Juvenile hormone agonists affect the occurrence of male Daphnia

The water flea Daphnia magna reproduces primarily by cyclic parthenogenesis. Environmental stimuli that signal a change to adverse conditions induce the organisms to switch from parthenogenesis to gamogenetic reproduction. During the gamogenetic period, they produce male daphnids and dormant resting eggs, which can survive prolonged periods of environmental adversity. However, little is known about the mechanisms associated with the switch from parthenogenesis to gamogenetic reproduction. We investigated the effects of several juvenoids on sex determination in Daphnia. Females less than 24 h old were exposed to various concentrations of the test substance and were observed for 21 days. It was found that they can trigger the appearance of male daphnids: the percentage of males in the population increases to a level greater than what occurs under ordinary environmental conditions. We found that methylfarnesoate, juvenile hormone III, methoprene, and the phenoxyphenoxy derivatives pyriproxyfen and fenoxycarb (both insecticides) reduced the production of offspring and produced sex ratios dominated by male daphnids. Pyriproxyfen and fenoxycarb showed striking effects at low concentrations. Exposure to either of these chemicals at a concentration of 330 ngl(-1) caused adult females to produce almost all male neonates. Methylfarnesoate, juvenile hormone III, and methoprene showed an effect in inducing male production at higher concentrations (3.7 x 10(3), 3.3 x 10(5), and 1.3 x 10(5) ngl(-1), respectively). Our findings suggest that juvenile hormone agonists, including some insecticides, affect the chemical signaling responsible for inducing the production of male offspring.     

Improved method for the formation of recycled resins from depolymerized products of waste fiber-reinforced plastics: simple and effective purification of recovered monomers by washing with water

The synthesis of recycled plastics from recovered monomeric materials obtained from the depolymerization reaction of fiber-reinforced plastics (FRP) was examined. The depolymerization reaction of FRP in the presence of N,N-dimethylaminopyridine (DMAP) smoothly yielded the corresponding monomers, which mainly consisted of dimethyl phthalates. The polymerization reaction with this monomer failed to form the corresponding unsaturated polyesters due to contamination by N-methyl-4-pyridone, a decomposition product of DMAP. An efficient purification of the recovered monomer was achieved by washing with water, and the purified monomer successfully yielded the corresponding polymers. A hardness test revealed that the polymers were as hard as the polyester made from virgin materials. The present modification provides a practical method for the preparation of recycled plastics from depolymerized plastics.     

Molecular taxonomy of vestimentiferans of the western Pacific and their phylogenetic relationship to species of the eastern Pacific. I. Family Lamellibrachiidae

Phylogenetic relationships among vestimentiferans in the family Lamellibrachiidae collected from ten sites in the western Pacific were analyzed on the basis of the nucleotide sequence of part of a mitochondrial gene for cytochrome oxidase I. The 103 individuals analyzed were tentatively classified into five species: namely, Lamellibrachia satsuma, three tentative species inhabiting Japanese waters and one tentative species from the Manus Basin. Phylogenetic analysis of the four tentative species, L. satsuma, and two lamellibrachiids, whose sequences had been reported previously, namely L. columna from the Lau Basin and L. barhami from the Oregon Margin and the Middle Valley, revealed that the lamellibrachiids from Japanese waters were not monophyletic. While two tentative species from Japanese waters and L. columna formed a monophyletic group, the other tentative species from Japanese waters was closely related to the tentative species from the Manus Basin. L. satsuma was shown to be phylogenetically distinct from other lamellibrachiids of the western Pacific. A lamellibrachiid that had been collected from the Nikko Seamount was also demonstrated to be L. sastuma.     

Characteristics of dioxin emissions at startup and shutdown of MSW incinerators

Dioxin concentrations from municipal waste incinerators in Japan and elsewhere often show low concentrations that comply with legal limits (in this paper, the term "dioxin" designates WHO-TEQ: PCDD/Fs+dioxin-like PCB). However, such data is usually generated under normal steady state operational conditions, and there has been little investigation of releases occurring during startup and shutdown. It is important, therefore, to ascertain quantitatively emissions in an unsteady state (startup and shutdown) in order to correctly evaluate the relationship between emissions from a facility and the surrounding environment. The present study aimed to examine dioxin emissions of a continuously operated incinerator at startup and shutdown, and estimating the time period of greatest emission, and the processes causing dioxin generation. The startup process was divided into five stages and the shutdown into two; at each stage, dioxins in the flue gas were measured at the boiler outlet and the stack. From the concentration of dioxins and the flue gas volume at each stage, the amount of dioxins at startup and shutdown were calculated, and these were compared with that under steady state conditions. Dioxin concentration at the stack under steady state conditions was a very low level, while those at startup and shutdown were higher. In the case where dioxin concentration under a steady state is a low level like in this study, it is indicated that the total annual dioxin emission from a facility could be attributed to the startup periods.     

