EN 15853:2010
(Main)Ambient air quality - Standard method for the determination of mercury deposition
Ambient air quality - Standard method for the determination of mercury deposition
This European Standard specifies a method for the determination of the total deposition of mercury. This standard can be used within the framework of the European Council Directive on Ambient Air Quality Assessment and Management and Directive 2004/107/EC. Performance requirements with which the method should comply are specified in this European Standard. The performance characteristics of the method were determined in comparative field validation tests carried out at two European locations.
This European Standard is applicable to background sites that are in accordance with the requirements of Directive 2004/107/EC and to urban and industrial sites.
This standard allows the sampling of deposition using cylindrical deposition gauges, and analysis using Cold Vapour Atomic Absorption Spectrometry (CVAAS) or Cold Vapour Atomic Fluorescence Spectrometry (CVAFS) following existing harmonised and standardised procedures. The standard is applicable for the measurement of mercury in deposition between 1 ng/(m2•d) and 100 ng/(m2•d).
The standard is validated for the deposition range listed in Table 1.
NOTE The range given is based upon the values measured in the field validation test. The upper and lower limits are the observed minimum and maximum values measured during the field validation tests. The actual lower limits of the working range depends on the variability of the laboratory blank, for bulk and wet-only collectors, and the precipitation. The method can be applied to higher and lower deposition rates provided that the collection characteristics are not compromised.
Außenluftbeschaffenheit - Standardisiertes Verfahren zur Bestimmung der Quecksilberdeposition
Diese Europäische Norm legt ein Verfahren für die Bestimmung der Gesamtdeposition von Queck¬silber fest. Die vorliegende Norm kann im Rahmen der Richtlinie des Europäischen Rates über die Beurteilung und die Kontrolle der Außenluftbeschaffenheit und der Richtlinie 2004/107/EG angewendet werden. In der vorliegenden Europäischen Norm sind die Leistungsanforderungen festgelegt, die dieses Verfahren erfüllen sollte. Die Verfahrenskenngrößen des Verfahrens wurden mit Vergleichsuntersuchungen zur Validierung von Feldversuchen bestimmt, die an zwei Standorten in Europa durchgeführt wurden.
Diese Europäische Norm ist anwendbar auf Hintergrundstationen, die den Anforderungen der Richtlinie 2004/107/EG entsprechen, und auf Stadtgebiete sowie Gebiete mit Industrieeinfluss.
Das Verfahren ermöglicht die Probenahme zur Bestimmung von Depositionen mit zylindrischen Auffanggefäßen und die Analyse mit der Kaltdampf Atomabsorptionsspektrometrie (CVAAS) oder Kaltdampf-Atomfluoreszenzspektro¬metrie (CVAFS) nach bestehenden, harmonisierten und standardisierten Verfahren. Das Verfahren ist anwendbar für die Messung von Quecksilberdepositionen zwischen 1 ng/(m2 d) und 100 ng/(m2 d).
Die Norm wurde für den in Tabelle 1 aufgeführten Depositionsbereich validiert.
Qualité de l'air ambiant - Méthode normalisée pour la détermination des dépôts de mercure
La présente Norme européenne spécifie une méthode pour le mesurage du dépôt total de mercure. La
présente norme peut être utilisée dans le cadre de la Directive européenne du Conseil concernant l’évaluation
et la gestion de la qualité de l’air ambiant et de la Directive 2004/107/CE. La présente Norme européenne
spécifie les exigences de performance auxquelles doit se conformer la méthode. Les caractéristiques de
performance de la méthode ont été déterminées par des essais comparatifs de validation sur le terrain
réalisés sur deux sites européens.
La présente Norme européenne s’applique aux sites de fond conformes aux exigences de la
Directive 2004/107/CE et aux sites urbains et industriels.
La présente norme spécifie l’échantillonnage de dépôts à l’aide de jauges de dépôt cylindriques, et l’analyse
par spectrométrie d’absorption atomique de vapeur froide (SAAVF) ou par spectrométrie de fluorescence
atomique de vapeur froide (SFAVF) suivant les procédures normalisées et harmonisées existantes. La norme
s’applique au mesurage du mercure dans les dépôts entre 1 ng/(m2·j) et 100 ng/(m2·j).
La norme est validée pour la plage de dépôt donnée dans le Tableau 1.
