Zobrazení zdroje stránky Olssonantonsen5893

Radioactive materials released during the two most serious nuclear accidents in history, at Chernobyl and Fukushima, caused exceptionally significant contamination and perturbations of the environment. Among them, this paper focuses on the effects related to the atmospheric electricity (AE). Measurements of the most significant disturbances in the values of various AE parameters recorded near ground level are reviewed and the corresponding results are jointly evaluated. The Chernobyl and Fukushima events caused changes in the AE parameters both after long-distance transport (Chernobyl) and short-distance transport including re-suspension (Fukushima). The data indicates that the electrical conductivity of the air is more sensitive to the presence of airborne radioactivity than the atmospheric electric potential gradient (PG). PG, on the other hand, can be monitored more easily and its variation also reflects the vertical redistribution of radionuclides in the air due to their transport, deposition, and re-suspension from the ground. A brief overview of studies on atmospheric transport and deposition of radioactive clouds is given to facilitate the importance of considering the AE measurements in these subjects, and to incorporate those studies in interpreting the results of AE measurements. The AE measurements are particularly important in studying microphysical effects of enhanced radioactivity in the air where no other distance monitoring method exists, both for fair weather conditions wet conditions.An innovative ammoniation-hydrothermal method of biochar production was developed for the adsorption of phenanthrene (PHE) from aqueous solutions in this paper. Phragmites australis (PA) was used to produce biochar in a hydrothermal kettle at 280 °C in muffle furnace using urea as an ammoniation reagent. Characterizations were executed by scanning electron microscope (SEM), N2 adsorption/desorption isotherms, X-ray diffraction (XRD), elemental analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) to explore its morphological, physical, and chemical properties. Batch experiments of PHE adsorption were carried out to study the adsorption isotherms and kinetics. Quantum chemistry computational simulations were employed based on density functional theory (DFT) to establish and optimize adsorption configurations and analyze the biochar's structural effects on adsorption performance. Results showed that the ammoniation-hydrothermal method produced biochar with a higher surface area and a maximum equilibrium adsorption capacity of 1.97 mg/g. The adsorption fitted well with Freundlich isotherm model (R2 &gt; 0.96) and Pseudo-second-order kinetic model (R2 &gt; 0.82). Adsorption energy calculation revealed that the N functionalities, especially pyridine N in the N-doped biochar structure, exhibited stronger binding ability with PHE, which contributed most to the favorable adsorption ability of the ammoniation-hydrothermal biochar.Peroxymonosulfate (PMS) was employed as an activator of ozone (O3) to degrade non-steroidal anti-inflammatory drugs (NSAIDs) (aspirin (ASA) and phenacetin (PNT)) in study. The combination of PMS in O3 system promoted the O3 decomposition and NSAIDs removal significantly. O3 molecule, hydroxyl radical (OH) and sulfate radical (SO4-) were responsible for the removal of target pollutants in O3/PMS system. The second-rate constants between O3, OH and SO4- with ASA were determined to be 7.32, 4.18 × 109 and 3.46 × 108 M-1·s-1, and 37.3, 4.99 × 109 and 5.64 × 108 M-1·s-1 for PNT, respectively. The pattern of pollutant removal and contributions of oxidative species were fitted by experiments and two models. Nevertheless, the wide variety of two models suggested that a comprehensive model for O3/PMS based on a first-principles approach was not yet possible, due to the number of radicals and subsequent chain reaction, such as SO5- or O3-. In addition, the formation of five typical CX3R -type disinfection by products was evaluated from post‑chlorine tests and theoretically calculation by frontier electron density calculation. The calculated toxicity of typical CX3R -type DBPs was found to decrease with the increase of pH. The results of this study provide a basis for exploring the mechanism of pollutant degradation in O3 system.Grain and soil were sampled across a large part of Amhara, Ethiopia in a study motivated by prior evidence of selenium (Se) deficiency in the Region's population. The grain samples (teff, Eragrostis tef, and wheat, Triticum aestivum) were analysed for concentration of Se and the soils were analysed for various properties, including Se concentration measured in different extractants. Predictive models for concentration of Se in the respective grains were developed, and the predicted values, along with observed concentrations in the two grains were represented by a multivariate linear mixed model in which selected covariates, derived from remote sensor observations and a digital elevation model, were included as fixed effects. In all modelling steps the selection of predictors was done using false discovery rate control, to avoid over-fitting, and using an α-investment procedure to maximize the statistical power to detect significant relationships by ordering the tests in a sequence based on scientific understanding of the underlying processes likely to control Se concentration in grain. Cross-validation indicated that uncertainties in the empirical best linear unbiased predictions of the Se concentration in both grains were well-characterized by the prediction error variances obtained from the model. [https://www.selleckchem.com/Caspase.html Caspase inhibition] The predictions were displayed as maps, and their uncertainty was characterized by computing the probability that the true concentration of Se in grain would be such that a standard serving would not provide the recommended daily allowance of Se. The spatial variation of grain Se was substantial, concentrations in wheat and teff differed but showed the same broad spatial pattern. Such information could be used to target effective interventions to address Se deficiency, and the general procedure used for mapping could be applied to other micronutrients and crops in similar settings.