Evaluation study of the suitability of instrumentation to measure ambient NH3 concentrations under field conditions

The uncertainties in emissions of ammonia (NH3) in Europe are large, partially due to the difficulty in monitoring of ambient concentrations due to its sticky nature. In the European Monitoring and Evaluation Program (EMEP) the current recommended guidelines to measure NH3 are by coated annular denuders with offline analysis. This method, however, is no longer used in most European countries and each one has taken a different strategy to monitor atmospheric ammonia due to the increase of commercial NH3 monitoring instrumentation available over the last 20 years. In June 2014, a 3 year project funded under the European Metrology Research Programme, “Metrology for Ammonia in Ambient Air” (MetNH3), started with the aim to develop metrological traceability for the measurement of NH3 in air from primary gas mixtures and instrumental standards to field application. This study presents the results from the field intercomparison (15 instruments) which was held in South East Scotland in August 2016 over an intensively managed grassland. The study compared active sampling methods to a meteorological traceable method which was developed during the project with the aim to produce a series of guidelines for ambient NH3 measurements. Preliminary results highlight both the importance of inlets and management of relative humidity in the measurement of ambient NH3 and of the requirement to carry out frequent intercomparison of NH3 instrumentation. Overall, it would be recommended from this study that a WMO-GAW world centre for NH3 would be established and support integration of standards into both routine and research measurements

What are the limitations for the use of Carbopack X as passive or active sampling adsorbent for determination of 1,3-butadiene in ambient environment?

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Measuring ambient 1,3-butadiene levels using diffusive samplers filled with Carbopack X adsorbent.

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Development and laboratory characterization of passive sampling method for amines in ambient air.

International audienceAtmospheric amines are basic organic compounds that originate from both natural and anthropogenic sources. They are recognized to have a significant role in the formation of fine particulate matter (PM) in the atmosphere by acid-base reactions with atmospheric acids like sulfuric or nitric acids (H2SO4; HNO3) and also to play a role in the growth of particles, either directly by dissolution of amines in partially liquefied aerosols, or indirectly, by oxidation, oligomerization, or nucleation processes (Ge et al., 2011; Xiao et al., 2021). Depending on the proximity with the sources, amines are found at varying concentrations in the atmosphere ranging from a few pptv to several hundred of ppbv and there are only a few methods for identifying and characterizing these amines in ambient air and there is no passive method well adapted to determine the spatial distribution of these compounds. In consequence, this study examined the performances of a chemical radial diffusive sampler (RAD168 from Radiello®) for the weekly measurement of 7 amines mostly found in the atmosphere (methylamine; ethylamine; dimethylamine; diethylamine; trimethylamine; dimethylethylamine; butylamine). A test program was carried in an annular exposure chamber with the aim of validating the passive sampling method. It allowed the estimation of all the parameters of the method for each compound (calibration, analytical precision, desorption efficiency, uptake rate in standard conditions, detection limit and stability of sample before and after exposure) and also the examination of the influence of the presence of ammonia on the sampling rate. The results of this evaluation demonstrated that the method has turned out to be suitable for the seven amines tested. In standard conditions (i.e. temperature = 20°C; relative humidity = 50%) and depending upon the compounds, the experimental values of uptake rate for one-week exposure are between 503 mL.min-1 (dimethylamine) and 3287 mL.min-1 (methylamine) which give relatively low detection limits in air between 0.2 and 7.1 ng.m-3 (0.1 to 3.9 pptv) without any interference of ammonia even at 10-folder concentration. References:Ge X. et al. (2011). Atmospheric amines - Part I. A review. Atmospheric Environment, 45(3), 524–546.Xiao M. et al. (2021). The driving factors of new particle formation and growth in the polluted boundary layer. Atmospheric Chemistry and Physics, 21, 14275-14291

A preconcentration method based on a new sorbent for the measurement of selected reduced sulfur compounds at ppb level in ambient air

International audienceOdour annoyance forms the main source of environmental stress in residents living nearby industrial or agricultural fields. However, despite a relative simplicity of odour measurement at the emission source, odour measurement in the field is a quite more complicated task. Because of their low odour threshold and offensive odour, this study focuses on 6 reduced sulfur compounds (RSCs): methylmercaptan (MM), ethylmercaptan (EM), dimethylsulfide (DMS), isopropylmercaptan (IPM), tertbutylmercatpan (TBM), diethylsulfide (DES). Because of their very low concentrations in ambient air (few ppb), a preconcentration step is usually required. The literature points Tenax TA® as the more suitable sorbent for sulfur compounds adsorption but shows also an important impact of humidity and storage parameters inducing an underestimation of sulfur ambient air concentrations. So only qualitative or semi-quantitative data results are obtained with Tenax TA® samplings of targeted compounds. To guarantee quantitative concentration data, a new sampling device, using a S-Sorbent Tube450 combined with an optimal drying device, was performed and optimized sampling and analysis parameters were determined. The assessment of uncertainties attests of quantitative measurements for 5 of the 6 RSCs (EM, DMS, IPM, TBM, DES) with relative expanded uncertainties less than 33% considering that samples were stored properly in freeze during 7 days. Only semi-quantitative measurements could be considered for MM with a global uncertainty estimated to 48%, storage contributing for a half. © 2018 Elsevier B.V