Kakovost zunanjega zraka - Standardna metoda za določevanje živega srebra v usedlinah
Ta evropski standard opredeljuje metodo za določevanje celotnega živega srebra v usedlinah. Ta standard se lahko uporablja v okviru Direktive Evropskega sveta o ocenjevanju kakovosti zunanjega zraka in Direktive 2004/107/ES. V tem evropskem standardu so določene zahteve za delovanje, ki jih mora izpolnjevati ta metoda. Značilnosti delovanja metode so bile določene s primerjalnimi validacijskimi preskusi na terenu, opravljenimi na dveh evropskih lokacijah. Ta evropski standard velja za zaledna območja, ki so v skladu z zahtevani Direktive 2004/107/ES, ter za urbana in industrijska območja. Ta standard omogoča vzorčenje usedlin s cilindričnimi merilniki usedlin in analizo z atomsko absorbcijsko spektrometrijo hladnih par (CVAAS) ali atomsko fluorescenčno spektrometrijo hladnih par (CVAFS), ki sledijo usklajenim in standardiziranim postopkom. Ta standard velja za merjenje živega srebra v usedlinah med 1 ng/(m2•d) in 100 ng/(m2•d). Standard je potrjen za razpone usedlin, navedene v preglednici 1.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.XVHGOLQDKAußenluftbeschaffenheit - Standardisiertes Verfahren zur Bestimmung der QuecksilberdepositionQualité de l'air ambiant - Méthode normalisée pour la détermination des dépôts de mercureAmbient air quality - Standard method for the determination of mercury deposition13.040.20Kakovost okoljskega zrakaAmbient atmospheresICS:Ta slovenski standard je istoveten z:EN 15853:2010SIST EN 15853:2010en,fr,de01-november-2010SIST EN 15853:2010SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 15853
June 2010 ICS 13.040.20 English Version
Ambient air quality - Standard method for the determination of mercury deposition
Qualité de l'air ambiant - Méthode normalisée pour la détermination des dépôts de mercure
Außenluftbeschaffenheit - Standardisiertes Verfahren zur Bestimmung der Quecksilberdeposition This European Standard was approved by CEN on 5 May 2010.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions 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 Management Centre or to any CEN member.
This European Standard exists 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 Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15853:2010: ESIST EN 15853:2010
Sampling equipment that can be used for precipitation sampling . 17Annex B (informative)
Sampling procedure . 20Annex C (informative)
Analytical procedure . 22Annex D (informative)
Summary of field trial validation tests . 27Annex E (informative)
Relationship between this European Standard and the Essential Requirements of EU Directives . 32Bibliography . 33 SIST EN 15853:2010
This European Standard specifies a method for the determination of the total deposition of mercury. This standard can be used within the framework of the European Council Directive on Ambient Air Quality Assessment and Management and Directive 2004/107/EC. Performance requirements with which the method should comply are specified in this European Standard. The performance characteristics of the method were determined in comparative field validation tests carried out at two European locations. This European Standard is applicable to background sites that are in accordance with the requirements of Directive 2004/107/EC and to urban and industrial sites.
This standard allows the sampling of deposition using cylindrical deposition gauges, and analysis using Cold Vapour Atomic Absorption Spectrometry (CVAAS) or Cold Vapour Atomic Fluorescence Spectrometry (CVAFS) following existing harmonised and standardised procedures. The standard is applicable for the measurement of mercury in deposition between 1 ng/(m2·d) and 100 ng/(m2·d). The standard is validated for the deposition range listed in Table 1. Table 1 — Working range of this standard method Working range ng/(m2.d) Lower limit Upper limit 1 100
NOTE The range given is based upon the values measured in the field validation test. The upper and lower limits are the observed minimum and maximum values measured during the field validation tests. The actual lower limits of the working range depends on the variability of the laboratory blank, for bulk and wet-only collectors, and the precipitation. The method can be applied to higher and lower deposition rates provided that the collection characteristics are not compromised. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ENV 13005, Guide to the expression of uncertainty in measurement CR 14377, Air quality — Approach to uncertainty estimation for ambient air reference measurement methods EN ISO 17852, Water quality — Determination of mercury — Method using atomic fluorescence spectrometry (ISO 17852:2006) EN ISO 20988, Air quality — Guidelines for estimating measurement uncertainty (ISO 20988:2007) 3 Terms, definitions and abbreviations For the purposes of this document, the following terms, definitions and abbreviations apply. SIST EN 15853:2010
outdoor air in the troposphere, excluding workplace air
3.1.2 atmospheric deposition mass flow rate (unit of mass per unit of area per unit of time) describing the process of the transfer of any species from the atmosphere to an environmental compartment, e.g. air to water, air to soil
NOTE
Atmospheric deposition is the sum of the depositions of sedimenting particles, non-sedimenting particles and gases. 3.1.3 bulk collector equipment to collect bulk deposition
NOTE
Bulk collectors sample deposition at all times. A bulk sampler can consist of a funnel-bottle combination or a wide mouthed jar. 3.1.4 bulk deposition sum of the deposition of sedimenting wet and dry particles
NOTE Bulk deposition is a part of the atmospheric deposition. 3.1.5
combined standard measurement uncertainty