PCB decomposition and formation in thermal treatment plant equipment

In this study we investigated both the decomposition and unintentional formation of polychlorinated biphenyl congeners during combustion experiments of refuse-derived fuel (RDF) and automobile shredder residue (ASR) at several stages in thermal treatment plant equipment composed of a primary combustion chamber, a secondary combustion chamber, and other equipments for flue gas treatment. In both experiments, the unintentional formation of PCB occurred in the primary combustion chamber at the same time as the decomposition of PCB in input samples. By combusting RDF, non-ortho-PCB predominantly formed, whereas ortho-PCB and symmetric chlorinated biphenyls (e.g., #52/69, #87/108, and #151) tended to be decomposed. ASR formed the higher chlorinated biphenyls more than RDF. These by-products from ASR had no structural relation with ortho-chlorine. Lower chlorinated biphenyls appeared as predominant homologues at the final exit site, while all congeners from lower to higher chlorinated PCB were unintentionally formed as by-products in the primary combustion chamber. This result showed that the flue gas treatment equipments effectively removed higher chlorinated PCB. Input marker congeners of RDF were #11, #39, and #68, while those for ASR were #11, #101, #110/120, and #118. Otherwise, combustion marker congeners of RDF were #13/12, #35, #77, and #126, while those for ASR were #170, #194, #206, and #209. While the concentration of PCB increased significantly in the primary combustion chamber, the value of toxicity equivalency quantity for dioxin-like PCB decreased in the secondary combustion chamber and the flue gas treatment equipments.     

Seasonal variation of 228Ra/226Ra ratio in seaweed: implications for water circulation patterns in coastal areas of the Noto Peninsula, Japan

To examine water circulation patterns of coastal water, 72 seaweed (Sargasso) samples and 27 coastal water samples were collected from coastal areas of the Noto Peninsula, Japan, during the period from December 1998 to June 2002. The (228)Ra and (226)Ra activities of those samples were measured by low-background gamma-ray spectrometry. There was a wide range of activities of (228)Ra (0.5-2Bq/kg-fresh) and (226)Ra (0.5-1.2Bq/kg-fresh) in the Sargasso samples. The (228)Ra/(226)Ra activity ratio of Sargasso samples exhibited seasonal variation with minimum values in June ((228)Ra/(226)Ra= approximately 1) and maximum values in December (1.5-2.5), which was mainly governed by changes in (228)Ra activity. It is also notable that the seasonal variation of the (228)Ra/(226)Ra ratio of Sargasso is in approximate agreement with that of the ambient coastal water. Sargasso samples appear to have retained the (228)Ra/(226)Ra ratio of the ambient coastal waters, and the temporal variations in that ratio provide insight into seasonal changes in water circulation in the Noto Peninsula coastal area.     

Color analysis of combustion ashes of seawater-soaked wood: estimation of salt concentration

The color of wood ash is normally white, but black color ash was observed when seawater-soaked wood was combusted. In order to check the conditions for generation of black ash, we examined both ashing temperatures from 500 to 800 °C and seawater salt densities for wood soaking. As seawater salt densities rose, the ash color got black at ashing temperatures of 500 and 700 °C. The colors of the ash were analyzed by a spectrophotometer, and color space L* a* b* was measured. The L* value and wood ash yield showed a negative correlation when the ashing temperature was at 600 °C. Salt concentration in wood (SC) was practicably estimated from the L* value (R ² = 0.51) by the approximation formula [SC (%) = 11.82e^?0.038L*]. By scanning electron microscope (SEM) observation, black ash of 600 °C was fully covered by translucent material. It was composed of Na, Mg and Cl by energy dispersive X-ray spectroscopy analysis, and seemed to be crystallized seawater salt. Washed black ash was also observed by SEM, translucent seawater salt was removed and the wood tissue was observed. Black ash was found to be carbonized wood tissue residue, and it was generated when seawater salt exists with a woody biomass.     

Seasonal variation of Ra/Ra ratio in seaweed: implications for water circulation patterns in coastal areas of the Noto Peninsula, Japan

To examine water circulation patterns of coastal water, 72 seaweed (Sargasso) samples and 27 coastal water samples were collected from coastal areas of the Noto Peninsula, Japan, during the period from December 1998 to June 2002. The (228)Ra and (226)Ra activities of those samples were measured by low-background gamma-ray spectrometry. There was a wide range of activities of (228)Ra (0.5-2Bq/kg-fresh) and (226)Ra (0.5-1.2Bq/kg-fresh) in the Sargasso samples. The (228)Ra/(226)Ra activity ratio of Sargasso samples exhibited seasonal variation with minimum values in June ((228)Ra/(226)Ra= approximately 1) and maximum values in December (1.5-2.5), which was mainly governed by changes in (228)Ra activity. It is also notable that the seasonal variation of the (228)Ra/(226)Ra ratio of Sargasso is in approximate agreement with that of the ambient coastal water. Sargasso samples appear to have retained the (228)Ra/(226)Ra ratio of the ambient coastal waters, and the temporal variations in that ratio provide insight into seasonal changes in water circulation in the Noto Peninsula coastal area.