The report describes the considerations, essential steps and organisational aspects of the development of the OECD Test Guideline for the determination of particle size and particle size distributions of nanomaterials. It gives furthermore insights into the selection, preparation and pre-validation of test materials used in an interlaboratory comparison and presents the results of this international laboratory comparison tests and their impact on the final version of the OECD Test Guideline. Upon adoption at OECD level, the Test Guideline for the determination of particle size and particle size distributions of nanomaterials will be available at the webpages of the OECD Test Guideline Programme. Veröffentlicht in Texte | 161/2021.
Im Rahmen des Forschungsprojekts wurde eine neue OECD-Prüfrichtlinie (TG) für die Bestimmung von Partikelgrößen und Partikelgrößenverteilungen von Nanomaterialien entwickelt, da die existierende OECD TG 110 zur Bestimmung von Partikelgrößen in Bezug auf den anwendbaren Größenbereich und die gegebenen Methoden veraltet ist bzw. den Nanometerbereich < 200 nm nicht abdeckt. Mit ihrem Anwendungsbereich von 1 bis 1000 nm deckt die neue Prüfrichtlinie (TG PSD) die gesamte Nanoskala ab. Die TG PSD ist für partikel- und faserförmige Nanomaterialien anwendbar. Durch die, in der TG PSD vorgeschriebene, paarweise Messung von Faserdurchmesser und -länge ermöglicht diese TG zum ersten Mal Fasern hinsichtlich ihrer größenabhängigen Gefahrstoffeigenschaften zu unterscheiden. Die Messanweisungen aller enthaltenen Methoden wurden im Rahmen von zwei getrennten Ringversuchen validiert, da bei der Anwendung der Methoden eine Unterscheidung zwischen Partikeln und Fasern gemacht werden muss. Neben Angaben zum Inhalt und Struktur der TG PSD, befasst sich der vorliegende Abschlussbericht mit den wesentlichen Schritten, Überlegungen und organisatorischen Aspekten bei der Entwicklung der Prüfrichtlinie. Darüber hinaus werden Einblicke in die Auswahl, Vorbereitung und Prävalidierung der im Ringversuch verwendeten Testmaterialien gegeben. Schließlich werden die wichtigsten Ergeb-nisse aus den Ringversuchen und ihre Auswirkungen auf die TG PSD vorgestellt. Quelle: Forschungsbericht
Dieser Text stellt den Stand und die Lücken des Wissens zu Ultrafeinen Partikeln aus regulatorischer Sicht dar. Obwohl bereits erste Schritte der Vereinheitlichung gemacht sind zeigt sich ein deutlicher Normungs-, Regelungs- und Untersuchungsbedarf. Quelle: Texte-Band
This dataset provides detailed information on the three-dimensional variability of biogeochemical properties in Wustebach, a small headwater catchment in Germany. This catchment is situated within the National Park Eifel and is part of the TERENO (Terrestrial Environmental Observatories) project. The dataset includes pH, total P, plant available P , K, Mn, Fe, Na, C, N, S, Ca, NO3-N, SO4, Bulk density, gravimetric water content, particle size distributions and detailed soil descriptions.
An investigation of microplastic (MP) occurrence in a municipal wastewater treatment plant (WWTP) effluent with tertiary treatment was carried out. Representative sample volumes of 1 m3 were taken by applying a fractionated filtration method (500, 100, and 50 (micro)m mesh sizes). The detection of MP mass fractions by thermal extraction desorption-gas chromatography/mass spectrometry (TED-GC/MS) was achieved without the previously required additional sample pretreatment for the first time. Different types of quantification methods for the evaluation of TED-GC/MS data were tested, and their accuracy and feasibility have been proven for real samples. Polyethylene, polystyrene, and polypropylene were identified in effluent samples. The polymer mass content varied significantly between 5 and 50 mg m-3. A correlation between the MP load and the quantity of suspended matter in the WWTP effluents, particle size distribution, particle type, and operation day (i.e., weekday, season, and capacity) was not found. It can be concluded that a meaningful assessment of WWTPs requires a comprehensive sampling campaign with varying operation conditions. © 2022 The Authors
Aerodynamic particle size spectrometers are a well-established method to measure number size distributions of coarse mode particles in the atmosphere. Quality assurance is essential for atmospheric observational aerosol networks to obtain comparable results with known uncertainties. In a laboratory study within the framework of ACTRIS (Aerosols, Clouds, and Trace gases Research Infrastructure Network), 15 aerodynamic particle size spectrometers (APS model 3321, TSI Inc., St. Paul, MN, USA) were compared with a focus on flow rates, particle sizing, and the unit-to-unit variability of the particle number size distribution. Flow rate deviations were relatively small (within a few percent), while the sizing accuracy was found to be within 10?% compared to polystyrene latex (PSL) reference particles. The unit-to-unit variability in terms of the particle number size distribution during this study was within 10?% to 20?% for particles in the range of 0.9 up to 3 Nano-m, which is acceptable for atmospheric measurements. For particles smaller than that, the variability increased up to 60?%, probably caused by differences in the counting efficiencies of individual units. Number size distribution data for particles smaller than 0.9?Ţm in aerodynamic diameter should only be used with caution. For particles larger than 3?Ţm, the unit-to-unit variability increased as well. A possible reason is an insufficient sizing accuracy in combination with a steeply sloping particle number size distribution and the increasing uncertainty due to decreasing counting. Particularly this uncertainty of the particle number size distribution must be considered if higher moments of the size distribution such as the particle volume or mass are calculated, which require the conversion of the aerodynamic diameter measured to a volume equivalent diameter. In order to perform a quantitative quality assurance, a traceable reference method for the particle number concentration in the size range 0.5-3 Nano-m is needed. Quelle: http://www.atmos-meas-tech.net
