Geochemical studies on the Chernobyl radioactivity in environmental samples

Artificial radionuclides in deposition and airborne dust samples in 1986 were measured at Tsukuba and 11 stations in Japan. In May 1986, the Chernobyl radioactivity was observed in rain and air samples in Japan. The Chernobyl-derived Pu isotopes, which are characterized by higher²³⁸Pu/^239,240Pu (85) and²⁴¹Pu/²³⁸Pu (0.5) activity ratios than those of the nuclear test-derived Pu and⁹⁰Sr, were detected in deposition and airborne dust samples in Japan, as well as volatile radionuclides such as¹³¹I and¹³⁷Cs. However, the activities of Pu isotopes and⁹⁰Sr observed in Japan were about two and three orders of magnitude lower than those expected from the activity ratios in the total release at Chernobyl, which means that the residence time of Pu in the air was shorter than that of¹³⁷Cs. In order to understand the fractionation between the Chernobyl radionuclides we studied about individual wet and dry deposition. The results suggest that this cause is due to the difference of the particle size of radionuclide-bearing particles, which may be related to the release process of Chernobyl radionuclides.     

Simulation of organic reactions: from the degradation of chemicals to combinatorial synthesis

Organic reactions can be run under a variety of conditions, from laboratory experiments, through technical processes, to combinatorial chemistry. The scope is further extended when the metabolism of compounds and the reactions in the mass spectrometer are included. We present here several concepts: reactors, phases, and modes, which, together with a kinetic modeling, allow the treatment of such a broad scope of organic reactions. These concepts have been implemented in a knowledge-based system, EROS. Several applications of this system to the wide world of organic reactions are given.     

New progress in photocatalytic degradation of bisphenol A as representative endocrine disrupting chemicals

Endocrine disrupting chemicals (EDCs) are a kind of hazardous pollutants in the environment which threaten the health of humans and animals at very low concentrations. EDCs and corresponding processing methods have been the hottest topics of scientific research in recent years. In this article, the classification, risks, occurrence, fate, and treatment methods of EDCs were briefly summarized. Among all of the treatment methods, photocatalytic degradation was one of the most ideal methods with bright prospects for BPA removal in the future. We summarized several problems restricting the efficiency of photocatalytic degradation and the latest progress, and proposed some suggestions on the improvement of photocatalytic degradation. Finally, mechanism of BPA's photocatalytic degradation had been summarized on the basis of free radical theory. New progress and opinions were provided in this review and we wish to provide a helpful guidance of EDCs removal for international readers.     

Mechanism of degradation induced embrittlement in polyethylene

The thermal oxidation of polyethylene films in air at 80 °C and 90 °C has been studied by tensile testing, IR spectrophotometry and molar mass determination from rheometric measurements. In the conditions under study, the polymer predominantly undergoes chain scission and embrittles suddenly when the weight average molar mass reaches a critical value (90 kg mol⁻¹), far before significant damage of the entanglement network (M_e = 1.9 kg mol⁻¹) in the amorphous phase.The following embrittlement mechanism is proposed: chain scission in the amorphous phase induces chemicrystallization. The thickness of the interlamellar amorphous layer (l_a) decreases until a critical value of the order of 6-7 nm, below which plasticity cannot be activated and the polymer behaves in a brittle manner, as previously shown for virgin polyethylene. Using (l_a, M_W) maps, it is possible to explain the differences observed in the embrittlement behaviour of semi-crystalline polymers predominantly undergoing chain scission.     

A tungsten oxide-based photoelectrocatalyst for degradation of environmental contaminants

The use of photocatalysts in the remediation of contaminated water is now well established in the scientific literature, the most common photocatalyst being nano-dimensional particulate titanium dioxide. The generation of charge and charge transfer mechanisms on titanium dioxide are also well described, but this paper addresses the use of tungsten oxide and discusses its potential in water remediation when supported as a photoelectrocatalytic electrode. A photoelectrocatalytic cell is described and its performance in the context of the band structure of tungsten oxide is discussed.     

Nuclear magnetic resonance analysis of trace sulfur mustard chemicals in the environmental samples

Nuclear magnetic resonance （NMR） technique was used to screen and identify trace sulfur mustard chemicals in the organic and aqueous waste samples. 1H-NMR and one dimensional total correlation spectroscopy （1D TOCSY） were used for non-destructive screening analysis of the original samples. 1D TOCSY-TOCSY and 1D TOCSY incorporated with a chemical shift selective filter （1D CSSF-TOCSY） were applied in screening the contained sulfur mustard related compounds in the unknown samples. In order to meet the criteria for 1H-NMR data presentation, sample pretreatment technologies including liquid-liquid extraction, solvent exchange and solid phase extraction were used to eliminate the interference of the target resonances. Bis（2-chloroethyl） sulfide, 1, 3-Bis（vinylthio）propane and 1,3-Bis（2-hydroxyethylsulfonyl） propane were identified based on 1HNMR spectra comparison. The results were in good agreement with the list of spiking chemicals. The analytical strategies of this work can provide reference for the 1H-NMR analysis of the trace chemical warfare related compounds in official OPCW proficiency test. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Detection of environmental chemicals by SPR assay using branched cyclodextrin as sensor ligand