standard measurement uncertainty that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model NOTE
In case of correlations of input quantities in a measurement model, covariances should also be taken into account when calculating the combined standard measurement uncertainty [ISO/IEC Guide 99 (VIM)]. 3.1.6 coverage factor
number larger than one by which a combined standard measurement uncertainty is multiplied to obtain an expanded measurement uncertainty NOTE
A coverage factor is usually symbolized k [ISO/IEC Guide 99 (VIM)]. 3.1.7 detection limit (DL), instrumental lowest amount of an analyte that is detectable using an instrument as determined by repeated measurements of a reagent blank 3.1.8 detection limit (DL), method lowest amount of an analyte detectable after the whole measurement process as determined by repeated measurements of different field blanks 3.1.9 dry deposition sum of the deposition of sedimenting dry particles, non sedimenting particles and gases
NOTE
Dry deposition includes the following processes: atmospheric turbulent diffusion, adsorption, absorption, impaction and gravitational settling. The dry deposition process is affected by the type of underlying surface and surface conditions. Dry deposition is a part of the atmospheric deposition. SIST EN 15853:2010
expanded uncertainty
product of a combined standard measurement uncertainty and a factor larger than the number one
NOTE 1
The factor depends upon the type of probability distribution of the output quantity in a measurement model and on the selected coverage probability.
NOTE 2
The term "factor" in this definition refers to a coverage factor.
NOTE 3
Expanded measurement uncertainty is termed "overall uncertainty" in paragraph 5 of Recommendation INC-1 (1980) (see the GUM) and simply "uncertainty" in IEC documents [ISO/IEC Guide 99 (VIM)].
NOTE 4 For the purpose of this document the expanded uncertainty is the combined standard uncertainty multiplied by a coverage factor k = 2 resulting in an interval with a level of confidence of 95 %.
3.1.11 field blank artificial sample (e.g. de-ionised water) taken through the same procedure as the precipitation sample, except that this has not been exposed to precipitation NOTE
It is transported to the sampling site, mounted in the sampling unit, returned to the laboratory and worked up in the same way as the deposition sample. 3.1.12 laboratory blank artificial sample (e.g. de-ionised water) taken through the same procedure in the laboratory as the precipitation sample, worked up in the same way as the deposition sample 3.1.13 measurement uncertainty non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used
NOTE 1 Measurement uncertainty includes components arising from systematic effects, such as components associated with corrections and the assigned quantity values of measurement standards, as well as the definitional uncertainty. Sometimes estimated systematic effects are not corrected for but, instead, associated measurement uncertainty components are incorporated. NOTE 2 The parameter may be, for example, a standard deviation called standard measurement uncertainty (or a specified multiple of it), or the half-width of an interval, having a stated coverage probability. [ISO/IEC Guide 99:2007 (VIM)]
3.1.14 precipitation rain, snow, sleet, snow pellets ("graupel") and hail 3.1.15 reagent blank artificial sample (e.g. de-ionised water) processed through the analytical measurement steps 3.1.16 wet deposition sum of depositions of sedimenting wet particles and droplets
NOTE Wet particles and droplets in the atmosphere undergo the process of scavenging of any gases and/or particles. Wet deposition is a part of the atmospheric deposition.
3.1.17 wet-only collector equipment to collect wet deposition, typically a funnel-bottle combination SIST EN 15853:2010
Wet-only collectors collect only during wet precipitation events 3.2 Abbreviations CRM
Certified Reference Material CVAAS Cold Vapour Atomic Absorption Spectrometry CVAFS Cold Vapour Atomic Fluorescence Spectrometry EMEP Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air
pollutants in Europe (European Monitoring and Evaluation Programme) WMO/GAW World Meteorological Organization/Global Atmosphere Watch 4 Principle of mercury deposition determinations
Atmospheric deposition is defined as the sum of the depositions of sedimenting particles, non-sedimenting particles and gases. Total atmospheric deposition is the sum of dry deposition and wet deposition. Bulk deposition is the sedimenting part of the atmospheric deposition. There is no method available to determine total atmospheric deposition in one measurement. The determination of the dry deposition requires micrometeorological measurements, taking into account the turbulent atmospheric transport processes. Wet deposition and bulk deposition, however, can be estimated using suitable collectors. This standard describes methods to determine wet deposition and bulk deposition of mercury using wet-only- and bulk collectors. The wet-only collector is designed to collect sedimenting water containing wet particles only, while the bulk collector is designed to collect all sedimenting wet and dry particles. However, since the deposition process is affected by various factors, e.g. wind speed, temperature, vegetation, surface type, etc., the wet-only collector will not catch all sedimenting wet particles while some sedimenting dry particles, non-sedimenting particles and gases will be collected. Also, the bulk collector will not catch all sedimenting particles while some non-sedimenting particles and gases will be collected. The method is divided into two main parts:
a) sampling of precipitation in the field;
b) mercury analysis in the laboratory.
