Korea. J Environ Manage. 2007 Feb 28.
Lee, J.,Y. Kim, B. Kuk, A.Geyer, and U. Platt. 2005. Simultaneous Measurements of Atmospheric Pollutants and Visibility with a Long-Path DOAS System in Urban Areas.
Environmental Monitoring and Assessment, Vol. 104, No. 1-3: 281. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15931992&dopt=Abstract
Lefevre, F., G. Brasseur, I. Folkins, A. K. Smith, and P. Simon. 1994. Chemistry of the 1991-1992 stratospheric winter: Three-dimensional model simulations. Journal of Geophysical Research, Vol 99, pp 8183-8195. http://www.cluin.org/programs/21m2/lit_show.cfm?id=982
Leigh, R., G. Corlett, and P. Monks. 2006. Measurement of NO2 in Leicester by concurrent multi-axis DOAS. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Liu, X., K. Chance, C. Sioris, M. Newchurch, T.Kurosu. 2006. A new retrieval method for tropospheric ozone profiles from a ground-based ultraviolet spectrometer. Applied Optics, Vol. 45, Issue 10, pp. 2352-2359 (April 2006). http://www.atmos.uah.edu/atmchem/pub/fulltext/r2005/gndspec_manuscript_accepted.pdf
Mathew, L., W. R. Tai, and Ji.-G. Lo. 2001. Measurements of sulfur dioxide and formaldehyde in Taipei using a differential optical absorption spectrometer. Journal of the Air & Waste Management Association, Vol 51 No 1, p 94-101, Jan 2001. http://www.cluin.org/programs/21m2/lit_show.cfm?id=903
Merten, A. 2006. New application software for differential optical absorption spectroscopy (DOAS). Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Merten, A. and U. Platt. 2006. Improvement of the detection limit of active-DOAS-measurements by use of fibre light source. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Mettendorf, K., C. Kunz, V. Knab, H. Sun, and I. Pundt. 2003. The multibeam DOAS long path DOAS system; a new apparatus for simultaneous measurements along different light paths. Geophysical Research Abstracts, Vol. 5, 12055. http://www.cosis.net/abstracts/EAE03/12055/EAE03-J-12055.pdf
Mettendorf, K., A. Hartl, U. Platt, and I. Pundt. 2005. Long path DOAS tomography by the use of multibeam DOAS instruments: Results of an indoor validation campaign. Geophysical Research Abstracts, Vol. 7, 08543. http://www.cosis.net/abstracts/EGU05/08543/EGU05-J-08543.pdf
Mount, G., B. Rumburg, J. Havig, B. Lamb, H. Westberg, D. Yonge, K. Johnson, and R. Kincaid. 2002. Measurement of atmospheric ammonia at a dairy using differential optical absorption spectroscopy in the mid-ultraviolet. Atmospheric Environment, 2002, 36(11), pp 1799-1810.
Mï¿½ller, T., D. Mï¿½ller, and R. Dubois. 2006. Particle extinction measured at ambient conditions with differential optical absorption spectroscopy. 2. Closure study. Applied Optics, Vol. 45, Iss. 10, pp 2295-2305.
Oetjen, H., F. Wittrock, S. Fietkau, T. Medeke, A. Richter, and J. P. Burrows. 2005. MAX-DOAS observations of reactive halogen compounds at different latitudes. Geophysical Research Abstracts, Vol. 7, 08870, 2005. http://www.cosis.net/abstracts/EGU05/08870/EGU05-J-08870.pdf
Pisano, J. et al. 2003. A UV differential optical absorption spectrometer for the measurement of sulfur dioxide emissions from vehicles. Meas. Sci. Technol. 14, pp 2089-2095.
Platt, U. 2006. Spatially resolved DOAS measurements of trace gases and aerosols. Third International DOAS Workshop, University of Bremen, March 20-26, 2006. http://troposat.iup.uni-heidelberg.de/AT2/DOAS_workshop/platt_ulrich_o101.pdf
Poehler, D., A. Hartl, and U. Platt. 2006. Tomographic DOAS measurements of 2D trace gas distributions above the city centre of Heidelberg, Germany. Third International DOAS Workshop, University of Bremen, March 20-26, 2006. http://troposat.iup.uni-heidelberg.de/AT2/DOAS_workshop/doas_ws_2006_program.html
Poehler, D., B. Rippel, A. Stelzer, K. Mettendorf, A. Hartl, U. Platt, and I. Pundt. 2005. Tomographic DOAS measurements of the 2D trace gas distribution above the city centre of Heidelberg, Germany.
