SIST EN 15841:2010
(Main)Ambient air quality - Standard method for determination of arsenic, cadmium, lead and nickel in atmospheric deposition
Ambient air quality - Standard method for determination of arsenic, cadmium, lead and nickel in atmospheric deposition
This European Standard specifies three methods for the determination of deposition of arsenic (As), cadmium (Cd) nickel (Ni) and lead (Pb), that can be used in the framework of the European Council Directive on Ambient Air Quality Assessment and Management and the 4th Air Quality Daughter Directive. This European Standard specifies performance requirements with which the method has to comply in order to meet the data quality objectives given in the Directives. The performance characteristics of the method were determined in comparative field validation tests carried out at four European locations. This European Standard specifies methods for sampling wet-only and bulk deposition of As, Cd, Ni and Pb, sample treatment and analysis by graphite furnace atomic absorption spectrometry (GF-AAS) or by inductively coupled plasma mass spectrometry (ICP-MS). The method is applicable for deposition measurements in a) rural and remote areas; b) industrial areas; c) urban areas. The standard is validated for the working ranges listed in Table 1.
Luftbeschaffenheit - Messverfahren zur Bestimmung von Arsen, Cadmium, Blei und Nickel in atmosphärischer Deposition
Diese Europäische Norm legt ein Verfahren zur Bestimmung der Deposition von Arsen (As), Cadmium (Cd), Nickel (Ni) und Blei (Pb) fest, das im Rahmen der Europäischen Richtlinie 96/62/EG des Rates über die Beurteilung und die Kontrolle der Luftqualität [1] sowie der 1. [2] und der 4. [3] Tochterrichtlinie eingesetzt werden kann. Diese Europäische Norm legt Leistungsanforderungen fest, denen das Verfahren entsprechen muss, um die in den Richtlinien angegebenen Ziele in Bezug auf die Qualität der Daten zu erreichen. Die Kenngrößen des Verfahrens wurden in vergleichenden Feld-Validierungsversuchen bestimmt, die an vier Orten in Europa durchgeführt wurden [4].
Die vorliegende Europäische Norm legt Verfahren zur Probenahme der atmosphärischen Deposition von As, Cd, Ni und Pb, zur Probenbehandlung und zur Probenanalyse mit Hilfe der Graphitofen-Atomabsorptions¬spektrometrie (GF-AAS) oder der Massenspektrometrie mit induktiv gekoppeltem Plasma (ICP MS) fest.
Das Verfahren ist anwendbar auf Depositionsmessungen in
ländlichen und entlegenen Gebieten;
industriellen Gebieten;
städtischen Gebieten.
Die Norm wurde für den in Tabelle 1 aufgeführten Depositionsbereich validiert.
Qualité de l'air ambiant - Méthode normalisée pour la détermination des dépôts d'arsenic, de cadmium, de nickel et de plomb
La présente Norme européenne spécifie trois méthodes de détermination des dépôts d'arsenic (As), de cadmium (Cd), de nickel (Ni) et de plomb (Pb) qui peuvent être utilisées dans le cadre de la Directive du Conseil Européen sur l'évaluation et la gestion de la qualité de l'air ambiant [1] et la 4ème directive fille [2]. La présente Norme européenne spécifie les exigences de performance que doivent respecter ces méthodes pour satisfaire aux objectifs de qualité des données indiqués dans les directives. Les caractéristiques de performance des méthodes ont été déterminées lors d'essais de validation comparative sur le terrain réalisés en quatre lieux d'Europe [3].
La présente Norme européenne spécifie des méthodes d'échantillonnage de dépôts humides et de dépôts totaux de As, Cd, Ni et Pb, des traitements et des analyses d'échantillons par spectrométrie d'absorption atomique à four graphite (GF-AAS) ou par spectrométrie de masse à plasma induit (ICP-MS).
Les méthodes s'appliquent à des mesures de dépôts dans
a) des zones rurales et éloignées des sources ;
b) des zones industrielles ;
c) des zones urbaines.
La norme est validée pour les plages de fonctionnement indiquées au Tableau 1.
Tableau 1 - Plages de fonctionnement validées pour les méthodes
Limite inférieure (µg/m2 jour) Limite supérieure (µg/m2 jour)
As 0,05 2
Cd 0,01 1
Ni 0,05 25
Pb 0,1 65
NOTE Les plages indiquées sont basées sur les valeurs mesurées au cours des essais de validation sur le terrain. Les limites supérieures et inférieures observées sont les valeurs minimales et maximales mesurées pendant les essais de validation sur le terrain. Les limites inférieures réelles des plages de fonctionnement dépendent de la variabilité du blanc de laboratoire et des quantités de pluie dans les dépôts totaux et les dépôts humides.