The precipitation sample is stabilized with hydrochloric acid and transferred to the laboratory in the collection vessel. Mercury in the precipitation sample is oxidised using bromine monochloride. Mercury is analysed either by CVAAS or CVAFS detection. 5
Siting requirements for mercury deposition determinations
The following guidelines shall be met as far as practicable (Annex III.II of Directive 2004/107/EC [10]): a) The site chosen for sampling and measurements shall be representative of a larger area. The size of this area is determined by site characteristic (urban, industrial or rural) and the variability of the air and precipitation quality. b) The collector shall as far as possible not be exposed to areas where unrepresentative strong winds occur like shores, cliffs and top of hills, but it shall also not be sheltered by tall trees or buildings. The flow SIST EN 15853:2010
6.1 Concentrated hydrochloric acid, 30 % HCl or 36 to 38 % HCl (low mercury blank required, e.g. Suprapur® 1) quality).
WARNING — Concentrated hydrochloric acid is corrosive, and hydrogen chloride fumes are an irritant. Avoid exposure by contact with the skin or eyes, or by inhalation of fumes. Carry out the work in a fume cupboard. Use suitable personal protective equipment (including suitable gloves, face shield or safety glasses, etc.) when working with the concentrated or dilute hydrochloric acid. 6.2 Concentrated hydrochloric acid, 37 % HCl (e.g. p.a. quality) for cleaning purposes. 6.3 Ultrapure water, de-ionised water with a resistivity greater than 18 M·cm at 25 °C.
Water shall be monitored for Hg, especially after ion exchange beds are changed. 6.4 Hydrochloric acid, 2 % HCl for cleaning purposes, prepared from concentrated HCl (6.2) by dilution with ultrapure water (6.3).
6.5 Hydrochloric acid, 2 % HCl for for acidification of the precipitation samples, prepared from concentrated HCl (6.1) by dilution with ultrapure water (6.3).
6.6 Potassium bromate (KBrO3), e.g. p.a. quality; if necessary preheated overnight at (240 ± 20) °C to evaporate mercury.
WARNING — Potassium bromate can cause cancer. 6.7 Potassium bromide (KBr), e.g. Suprapur® 1) quality; if necessary preheated overnight at (240 ± 20) °C to evaporate mercury. 6.8 Bromine monochloride (BrCl) solution. Dissolve 1,10 g KBrO3 (6.6) and 1,5 g KBr (6.7) by adding to 20 ml ultrapure water (6.3) with careful shaking and heating, if necessary. Afterwards, slowly add 80 ml HCl (6.1) whilst stirring. To avoid contamination, store in a mercury free environment.
1) Suprapur® is an example of a suitable product available commercially. This information is given for the convenience of users of this European Standard and does not constitute an endorsement by CEN of this product. SIST EN 15853:2010
6.9 Bromine monochloride (BrCl) solution, 0,5 % V/V for cleaning purposes, prepared of Bromine monochloride (BrCl) solution (6.8) by dilution with ultrapure water (6.3). 6.10 Hydroxylammonium hydrochloride solution. Dissolve 12,0 g NH2OH·HCl in 100 ml water (6.3). This chemical reagent sometimes contains high mercury concentrations. Adding 0,1 g Chelex 100 ion exchange material can lower the mercury content. Blanks shall be checked carefully.
NOTE Instead of hydroxylammonium hydrochloride solution ascorbic acid can be used. Ascorbic acid solution can be prepared weekly by dissolving 10 g of L-ascorbic acid in 100 ml water (6.3).
Sampling
7.1
Sampling equipment – General requirements Use collectors with a defined horizontal opening, either a funnel/bottle combination (see A.1 and A.3) or a wide-mouthed jar (see A.2). The collectors can be bulk samplers, which collect at all times, or wet-only samplers which collect only during wet precipitation events.
