Effect of metabolism on bioconcentration of geometric isomers of d-phenothrin in fish

Yearling carp (Cyprinus carpio) were exposed to d-phenothrin (a 1:4 mixture of d-cis and d-trans isomers) in the absence and the presence of piperonyl butoxide under the flow-through test condition and the bioconcentration factors (BCF's) of the geometric isomers were separately evaluated. It was demonstrated that BCF values for the d-cis isomer were significantly higher by 1.1 to 2.2-fold than those for the d-trans isomer and the subsequent exposure in the presence of piperonyl butoxide resulted in elevated BCF values for the d-cis isomer, but no remarkable change in BCF's was observed for the d-trans isomer. The elevation observed here was presumably attributable to a reduced elimination caused by inhibited oxidative reactions characteristic to the d-cis isomer. The contribution of biotransformation to the elimination rate constant (K₃/K₂ was estimated to be 2.3–11. Thus, the result was well explained by a distinct oxidative metabolism of the d-cis isomer and a significance of metabolism in bioconcentration phenomenon was exemplified.     

Effect of additives on dechlorination of PVC by mechanochemical treatment

Polyvinyl chloride (–CH₂–CHCl–) _n (PVC) was ground with a powdered inorganic material (CaO, CaCO₃, SiO₂, Al₂O₃, or slag) in a planetary ball mill under atmospheric conditions to investigate the effect of additions on its dechlorination. The grinding causes a dehydrochlorinating reaction, forming a mixture of partially dechlorinated PVC and inorganic chloride, depending on the grinding time. The dechlorination increases as the grinding progresses, and is improved with increasing amounts of additives. The most effective additive is a mixture of CaO, SiO₂, and Al₂O₃, which has the same constituent components as blast furnace slag. CaO, a mixture of CaO, SiO₂, and blast furnace slag, are also effective, but CaCO₃ is the least effective additive tired. Received: August 3, 2000 / Accepted: September 21, 2000     

Biodegradability and Biodegradation of Polyesters

A variety of biodegradable plastics have been developed in order to obtain useful materials that do not cause harm to the environment. Among the biodegradable plastics, aliphatic polyesters such as: poly(3-hydroxybutyrate) (PHB), poly(ε-caprolactone) (PCL), poly(butylene succinate) (PBS), and poly(l-lactide) (PLA) have become the focus of interest because of their inherent biodegradability. However, before their widespread applications, comprehensive studies on the biodegradability and biodegradation mechanisms of these polyesters are necessary. Thus, this paper describes the degradation mechanisms and the effects of various factors on the degradation of polyesters. The distribution of polymer-degrading microorganisms in the environment, different microorganisms and enzymes involved in the degradation of various polyesters are also discussed.     

Alkaline hydrolysis of photovoltaic backsheet containing PET and PVDF for the recycling of PVDF

Recovering fluorine from end-of-life products is crucial for the sustainable production and consumption of fluorine-containing compounds because fluorspar, an important natural resource for fluorine, is currently at a supply risk. In this study, we investigated the feasibility of chemically recycling a fluorine-containing photovoltaic (PV) backsheet for fluoropolymer recycling. Herein, a PV backsheet consisting of laminated polyethylene terephthalate (PET) and polyvinylidene fluoride (PVDF) was treated with different concentrations of sodium hydroxide (NaOH) to hydrolyze the PET layer to water-soluble sodium terephthalate (Na₂TP) and to separate pure PVDF layer as a solid material. Optimized alkaline conditions (up to 10 M NaOH at 100 °C for 2 h) were determined, under which 87% of the PET layer could be decomposed without any significant deterioration of the PVDF layer. The hydrolysis kinetics of PET layer in NaOH could be explained by the modified shrinking-core model. Considering that the mass of end-of-life PV panels in Japan is estimated to increase to approximately 280,000 tons per year by 2036, PV backsheets are attractive candidates for fluoropolymer recycling, which can be effectively achieved using chemical recycling approach demonstrated in this study.

     

Use of two population metrics clarifies biodiversity dynamics in large-scale monitoring: the case of trees in Japanese old-growth forests

An alkaline comet assay and a micronucleus test were carried out on erythrocytes of the European chub, Squalius cephalus L., collected in spring and autumn in 2005 and 2006 at three sampling sites in River Sava, near Zagreb, Croatia. The results of comet assay showed the lowest genotoxic influence at the least polluted site, while higher DNA damage was observed at the polluted sites. Although the basal levels of DNA damage were elevated, a clear gradation of DNA damage was found due to pollution intensity in all sampling periods. The lowest cytogenetic damage as revealed by the micronucleus test (MNT) was observed as well at the least polluted site. High variations in MN frequency were observed between sampling periods, although the number of micronucleated erythrocytes was consistently the highest one at the polluted site. The comet assay as a biomarker of genotoxic effect exhibited higher sensitivity in discriminating the genotoxic capacity of studied polluted sites while the MNT was less sensitive. However, both tests should be used together in biomonitoring studies because they can reveal different aspects of DNA damage; comet assay, the early event of genotoxic exposure, and MNT, its final result as a mutagenic potential.     

Applications of time-resolved laser fluorescence spectroscopy to the environmental biogeochemistry of actinides

Time-resolved laser fluorescence spectroscopy (TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS differentiates chemical species of a fluorescent metal ion through analysis of different excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fluorescence decay lifetimes on the order of microseconds, such as UO , Cm, and Eu, continuing development of ultra-fast and cryogenic TRLFS systems offers the possibility to obtain speciation information on metal ions having room-temperature fluorescence decay lifetimes on the order of nanoseconds to picoseconds. The main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of (i) metal speciation in aqueous and solid phases and (ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Significant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry.