Automobile exhaust gas as a source of aqueous phase OH radical in the atmosphere and its effects on physiological status of pine trees

Free radical generation potential of automobile exhaust gas was examined by measuring hydroxyl (OH) radical photo-formation rates in exhaust gas-scrubbing water. Effects of automobile exhausts on physiological status of Japanese red pine trees (Pinus densiflora Sieb. et Zucc.) were also investigated to elucidate the mechanism how the free radicals derived from exhaust gas damage higher plants. Gasoline and diesel exhaust gases were scrubbed into pure water. Potential photo-formation rates of OH radical in aqueous phase (normalized to sun light intensity of clear sky midday on May 1 at 34°N) for gasoline and diesel cars were ave. 51 and 107 μM h⁻¹ m⁻³ of exhaust gas, respectively. Nitrite was a dominant source (ca. 70-90%) of photochemical formation of OH radical in both gasoline and diesel car exhausts. The scrubbed solution of diesel car exhaust gas was sprayed for six times per week to needles of pine tree seedlings in open top chambers. Control, exhaust + mannitol (added as OH radical scavenger), and nitrite + nitrate standard solution (equivalent levels existed in the exhaust gas) were also sprayed. Two months sprays indicated that the sprayed solutions of diesel exhaust and nitrite + nitrate caused a decrease of maximum photosynthetic rate and stomata conductance in pine needles while the control and exhaust + mannitol solution showed no effects on photosynthetic activities of pine needles. These results indicated that OH radicals generated mainly from photolysis of nitrite occurring in the scrubbing solution of exhaust gas are responsible for the decrease of photosynthetic activities of pine needles.     

Concentrations of organochlorine pollutants in mothers who gave birth to neonates with congenital hypothyroidism

We have investigated the effects of prenatal exposure to dioxin-like compounds (PCDDs, PCDFs and dioxin-like PCBs), PCBs and organochlorine pesticides (DDT, HCH, chlordane, HCB and their metabolites) on the incidence of congenital hypothyroidism and/or cretinism in Fukuoka, Japan from 2001 to 2004. Thirty-four positive neonates of the mass-screening for cretinism were classified into three groups by the pediatrician after the reevaluation of the serum TSH level, that is, negative in reevaluation group, hyper thyroid stimulating hormone (TSH) emia group and cretinism group. One-hundred and two negative neonates of the mass-screening were classified into the normal group. Concentrations of these organochlorine compounds in the breast milk of mothers, which were considered as the indicator of prenatal exposures to them, were gradually increased from the normal group to the cretinism group in the four groups and were around two times higher in the cretinism group than in the normal group. According to the case-control study adjusted for the parity and mother's age, odds ratios of PCBs, DDT and HCB were 10 (p=0.003), 10 (p=0.003) and 22 (p=0.004), respectively and in dioxin-like compounds, PCDFs showed the highest odds ratio, 9.8 (p=0.005). Based upon those findings, these compounds seemed play an important role in the incidence and/or causation of the cretinism.     

Immunologic effects of perinatal exposure to dioxins, PCBs and organochlorine pesticides in Japanese infants

Effects of perinatal exposure to dioxins, PCBs and organochlorine pesticides on lymphocyte subsets were investigated in the peripheral blood from 101 Japanese infants with approximately 10 months of age. Perinatal exposure to these organochlorine compounds were estimated by their contamination levels in the breast milk of the mothers. Lymphocyte subsets such as CD16+, HLA-DR+, CD4+, CD4+8+, CD8+, CD3+ and CD20+ cells in peripheral venous blood were assessed in a subgroup of 92 infants. Greater exposures to HCE, chlordane and dioxins were significantly associated with the increase in the percentages of CD8+ and CD3+ T lymphocytes and CD4+/CD8+ T cell ratios, respectively. In addition, higher HCH exposure was also associated with a decrease in the percentage of HLA-DR+ T lymphocytes. Furthermore effects of dioxins, DDT and PCBs on the percentage of CD16+ T lymphocyte were more pronounced by the combined exposure of dioxins and PCBs or by the combined exposure of DDT and PCBs. Effects of HCE on the percentages of CD8+ T lymphocyte were also more pronounced by the combined exposure of HCE and chlordane. In conclusion, our study suggests that greater exposures to dioxins, PCBs and organochlorine pesticides determined in this study (except dieldrin) influence the immune system of Japanese infant, although the clinical significance of these changes is uncertain.     

Dioxins in human milk and smoking of mothers

BACKGROUND: The relation between the levels of dioxins in human breast milk and the smoking habits of the mothers is controversial. To clarify this relationship, we analyzed data from the human milk survey in Japan. METHODS: The human milk survey has been conducted in Japan since 1997. Healthy pregnant women aged 20-39 years were recruited and 50 ml of breast milk was collected from them at 30 days after delivery. PCDDs, PCDFs, and dioxin-like PCBs were measured by using GC/MS. The smoking habits of the mothers were established by interviewing them soon after delivery and were classified into four categories: current smokers, ever smokers who quit smoking at the pregnancy, ever smokers who quit smoking before the pregnancy, and never smokers. The levels of dioxins in breast milk were compared in the four categories of smoking among 853 primiparas. In addition, we analyzed the association between dioxin levels and passive smoking among never smokers. The geometric means of the dioxin concentrations were calculated in order to compare the differences between dioxins. RESULTS: The geometric means of dioxin-like PCBs in milk of never smokers was the highest (9.2 pg TEQ/g fat); followed by ever smokers who quit smoking before the pregnancy, ever smokers who quit smoking at the pregnancy, and current smokers (7.5, 7.2, and 6.6 pg TEQ/g fat, respectively). The differences between these levels were statistically significant (ANOVA, p<0.001). No significant difference was observed between the level of dioxins in milk from never smokers subjected to passive smoking status and those who had not experienced passive smoking. CONCLUSION: The levels of dioxin-like PCBs in human milk were negatively related to the smoking habits of mothers.     