If a funnel/bottle collector is used, the funnel shall have a cylindrical vertical section of sufficient height to avoid sampling losses resulting from splashing. If a jar is used, it shall have a sufficient depth to avoid such sampling losses.
Collector dimensions shall be selected with respect to the expected precipitation collected in the sampling period used. Typical sampling periods vary between one week and one month. The funnel area shall be large enough to provide sufficient sample for chemical analysis at a minimum precipitation depth of 1 mm per week.
It is recommended that short sampling periods (weekly) and/or two or three samplers in parallel are used. The sampling efficiency of funnel/bottle collectors can be checked by comparing the collected precipitation with the precipitation determined using a standard meteorological rain gauge. The difference in precipitation between the standard rain gauge and the heavy metal sample collector shall not be greater than 20 % for precipitation depths between 1 mm to 2,5 mm, and not greater than 10 % for precipitation depths larger than 2,5 mm of precipitation [9]. Checking sampling efficiency is especially important if a wet-only collector is used. Mercury deposition is collected in special precipitation samplers, which are used only for mercury deposition determinations. All parts of the precipitation collector that are in contact with the sample shall consist of materials that do not alter the mercury content of the sample (e.g. glass, fluorocarbon polymers). Also, all parts of the sampling collectors shall be easy to clean. In order for the sample not to be contaminated during heavy rain, the rim of the funnel shall be positioned
1,5 m to 2,0 m above the ground level.
NOTE
Sample contamination can be caused by insects, bird droppings or other material in the sampling vessels, especially when using extended sampling periods. This is a major drawback to bulk sampling.
For extended sampling periods − especially if HCl is used to preserve the sample during exposure − it is necessary to prevent the diffusion of Hg0 into the precipitation sample collected, since it could contribute to the mercury content of the sample via oxidation to water-soluble forms. For funnel/bottle collectors this can be done easily by using a capillary tube between the funnel and the bottle.
It is also necessary to shield the sample bottles from light to avoid photo-induced reduction of the mercury in the precipitation sample.
7.2 Sampling equipment − Special requirements for different collector types 7.2.1 Bulk collector: Funnel/bottle combination Sampling equipment as described in A.1 can be used for sampling.
If a bird ring is needed, it shall be covered by a suitable inert material, e.g. polyethylene. In order to prevent insects, leaves, etc. from entering the collection bottle a sieve made of e.g. polycarbonate can be used. The sieve shall not obstruct the funnel neck.
Funnel/bottle combination bulk collectors can be used at all types of sampling sites. 7.2.2 Bulk collector: Wide-mouthed jar Sampling equipment as described in A.2 can be used for sampling. If a bird ring is needed, it shall be covered by a suitable inert material, e.g. polyethylene.
Wide-mouthed jar bulk collectors can be used at all types of sampling sites.
7.2.3 Wet-only collector: Funnel/bottle combination Sampling equipment as described in A.3 can be used for sampling.
Wet only collectors are equipped with an automatic lid, which opens after activation of a precipitation sensor. The sensitivity of the sensor might affect the sampling efficiency. A precipitation of 0,05 mm/h shall be sufficient for the lid opening mechanism to be activated.
Wet-only collectors can be used at all types of sampling sites. NOTE
Especially at industrial sites or at costal sites, corrosion by e.g. reactive gases or sea salts can occur to precipitation sensors based on measuring the electrical conductivity. At such sites it can be useful to use optical sensors. 7.3 Preparation of precipitation collectors
All parts of the precipitation collector that are in contact with the sample shall be cleaned extensively before use. Plastic gloves shall be used during all steps of the cleaning procedure. It is recommended to store cleaned sampling vessels in double plastic bags. A suitable cleaning procedure is given below.
a) Wash with an alkaline detergent. Rinse thoroughly with ultrapure water;
b) Leach with 2 % HCl (6.4) for one day to two days. This can be done in a polyethylene tank. Rinse thoroughly with ultrapure water; c) Leach contaminated labware in BrCl solution (6.9). Leave to stand for at least 24 h. Add Hydroxylammonium hydrochloride solution (6.10) to remove BrCl from the solution. Rinse thoroughly with ultrapure water. SIST EN 15853:2010
Additional cleaning steps can be necessary. Pre-addition of HCl to funnel/bottle collectors with a capillary tube: add 5 ml concentrated HCl (6.1) per litre of collector volume. Alternatively add 50 ml of diluted HCl (6.5) per litre of collector volume. Do not add acid if an open jar is used for sampling.