The potential risk from human exposure to Respirable Crystalline Silica (RCS) includes a range of serious non-malignant effects as well as lung cancer, which may occur at relatively low levels. In a previous study, investigating several industrial sectors, we found the highest emission levels of RCS in the industrial silica sand operations. 28 different sand processing facilities were examined in two complex emission measurement programmes. A two-stage cascade impactor was used to separate the particle fractions: > 10 Ìm, 10-4 Ìm and < 4 Ìm of aerodynamic diameter. The size of particles of most concern is the so-called particulate matter 4 (PM4). The analytical procedure for determining RCS in emission samples consists of using X-ray diffraction and infrared spectroscopy methods. The relationship between Total Particulate Matter (TPM), PM4 and RCS (as a percentage of PM4) was evaluated. In the case of increased Total Particulate Matter concentration in the stack gas (more than 20 mg/m3) combined with increased percentage of RCS in PM4 an exceedance of an Emission Limit Value (ELV) of 1 mg/m3 is more likely to occur. The evaluation of the emission data helped to formulate differentiated emission control requirements of the plants concerning the draft of the new German Technical Instructions on Air Quality Control (new German TA Luft). It was possible to demonstrate, under which conditions for the specific processing techniques used, emission limits for Total Particulate Matter can be used as a threshold value for the Respirable Crystalline Silica emission. If the mass fraction of quartz in the source rock to be processed is more than 20%, periodic measurements of Respirable Crystalline Silica will be necessary every three years on grinders, whereas they will be only necessary on dryers if the Total Dust concentration exceeds 5 mg/m3. © 2021, VDI Fachmedien GmBH & Co. KG. All rights reserved.
Microplastic (MP) contamination in natural water circulation is a concern for environmental issues and human health. Various types of polymer materials have been identified and were detected in MP analytic test procedures. Beyond MP polymer type, particle size and form play a major role in water analysis due to possible negative toxicologic effects on flora and fauna. However, the correct quantitative measurement of MP size distribution over several orders of magnitude is strongly influenced by sample preparation, filtration materials and processes, and microanalytical techniques, as well as data acquisition and analysis. In this paper, a reference methodology is presented aiming at an improved quantitative analysis of MP particles. An MP analysis workflow is demonstrated including all steps from reference materials to sample preparation, filtration handling, and MP particle size distribution analysis. Background-corrected particle size distributions (1â€Ì1000†Ìm) have been determined for defined polyethylene (PE) and polyethylene terephthalate (PET) reference samples. Microscopically measured particle numbers and errors have been cross-checked with the total initial mass. In particular, defined reference MP samples (PE, PET) are initially characterized and applied to filtration experiments. Optical microscopy imaging on full-area Si filters with subsequent image analysis algorithms is used for statistical particle size distribution analysis. To quantify the effects of handling and filtration, several blind tests with distilled water are carried out to determine the particle background for data evaluation. Particle size distributions of PE and PET reference samples are qualitatively and quantitatively reproduced with respect to symmetry, and maximum and cut-off diameter of the distribution. It is shown that especially MP particles with a radius of >50†Ìm can be detected and retrieved with high reliability. For particle sizes <50†Ìm, a significant interference with background contamination is observed. Data from blank samples allows a correction of background contaminations. Furthermore, for enhanced sampling statistics, the recovery of the initial amount of MP will be qualitatively shown. The results are intended as an initial benchmark for MP analytics quality. This quality is based on statistical MP particle distributions and covers the complete analytic workflow starting from sample preparation to filtration and detection. Microscopic particle analysis provides an important supplement for the evaluation of established spectroscopic methods such as Fourier-transform infrared spectroscopy or Raman spectroscopy. © 2022 The Authors
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