1、BSI Standards PublicationBS EN 16253:2013Air quality Atmosphericmeasurements near groundwith active Differential OpticalAbsorption Spectroscopy(DOAS) Ambient air anddiffuse emission measurementsBS EN 16253:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 162
2、53:2013.The UK participation in its preparation was entrusted to TechnicalCommittee EH/2/3, Ambient atmospheres.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Use
3、rs are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 74164 7ICS 13.040.20Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of t
4、heStandards Policy and Strategy Committee on 31 July 2013.Amendments issued since publicationDate Text affectedBS EN 16253:2013EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16253 July 2013 ICS 13.040.20 English Version Air quality - Atmospheric measurements near ground with active Differentia
5、l Optical Absorption Spectroscopy (DOAS) - Ambient air and diffuse emission measurements Qualit de lair - Mesurages atmosphriques proximit du sol par Spectroscopie dAbsorption Optique Diffrentielle (DOAS) - Mesurages de lair ambiant et des missions diffuses Luftqualitt - Messungen in der bodennahen
6、Atmosphre mit der aktiven Differentiellen Optischen Absorptionsspektroskopie (DOAS) - Immissionsmessungen und Messungen von diffusen Emissionen This European Standard was approved by CEN on 15 May 2013. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the con
7、ditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exis
8、ts in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national sta
9、ndards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, S
10、lovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwid
11、e for CEN national Members. Ref. No. EN 16253:2013: EBS EN 16253:2013EN 16253:2013 (E) 2 Contents Page Foreword 3 Introduction .4 1 Scope 5 2 Terms and definitions .5 3 Symbols and abbreviations 6 3.1 Symbols 6 3.2 Abbreviations .7 4 Principle 7 4.1 General 7 4.2 Configuration of the measurement sys
12、tem 8 4.3 The Beer-Lambert law .9 4.4 Extended Beer-Lambert law 10 4.5 Differential optical density . 11 5 Measurement procedure 15 5.1 General . 15 5.2 Principle . 16 6 Measurement planning . 19 6.1 Definition of the measurement task 19 6.2 Selection of measurement parameters of the DOAS system . 1
13、9 7 Procedure in the field . 20 7.1 Installation and start-up of the instrument 20 7.2 Verification of optical properties . 21 7.3 Visibility . 21 8 Calibration methods . 22 8.1 General . 22 8.2 Gas cell calibration . 22 8.3 Calibration with complete spectral modelling . 23 9 Quality assurance . 25
14、9.1 Measurement procedure 25 9.2 Apparent saturation of absorption bands 26 Annex A (informative) Components of the measurement system 27 Annex B (informative) Influence of scattered solar radiation 34 Annex C (informative) Examples of implementations of the DOAS technique 36 Annex D (informative) P
15、erformance characteristics . 46 Annex E (informative) SI and common symbols and units in spectroscopy . 51 Annex F (informative) Application examples 52 Annex G (informative) Example of sample form for a measurement record 80 Bibliography . 84 BS EN 16253:2013EN 16253:2013 (E) 3 Foreword This docume
16、nt (EN 16253:2013) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 2014, and con
17、flicting national standards shall be withdrawn at the latest by January 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. Accordin
18、g to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Gr
19、eece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 16253:2013EN 16253:2013 (E) 4 Introduction Differential Optical Absorption Spectroscopy (
20、DOAS) has been successfully progressed, starting in the late 1970s, from a laboratory based method to a versatile remote sensing technique for atmospheric trace gases. In the DOAS measuring process, the absorption of radiation in the ultraviolet, visible or infrared spectral range by gaseous constit
21、uents is measured along an open monitoring path between a radiation source and a spectrometer, and the integral concentration over the monitoring path is determined. DOAS systems support direct multi-constituent measurements. They provide alternative measuring techniques in that they can handle a la
22、rge number of measuring tasks which cannot be adequately addressed by in situ techniques based on point measurements. Examples of such tasks include the monitoring of diffuse emissions from area sources such as urban settlements 1, traffic routes, sewage treatment plants and industrially or agricult
23、urally used surface areas; the minimisation of production losses through a detection of leaks in equipment zones or pipeline systems; or ambient air monitoring in any of the above-mentioned applications. With an appropriate measuring set-up, the local air pollution can usually be assessed very quick
24、ly. Measurements can be taken effectively even in areas which are difficult or impossible to access, or where the direct presence of personnel or equipment would be hazardous. The measurement in the open atmosphere eliminates potential losses by sample handling. An overview on the DOAS measurement t
25、echnique can be found in 2. BS EN 16253:2013EN 16253:2013 (E) 5 1 Scope This European Standard describes the operation of active DOAS measuring systems with continuous radiation source, the calibration procedures and applications in determining gaseous constituents (e.g. NO2, SO2, O3, BTX, Hg) in am
26、bient air or in diffuse emissions. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 active DOAS DOAS with artificial radiation source 2.2 background spectrum spectrum taken by the DOAS system with the light beam blocked or the lamp switched of
27、f Note 1 to entry: The background spectrum results mainly from scattered sunlight. 2.3 complete spectral modelling process of using synthetic spectra to match with observed experimental spectra 2.4 dark spectrum spectrum which identifies the thermal effects of the detector when no radiation is admit
28、ted to the detector 2.5 electronic offset spectrum spectrum which identifies the electronic effects of the detector when no radiation is admitted to the detector 2.6 instrument line shape ILS mathematical function which describes the effect of the instruments response on a monochromatic line 2.7 int