7.4 Sampling and storage procedure All parts of the deposition collector that are in contact with the sample shall be handled with care in order to avoid contamination during transport and storage. Sample vessels shall only be handled using plastic gloves and it is recommended to keep all vessels in double plastic bags during transport and storage.
At the end of the sampling period, sampling vessels are exchanged. If funnel/bottle collectors are used for weekly (or biweekly) sampling, replace with clean funnels after four weeks. If there is obvious contamination (e.g. bird droppings) visible, replace earlier.
For exchange of samples, bring a new collection vessel to the sampler. Remove the used sample vessel from the sampler and immediately seal it e.g. with a screw cap or a glass stopper. Open a new sampling vessel (bottle or jar) and place it in the sampler. The complete sample shall be sent to the analysing laboratory in the sampling vessel. The sample shall be weighed in the laboratory. The empty sampling bottle shall be weighed before use and then weighed after the sampling period is finished to determine the mass of the collected sample. This mass is needed for the calculation of the results (see 10.1). The samples collected in wide-mouthed jar collectors shall be acidified with 5 ml of HCl (6.1) per litre sample after sampling.
Samples shall be refrigerated and kept in the dark if stored. The samples shall be analyzed as soon as possible after sampling. Alternatively, they can be stored for longer periods provided that the long-term stability is proved. This includes the testing of sample blanks stored for corresponding periods. An example of a suitable sampling procedure for a bulk funnel/bottle collector is described in Annex B. 8 Analysis
For sample preparation and analysis follow the procedures of EN ISO 17852. NOTE The EMEP manual can also be used for sample preparation and analysis [1].
An example of a suitable procedure is given in Annex C. 9 Quality control 9.1 Introduction As mercury concentrations in precipitation can be as low as a few nanograms per litre, sample contamination (by accidental contamination or inappropriate handling) can occur easily.
The laboratories determining mercury deposition shall therefore have a QA/QC procedure. 9.2 Reagent blanks, laboratory blanks and field blanks Field blanks shall be taken regularly to check for potential contamination.
Field blanks shall be used to check if there are problems with the procedures and to calculate the method detection limit. Field blanks shall be taken at least four times each year. If the mercury amount in the field blank sample exceeds 20 % of the average mercury amount in the sample during the sampling period, investigate and, if possible, eliminate any identified sources of contamination. If there is evidence of significant contamination, the result of the associated field samples shall be rejected.
9.3 Adsorption and deposition to the funnel walls In funnel/bottle collectors mercury can adsorb on the surface of the funnel. To investigate this, rinse the funnel with a known volume (e.g. 200 ml 0,5 % (v/v)) hydrochloric acid and collect this solution in a clean, empty sampling bottle. This blank solution shall be treated like a normal precipitation sample. Such funnel blanks shall be taken at least four times each year.
The mercury content of the blank solution shall be compared to that of samples stored in a clean laboratory environment. If the mercury content of the funnel blank exceed 20 % of the mercury values normally measured at the site, measures shall be taken to reduce the blanks (e.g. by exchanging or by cleaning the sampling devices).
9.4 External QA/QC If laboratories carry out analysis of mercury on a regular basis it is recommended that they participate in a relevant external quality assessment scheme or proficiency testing scheme like participating in laboratory and field intercomparison.
Calculation of results 10.1 Calculation of deposition in wet only and bulk collectors The sample mass is calculated according to Equation (1). actotsmmmm−−= (1) where
ms is the sample mass in kilograms; mtot is the mass of the collector vessel (bottle or jar) in kilograms (including sample and acid, but without cap); mc is the mass of the empty sampling collector (bottle or jar, without cap) in kilograms; ma is the mass of acid added to the sampling bottle before sampling in kilograms. For further calculations it is assumed that the sample collected has a density (ρ) of 1 kg/l: ρ/ssmV= (2) where Vs is the sample volume in litres; SIST EN 15853:2010
srlbrscHg/])([VVCVVCC×−+×= (3)
where
CHg is the concentration of mercury in the precipitation sample given in nanograms per litre;
Cc is the concentration of mercury in the acidified and digested sample given in nanograms per litre;
Vs is the volume of the precipitation sample given in litres;
Vr is the volume of the reagents added to the sample (acid, BrCl solution, etc.) given in litres;
Clb is the concentration of mercury in the laboratory blank solution, given in nanograms per litre. The mercury deposition is calculated according to Equation (4). trVDsπ2HgHgC= (4) where
DHg is the deposition of mercury given in nanograms per square metre per day;
CHg is the concentration of mercury given in nanograms per litre;
t is the number of days the sampling period lasted;
Vs is the sample volume in litres;
r is the radius of collector surface in metres.