A sex pheromone component novel to Ostrinia identified from Ostrinia latipennis (Lepidoptera: Crambidae)

Summary. Extracts from the sex pheromone gland of Ostrinia latipennis (Lepidoptera: Crambidae) were analyzed by gas chromatography-electroantennographic detection (GC-EAD) and GC-mass spectrometry. Only an EAD-active compound was detected in the extract, and it was identified as (E)-11-tetradecenol (E11-14:OH). In a wind-tunnel bioassay, E11-14:OH elicited a series of mate finding behaviors from males, although it was far less active than virgin females and crude extract of the pheromone gland. The attractiveness of E11-14:OH to O. latipennis males was confirmed by field trapping experiments. Based on these findings, we concluded that E11-14:OH, which is novel to the genus Ostrinia, is a major component of the sex pheromone in O. latipennis. The significance of the use of alcohol in place of the usual acetates in Ostrinia is discussed in relation to the pheromone biosynthesis system. Received 9 December 1999; accepted 14 March 2000     

Decomposing detonation and deflagration properties of ozone/oxygen mixtures

In this study, the decomposing detonation and deflagration properties of ozone/oxygen mixtures of up to 20 vol.% of ozone in oxygen under high pressure of up to 1.0 MPa in a tube were experimentally investigated. The mixtures were ignited by an electric spark at the end of the tube. Flame propagation properties such as flame velocity and pressure were measured with thermocouples and piezo electric transducers mounted along the tube. Slow and constant flame propagation profiles were obtained. We also investigated the quenching ability of a wire gauze as well as the concentration limit for flame propagation. However, in spite of slow flame propagation velocity and easy flame quenching properties under these experimental conditions, direct initiation of detonation by the driver detonation of the stoichiometric oxy-hydrogen mixture was easily achieved at much lower concentrations than the limit of deflagration. The observed detonation properties, such as wave velocity and pressure, agreed fairly well with C–J calculated values. The detonation velocity (900–1200 m/s) and the pressure ratio to initial pressures (5–9.5) were not affected by the initial pressure of the mixtures. Near the detonation limit, typical spinning detonations with oscillatory pressure waves were observed.     

Metabolism and excretion of orally and intraperitoneally administered trimethylarsine oxide in the hamster

When trimethylarsine oxide (TMAO) was administered orally to hamsters once only, 86.9±11.1% of the administered dose of the compound was exreted in the urine during the following 24 hours: TMAO proved to be an arsenic compound eliminated extremely rapidly. The unchanged form of TMAO was the one and only trimethylarsenic compound (TMA) detected in the urine: in othe words, TMAO proved neither to be demethylated nor to be converted to arsenobetaine. It was shown, on the other hand, that TMAO is partly reduced in vivo and that only trimethylarsine was detected in expired air.     

Effects of buoyancy, transparency and zooplankton feeding on surface maxima and deep maxima: Comprehensive mathematical model for vertical distribution in cyanobacterial biomass

Inhomogeneous vertical distributions of the cyanobacterial biomass are widely observed during the summer season in stratified lake ecosystems. Among these are surface maxima characterized by surface scum formation and deep or subsurface maxima also known as deep chlorophyll maxima (DCM). The former occurs at the epilimnion in eutrophic lakes, and are usually caused by colonial cyanobacteria such as Microcystis. On the other hand, the latter occurs at the metalimnion and the upper part of the hypolimnion near the thermocline in oligotrophic lakes, and are referred to filamentous cyanobacteria such as Oscillatoria. The aim of this paper is to present a simple mathematical model that can simultaneously describe these phenomena including the annual and diurnal variations, emphasizing the roles of buoyancy regulation, transparency of the lake and zooplankton feeding on cyanobacteria. According to our computer analyses, the increased buoyancy, the low clarity of the lake and the low rate of zooplankton feeding take significant roles in formation of surface maxima, while the reversal of these factors makes deep maxima predominant. Our two-component model with nutrients and cyanobacteria can distinguish between two phenomena by changing the parameters for these factors, without altering the model itself.     

Development of waste gasification and gas reforming system for municipal solid waste (MSW)

To achieve both high-efficiency power generation and high detoxification performance, advanced-type waste power generation plants such as pyrolysis and gas reforming plants are suggested. Further surveys on actual operational data of these plants are required in terms of reliability of the system when it is introduced to waste disposal sites. To verify the technical effectiveness of advanced-type waste power generation using the pyrolysis and gas reforming method, we evaluated 10?tons/day of municipal solid wastes (MSW) treated in a demonstration plant. A demonstration test was conducted over 100?days including 35?consecutive days of operation treating MSWs. The test results show high recycling performance and harmless nature of the plant which proves it to be an excellent waste recycling system. Major test results are as follows: (1) stabilization of waste treatment is possible with the wastes of various qualities, (2) clean gas is produced from the waste whose energy recovery ratio is approximately 40?%. (3) 99.3?% weight % of dried waste are recovered as valuable materials such as clean gas, char and metal, (4) total amount of dioxin emission to the outside of the plant is very small, down to 0.0051–0.018?μg?TEQ per ton waste.