29、ensity radiant power per unit solid angle (non-collimated beam) or per unit area (collimated beam) 2.8 lamp spectrum spectrum which is achieved by admitting direct light from the lamp to the spectrometer 2.9 monitoring path actual path in space over which the pollutant concentration is measured and
30、averaged 2.10 open-path measurement measurement which is performed in the open atmosphere 2.11 path length distance that the radiation travels in the open atmosphere BS EN 16253:2013EN 16253:2013 (E) 6 2.12 reference spectrum spectrum of the absorbance versus wavelength for a pure gaseous sample und
31、er defined measurement conditions and known and traceable concentrations 2.13 signal-to-noise ratio ratio between the signal strength and its standard deviation 3 Symbols and abbreviations 3.1 Symbols a() specific absorption coefficient at wavelength ai() specific absorption coefficient of constitue
32、nt i at wavelength a0i() portion of the specific absorption coefficient which varies little with the wavelength )(ia portion of the specific absorption coefficient which varies strongly with the wavelength aMMie scattering coefficient aRRayleigh scattering coefficient c mass concentration cAEaerosol
33、 mass concentration cimass concentration of constituent i cLMdensity of air djcoefficient j of a polynomial D() optical density D() differential optical density i index number I(, l) intensity of received radiation of wavelength after a path-length l I0() intensity of emitted radiation of wavelength
34、 )(0l,I differential initial intensity Imod() modelled intensity l length of the monitoring path Mimolar mass of component i BS EN 16253:2013EN 16253:2013 (E) 7 p atmospheric pressure R molar gas constant (= 8,3145 J/(molK) S() intensity of scattered solar radiation of wavelength T ambient temperatu
35、re ximixing ratio of component i () attenuation factor of the optical system 3.2 Abbreviations DOAS Differential Optical Absorption Spectroscopy IR Infrared UV Ultraviolet UV/VIS Ultraviolet/Visible 4 Principle 4.1 General The DOAS measurement is based on the principle whereby the atmospheric concen
36、tration of gaseous constituents is quantified on the basis of their characteristic absorption of radiation. The radiation spectrum examined for this purpose ranges from near ultraviolet to near infrared (approximately 250 nm to 2 500 nm). Accordingly, the analysed absorption of radiation will be bas
37、ed on electronic transitions in molecules and, possibly, atoms and in the near infrared on molecular vibrational transitions. The method shows high selectivity and sensitivity due to the following combination of features: The measurement of radiation intensities is conducted with a high spectral res
38、olution (0,1 nm to 1 nm) over a broad spectral range comprising numerous vibrational and/or rotational bands of one or more electronic transition(s). Reference spectra are fitted to the measured spectra by the least squares method. Thus, the characteristic absorption structures of the target compoun
39、ds are employed to identify the measured compounds. Superimposed absorption structures of other constituents may be separated. Since the structured spectral absorption is analysed, unusually low optical densities (in some cases below 103) can be identified. This fact, in conjunction with the long mo
40、nitoring paths (usually from ca. 100 m to several kilometres, depending on the compounds to be measured) in the open atmosphere, yields low limits of detection for the trace gases. Quasi-continuous absorptions resulting from absorption processes by particles and droplets (e.g. radiation attenuation
41、due to aerosol dispersion or decreasing transmittance of the optical system) as well as moderate fluctuations of the radiation intensity will not affect the result over a wide measurement range because in this technique differential absorption is used rather than the absolute absorption. BS EN 16253
42、:2013EN 16253:2013 (E) 8 4.2 Configuration of the measurement system Open-path techniques measure the concentration path-length product of one or more species in the atmosphere within a defined, extended optical path. The concentration of the species is derived from this measurement value. Two of th
43、e basic configurations for an open-path monitoring system are given in Figure 1 and Figure 2. In the bistatic system (Figure 1) the transmitter and the detector are separated at the two ends of the optical path. The monostatic system (Figure 2) operates by transmitting the optical beam into the atmo
44、sphere to a passive retroreflector which returns the beam to the detector. Key 1 DOAS spectrometer 2 Telescope for radiation collection 3 Ambient air 4 Monitoring path 5 Radiation source with collimating optics Figure 1 Bistatic arrangement for DOAS remote sensing BS EN 16253:2013EN 16253:2013 (E) 9
45、 Key 3 Ambient air 4 Monitoring path 6 DOAS spectrometer including radiation source 7 Telescope for transmission and collection of radiation 8 Retro-reflector Figure 2 Monostatic arrangement for DOAS remote sensing In the bistatic measurement set-up, the radiation source (5) and the DOAS spectromete
46、r (1) are spatially separated. The two instrumental parts are oriented in such a way that the radiation emitted from the radiation source and collimated by a parabolic mirror is collected by the DOAS spectrometer telescope (2). The monitoring path length is the distance between collimating and recei
47、ving optics. For a monostatic measurement set-up, transmitting and receiving optics are an integral part of the DOAS spectrometer (6), which also includes the radiation source and a beam splitter serving to separate the received and transmitted beams. By means of a retroreflector (8) the radiation b
48、eam passes twice through the measurement volume. The monitoring path length in this case is twice the distance between the transmitter/receiver and the retroreflector optics. 4.3 The Beer-Lambert law When radiation passes through a medium, e.g. the atmosphere, it undergoes a change in intensity that
49、 can be expressed by means of the Beer-Lambert law: ( )lcaIl,I = )(exp)()(0 (1) where I(, l) is the intensity of the radiation of wavelength incident on the receiver after passing the atmosphere along the monitoring path l; I0() is the intensity of the radiation of wavelength emitted by the radiation source; a() is the specific absorption coefficient of the medium at wavelength in (g/m3)1m1; c is the concentration of the measured constituent in g/m3; l is the length of the monitoring path in m. BS
