Polychlorinated dibenzo-p-dioxins and dibenzofurans in commercial diphenyl ether herbicides,and in freshwater fish collected from the application area

This paper describes the analyses of polychlorinated dibenzodioxins, dibenzofurans, and related compounds in diphenyl ether herbicides, CNP, NIP, and X-52. The levels of tetra-, penta-CDDs, and tetra-CDFs were about 150, 30, and 15 ppm, respectively in CNP formulations. NIP and X-52 contained lower chlorine alalogs. Isomer distribution of PCDDs in CNP agreed with an estimate from the reaction of chlorophenols. Freshwater fish samples heavily contaminated with CNP in the application season also contained 0.2 ppb of 1,3,6,8-tetra-CDD.     

GC/MS analysis of polybrominated diphenyl ethers in fish collected from the Inland Sea of Seto, Japan

Development of an analytical method for polybrominated diphenyl ethers (PBDEs) in fish and their concentration in Japanese marine fish were investigated. Fish homogenate was extracted with diethyl ether/hexane (1 + 3). The extract was cleaned up by automated gel permeation chromatography (GPC) and then by mini-column chromatography, which consisted of three layers of silica gel and sulfuric acid-impregnated silica gel. The PBDE fraction was concentrated and injected into a GC/MS with negative chemical ionization (NCl). Recoveries of the 15 individual PBDEs (BDE-15, 28, 37, 47, 66, 71, 75, 77, 85, 99, 100, 119, 153, 154, and 209) each at a fortification level of 4 ng/g lipid were in the range of 88-128% and the relative standard deviations (RSD) were 0.43-7.6% (n = 4). Seven species of marine fish (conger eel, flounder, gray mullet, horse mackerel, red sea bream, sea bass, and yellowtail) were collected from the Inland Sea of Seto, and were analyzed with the developed method. Seven PBDEs (BDE-28, 47, 66, 99, 100, 153, and 154) were detected in all the samples. The most abundant PBDE congener was BDE-47 found in all the samples. Relatively high levels of PBDEs were found in the gray mullets and yellowtails.     

Nitrifiers activity and community characteristics under stress conditions in partial nitrification systems treating ammonium-rich wastewater

Long-term exposure of nitrifiers to high concentrations of free ammonia(FA) and free nitrous acid(FNA) may affect nitrifiers activity and nitrous oxide(N_2O) emission.Two sequencing batch reactors(SBRs) were operated at influent ammonium nitrogen(NH_4-N) concentrations of 800 mg/L(SBRH) and 335 mg/L(SBRL),respectively.The NH_4-N removal rates in SBRHand SBRLwere around 2.4 and 1.0 g/L/day with the nitritation efficiencies of 99.3% and 95.7%,respectively.In the simulated SBR cycle,the N_2O emission factors were 1.61% in SBRH and 2.30% in SBRL.N_2O emission was affected slightly by FA with the emission factor of0.22%–0.65%,while N_2O emission increased with increasing FNA concentrations with the emission factor of 0.22%–0.96%.The dominant ammonia oxidizing bacteria(AOB) were Nitrosomonas spp.in both reactors,and their relative proportions were 38.89% in SBRHand13.36% in SBRL.Within the AOB genus,a species(i.e.,operational taxonomic unit [OTU] 76) that was phylogenetically identical to Nitrosomonas europaea accounted for 99.07% and 82.04% in SBRHand SBRL,respectively.Additionally,OTU 215,which was related to Nitrosomonas stercoris,accounted for 16.77% of the AOB in SBRL.     

Oxidation catalyst of iron oxide suppressing dioxin formation in polyethylene combustion

A new iron oxide catalyst, which has a superior oxidation activity in carbon monoxide and polyethylene (PE) combustion, was synthesized by an aqueous solution reaction. Catalytic oxidation of carbon monoxide over six kinds of hematite obtained from the goethite was done using a microcatalytic pulse reactor, and the composition of the hematite with the highest oxidation activity was determined. With the aim of suppressing dioxin formation on combustion, incineration tests of solid wastes in PE refuse bags with and without the goethite were carried out using a commercial semibatch-type incinerator with a combustion chamber of 6.2 m³. The result confirmed that the concentration of dioxins in the flue gas decreased considerably when the refuse was incinerated in PE bags manufactured with goethite. Received: July 24, 2000 / Accepted: October 18, 2000     

Population genetic structure of the neon damselfish (<Emphasis Type="Italic">Pomacentrus coelestis</Emphasis>) in the northwestern Pacific Ocean

The population genetic structure of the neon damselfish (Pomacentrus coelestis) in the northwestern Pacific Ocean was revealed by the hypervariable control region of the mitochondrial gene (343 bp). In total, 170 individuals were sampled from 8 localities distributed between Taiwan and Japan, and 71 haplotypes were obtained through sequence alignment. High haplotype diversity (h = 0.956 ± 0.008) with low nucleotide diversity (π = 0.010 ± 0.006) was observed, and the results of the mismatch distribution test suggested that a historical population expansion after a period of population bottleneck might have occurred among P. coelestis populations. Based on the results of the UPGMA tree and AMOVA (Φct = 0.193, P < 0.05) analyses, fish populations from eight localities could be divided into two groups: one includes populations from localities around mainland Japan, and the other includes those from Okinawa and southern Taiwan. A genetic break was found between populations from mainland Japan and Okinawa, and this break was congruent with the pattern of phenotypic variations documented in previous studies. This evidence supports the latitudinal variation of reproductive traits among P. coelestis populations likely being genetically based. It is suggested that the changes in sea level and sea surface temperatures during past glaciations might have resulted in population bottlenecks in P. coelestis and the modern populations in the northern West Pacific are likely the results of recolonization after such events. The Kuroshio Current acts not only as a vehicle for larval transport along its pathway (between populations in southern Taiwan and Okinawa) but also as a barrier for larval dispersal across the Kuroshio axis (between populations in mainland Japan and Okinawa). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Accumulation properties of polychlorinated biphenyl congeners in Yusho patients and prediction of their cytochrome P450-dependent metabolism by in silico analysis

