scholarly journals Cryoconite as an efficient monitor for the deposition of radioactive fallout in glacial environments

2019 ◽  
Author(s):  
Giovanni Baccolo ◽  
Edyta Łokas ◽  
Paweł Gaca ◽  
Dario Massabò ◽  
Roberto Ambrosini ◽  
...  
Keyword(s):  
Radioactive Fallout ◽  
Radioactive Isotopes ◽  
Environmental Matrices ◽  
Artificial Radioactivity ◽  
Activity Concentrations ◽  
Activity Ratios ◽  
Glacial Environments ◽  
Nuclear Weapon Tests ◽  
Radioactive Species

Abstract. Cryoconite is extremely rich in natural and artificial radionuclides, but a comprehensive discussion about its ability to accumulate radioactivity is lacking. A characterization of cryoconite from two Alpine glaciers is presented and discussed. Results confirm that cryoconite is among the most radioactive environmental matrices, with activity concentrations exceeding 10,000 Bq kg−1 for single radionuclides. Atomic and activity ratios of Pu and Cs radioactive isotopes reveal that the artificial radioactivity of Alpine cryoconite is mostly related to the stratospheric fallout from nuclear weapon tests and to the 1986 Chernobyl accidents. The signature of cryoconite radioactivity is thus influenced by both local and more widespread events. The extreme accumulation of radioactivity in cryoconite can be explained only considering the glacial environment as a whole, and particularly the interaction between ice, meltwater, cryoconite and atmospheric deposition. Cryoconite is an ideal monitor to investigate the deposition and occurrence of natural and artificial radioactive species in glacial environment.

scholarly journals Cryoconite: an efficient accumulator of radioactive fallout in glacial environments

2020 ◽  
Vol 14 (2) ◽  
pp. 657-672 ◽  
Author(s):  
Giovanni Baccolo ◽  
Edyta Łokas ◽  
Paweł Gaca ◽  
Dario Massabò ◽  
Roberto Ambrosini ◽  
...  
Keyword(s):  
Global Fallout ◽  
Artificial Radioactivity ◽  
Chernobyl Fallout ◽  
Alpine Glaciers ◽  
Activity Ratios ◽  
Natural And Artificial Radioactivity ◽  
Glacial Environments ◽  
Radioactive Species ◽  
Ideal Matrix

Abstract. Cryoconite is rich in natural and artificial radioactivity, but a discussion about its ability to accumulate radionuclides is lacking. A characterization of cryoconite from two Alpine glaciers is presented here. Results confirm that cryoconite is significantly more radioactive than the matrices usually adopted for the environmental monitoring of radioactivity, such as lichens and mosses, with activity concentrations exceeding 10 000 Bq kg−1 for single radionuclides. This makes cryoconite an ideal matrix to investigate the deposition and occurrence of radioactive species in glacial environments. In addition, cryoconite can be used to track environmental radioactivity sources. We have exploited atomic and activity ratios of artificial radionuclides to identify the sources of the anthropogenic radioactivity accumulated in our samples. The signature of cryoconite from different Alpine glaciers is compatible with the stratospheric global fallout and Chernobyl accident products. Differences are found when considering other geographic contexts. A comparison with data from literature shows that Alpine cryoconite is strongly influenced by the Chernobyl fallout, while cryoconite from other regions is more impacted by events such as nuclear test explosions and satellite reentries. To explain the accumulation of radionuclides in cryoconite, the glacial environment as a whole must be considered, and particularly the interaction between ice, meltwater, cryoconite and atmospheric deposition. We hypothesize that the impurities originally preserved into ice and mobilized with meltwater during summer, including radionuclides, are accumulated in cryoconite because of their affinity for organic matter, which is abundant in cryoconite. In relation to these processes, we have explored the possibility of exploiting radioactivity to date cryoconite.

scholarly journals New Insights into the Crystal Chemistry of Elpidite, Na2Zr[Si6O15]·3H2O and (Na1+YCax□1−X−Y)Σ=2Zr[Si6O15]·(3−X)H2O, and Ab Initio Modeling of IR Spectra

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2160
Author(s):  
Alexander Bogdanov ◽  
Ekaterina Kaneva ◽  
Roman Shendrik
Keyword(s):  
Ir Spectra ◽  
Structural Models ◽  
Chemical Characterization ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Special Group ◽  
X Ray ◽  
Influence Of Water ◽  
Radioactive Species

Elpidite belongs to a special group of microporous zirconosilicates, which are of great interest due to their capability to uptake various molecules and ions, e.g., some radioactive species, in their structural voids. The results of a combined electron probe microanalysis and single-crystal X-ray diffraction study of the crystals of elpidite from Burpala (Russia) and Khan-Bogdo (Mongolia) deposits are reported. Some differences in the chemical compositions are observed and substitution at several structural positions within the structure of the compounds are noted. Based on the obtained results, a detailed crystal–chemical characterization of the elpidites under study was carried out. Three different structure models of elpidite were simulated: Na2ZrSi6O15·3H2O (related to the structure of Russian elpidite), partly Ca-replaced Na1.5Ca0.25ZrSi6O15·2.75H2O (close to elpidite from Mongolia), and a hypothetical CaZrSi6O15·2H2O. The vibration spectra of the models were obtained and compared with the experimental one, taken from the literature. The strong influence of water molecule vibrations on the shape of IR spectra of studied structural models of elpidite is discussed in the paper.

scholarly journals Insight into Biochemical Characterization of Plant Sesquiterpene Synthases

2016 ◽  
Vol 11s1 ◽  
pp. ACI.S40292
Author(s):  
Tom Manczak ◽  
Henrik Toft Simonsen
Keyword(s):  
Kinetic Parameters ◽  
Biochemical Characterization ◽  
Radioactive Isotopes ◽  
Published Data ◽  
Enzymatic Characterization ◽  
Turnover Number ◽  
Terpene Synthases ◽  
Thapsia Garganica ◽  
Insight Into

A fast and reproducible protocol was established for enzymatic characterization of plant sesquiterpene synthases that can incorporate radioactivity in their products. The method utilizes the 96-well format in conjunction with cluster tubes and enables processing of >200 samples a day. Along with reduced reagent usage, it allows further reduction in the use of radioactive isotopes and flammable organic solvents. The sesquiterpene synthases previously characterized were expressed in yeast, and the plant-derived Thapsia garganica kunzeaol synthase TgTPS2 was tested in this method. KM for TgTPS2 was found to be 0.55 μM; the turnover number, kcat, was found to be 0.29 s−1, kcat for TgTPS2 is in agreement with that of terpene synthases of other plants, and kcat/ KM was found to be 0.53 s−1 μM−1 for TgTPS2. The kinetic parameters were in agreement with previously published data.

scholarly journals The Severe Acute Respiratory Syndrome Coronavirus Nsp15 Protein Is an Endoribonuclease That Prefers Manganese as a Cofactor

2004 ◽  
Vol 78 (22) ◽  
pp. 12218-12224 ◽  
Author(s):  
Kanchan Bhardwaj ◽  
Linda Guarino ◽  
C. Cheng Kao
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Biochemical Characterization ◽  
Nonstructural Protein ◽  
Tryptophan Fluorescence ◽  
Conformation Change ◽  
Activity Concentrations ◽  
Level Of Activity ◽  
Novel Coronavirus ◽  
Endoribonuclease Activity

ABSTRACT Nonstructural protein 15 (Nsp15) of the severe acute respiratory syndrome coronavirus (SARS-CoV) produced in Escherichia coli has endoribonuclease activity that preferentially cleaved 5′ of uridylates of RNAs. Blocking either the 5′ or 3′ terminus did not affect cleavage. Double- and single-stranded RNAs were both substrates for Nsp15 but with different kinetics for cleavage. Mn2+ at 2 to 10 mM was needed for optimal endoribonuclease activity, but Mg2+ and several other divalent metals were capable of supporting only a low level of activity. Concentrations of Mn2+ needed for endoribonuclease activity induced significant conformation change(s) in the protein, as measured by changes in tryptophan fluorescence. A similar endoribonucleolytic activity was detected for the orthologous protein from another coronavirus, demonstrating that the endoribonuclease activity of Nsp15 may be common to coronaviruses. This work presents an initial biochemical characterization of a novel coronavirus endoribonuclease.

Radiological Characterization of the Nuclear Waste Streams of the Belgian Nuclear Research Centre SCK•CEN

2007 ◽  
Author(s):  
Patrick Maris ◽  
Rene´ Cornelissen ◽  
Michel Bruggeman
Keyword(s):  
Nuclear Research ◽  
Physical Models ◽  
Research Centre ◽  
Waste Streams ◽  
Activity Ratios ◽  
Disposal Option ◽  
The Many ◽  
Non Destructive ◽  
Radiological Characterization

The radiological characterization of nuclear wastes of a research centre is difficult seen the many different processes that generate waste. Since these wastes may contain radionuclides relevant for the disposal option, the nuclide content and activity have to be known. Considering the fact that some wastes are generated only in minor quantities, complex approaches, involving sampling and successive analysis are not justified. Basic physical models can generally be applied to estimate activity ratios, from which the radionuclide inventory can be determined by non-destructive assay on waste-packages. This article discusses waste streams at the Belgian Nuclear Research Centre SCK•CEN and explains how nuclide inventories and activity are determined. The physical models, used to derive activity ratios, and other simple approaches are discussed.

scholarly journals Characterization of dissolved organic matter (DOM) from glacial environments using total fluorescence spectroscopy and parallel factor analysis

2010 ◽  
Vol 51 (56) ◽  
pp. 111-122 ◽  
Author(s):  
Ashley Dubnick ◽  
Joel Barker ◽  
Martin Sharp ◽  
Jemma Wadham ◽  
Grzegorz Lis ◽  
...  
Keyword(s):  
Factor Analysis ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Parallel Factor Analysis ◽  
Glacier Ice ◽  
Total Fluorescence ◽  
Glacial Environments ◽  
Parallel Factor ◽  
And Cluster Analysis

AbstractAquatic dissolved organic matter (DOM) is a major reservoir of reduced organic carbon and has a significant influence on heterotrophic biological productivity and water quality in marine and freshwater environments. Although the forms and transformations of DOM in temperate aquatic and soil environments have been studied extensively, this is not the case for glacial environments. In this study, fluorescent excitation–emission matrices (EEMs), parallel factor analysis (PARAFAC) and cluster analysis were used to characterize the fluorescing components of DOM in ice and water samples from supraglacial, englacial, subglacial and proglacial environments of seven glaciers in the Canadian Arctic, Norway and Antarctica. At least five significant fluorescent DOM fractions were identified, which accounted for 98.2% of the variance in the dataset. These included four protein-like components and one humic-like component. The predominantly proteinaceous character of DOM from these glaciers is very different from the more humic character of DOM described previously from lacustrine, fluvial, estuarine and marine environments. DOM from the sampled glaciers is broadly similar in character despite their geographically distinct locations, different thermal regimes and inter- and intra-site differences in potential organic matter sources. Glacier ice samples had a relatively low ratio of humic-like :protein-like fluorescence while meltwater samples had a higher ratio.

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