Influence of dustiness on small-scale vented dust explosions

A new safety characteristic the “dustiness” according to VDI 2263 – part 9 (Verein Deutscher Ingenieure, 2008) is investigated. Dustiness means the tendency of a dust to form clouds. The paper deals with the physical reasons for the different behavior of dusts, even if they have similar properties such as particle size and density and the influence of the dustiness on dust explosions. In order to study the effects of the dustiness on dust cloud formation for different dispersion methods experiments in a vertical dust dispersion glass tube apparatus were carried out. Furthermore vented dust explosion experiments were done for two different dispersion methods and two static activation pressures.Experiments show that particle size and density are not the only factors which influence dispersibility. Particle shape, specific surface area, flow and dispersion method have an influence which can outweigh size and density. Preliminary explosion experiments showed that the dustiness has an influence on the reduced explosion pressure and flame speed in a vented 75 L test apparatus. In order to verify the results for applications in the process industries further tests with industrial scale experiments are planned.     

Leveraging social media and deep learning to detect rare megafauna in video surveys

Deep learning has become a key tool for the automated monitoring of animal populations with video surveys. However, obtaining large numbers of images to train such models is a major challenge for rare and elusive species because field video surveys provide few sightings. We designed a method that takes advantage of videos accumulated on social media for training deep-learning models to detect rare megafauna species in the field. We trained convolutional neural networks (CNNs) with social media images and tested them on images collected from field surveys. We applied our method to aerial video surveys of dugongs (Dugong dugon) in New Caledonia (southwestern Pacific). CNNs trained with 1303 social media images yielded 25% false positives and 38% false negatives when tested on independent field video surveys. Incorporating a small number of images from New Caledonia (equivalent to 12% of social media images) in the training data set resulted in a nearly 50% decrease in false negatives. Our results highlight how and the extent to which images collected on social media can offer a solid basis for training deep-learning models for rare megafauna detection and that the incorporation of a few images from the study site further boosts detection accuracy. Our method provides a new generation of deep-learning models that can be used to rapidly and accurately process field video surveys for the monitoring of rare megafauna.     

Methods for the assessment of health risk induced by contaminants in atmospheric particulate matter: a review

Environmental Chemistry Letters - Air pollution is a major issue for human health with more than 7 million premature deaths per year due to indoor and outdoor air pollution. Exposure to particulate...     

Combining target analysis with sum parameters—a comprehensive approach to determine sediment contamination with PFAS and further fluorinated substances

Recent studies aiming at a fluorine mass balance analysis in sediments combined the determination of extractable organic fluorine (EOF) with target analysis. They reported high fractions of unidentified organic fluorine (UOF) compounds, as the target analysis covers only a limited number of per- and polyfluoroalkyl substances (PFAS). For this reason, in this study, a comprehensive approach was used combining target analysis with an extended PFAS spectrum, the EOF and a modified total oxidisable precursor (TOP) assay, which includes trifluoroacetic acid, to determine the PFAS contamination in sediments (n=41) and suspended solids (n=1) from water bodies in Northern Germany (Lower Saxony). PFAS are ubiquitous in the sediments (detected in 83% of the samples). Perfluorinated carboxylic acids (PFCAs) were found in 64% of the samples; perfluorinated sulfonic acids (PFSAs) were detected less frequently (21%), with the highest concentration observed for perfluorooctanesulfonic acid (PFOS). Levels of precursors and substitutes were lower. Applying the TOP assay resulted in an increase in PFCAs in 43% of the samples analysed. In most cases, target analysis and the TOP assay could not account for the EOF concentrations measured. However, as the fraction of UOF decreased significantly, the application of the TOP assay in fluorine mass balance analysis proved to be an important tool in characterising the PFAS contamination of riverine sediments.

     

Distribution of lead in urban roadway grit and its association with elevated steel structures

In an effort to determine the source of exterior lead contamination, we investigated the concentration of lead in roadway grit along major thoroughfares in New York City and in certain areas under elevated steel structures supporting elevated rails. Such structures represent only one source of lead in roadway grit. While data revealed that the median lead concentration in roadway grit did not exceed the standard for a lead hazard in bare residential soil in any borough, the limit of 400 microg/g was exceeded 22%, 18%, 10.5%, and 7.7% of the time in Manhattan, Brooklyn, The Bronx, and Queens, respectively. The second part of the study revealed the presence of high concentrations of lead in roadway grit directly under elevated steel structures. The differences in the concentration of lead in roadway grit under steel structures in comparison to areas in NYC not near elevated rails was statistically significant. Of the eight sites studied from 225 total samples, the median roadway grit lead level was 340 ppm, while the level under steel structures was 1480 ppm. Preliminary efforts to determine particle size distribution revealed that 84% of the particles were in the range of 125-500 microm, but the highest concentration of lead was in the smallest fraction analyzed (<63 microm). Lead contamination of roadway grit from restoration of elevated painted steel structures is a public health problem as these lead particulates get re-suspended in the ambient environment and are wafted and tracked into residences.     

Distribution of carbon 14 in the terrestrial environment close to French nuclear power plants

For 10 years, (14)C measurements have been performed around French nuclear power plant sites, both in zones influenced and zones not influenced by gaseous releases. Examining the results from these measurements in the terrestrial environment shows that the discharges have a very slight impact on the radiocarbon level (with a relative increase in the specific activity of the order of 3 Bqkg(-1)C in the influenced areas). In correlation, there is a near-negligible increase in dose, on average less than 0.1 microSvyr(-1), with reference to a dose from background radiation, which is of the order of 10 microSvyr(-1). The deltaC13 values are very similar between the influenced zone and the non-influenced zone, with a mean of -27 per thousand. The mean DeltaC14 varies from 101 per thousand in the non-influenced zone to 123 per thousand in the influenced zone. Moreover, a general reduction in (14)C concentration was found, with a time constant of the order of 95 years. The current level of (14)C specific activity in terrestrial environment is estimated to be 242+/-6 Bqkg(-1)C.     

Economic and other implications of integrated chain management: a case study

In this article, the concept of Integrated (Substance) Chain Management (ISCM) is discussed. The definition of ISCM, motives for ISCM, conditions for implementation, different points of view and a five-step model are dealt with. In addition, a number of possible barriers on the road to ISCM are discussed. The model is applied to a stonewool-producing company in the Netherlands. This company set up a recycling project in the form of a briquetting factory. The substance-flow sheets show that after implementing the briquetting factory, almost all process wastes are used in the factory and that fewer virgin materials have to be used. From an economic point of view, production in a more sustainable fashion is very unattractive: production costs per ton of stonewool product rose as a consequence of the use of the briquettes as an input. The barriers connected to ISCM are mainly economic and regulatory. Solutions for the Rockwool company may include engaging in environmental product stewardship and a realignment of the government policy towards dumping re-usable and non-separated building and construction waste.