Intercomparison Exercise for Heavy Metals in PM10

The Joint Research Centre (JRC) has carried out an Intercomparison Exercise (IE) for the determination of heavy metals in particulate matter (PM10). The IE focussed on Lead (Pb), Arsenic (As), Nickel (Ni) and Cadmium (Cd), the heavy metals regulated by the 1st and 4th Daughter Directives for Air Pollution. Copper (Cu), Chromium (Cr) and Zinc (Zn), the elements included in the EMEP programme together with Aluminium (Al), Cobalt (Co), Iron (Fe), Manganese (Mn) and Vanadium (V) were also tested. Fourteen Laboratories, generally members of the Network of Air Quality Reference Laboratories (AQUILA), participated in the IE. The participants mainly used microwave digestion with nitric acid and hydrogen peroxide and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or Graphite Furnace Atomic Absorption Spectrometry (GF-AAS) for analysis as recommended in the reference method (EN 14902). However, a few participants used other methods: Energy Dispersive X-ray Fluorescence (EDXRF), Atomic Emission Spectrometry (ICP-AES) and Voltammetry for analysis and vaporisation on hot plate before microwave digestion, Soxhlet extraction, high pressure or cold Hydrogen Fluoride methods for digestion. Each participant received 5 samples to be analysed: a liquid sample prepared by dilution of a Certified Reference Material (CRM), a solution of a dust CRM sample digested by the JRC13F, a sub-sample of a dust CRM that each participating laboratory had to digest and analyse, a solution prepared by JRC after digestion of an exposed filter and a pair of filters (one blank filter and one exposed filter) to be digested and analysed by each participant. For 89 % of all types of samples, the DQOs of the 1st and 4th European Directives (uncertainty of 25 % for Pb and 40 % for As, Cd and Ni) were met. All together, this is a very good score. The best results were obtained for the liquid CRM, dust CRM digested by JRC, dust CRM and filter digested by JRC with 92, 90, 96 and 93 % of DQOs being met, respectively. It was found that the DQOs were not met if the difference of acidity between test samples and participant calibration standards was high. Conversely, only 76 % of DQOs were met for the filter to be digested by each participant with (about 85 % for Cd and Ni, 73/64 % for Pb and As, the most difficult element to determine). The worst results were associated with special events: explosion in microwave oven during digestion for two participants, a wrong dilution factor used by one participant and a huge contamination in the blank filter for another participant. Among the two explosions, one of them was probably the effect of a lack of temperature control in the digestion vessel. For the other explosion, the microwave digestion and the digestion program advised by EN 14902 is to be questioned. Moreover, satisfactory results were obtained using Soxhlet extraction, high pressure method and cold Hydrogen Fluoride digestion methods which are not presented in EN 14902. The DQOs of As and Cd could not be met with EDXRF whose limit of detection was too high for these two elements and for Cd using Voltammetry which suffered a strong interference for this element. Regarding the methods of analysis, apart the points mentioned just before about EDXRF and Voltammetry, good results were observed using ICP-OES for Cd, Ni and Pb. A few discrepancies were also registered for GF-AAS and ICP-MS but they were created by the special events or acidity problem mentioned before. This shows that even though GF-AAS and ICP-MS are found suitable, the implementation by each participant may be responsible for important mistakes.JRC.H.4-Transport and air qualit

Determination of NO2 and SO2 by Ion Chromatography in Ambient Air by Use of Membrane - Closed Palmes Tube

Several authors have investigated the diffusive sampler method for measuring NO2 and SO2 in ambient air. The two pollutants are either independently or simultaneously analysed using the diffusive sampler. Different types of diffusive samplers can be used e.g badge type, radial type or open-ended longitudinal diffusion tubes. The Palmes tube, coated with triethanolamine (TEA), allows the simultaneous determination of NO2 and SO2. However, field measurements showed that the open-ended diffusion tube is affected by a strong artefact on the SO2 determination arising from sulphate particulate matter. To avoid this interference, a teflon membrane has been introduced at the open end of the Palmes tube able to prevent contamination coming from the particulate matter. However the introduction of the membrane creates an additive resistance to the diffusion of molecules to the absorbent and therefore modifies the uptake rate of the Palmes tube. The evaluation of NO2 membrane-closed Palmes diffusion tubes (MCPTs) is already presented somewhere else . Hereafter, an evaluation of the modified Palmes sampler with a membrane for the determination of SO2 is presented.JRC.H.4-Transport and air qualit

The Equivalence of Diffusive Samplers to Reference Methods for Monitoring O3, Benzene and NO2 in Ambient Air