Kakovost zunanjega zraka - Standardna metoda za določevanje arzena, kadmija, svinca in niklja v atmosferskih usedlinah
Ta evropski standard določa tri metode za določevanje usedlin arzena (As), kadmija (Cd), niklja (Ni) in svinca (Pb), ki se lahko uporablja v okviru Direktive Evropskega sveta o ocenjevanju in upravljanju kakovosti zunanjega zraka ter 4. hčerinske direktive o kakovosti zraka. Ta evropski standard določa zahteve za zmogljivost, ki jim mora metoda ustrezati, da dosega cilje kakovosti podatkov, podane v direktivah. Značilnosti zmogljivosti metode so določili s primerjalnimi validacijskimi preskusi na terenu, opravljenimi na štirih evropskih lokacijah. Ta evropski standard določa metode za vzorčenje samo mokrih in skupnih usedlin As, Cd, Ni in Pb, obdelavo in analizo vzorcev z atomsko absorpcijsko spektrometrijo z grafitno kiveto (GF-AAS) ali z masno spektrometrijo z induktivno sklopljeno plazmo(ICP-MS). Metoda velja za meritve usedlin a) na podeželju in oddaljenih območjih, b) v industrijskih območjih, c) v mestnih okoljih. Standard je potrjen za delovne razpone, navedene v Tabeli 1.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Luftbeschaffenheit - Messverfahren zur Bestimmung von Arsen, Cadmium, Blei und Nickel in atmosphärischer DepositionQualité de l'air ambiant - Méthode normalisée pour la détermination des dépôts d'arsenic, de cadmium, de nickel et de plombAmbient air quality - Standard method for determination of arsenic, cadmium, lead and nickel in atmospheric deposition13.040.20Kakovost okoljskega zrakaAmbient atmospheresICS:Ta slovenski standard je istoveten z:EN 15841:2009SIST EN 15841:2010en,fr,de01-februar-2010SIST EN 15841:2010SLOVENSKI
STANDARD
SIST EN 15841:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 15841
November 2009 ICS 13.040.20 English Version
Ambient air quality - Standard method for determination of arsenic, cadmium, lead and nickel in atmospheric deposition
Qualité de l'air ambiant - Méthode normalisée pour la détermination des dépots d'arsenic, de cadmium, de nickel et de plomb
Luftbeschaffenheit - Messverfahren zur Bestimmung von Arsen, Kadmium, Blei and Nickel in atmosphärischer Deposition This European Standard was approved by CEN on 17 October 2009.
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, 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 © 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15841:2009: ESIST EN 15841:2010
EN 15841:2009 (E) 2 Contents Page Foreword .31Scope .42Normative references .43Terms, definitions and abbreviations .54Principle .75Apparatus and reagents .86Sampling . 117Sample preparation . 128Quality control . 149Calculation of results . 1410Performance characteristics determined in lab and field tests . 1711Reporting of results . 20Annex A (informative)
Standard operating procedures for sampling . 22Annex B (informative)
Estimation of the measurement uncertainty of the method . 26Annex C (informative)
Uncertainty budget . 30Annex ZA (informative)
Relationship between this European Standard and the essential requirements of EU Directives . 31Bibliography . 32 SIST EN 15841:2010
EN 15841:2009 (E) 3 Foreword This document (EN 15841:2009) 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 May 2010, and conflicting national standards shall be withdrawn at the latest by May 2010. 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. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, 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 the United Kingdom. SIST EN 15841:2010
EN 15841:2009 (E) 4
1 Scope This European Standard specifies three methods for the determination of deposition of arsenic (As), cadmium (Cd) nickel (Ni) and lead (Pb), that can be used in the framework of the European Council Directive on Ambient Air Quality Assessment and Management [1] and the 4th Air Quality Daughter Directive [2]. This European Standard specifies performance requirements with which the method has to comply in order to meet the data quality objectives given in the Directives. The performance characteristics of the method were determined in comparative field validation tests carried out at four European locations [3]. This European Standard specifies methods for sampling wet-only and bulk deposition of As, Cd, Ni and Pb, sample treatment and analysis by graphite furnace atomic absorption spectrometry (GF-AAS) or by inductively coupled plasma mass spectrometry (ICP-MS).
