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.     

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.     

Convenient dioxin measuring method using an efficient sampling train, an efficient HPLC system and a highly sensitive HRGC/LRMS with a PTV injector

An efficient sampling method for dioxins from flue gas, an efficient automatic purification and fractionation method by a new HPLC system using a sulfuric acid-silica/silica column, a Nitro column and a PGC column, and sensitive determination method by an economical HRGC/LRMS using a programmable temperature vaporization (PTV) injector were developed. It was confirmed that the dioxins could be easily collected by the proposed simple sampling train consisting of only two bottles, and the extracted sample could be purified sufficiently and separated as mono-ortho PCBs, non-ortho PCBs and PCDDs/PCDFs completely with the proposed HPLC system. The peak areas of GC/MS were increased linearly with the injection volume up to 40 microl by the PTV technique, and the sensitivity could be increased to 20 times higher than usual. This convenient measuring method can drastically reduce operation time, consumption of hazardous solvent and cost.     

Studies on the dechlorination and oil-production technology of waste plastics

 Recycle technology for waste plastics containing polyvinyl chloride (PVC) has been developed in the Hokkaido National Industrial Research Institute for the production of solid and liquid fuel, and has established a recycling process which includes a dechlorination process for PVC plastics, and a two-stage catalytic pyrolysis process for plastics using zeolite catalysts. The dechlorination equipment consists of a two-axis screw extruder with a heating element, which can remove chlorine up to 99.9 wt. % from PVC containing plastics as hydrogen chloride. The product had about 44 000 kJ/kg calorific value and was fed into the next oil production process, although it could also be used as a solid fuel. Natural and synthetic zeolite were used as catalysts for the two-stage catalytic process, which produced a light oil with a boiling point which was between those of kerosene and gasoline. The yield of this oil reached 82 wt. %. The chemical type was analyzed using liquid chromatography, and was found to have many aromatic compounds. These technologies make it possible to produce a nonpolluting, high-calorie solid fuel and a liquid fuel very efficiently. Received: July 19, 2000 / Accepted: September 21, 2000     

Biochemical and Genetic Characterization of an Extracellular Poly(3-Hydroxybutyrate) Depolymerase from Acidovorax Sp. Strain TP4

To determine the properties of enzymes from bacteria that degrade polypropiolactone (PPL), we isolated 13 PPL-degrading bacteria from pond water, river water, and soil. Nine of these strains were identified as Acidovorax sp., three as Variovorax paradoxus, and one as Sphingomonas paucimobilis. All the isolates also degraded poly(3-hydroxybutyrate) (PHB). A PPL-degrading enzyme was purified to electrophoretical homogeneity from one of these bacteria, designated Acidovorax sp. TP4. The purified enzyme also degraded PHB. The molecular weight of the enzyme was estimated as about 50,000. The enzyme activity was inhibited by diisopropylfluorophosphate, dithiothreitol, and Triton X-100. The structural gene of the depolymerase was cloned in Escherichia coli. The nucleotide sequence of the cloned DNA fragment contained an open reading frame (1476 bp) specifying a protein with a deduced molecular weight of 50,961 (491 amino acids). The deduced overall sequence was very similar to that of a PHB depolymerase of Comamonas acidovorans YM1609. From these results it was concluded that the isolated PPL-degrading enzyme belongs to the class of PHB depolymerases. A conserved amino acid sequence, Gly-X₁-Ser-X₂-Gly (lipase box), was found at the N-terminal side of the amino acid sequence. Site-directed mutagenesis of the TP4 enzyme confirmed that ²⁰Ser in the lipase box was essential for the enzyme activity. This is the first report of the isolation a PHB depolymerase from Acidovorax.     

Development of an environmentally acceptable volatile organic compounds recovery and reuse system based on vacuum spray flash with dibasic acid esters as absorbents

We used dibasic acid esters as the absorbent for a volatile organic compounds (VOC) recovery and reuse system geared mainly toward VOCs from painting and presswork. The system consists of three elements: absorption using dibasic acid esters, separation by vacuum spray flash method, and recovery by condensation. The concentration of both ethyl acetate (EtAc) and isopropyl alcohol (IPA) decreased around 90% at room temperature. Vacuum spray flash was found as a useful process for cost-effective and energy-effective VOC removal system. The difference in the dissolubility parameters (Hansen constant) between dibasic acid esters and VOCs and the boiling point of VOCs was the main contributor to the separation behavior.     

Biodegradability of surfactants and inhibition of surfactants to biodegradation of other pollutants

Changes of BOD/TOD and DOC with time were obtained for solutions of 9 synthetic surfactants and 2 fatty acid salts under various conditions. The cationic surfactants, ABM and ABDM, were not biodegraded at all and inhibited the biodegradation of a synthetic sewage. LAS was not biodegraded at concentration of 30 mg/l and higher and inhibited the biodegradation of the sewage.     

Obligate commensalism of <Emphasis Type="Italic">Curvemysella paula</Emphasis> (Bivalvia: Galeommatidae) with hermit crabs

Curvemysella paula is a markedly crescent-shaped bivalve that lives inside snail shells occupied by hermit crabs. Here, we describe the unique symbiotic life, growth pattern, and reproductive biology of this bivalve, based on specimens collected from the shallow, muddy bottom of the Seto Inland Sea, Japan. C. paula was found attached to columellae in the siphonal canal, mainly of nassariid snail shells occupied by two types of hermit crabs: Diogenes edwardsii (Diogenidae) and Spiropagurus spiriger (Paguridae). The crescent-shaped shell of C. paula is an adaptation to symbiotic life in the narrow interspace between the snail shell and the hermit-crab abdomen. C. paula is a protandric hermaphrodite. In our samples, each host snail shell harbored one (or rarely a few) large female and several males. All the female bivalves settled on the host shells with their anterior end facing outward and benefited from currents created by the hermit crab when feeding. In the muddy bottom, snail shells are a limited resource for both the hermit crabs and symbiotic bivalves. The bivalves benefit from the mobility of the hermit crabs, which prevent the shells from becoming buried in the mud. C. paula represents the only example of obligate commensalism with hermit crabs found in Bivalvia.     

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.