A study of the equivalence to the reference methods of the Radiello samplers for ozone (O3) and benzene as well as the membrane-closed Palmes tube (MCPT) for nitrogen dioxide (NO2) is presented. These samplers benefit from new model equations capable of estimating their uptake rate. For O3, the aim here was to demonstrate the equivalence for the reference period of 8 hours and 120 µg m-³, the target value stated in the 3rd Daughter Directive. For benzene, the demonstration of equivalence to the annual limit value of 5 µg.m-3 as stated in the 2nd Daughter Directive was examined. In the case of NO2, the equivalence to the annual limit value as stated in the 1st Daughter Directive (40 µg m-³) was considered. Results show that the radial sampler for O3 fails to meet the Data Quality Objective (DQO) for continuous monitoring. However, with an expanded uncertainty of less than 30%, the O3 diffusive sampler fulfils the DQO for indicative measurements. For benzene, the Radiello sampler exposed for 7 days gave satisfying results showing the ability of the sampler to meet the DQO of the reference method. Nevertheless, the field tests should be complemented by measurements for a wider range of benzene concentrations. In the case of NO2, all the results of the laboratory and field experiments respected the requirements of the demonstration of equivalence. Overall, these findings thus show that the Radiello sampler and the MCPT are equivalent to the reference methods only for assessment of benzene and NO2 respectively.JRC.F.8-Sustainable Transpor

Laboratory and Field Comparison of Measurements Obtained Using the Available Diffusive Samplers for Ozone and Nitrogen Dioxide in Ambient Air

This study presents an evaluation of the extent of differences between measurements performed by O3 and NO2 diffusive samplers and by the reference methods for diffusive samplers commercially available. The tests were performed in an exposure chamber under extreme conditions of controlling factors and under field conditions. For NO2, the results of the laboratory experiments showed that most of the diffusive samplers were affected by extreme exposure conditions. The agreement between the samplers and the reference method was better for the field tests than for the laboratory ones. The estimate of the uptake rate for the exposure conditions using a model equation improved the agreement between the diffusive samplers and the reference methods. The agreement between O3 measured by the diffusive samplers and by the reference method was satisfactory for 1-week exposure. For 8-hour exposures, the diffusive samplers with high uptake rates quantifiyed better the O3 concentration than the samplers with low uptake rates. As for NO2, the results of the O3 field tests were in better agreement with the reference method than the ones of the laboratory tests. The field tests showed that the majority of diffusive samplers fulfils the 25% uncertainty requirement of the NO2 European Directive and the 30% uncertainty requirement of the O3 European Directive for 1-week exposure .JRC.H.4-Transport and air qualit

Feasibility Study of Preparation and Certification of Reference Materials for Nitrogen Dioxide and Sulfur Dioxide in Diffusive Samplers

Feasibility study of preparation and certification of reference materials for nitrogen dioxide and sulfur dioxide in diffusive samplers Michel Gerboles*, Daniela Buzica, Luciano Amantini, Friedrich Lagler and Theo Hafkenscheid+ European Commission - Joint Research Centre, Institute for Environment and Sustainability, Emissions and Health Unit, 21020 Ispra, Italy. Fax: +39-332-785652; Tel: +39-332-789364; E-mail: [email protected] +Dutch Measurement Institute, Delft, Netherlands This paper presents the results of a feasability study for the preparation and certification of reference materials (RMs) for nitrogen dioxide (NO2) and sulphur dioxide (SO2) in diffusive samplers. RMs for NO2 were prepared by exposure to gas mixtures in a chamber while the RMs for SO2 were prepared by liquid spiking. Certification of RMs for NO2 was found feasible with a certified uncertainty of 5.8 % and a proposed shelf life of 5 years. The uncertainty was calculated with contribution from the homogeneity of preparation, stability and transport of the CRMs and from an external verification of the certified value. To reach 5.8 % of uncertainty, the contribution of the differences between the results of analysis by ion chromatography and colorimetry must be eliminated. It is proposed to solve this by pre-extracting the samplers with water before analysis. The results of this study indicate that the samplers are stable for at least two years before and after exposure when stored in refrigerator. On the opposite, the certification of RMs for SO2 was found not feasible due to instability problems. This instability was attributed to reaction of sulfate on the walls of the samplers. Alternatively, the preparation of RMs by simultaneous exposure to SO2 and NO2 have been tested. Satisfying homogeneities has been reached both for NO2 and SO2.JRC.H.4-Transport and air qualit

Modification of the Palmes diffusion tube and semi-empirical modelling of the uptake rate for monitoring nitrogen dioxide

Hereafter, a modification of the traditional Palmes diffusion tube by fitting a membrane at the open end of the tube is presented. The membrane is placed to avoid the effect of turbulence due to wind speed. Further optimisations of the volume of absorbent and number of meshes retaining the absorbent are also described. Finally, the sampler is placed in an air proof container and is ready to use in order to improve the quality of measurement. In order to evaluate the performance of the membrane-closed Palmes diffusion tube to monitor nitrogen dioxide (NO2), experiments were carried out in an exposure chamber. The relative effect of NO2, temperature, humidity, averaging time and wind speed on the uptake rate of the sampler were then studied. Among the uncontrolled variables, temperature and humidity are found to be the most important ones leading to variability of the uptake rate. Two equations, used to estimate the uptake rate are established. These equations were then applied on some field data and laboratory inter-comparison tests. The agreement between the chemiluminescence method and diffusive samplers changes from 20% of mean bias with the traditional Palmes diffusion tubes to 5% of mean bias with the membraneclosed Palmes tube (MCPT) at the same monitoring site. In the laboratory inter-comparison, the MCPT has shown to be able to correctly measure NO2 under two extreme exposure conditions in contrast with other diffusive samplers. The uncertainty of the sampler is evaluated. It fulfils the European Directive data quality objective of 25% for accuracy and therefore the sampler qualifies as an indicative method for NO2 monitoring.JRC.H.4-Transport and air qualit

Modelling of the Uptake Rate of the Nitrogen Dioxide Palmes Diffusive Sampler Based on the Effect of Environmental Factors

The influence of environmental parameters on the uptake rate of the nitrogen dioxide (NO2) Palmes diffusive sampler was investigated. The main factors affecting the uptake rate were found to be wind speed, the preponderant factor, followed by relative humidity and temperature. The NO2 concentration and exposure time, as well as the interactions among the factors were not found to have a significant influence on the uptake rate of the Palmes sampler. As a result, a model able to predict the uptake rate of the Palmes sampler was established. In addition, by using the model-predicted uptake rate, the agreement between chemiluminescence and the Palmes sampler during the field tests was improved. The NO2 Palmes diffusive sampler was shown to comply with the requirement on accuracy defined by the European Directive for the indicative methods of measurements.JRC.H.4-Transport and air qualit

Comparison of Voltammetry and Inductively Coupled Plasma - Mass Spectrometry for the Determination of Heavy Metals in PM10 Airborne Particulate Matter

Voltammetry was examined for the determination of heavy metals in ambient air particulate matter on quartz filter. Cd, Pb, Cu, Zn, As were determined by anodic stripping voltammetry (ASV) while adsorptive stripping voltammetry (AdSV) was used for Ni. The method detection limit and recovery of the voltammetric method were evaluated and found to satisfy the requirements of the EN 14902. A comparison of analytical data for analyzing real samples was carried out between voltammetry and Inductively Coupled Plasma – Mass Spectrometry on a NIST Certified Reference Material and PM10 filters. Here also the differences between the measurements by ICP-MS and voltammetry remained consistent with the level of uncertainty requested in the European Directives for heavy metals.JRC.H.4-Transport and air qualit

PM Measurements in Krakow During a Winter Campaign

see attached documentJRC.H.4-Transport and air qualit

The fourth radiation transfer model intercomparison (RAMI-IV): Proficiency testing of canopy reflectance models with ISO-13528

The Radiation Transfer Model Intercomparison (RAMI) activity aims at assessing the reliability of physics-based radiative transfer (RT) models under controlled experimental conditions. RAMI focuses on computer simulation models that mimic the interactions of radiation with plant canopies and that are increasingly used in the development of satellite retrieval algorithms for terrestrial Essential Climate Variables (ECVs). Rather than applying ad hoc performance metrics, RAMI-IV makes use of existing ISO standards to enhance the rigour of its protocols evaluating the quality of RT models. ISO-13528 was developed “to determine the performance of individual laboratories for specific tests or measurements”. More specifically, it aims to guarantee that measurement results fall within specified tolerance criteria from a known reference. Of particular interest to RAMI is that ISO-13528 provides guidelines for comparisons where the true value of the target quantity is unknown and hence must be replaced by a reliable “conventional reference value” to enable absolute performance tests. This contribution will show, for the first time, how international standards developed by the chemical and physical measurement communities can be applied to the proficiency testing of computer simulation models (in the field of canopy radiation transfer). Detailed performance statistics will be provided and the role of the accuracy of the reference solutions as well as the choice of the criteria to determine model proficiency will be discussed.JRC.H.7-Climate Risk Managemen