The method is applicable for deposition measurements in a) rural and remote areas; b) industrial areas; c) urban areas. The standard is validated for the working ranges listed in Table 1. Table 1 — Validated working ranges for the methods Lower limit(µg/m² day) Upper limit(µg/m² day) As 0,05 2 Cd 0,01 1 Ni 0,05 25 Pb 0,1 65 NOTE The ranges given are 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 ranges depend on the variability of the laboratory blank and the precipitation amount range in bulk and wet-only.
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. EN 14902:2005, Ambient air quality – Standard method for the measurement of Pb, Cd, As and Ni in the PM10 fraction of suspended particulate matter
EN ISO 20988:2007, Air quality – Guidelines for estimating measurement uncertainty (ISO 20988:2007) ISO 5725-2, Accuracy (trueness and precision) of measurement method and results – Part 2: Basic
method for the determination of repeatability and
reproducibility of a standard measurement method
SIST EN 15841:2010
EN 15841:2009 (E) 5 3 Terms, definitions and abbreviations 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 analysis all operations carried out after sample preparation to determine the amount or concentration of the metals or metalloids of interest present in the sample 3.1.2 Bergerhoff collector wide mouthed bucket mounted on a post, openly exposed at all time 3.1.3 bulk collector funnel-bottle combination openly exposed at all time NOTE In this standard two methods for the bulk collector are described: the “bulk bottle method” (only the liquid collected in the bottle is analysed) and the “bulk bottle+funnel method” (the liquid collected in the bottle plus the solid collected on the funnel are analysed). 3.1.4 bulk deposition sum of the deposition of sedimenting wet and dry particles NOTE Both bulk and Bergerhoff collectors sample bulk deposition. 3.1.5 coverage factor numerical factor used as multiplier of the combined standard uncertainty in order to obtain an expanded uncertainty
[EN ISO 20988:2007, 3.3; ISO/IEC Guide 98:2008, 2.3.6] 3.1.6 detection limit (DL), instrumental lowest amount of an analyte that is detectable using an instrument as determined by repeated measurements of a reagent blank 3.1.7 detection limit (DL), method lowest amount of an analyte detectable after the whole measurement process as determined by repeated measurements of different field blanks 3.1.8 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. SIST EN 15841:2010
EN 15841:2009 (E) 6 3.1.9 expanded uncertainty expanded measurement uncertainty quantity defining an interval [])();(yUyyUypp+− about the result of a measurement that can be expected to encompass a large fraction pof the distribution of values that could reasonably be attributed to the measurand [EN ISO 20988:2007, 3.4; ISO/IEC Guide 98:2008, 2.3.5] 3.1.10 field blank artificial sample (e.g. de-ionised water) transported to the sampling site, mounted in the sampling unit, but not exposed to ambient air, returned to the laboratory and worked up in the same way as the deposition sample 3.1.11 laboratory blank artificial sample (e.g. de-ionised water) worked up in the same way as the deposition sample in the laboratory 3.1.12 precipitation rain, snow, sleet, graupel and hail 3.1.13 reagent blank artificial sample (e.g. de-ionised water) that contains all the reagents used during analysis of the sample, but without the sample matrix 3.1.14 repeatability closeness of the agreement between the results of successive measurements of the same measurand carried out under the same conditions of measurements [ISO/IEC Guide 98:2008, B.2.15] 3.1.15 reproducibility closeness of the agreement between the results of measurements of the same measurand carried out under changed conditions of measurements [ISO/IEC Guide 98:2008, B.2.15] 3.1.16 sample digestion sample dissolution process to obtain a solution containing the analyte of interest 3.1.17 sample preparation all operations carried out on a sample, after transportation and storage, to prepare it for analysis, including transformation of the sample into a measurable state, where necessary 3.1.18 standard operating procedure
SOP written set of procedures that details the method of an operation, analysis, or action whose techniques and procedures are thoroughly prescribed and that is accepted as the method for performing certain routine or repetitive tasks SIST EN 15841:2010
EN 15841:2009 (E) 7 3.1.19 standard uncertainty standard measurement uncertainty measurements uncertainty expressed as a standard deviation [EN ISO 20988:2007, 3.18; ISO/IEC Guide 98:2008, 2.3.1] 3.1.20 uncertainty (of a measurement) measurement uncertainty parameter associated with the result of a measurement that characterises the dispersion of the values that could reasonably be attributed to the measurement [EN ISO 20988:2007, 3.18; ISO/IEC Guide 98:2008, B.2.18;] 3.1.21 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.