In what has become known as the Yusho incident, thousands of people in western Japan were poisoned by the accidental ingestion of rice bran oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins and dioxin-like compounds. In this study, we investigated the accumulation patterns of 69 PCB congeners in the blood of Yusho patients in comparison with those of non-exposed controls. The blood samples were collected at medical check-ups in 2004 and 2005. To compare the patterns of PCB congeners, we calculated the concentration ratio of each congener relative to the 2,2′,4,4′,5,5′-hexaCB (CB153) concentration. The concentration ratios of tetra- and penta-chlorinated congeners in the blood of Yusho patients were significantly lower than those of controls. To examine the cytochrome P450 (CYP)-dependent metabolic potential of the 2,3′,4,4′5-pentaCB (CB118), CB153, and 2,3,3′,4,4′5-hexaCB (CB156) congeners, we conducted PCB-CYP (CYP1A1, CYP1A2, CYP2A6, and CYP2B6) docking simulation by in silico analysis. The docking models showed that human CYP1A1, CYP2A6, and CYP2B6 isozymes have the potential to metabolize CB118 and CB153. On the other hand, it was inferred that CB156 is difficult to be metabolized by these four CYP isozymes. These results indicate that CYP1 and CYP2 isozymes may be involved in the characteristic accumulation patterns of PCB congeners in the blood of Yusho patients.     

Recovery of glass fibers from glass fiber reinforced plastics by pyrolysis

Fiber-reinforced plastic sheets containing unsaturated polyester cross-linked with styrene, CaCO₃ and glass fibers as fillers were pyrolyzed in a helium and steam atmosphere in order to recover glass fibers and valuable organic pyrolysis products. Glass fibers were separated from CaCO₃ and CaO by dissolving calcium salts in hydrochloric acid. Residual organic material was burnt afterwards. Best results were obtained at a pyrolysis temperature of 600 and 700 °C, resulting in a large liquid fraction high in styrene, leaving little residual organic material on the surface of the glass fibers. At a pyrolysis temperature of 500 °C, the degradation of the polymer matrix was incomplete, and at 900 °C, glass fibers were destroyed in the presence of CaO, leaving CaSiO₃ as a product.     

The choosing of sleeping position in the overnight aggregation by the solitary bees <Emphasis Type="Italic">Amegilla florea urens</Emphasis> in Iriomote Island of Japan

In addition to the process of joining the sleeping aggregation, the choice of sleeping position is an important night-time behaviour of small diurnal insects because of the increased risk for predator attacks as well as bad weather. The aggregation behaviour of the solitary bee Amegilla florea urens was investigated to elucidate the choice of sleeping position on substrates. Male and female constructed single-sex aggregations on hanging leaves during May and June, respectively. Most individuals tended to form aggregations with other individuals while few individuals slept alone. During the aggregation forming, both the number of individuals that tried to join the aggregation and the completion time of aggregation increased with the number of sleeping individuals, whereas the success rate of joining was unaffected. The sleeping positions of subsequent arrivals on the substrates were higher than those of the first arrivals in female aggregations. Therefore, the first female to arrive tended to be located near the bottom of a hanging substrate. Dissecting sleeping females showed that they contained mature oocytes, indicating that sexually mature individuals formed aggregations. In male aggregations, however, we could not find a clear relationship between the position on substrates and the arrival sequence. We suggest that the purpose for sleeping in aggregations might be a dilution effect for nocturnal predation and that the females that finished both nesting and foraging quickly could choose the optimal positions in the aggregation when they arrived on the sleeping substrates.     

Time-trend (1973-2000) of polybrominated diphenyl ethers in Japanese mother's milk

The time-trend and recent concentrations of polybrominated diphenyl ethers (PBDEs) in Japanese mother's milk were investigated. The time-trend of 16 PBDEs (BDE-28, 37, 47, 66, 71, 75, 77, 85, 99, 100, 119, 153, 154, 138, 183, and 190) in pooled milk samples from mothers living in Osaka between 1973 and 2000 was analyzed. Additionally, PBDE concentrations in individual milk samples collected from 13 mothers living in Kanagawa and Okayama in 1999 were measured. The total concentration of all PBDE congeners (SigmaPBDEs) measured in the pooled samples increased during the period between 1973 (<0.01 ng/g lipid) and 1988 (1.64 ng/g lipid), and remained low afterwards while showing remarkable changes in PBDE congener profiles. The SigmaPBDEs in the 1999 individual milk samples were also low (0.56-3.97 ng/g lipid), except for a single sample (291 ng/g lipid). The source of this exposure could not be identified.     

Real-time-monitored decrease of trichlorophenol as a dioxin surrogate in flue gas using iron oxide catalyst

The decrease of trichlorophenol by injecting oxidation catalyst into a municipal solid waste incinerator was monitored in real time. Direct sampling atmospheric pressure chemical ionization (APCI)/ion trap mass spectrometry (ITMS) was used for the real-time monitoring. The oxidation catalyst was iron oxide type, which exponentially reduced trichlorophenol emission. CO emission, however, did not show any correlation with the catalyst injection rate. Simultaneous analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/PCDFs) suggested that real-time monitoring of trichlorophenol as a surrogate of PCDDs/PCDFs, has a potential to timely control the optimum injection rate of PCDD/PCDF suppression catalyst continuously and economically.