We obtained the association constants Ka of estrogen (E2) and environmental chemicals by the surface plasmon resonance (SPR) assay using the immobilized mono-6-O-α-maltosyl-β-CD (G₂βCD) compared with the immobilized β-CD and the immobilized estrogen receptor (ER). The association behavior of G₂βCD was shown as a ER model compound. The calibration curve was determined by the initial rate of association depending on the various concentrations, and the minimum detectable concentrations in the order of parts per billion were calculated. The SPR assay has advantages that the pre-treatment of the sample is not necessary and the immobilized ligand is stable and useful for the repeated measurement.     

The development and inter-laboratory verification of LC-MS libraries for organic chemicals of environmental concern

The development, verification, and comparison study between LC-MS libraries for two manufacturers’ instruments and a verified protocol are discussed. Compounds in the libraries are among those considered by the U.S. EPA Office of Water as threats to drinking water including pesticides, drugs of abuse, and pharmaceuticals. The LC-MS library protocol was verified through an inter-laboratory study that involved Federal, State, and private laboratories. The results demonstrated that the libraries are transferable between the same manufacturer's product line, and have applicability between manufacturers. Although ion abundance ratios within mass spectra were shown to be different between the manufacturers’ instruments, the NIST search engine match probability was at 96% or greater for 64 out of 67 compounds evaluated.     

Chemical degradation of polystyrene induced by chlorinated nitrosobenzene

Chemically induced degradation of polystyrene (PSt) in the presence of 2,4,6-tri-chloronitrosobenzene (TCNB) as radical generator was investigated in benzene solution by means of the electron spin resonance (ESR) method. The ESR spectra observed after the addition of TCNB to PSt in benzene solution were assigned to the nitroxide radicals (spin adducts) of the PSt radicals,

,

and

. These assignments were deduced from comparisons between observed and computer simulated spectra and were supported by experiments using α-deuterated PSt. It was found by analyses of ESR spectra that two kinds of type (B) radicals were produced, which were different in local conformation. The radicals (A) and (B) were thought to be produced by hydrogen abstraction by the chlorinated phenyl radical which results from homolytic scission of the CN bond of TCNB on slight warming. On the other hand, it was concluded that β-scission of radical (A) results in the formation of the chain scission radical (C). The mechanism of degradation of PSt induced by TCNB as radical initiator is discussed, together with the decrease in molecular weight observed after the addition of TCNB to a PSt-benzene solution. From the decrease of molecular weight it is concluded that TCNB acts as a scission inducer.     

Peroxide induced crosslinking and degradation of polyvinyl chloride

Peroxide induced crosslinking and degradation of polyvinyl chloride (PVC) were experimentally investigated using an on-line electron spin resonance (ESR) spectroscopy technique. The reaction variables included temperature, peroxide type and concentration. A single line ESR spectrum was observed with its peak-to-peak width decreasing during the reaction. The mechanism involved in the reaction was elucidated based on the radical information. The radical concentration versus reaction time profile exhibited two distinct regions: the chemically initiated reaction continued by the thermal initiation. The addition of peroxide induced and significantly enhanced the thermal initiated crosslinking and degradation. The radical concentration data coupled with the extent of dehydrochlorination gave an estimate of the rate constant of polyene propagation. A significant decrease of the rate constant was observed during the reaction. The gel content and swelling ratio were also measured to provide additional information to the reaction process. The initial gelation rate increased with the increase of temperature and/or peroxide concentration. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 851–860, 1998     

Uses of speciation techniques in biomonitoring for assessing human exposure to organic environmental chemicals

Speciation analysis has been used for many years to identify and measure different forms of a given chemical in environmental and human samples. Although the term speciation is generally applied to the measurement of inorganic chemicals, the term can also be applied to many measurements of organic chemicals in complex samples, such as environmental media and biological matrices. We present several examples of achieving speciation analysis by selecting the appropriate biological matrix in which to measure a specific chemical(s), by a given analytical method, for the most accurate assessment of human exposure to the environmental chemical. Much of this information and many of these techniques are transferable to the measurement of inorganic elements in environmental and biological samples.     

Biotechnological progress in producing fuels and valuable chemicals and in bioremediating environmental impacts

Applied Biochemistry and Biotechnology - The 71 poster papers presented at the 16th Symposium on Biotechnology for Fuels and Chemicals provided new information on ethanol production, feedstock...     