10.2 Calculation of detection limits The instrumental detection limit shall be determined by the replicate analysis of a reagent blank. The method detection limit shall be determined by the analysis of a minimum of seven different field blanks. The detection limit shall be calculated as nanograms per litre. 1)(12(i))05,01(−−=×=∑=−nCCSDwithSDtDLni (5) where DL
is the detection limit of mercury in nanograms per litre; SD
is the standard deviation of mercury in nanograms per litre; SIST EN 15853:2010
is the number of blanks. 11 Estimation of the measurement uncertainty of the method 11.1 General approach The measurement uncertainty of the concentration of the mercury deposition in ambient air has to fulfil the data quality objective of 70 %, as specified in Directive 2004/107/EC.
The uncertainty (expressed at a 95 % confidence level) of the methods used for the assessment of ambient air concentrations shall be evaluated in accordance with the principles of EN ISO 20988, ENV 13005, ISO 5725, and the guidance provided in CR 14377. The percentages for uncertainty are given for individual measurements, which are averaged over typical sampling times, for a 95 % confidence interval. Fixed and indicative measurements shall be evenly distributed over the year in order to avoid skewing of results. The uncertainty of the method has been calculated from the results of a series of field trials to: a) demonstrate that this standard method meets the uncertainty requirements; and b) provide sufficient information on performance criteria which have to be met to ensure that individual users can also meet the uncertainty requirements. See Annex D for details of the results of the field trials. This European Standard uses appropriate parts of EN ISO 20988, CR 14377, ENV 13005, and ISO 5725-2 to produce a framework for assessing uncertainties against target values for individual laboratories (see 11.2). This approach to uncertainty estimation not only provides the user of this standard with a method of calculating his/her own uncertainty; more importantly it provides guidance as to the major uncertainty contributions to this method and identifies:
c) the maximum allowable level for each of these contributions; d) the maximum level for each contribution if the target overall uncertainty is to be met. 11.2 Assessment against target measurement uncertainty and uncertainty estimation for individual laboratories In the field trial three main factors contributing to measurement uncertainty were identified: analysis, sampling and systematic bias between sampler types. It is not expected that users shall perform an extensive field trial; however, some important uncertainty parameters shall be assessed by all laboratories. This includes an estimate of the uncertainty of the sampling and analytical procedure. An additional uncertainty component accounting for other contributions experienced in the field trial shall also be added.
The measurement uncertainty shall be less than or equal to 70 %, the minimum data capture shall be 90 %, and the minimum time coverage shall be 33 %, as specified in the data quality objectives of Directive 2004/107/EC. To be able to meet the uncertainty criteria the candidates shall meet the following performance criteria: SIST EN 15853:2010
EN ISO 20988;
the analytical uncertainty shall be below 20 %. This shall be calculated from laboratory inter-calibration test and using CRM. The standard uncertainty shall be calculated using the guidelines from
EN ISO 20988;
an additional uncertainty component of 20 % shall be added to account for possible systematic bias, determined in the field trials described in Annex D, not fully covered by the two above points, e.g. choice of collector and precipitation. The individual laboratories may otherwise calculate these contributing uncertainties by doing their own tests. NOTE These performance criteria are only valid for the mercury deposition range given in Table 1. 12
Performance characteristics determined in field tests
12.1 General The performance characteristics given in this clause are based upon the data gathered in the tests carried out to validate this method. The field validation tests were carried out at two measurement sites (one industrial and one remote site). These tests included all steps covering sampling, sample preparation and analysis of the samples. The results from these tests are used to estimate the measurement performance characteristics. 12.2 Method detection limit The detection limit obtained by the participating laboratories is given in Table 2. Table 2 — Detection limit as mercury concentration in field blanks, nanograms per litre
CVAAS/CVAFS
ng/l Hg 1,0
During the field trials the detection limit, expressed in nanograms per square metre per day, was calculated using the values of mercury concentration in field blanks, multiplied with the minimum detectable precipitation (1 mm) (7.1), divided by the number of sampling days (seven days) (see Table 3).