3.1.22 wet-only collector collector open only during precipitation events, typically a funnel-bottle combination 3.2 Abbreviations EMEP Co-operative programme for monitoring and evaluation of the long-range transmission of
air pollutants in Europe GF-AAS Graphite Furnace - Atomic Absorption Spectrometry ICP-MS Inductively Coupled Plasma - Mass Spectrometry SOP Standard Operating Procedure CRM Certified Reference Material WMO/GAW World Meteorological Organization/Global Atmosphere Watch 4 Principle Total atmospheric deposition of metals, which is defined as the sum of the deposition of sedimenting particles, non-sedimenting particles and gases, or sum of wet and dry deposition, cannot be determined by a single simple method.
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 using wet-only and bulk collectors. The wet-only collector is designed to collect only sedimenting wet particles, 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 and surface type, the wet-only collector will not catch all sedimenting wet particles while some sedimenting dry particles, non-sedimenting particles and gases SIST EN 15841:2010
EN 15841:2009 (E) 8 will be collected. Also, the bulk collector will not catch all sedimenting particles while some non-sedimenting particles and gases will be collected. The sample is transferred to the laboratory in the sampling bottle (wet only and bulk collector) or bucket (Bergerhoff collector). Arsenic, cadmium, nickel and lead are taken into solution by digestion techniques and analysed by appropriate analytical instruments (i.e. ICP-MS and GF-AAS) depending on deposition level to be measured. Close to industrial sources bulk deposition of metals comprises approximately their atmospheric deposition. At background sites with high precipitation the measurement of bulk and wet deposition is shown to be equivalent. 5 Apparatus and reagents 5.1 Reagents 5.1.1 Ultrapure water distilled or deionised It is recommended that the water used should be obtained from a water purification system that delivers ultrapure water having a resistivity of 18,2 M·cm or greater at 25 °C. 5.1.2 Nitric acid (HNO3), concentrated Density about 1,42 g/ml, mass fraction about 70 %, high purity grade (concentration stated by the manufacturer or supplier < 0,005 mg/l for As, Cd, Ni and Pb (typical concentrations are generally ten times lower)), sub-boiled before use if necessary. WARNING — Concentrated nitric acid is corrosive and oxidising, and nitric acid fumes are irritants. 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 nitric acid. 5.1.3 Nitric acid for cleaning purposes (2 % by volume) Add approximately 800 ml of ultrapure water to a 1 l acid cleaned volumetric flask. Carefully add 20 ml of concentrated nitric acid to the flask and swirl to mix. Allow to cool, dilute to 1 l with ultrapure water and mix thoroughly. 5.1.4 Nitric acid for filtration purposes (1 % by volume) Add approximately 900 ml of ultrapure water to a 1 l acid cleaned volumetric flask. Carefully add 10 ml of concentrated nitric acid (5.1.2) to the flask and swirl to mix. Allow to cool, dilute to 1 l with ultrapure water and mix thoroughly.
5.1.5 Hydrogen peroxide (H2O2), mass fraction about 30 % High purity grade (concentration stated by the manufacture or supplier < 0,005 mg/l for As, Cd, Ni and Pb (typical concentration are generally ten times lower)). 5.2 Sampling equipment 5.2.1 General Depending on site characteristics (6.1), three different types of collectors can be used to measure deposition of arsenic, cadmium, nickel and lead: wet-only (3.1.22), bulk (3.1.3) and Bergerhoff collector (3.1.2). The two SIST EN 15841:2010
EN 15841:2009 (E) 9 first types of collectors are bottle+funnel combinations while the latter is an open bucket. The choice of which sampler to use is discussed in 6.1. 5.2.2 General requirements for sampling equipment Collectors shall have a cylindrical vertical section of sufficient height to avoid sampling losses resulting from splashing. See Annex A for illustrations of the samplers used in the field trial. The diameter for the opening area and the volume of the collector need to be selected to be of appropriate size to collect all the precipitation for the required sampling duration. 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 height of 1 mm per week. In order for the sample not to be contaminated from the ground during heavy rain, the height of the opening through which precipitation enters the sampler (i.e., the collection orifice) shall be at least 1,5 m above ground. For areas that receive high snowfall accumulations, the sampler may be raised onto a platform above the snow [4]. No parts of the collector that are in contact with the sample shall be made of metal. All parts should be easily cleaned. The collector and all surfaces in contact with the samples should be inert for the analytes measured, for example high density polyethylene. NOTE Different samplers may have different sampling efficiency, which can lead to incomparable results. The sampling efficiency for precipitation may be checked conducting parallel measurement with a standard precipitation gauge. The difference in precipitation amount between the standard rain gauge and the bulk or wet-only collectors should not be greater than 20 %.