Method for estimating the human and environmental exposure potential of chemicals having designated uses

This paper describes a methodology that was designed to assist the Environmental Protection Agency in setting priorities for regulating chemicals in accordance with requirements of the Toxic Substances Control Act by indicating the extent of exposure potentially associated with a particular use of a chemical. Development and application of the methodology to actual chemical uses proceeded in four stages: (1) development of an exposure classification scheme, (2) development of a chemical use list, (3) assignment of exposure category scores to chemical uses, and (4) merging of exposure scores into ranked groups, creating the Index of Exposure. The purpose of the Index was to identify those chemical uses having the greatest potential for human and environmental exposure. Theoretically, the objectivity of the scoring methodology is such that, given the same data for a chemical use, different scorers will be able to arrive at the same exposure score for that use.     

Supported noble metal nanoparticles as photo/sono-catalysts for synthesis of chemicals and degradation of pollutants

This review summarizes the utilization of supported noble metal nanoparticles (such as Au/TiO2, Au/ZrO2, Ag/AgCl) as efficient photo/sono-catalysts for the selective synthesis of chemicals and degradation of environmental pollutants. Supported noble metal nanoparticles could efficiently catalyze the conversion of solar energy into chemical energy. Under UV/visible light irradiation, important chemical transformations such as the oxidation of alcohols to carbonyl compounds, the oxidation of thiol to disulfid...     

Radiation induced degradation of ketoprofen in dilute aqueous solution

The intermediates and final products of ketoprofen degradation were investigated in 0.4 mmol dm^?3 solution by pulse radiolysis and gamma radiolysis. For observation of final products UV?vis spectrophotometry and HPLC separation with diode array detection were used, and for identification MS was used. The reactions of ^?OH lead to hydroxycyclohexadienyl type radical intermediates, in their further reactions hydroxylated derivatives of ketoprofen form as final products. The hydrated electron is scavenged by the carbonyl oxygen and the electron adduct protonates to ketyl radical ^?OH is more effective in decomposing ketoprofen than hydrated electron. Chemical oxygen demand and total organic carbon content measurements on irradiated aerated solutions showed that using irradiation technology ketoprofen can be mineralised. The initial toxicity of the solution monitored by the Daphnia magna test steadily decreases with irradiation. Using 5 kGy dose no toxicity of the solution was detected with this test.     

Electron beam induced degradation of clopyralid in aqueous solutions

The degradation characteristics of clopyralid irradiated by electron beam (EB) was studied in aqueous solutions. The effects of factors, such as initial clopyralid concentrations, addition of radicals scavenger, initial solution pH and addition of H₂O₂, were investigated on clopyralid degradation efficiency and mechanism. It was found that the EB-radiolysis was an effective way to degrade clopyralid and its degradation rate decreased with the increasing of substrate concentration. In the investigated initial concentrations range of 100?C400 mg L^?1, the radiolytic degradation of clopyralid followed a pseudo-first kinetic order. The results from addition of radicals scavenger indicated that both ^?OH and e _aq ^? played significant roles in the degradation of clopyralid. Furthermore, the alkaline condition and addition of H₂O₂ (<10 mM) in the solution also slightly enhanced the efficiency of clopyralid degradation. The ion chromatography analysis showed that some organic acids (formic acid, acetic acid and oxalic acid) were formed, while the completely dechlorination of the substrate was achieved and organic nitrogen was recovered in the form of ammonium and nitrate ions during the irradiation process.     

Radiation induced degradation of EPR by IR oxidation profiling

Infrared absorption spectroscopy has been used to investigate the effect of γ-radiation on ethylene-propylene copolymer loaded with different amount of antioxidant. The oxidation profiles were obtained analyzing slices of the samples by an IR microscope. The IR spectra have shown that the antioxidant content does not affect the shape of the oxidation profiles; their dependence on thickness and dose rate is in good agreement with the Clough and Gillen model. Our results indicate that the antioxidant does not affect the reactions involved in the oxidation process and the oxygen distribution on the sample.     

Contributions to the on-line method for the extraction and isolation of pesticide residues and environmental chemicals

Summary A new extraction principle of the on-line method using the binary solvent system water + acetone is presented. The water amount of the organic phase containing the pesticides is removed by anhydrous MgSO₄, instead of previously used non-polar solvents. Therefore, a further reduction of the solvent emission into the environment is reached. In addition, the working sequences of the two simultaneous and sequential extraction steps of this new technique are discussed and illustrated.     

Contributions to the on-line method for the extraction and isolation of pesticide residues and environmental chemicals

Summary The principle of the on-line method is presented by the Gibbs triangle. It can be shown that in addition to the straight sequential or simultaneous working sequences also any combination of both can be used. Altogether, six working sequences are practicable with the on-line technique. Finally, the working sequences of two different online extraction procedures are discussed and presented by the Gibbs triangle.

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BeitrÄge zur on-line Methode für die Extraktion und Isolierung von PesticidrückstÄnden und UmweltchemikalienI. Das Prinzip der on-line Methode