Biohydrogen using leachate from an industrial waste landfill as inoculum

Since hydrogen is a renewable energy source, biohydrogen has been researched in recent years. However, data on hydrogen fermentation by a leachate from a waste landfill as inoculum are scarce. We investigated hydrogen production using a leachate from an industrial waste landfill in Kanagawa Prefecture. The results showed no methane gas production, and the leachate was a suitable inoculum for hydrogen fermentation. The maximum H₂ yield was 2.67 mol of H₂ per mol of carbohydrate added, obtained at 30°C and an initial pH of 7. The acetate and butyrate production was significant when the H₂ yield was higher. Oxidation–reduction potential analysis of the culture suggested that hydrogen-producing bacteria in the leachate were facultative anaerobic. Scanning electron microscope observations revealed that the hydrogen-producing bacteria comprised bacilli about 2 μm in length.     

Improvement of an efficient separation method for chemicals in diesel exhaust particles: analysis for nitrophenols

GOAL, SCOPE, AND BACKGROUND: Diesel exhaust is believed to consist of thousands of organic constituents and is a major cause of urban pollution. We recently reported that a systematic separation procedure involving successive solvent extractions, followed by repeated column chromatography, resulted in the isolation of vasodilatory active nitrophenols. These findings indicated that the estimation of the amount of nitrophenols in the environment is important to evaluate their effect on human health. The isolation procedure, however, involved successive solvent extractions followed by tedious, repeated chromatography, resulting in poor fractionation and in a significant loss of accuracy and reliability. Therefore, it was crucial to develop an alternative, efficient, and reliable analytical method. Here, we describe a facile and efficient acid-base extraction procedure for the analysis of nitrophenols. MATERIALS AND METHODS: Diesel exhaust particles (DEP) were collected from the exhaust of a 4JB1-type engine (ISUZU Automobile Co., Tokyo, Japan). Gas chromatography-mass spectrometry (GC-MS) analysis was performed with a GCMS-QP2010 instrument (Shimadzu, Kyoto, Japan). RESULTS: A solution of DEP in 1-butanol was extracted with aqueous NaOH to afford a nitrophenol-rich oily extract. The resulting oil was methylated with trimethylsilyldiazomethane and subsequently subjected to GC-MS analysis, revealing that 4-nitrophenol, 3-methyl-4-nitrophenol, 2-methyl-4-nitrophenol, and 4-nitro-3-phenylphenol were present in significantly higher concentrations than those reported previously. DISCUSSION: Simple acid-base extraction followed by the direct analysis of the resulting extract by GC-MS gave only broad peaks of nitrophenols with a poor detection limit, while the GC-MS analysis of the sample pretreated with (trimethylsilyl)diazomethane gave satisfactorily clear chromatograms with sharp peaks and with a significantly lowered detection limit (0.5 ng/ml, approximately 100 times). CONCLUSION: The present method involving an acid-base extraction, in situ derivatization, and GC-MS analysis has shown to be a simple, efficient, and reliable method for the isolation and identification of the chemical substances in DEP.     

Isoprene emission from tropical trees in Okinawa Island, Japan

This study surveyed isoprene emission from 42 indigenous and exotic tropical trees in subtropic Okinawa, Japan. Of the 42 trees studied, 4 emitted isoprene at a rate in excess of 20 μg g⁻¹ h⁻¹, and 28 showed the rates of 1–10 μg g⁻¹ h⁻¹. The remainder emitted less than 1 μg g⁻¹ h⁻¹. The majority of trees in this study may therefore fall within the lower emitting species. However, species in Moraceae that is indigenous in Okinawa emitted isoprene at relatively higher rates with an average of 14.2 μg g⁻¹ h⁻¹. The highest emission rate of 107.1 μg g⁻¹ h⁻¹ for Ficus virgata yielded the area basis rate of 47.4 nmol m⁻² s⁻¹, which is almost equivalent to the rate of high emitting species. Furthermore, a linear relationship between light intensity and isoprene emission was noted with Ficus virgata up to 1700 μmol m⁻² s⁻¹. These findings may show the potential importance of subtropical areas as sources of isoprene to the atmosphere.     

Reductive dechlorination of non-ortho substituted polychlorinated biphenyls by ultraviolet irradiation in alkaline 2-propanol

The photodechlorination pathways of 3,3′,4,5,5′-pentachlorobiphenyl (3,3′,4,5,5′-PentaCB) and the related lower polychlorinated biphenyl congeners irradiated at 254 nm in alkaline 2-propanol were elucidated. Steric effect is the most important factor for controlling the dechlorination pattern of these substrates. Electronic effect also influences the photoreactivity of chlorine substituents.     