Pszenny, A., J. Moldanovï¿½a, W. Keene, R. Sander, J. Maben, M. Martinez, P. Crutzen, D. Perner, and R. Prinn. 2003. Halogen cycling and aerosol pH in the Hawaiian marine boundary layer. Atmos. Chem. Phys. Discuss., 5, 7929ï¿½7964Atmos. Chem. Phys. Discuss., 3, 4701ï¿½4753.
Pundt, I. and K.-U. Mettendorf. 2005. Multibeam long-path differential optical absorption spectroscopy instrument: a device for simultaneous measurements along multiple light paths. Appl. Opt. 44, pp 4985-4994. http://www.opticsinfobase.org/abstract.cfm?URI=ao-44-23-4985
Pundt, I., K.-U. Mettendorf, T. Laepple, V. Knab, P. Xieb, J. Lï¿½sch, C. Friedeburg, U. Platt, and T. Wagner. 2005. Measurements of trace gas distributions using Long-path DOAS-Tomography during the motorway campaign BAB II: Experimental setup and results for NO2. Atmospheric Environment 39 (2005) pp 967ï¿½975.
Queensland Government. 2007. What is DOAS.
Reisinger, A., G. Fraser, P. Johnston, R. McKenzie, and W.A. Matthews. 1996. Slow-scanning DOAS system for urban air pollution monitoring. XVIII Quadrennial Ozone Symposium '96 University of L'Aquila - L'Aquila (Italy), 12-21 September 1996. http://www.cluin.org/programs/21m2/lit_show.cfm?id=980
Saiz-Lopez, A. and J. Plane. 2004. Recent applications of Differential Optical Absorption Spectroscopy: Halogen chemistry in the lower troposphere. J. Phys. IV France 121 (2004) 223-238.
Satellite Group. 2007. DOAS Analysis of Satellite Spectra. University of Heidelberg.
Schaefer, K., H. Hoffmann, I. Dormuth, C. Jahn, and S.M. Emeis. 2002. VOC emission source strengths of tankers during refueling activities determined by spectroscopic remote sensing and inverse dispersion modeling. Remote Sensing of Clouds and the Atmosphere VI. Proceedings of SPIE - The International Society for Optical Engineering, Vol 4539, p 247-257, 2002. http://www.cluin.org/programs/21m2/lit_show.cfm?id=1608
Schï¿½fer, K., et al. 2006. Determination of NO and NO2 aircraft emission indicies at airports by open-path DOAS. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Schï¿½fer, K., H. Hoffmann, S. Emeis, J. Wittig, and J. Vergeiner. 2006. Highway emission study by DOAS within the Inn valley near Innsbruck. Remote Sensing of Clouds and the Atmosphere XI, Proceedings of SPIE v. 6362, October 11, 2006.
Schlosser, E., J. Bossmeyer, T. Brauers, H.-P. Dorn, and R. Tillmann. 2006. HCHO detection by high-resolution laser DOAS. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Schï¿½rmann G., K. Schï¿½fer, C. Jahn, H. Hoffmann, V. Groma, S. Tï¿½rï¿½k, S. Emeis. 2006. Airport air quality and emission studies by remote sensing and inverse dispersion modelling. Remote Sensing of Clouds and the Atmosphere XI, Proceedings of SPIE Vol. 6362.
Secrest, C. 2001. Field measurement of air pollutants near swine confined-animal feeding operations using UV DOAS and FTIR. Water, Ground, and Air Pollution Monitoring and Remediation, 6-7 November 2000. Proceedings of SPIE--The International Society for Optical Engineering, Vol 4199, p 98-104, 2001. http://www.cluin.org/programs/21m2/lit_show.cfm?id=868
Smith, J., et al. 2007. Comprehensive Evaluation of a Low-Profile Cross-Ventilated Freestall Barn. Western Dairy Management Conference Reno, NV March 7-9, 2007. http://www.wdmc.org/2007/smithandharner.pdf
Stenberg, P. 2006. Current advances in open path DOAS measurements for criteria DOAS measurements for criteria and toxic parameters. 2006 Air Monitoring Conference 2006 Air Monitoring Conference Las Vegas, Nevada Las Vegas, Nevada, November 2006 (PowerPoint), 26 pp.