See Annex A for examples of sampling standard operating procedures. 5.2.3 Wet-only collector A wet-only collector is used to sample precipitation only (3.1.12). The wet-only collectors shall be open during precipitation events and be closed during dry periods. An automated wet-only collector should have the following components: a precipitation sample container (funnel+bottle combination), a lid that opens and closes over the sample container orifice, a precipitation sensor, a motorized drive mechanism with associated electronic controls, and a support structure to house the components.
It is recommended that the sampler is temperature controlled to avoid freezing and evaporation of the rain water.
The collection efficiency for a wet-only collector is dependent on the sensitivity of the sensor. The sensor should be designed with a response, which will cause the lid to open when the precipitation intensity exceeds 0,05 mm/h [5].
Samplers shall be designed for sampling during all seasons and all relevant climatic conditions. Thus, a heating device could be included for melting snow and to prevent the formation of ice in the funnel or bottle during winter.
NOTE Depending on climatic conditions, it can be useful to cool the samples in locations where high rates of evaporation are expected during summer. 5.2.4 Bulk collector
A bulk collector consists of a bottle+funnel combination openly exposed at all times (3.1.3). In order to prevent insects, leaves, etc. from entering the collection bottle use a sieve made of e.g. polycarbonate. The sieve should be free and not tied up in the funnel neck. SIST EN 15841:2010
EN 15841:2009 (E) 10 NOTE An extra large and deep cylindrical bucket could be used for snow sampling. This is in principle the same as a large type of Bergerhoff collector, but one should notice that the collector illustrated in A.1 is too small for proper snow sampling. 5.2.5 Bergerhoff collector sampler
A Bergerhoff collector is a bucket installed on a top of a post. Optionally this can be equipped with a bird guard. NOTE The Bergerhoff collectors used in the field trial had a collecting volume of 1,5 l and an opening of about 100 mm in diameter. 5.3 Laboratory equipment 5.3.1 General Ordinary laboratory apparatus and the laboratory equipment given in 5.3.2 to 5.3.5 are required. 5.3.2 Microwave digestion system
A microwave digestion system including chemical resistant vessels as described in EN 14902 shall be used for digestion of Bergerhoff samples (see 7.3) and filters (see 7.2.2). The microwave cavity shall be corrosion resistant and well ventilated, with all electronics protected against corrosion to ensure safe operation. Ensure that the manufacturer’s safety recommendations are followed. NOTE A leakage detection or pressure control system is very useful, since it provides a safeguard against the possibility of sample loss due to excessive pressure build-up and partial venting of the sample vessels. 5.3.3 Drying device This is either a hot plate or a furnace to evaporate the Bergerhoff samples to dryness. 5.3.4 Graphite furnace-atomic absorption spectrometer (GF-AAS)
Equipped with hollow cathode lamps or electrodeless discharge lamps for the elements of interest, capable of carrying out simultaneous background correction at the measurement wavelengths using a continuum source such as a deuterium lamp to correct for non-specific attenuation or using a Zeeman background correction system. 5.3.5 Inductively coupled plasma - mass spectrometer (ICP-MS)
Mass spectrometer (e.g. quadrupole instrument) capable of scanning the mass range from 5 u (unified atomic mass unit) to 250 u with a minimum resolution capability of 1 u peak width at 5 % peak height, equipped with a data system that allows correction of isobaric interferences and the application of the internal standard technique. NOTE The use of alternative ICP-MS instrumental configurations, e.g. high resolution mass spectrometers, quadrupole mass spectrometers equipped with reaction or collision cells, cold plasma systems, etc., can reduce spectral interferences. SIST EN 15841:2010
EN 15841:2009 (E) 11 6 Sampling 6.1 Sampling strategy Different sampling strategies are needed for rural and industrial sites. For urban areas the pollution level can be similar to rural sites, and in this case one should follow sampling strategy for rural sites. Other urban environments can be more polluted, and if so one should follow the sampling strategy for industrial sites. At background sites (rural and less polluted urban area) with high precipitation the bulk bottle or the wet-only methods should be used. In the field validation the results from these two types of collectors were found to be not significantly different within the data quality objectives given by the 4th Daughter Directive [2]. At sites where sedimentation of dry particles is important (e.g. industrial sites) either Bergerhoff collectors or bulk collectors (bottle+funnel method) should be used. For bottle+funnel methods the precipitation amount shall be measured by weight and no corrections should be made for sampling errors, such as undercatch, evaporation or part of the sample remaining in the collector.