Table 3 — Detection limit as mercury deposition, nanograms per square metre per day
CVAAS/CVAFS ng/(m²·d) Hg 0,14
12.3 Estimated expanded uncertainty For the two field trials the procedure described in D.3 yielded expanded uncertainties at the 95 % confidence interval of: rural site: 44,2 % at an average deposition value of 17 ng/m2·d; industrial site: 39,8 % at an average deposition value of 30 ng/m2·d. SIST EN 15853:2010
Reporting of results
13.1 Reporting results Results shall be reported as the deposition DHg as mass of mercury per unit area and per time. The unit used to express the deposition shall be nanograms per square metre per day, ng/(m2·d). When reporting the result of a measurement, and when the uncertainty quoted is the expanded uncertainty one shall: a) state the result of the measurement as Uy±, wherey is the measurement result and U is the expanded uncertainty, and give the units of y and U; b) give the value of the coverage factor k used to obtain U and the approximate level of confidence this factor confers on the interval Uy±. 13.2 Measurement report A report describing the measurement of mercury in deposition shall contain at least the following information: reference to this European Standard and supplementary standards; complete identification of the sample(s); type of analytical instrument and sampling equipment used; identification of each sampling location; sampling time period; results of the determinations expressed in ng/(m2·d);
expanded uncertainty and how this was calculated; method detection limits expressed in ng/(m2·d);
any unusual features noted during the determination; any deviations from this European Standard.
Sampling equipment that can be used for precipitation sampling A.1 Bulk collector (funnel/bottle combination) An example of a suitable bulk collector with funnel/bottle combination is shown in Figure A.1.
Key 1 glass funnel (diameter: ≈ 80 mm, height: 90 mm) 2 glass capillary (length: 0,2 m to 0,3 m, inner diameter: 2 mm) 3 gas wash bottle head equipped with a 20 mm long capillary with 0,4 mm inner diameter 4 receiver bottle (volume: 500 ml)
5 protective housing (length: 1,5 m)
NOTE
On the left: sampling equipment made from Borosilicate glass. On the right: protective housing made from polypropylene. The housing is electrically heated during winter to protect from freezing. Figure A.1 — Schematic of a bulk sampler
A.2 Bulk collector (wide-mouthed jar) An example of a suitable wide-mouthed jar type bulk collector is shown in Figure A.2.
Key 1
collecting pot 2
protective basket (with bird ring) 3
post Figure A.2 — Schematic of wide mouthed jar bulk collector NOTE It is essential to shield the sample bottles from light to avoid photo-induced reduction of the mercury in the precipitation sample. SIST EN 15853:2010
Dimensions
Height of collection area: ± 1 600 mm Diameter of funnel: 240 mm
Size of collection bottle: ± 2 l to 5 l
Figure A.3 — Schematic of wet-only collector SIST EN 15853:2010
Sampling procedure B.1 Bulk collector (funnel/bottle combination) An example of a suitable sampling procedure using a bulk collector with funnel/bottle combination (see A.1) as described in the EMEP manual [1] is given here. For alternative sampling devices, this procedure shall be adapted. All samples and replacement sample bottles shall be handled with care in order to avoid contamination during transport and storage. Sample bottles shall only be handled using plastic gloves and all bottles shall be kept in double plastic bags during transport and storage.
Before sending the precipitation bottle (500 ml) to the field 2,5 ml of concentrated HCl (6.1) or 25 ml of 2 % HCl (6.5) shall be added to the bottle.
The procedure described below is for the bulk sampler shown in Figure A.1:
a) bring a new collection bottle, plastic bags and container with high purity water to the sampler. All equipment needed for the bottle exchange shall be placed on a plastic cover either on the ground or available surface;
b) remove the outer plastic tube;
c) open the double bags of the new collection bottle (but leave the bottle in the bags);
d) carefully remove the ground glass joint connecting the bottle to the capillary. Use both hands, one for loosening the glass fitting the other for holding the funnel;
e) remove the stopper from the new collection bottle and close the bottle containing the precipitation sample. This bottle is then put in double plastic bags;
f) before mounting the new bottle, rinse the funnel and capillary with high purity water. If visible materials (dust, insect, etc.) are present, disconnect the funnel from the capillary and rinse separately. New plastic gloves shall be used if handling the watch glass or touching the inside of the funnel is necessary. If the funnel and capillary are visibly dirty even after rinsing, they shall be exchanged with newly washed pieces;
g) remove the new collection bottle from the plastic bags and place in the plastic casing. Connect the ground glass fitting and check all connections. Make sure that silicon tubing is exposed to the precipitation sample as little as possible;
h) replace the outer plastic tube.
Samples to be stored shall be refrigerated and kept in the dark. They may be stored up to 6 m provided that the long-term stability is checked. This also appl
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