Sussmann, R., W. Stremme, J.P. Burrows, A. Richter, W. Seiler, and M. Rettinger. 2006. NEW Retrieval approach to tropospheric NO2 by synergistic inversion of satellite nadir DOAS soundings and ground-based FTIR measurements. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
Taslakov, M., V. Simeonov, and H. Van den Bergh. 2006. Space-resolved open-path detection of trace gases by mid IR quantum cascade laser. Third International DOAS Workshop, University of Bremen, March 20-26, 2006.
University of Bremen DOAS Group. 2006. The MAXDOAS Instrument and Measurements. University of Bremen.
USEPA. 2002. Characterization of Mercury Emissions at a Chlor-Alkali Plant, EPA/600/R-02/007. Office of Research and Development. http://www.epa.gov/nrmrl/pubs/600r02007/600R02007.pdf
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Vandaele, A., C. Fayt, F. Hendrick, C. Hermans, F. Humbled, M. Van Roozendael, M. Gil, M. Navarro, O. Puentedura, M. Yela, G. Braathen, K. Stebel, K. Tï¿½rnkvist, P. Johnston, K. Kreher, F. Goutail, A. Mieville, J.-P. Pommereau, S. Khaikine, A. Richter, H. Oetjen, F. Wittrock, S. Bugarski, U. Frieï¿½, K. Pfeilsticker, R. Sinreich, T. Wagner, G. Corlett, and R. Leigh. 2005. An intercomparison campaign of ground-based UV-visible measurements of NO2, BrO, and OClO slant columns: Methods of analysis and results for NO2. Journal of Geophysical Research Atmosphere 2005; 110(April D8):D08305. http://www.joplink.net/prev/200101/cit/6z12.html
Veefkind, J., J. de Haan, E. Brinksma, M. Kroon, and P. Levelt. 2006. Total ozone from the ozone monitoring instrument (OMI) using the DOAS technique. IEEE Transactions on Geoscience and Remote Sensing,Volume: 44, Issue: 5, pp 1239- 1244. http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=1624602&isnumber=34107
Volkamer, R. et al. 2006. Secondary organic aerosol formation from anthropogenic air
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Wang, P. A. Richter, M. Bruns, V. Rozanov, J. Burrows, K.-P. Heue, T. Wagner, I. Pundt, and U. Platt. 2005. Measurements of tropospheric NO2 with an airborne multi-axis DOAS instrument. Atmos. Chem. Phys. 5, 337-343.
Wang, P., A. Richter, M. Bruns, J. Burrows, W. Junkermann, K.-P. Heue, T. Wagner, U. Platt, and I. Pundt. 2005. Airborne multi-axis DOAS measurements of tropospheric SO2 plumes in the Po-Valley, Italy. Atmos. Chem. Phys.6, 329-338.
Wang, P., G. Wang, and X. Guo. 2006. Air pollution monitoring by using DOAS. Third International DOAS Workshop, University of Bremen, March 20-26, 2006. http://troposat.iup.uni-heidelberg.de/AT2/DOAS_workshop/wang_pucai_o408.pdf
Wittrock, F., H. Oetjen, A. Richter, S. Fietkau, T. Medeke, A. Rozanov, and J. P. Burrows. 2004. MAX-DOAS measurements of atmospheric trace gases in Ny- ï¿½lesund - Radiative transfer studies and their application. Atmos. Chem. Phys., 4, 955ï¿½966. http://www.atmos-chem-phys.net/4/955/2004/acp-4-955-2004.pdf
Wittrock, F., A. Heckel, H. Oetjen, A. Richter, and J. Burrows. 2006. The retrieval of oxygenated volatile organic compounds by remote sensing techniques. Third International DOAS Workshop, University of Bremen, March 20-26, 2006. http://troposat.iup.uni-heidelberg.de/AT2/DOAS_workshop/wittrock_folkard_o308.pdf