NOTE 1 In southern Europe or other dry climatic regions the dry deposition can be of more importance than was tested in the field validation trial. Under these conditions, the wet-only and the bulk collector (bulk bottle method) can give misleading results. When establishing a new sampling site tests should be made before deciding on the sampling procedure. For bulk collector the deposition on the funnel walls should be analyzed (6.4) to estimate the contribution of deposition on the funnel. In addition, one should carry out filtration tests (7.2.2) to estimate the importance of non-dissolved metals in precipitation samples. NOTE 2 At high deposition levels both GF-AAS and ICP-MS may be used (see Table 2 to Table 4). For low concentration samples that often can be below the instrumental detection limit of GF-AAS, only ICP-MS is proven to work well. NOTE 3 At sites with much rainwater and/or snowfall the Bergerhoff collector may be inappropriate due to overflow of the sample collector. For sites with much snow and low temperature the addition of antifreezing and heavy metal free chemicals (e.g. ethylen glycol) can minimize overflow and/or prevent blasting of the collectors. 6.2 Sampling location The siting requirements should follow the guidelines in Annex III of the 4th Daughter Directive [2], which for deposition measurements in rural areas are harmonized with the guidelines from EMEP [4] and WMO/GAW [5]. 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. The collector should as far as possible not be exposed in areas where unrepresentative strong winds occur like shores, cliffs and top of hills, but it should also not be sheltered by tall trees or buildings. The flow around the collector should be unrestricted, without any obstructions affecting the airflow in the vicinity of the sampler. The criteria depend on the site characteristic: a) Rural sites: There should be no obstacles, such as trees, above 30° from the rim of the precipitation collector, and buildings, hedges, or topographical features which may give rise to updraughts or downdraughts. See EMEP manual [4] for details; b) Urban and industry sites: One should seek to meet the same requirements but should be at least some metres away from buildings, trees and other obstacles. 6.3 Sampling requirements Sample devices, measuring equipment, etc. should always be handled with care to prevent contamination. Clean disposable plastic gloves should be used when collecting the samples. The inside of the funnel or the SIST EN 15841:2010
EN 15841:2009 (E) 12 tip of the collector should not be touched. Equipment in the field should always be kept in as clean and dust-free place as possible. It should be particularly avoided to let the equipment be in contact with or close to metal surfaces. The bottles, buckets and funnels should be kept in double sealable plastic bags during transport and storage.
Extra precautions are needed when sampling heavy metals due to the sensitivity for contamination. The concentrations of heavy metals in precipitation are typically only a few nanograms per millilitre and it is important that the SOP is followed carefully. Immediately after disconnection of the sample bottle or bucket, close it with a screw cap. In order to prevent contamination, the precipitation bottle or bucket should be sent to the laboratory without transferring any precipitation into smaller transport bottles. It is important to avoid leaking during transport. NOTE 1 In some special cases it can be advisable to transport the collector in a cooling device to avoid algae growth. Acidification of the sample prevents algae growth, but this is usually not done before arrival at the laboratory (7.2.1). Further additives to prevent algae growth or freezing should in general be avoided due to the danger of contamination. The sample amount in the bulk and wet-only collectors shall be measured by weight. The sample mass is needed to calculate the sample volume (9.1). The precipitation shall be conserved in nitric acid, which is added either before or after the sampling (7.2.1). NOTE 2
If other measurements like nitrate are carried out at the site, it is recommended to avoid acidification of the sampler before sampling to prevent contamination of these measurements. Field blanks (3.1.10) shall be taken regularly, e.g. four times a year. These shall be used to check the procedure and not to correct the data. If the field blank is high, i.e. more than 20 % of the average deposition level of the corresponding site, necessary steps shall be taken to find the contamination sources and correct the procedure accordingly. Examples on how the SOP can be defined for the different collectors are described in Annex A. 6.4 Adsorption and deposition on the funnel walls (bottle+funnel method) At the start of a sampling program using wet-only or bulk collectors the funnel walls should be rinsed and the rinsing solution analysed to evaluate the importance of adsorption and deposition of As, Cd, Ni, and Pb on the funnel wall. If it turns out to have a significant influence, meaning more than 20 % of the measured deposition, the funnel rinsing needs to be included in the regular sampling procedure. The funnel should be was
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