Microcystin accumulation and biochemical responses in the edible clam Corbiculaleana P. exposed to cyanobacterial crude extract

We investigated the accumulation and effects of cyanobacterial crude extract(CCE)containing microcystins(MCs) on the edible clam Corbicula leana P. Toxic effects were evaluated through the activity of antioxidant and detoxification enzymes: catalase(CAT),superoxide dismutase(SOD), and glutathione-S-transferases(GSTs) from gills, foot, mantle and remaining soft tissues. Clams were exposed to CCE containing 400 μg MC-LReq/L for10 days and were then kept in toxin-free water for 5 days. Clam accumulated MCs(up to 3.41 ± 0.63 μg/g dry weight(DW) of unbound MC and 0.31 ± 0.013 μg/g DW of covalently bound MC). Detoxification and antioxidant enzymes in different organs responded differently to CCE during the experiment. The activity of SOD, CAT, and GST in the gills and mantle increased in MC-treated clams. In contrast, CAT and GST activity was significantly inhibited in the foot and mostly only slightly changed in the remaining tissues. The responses of biotransformation, antioxidant enzyme activity to CCE and the fast elimination of MCs during depuration help to explain how the clam can survive for long periods(over a week) during the decay of toxic cyanobacterial blooms in nature.     

The Effects of the Level of Alertness During the Rest Period on Subsequent Performance

The aim of this study was to examine how to take an effective rest to prevent a decline in alertness at work. The relationship between alertness during the rest period and subsequent task performance were investigated. The electroencephalogram (EEG) during the rest period was classified into 3 types, and these types had a significant effect on performance after the rest period. Type 1 (increasing in theta, alpha 2, and beta 1 power) was the best one for carrying out the task, whereas performance gradually declined in Type 3 (no change in EEG activity). In the case of Type 1, the method that would relieve sleep inertia had a more positive impact on performance after the rest period.     

Immunotoxic effects of environmental toxicants in fish �� how to assess them?

Numerous environmental chemicals, both long-known toxicants such as persistent organic pollutants as well as emerging contaminants such as pharmaceuticals, are known to modulate immune parameters of wildlife species, what can have adverse consequences for the fitness of individuals including their capability to resist pathogen infections. Despite frequent field observations of impaired immunocompetence and increased disease incidence in contaminant-exposed wildlife populations, the potential relevance of immunotoxic effects for the ecological impact of chemicals is rarely considered in ecotoxicological risk assessment. A limiting factor in the assessment of immunotoxic effects might be the complexity of the immune system what makes it difficult (1) to select appropriate exposure and effect parameters out of the many immune parameters which could be measured, and (2) to evaluate the significance of the selected parameters for the overall fitness and immunocompetence of the organism. Here, we present - on the example of teleost fishes - a brief discussion of how to assess chemical impact on the immune system using parameters at different levels of complexity and integration: immune mediators, humoral immune effectors, cellular immune defenses, macroscopical and microscopical responses of lymphoid tissues and organs, and host resistance to pathogens. Importantly, adverse effects of chemicals on immunocompetence may be detectable only after immune system activation, e.g., after pathogen challenge, but not in the resting immune system of non-infected fish. Current limitations to further development and implementation of immunotoxicity assays and parameters in ecotoxicological risk assessment are not primarily due to technological constraints, but are related from insufficient knowledge of (1) possible modes of action in the immune system, (2) the importance of intra- and inter-species immune system variability for the response against chemical stressors, and (3) deficits in conceptual and mechanistic assessment of combination effects of chemicals and pathogens.     

Basic Research on the Emission of Polycyclic Aromatic Hydrocarbons caused by Waste Incineration

The emission of polycyclic aromatic hydrocarbons (PAH) caused by municipal waste incineration varies according to waste composition and operating parameters such as furnace temperature and excess air. However, to obtain a sample sufficient to measure the emission of PAH at trace levels, it is necessary to operate the incinerator for many hours. Since during these lengthy periods it has not always been possible to maintain stable conditions, it is very difficult to determine the relationship between the emission and waste composition.

In our basic research, therefore, we used municipal waste with an artificially regulated composition for our combustion experiments, and by using an experimental Incinerator we examined the emission behavior of PAH with respect to changes in waste composition and combustion conditions. The following facts were revealed by the results: ? The PAH found in the flue gas were predominantly the more volatile compounds.

? When municipal waste was incinerated at over 850 °C, the concentration of PAH in the flue gas increased rapidly as the proportion of plastics in the waste increased from 0 to 24 percent.

? The elimination of plastics from municipal waste by separate collection and the improvement of combustion conditions can effectively diminish the emission of PAH.

     

Recent trends in ILO conventions related to occupational safety and health.

The present study was conducted to analyze the ratification status of International Labour Organization (ILO) conventions related to occupational safety and health (OSH) by ILO member states in terms of national indicators (length of ILO membership and national income status) and regional affiliation. 17 conventions designated as OSH-related by the 2003 International Labour Conference were examined. In general, countries with longer ILO membership ratified higher numbers of conventions related to OSH. With some variation, long-membership countries had the largest number of ratifications, followed by middle- and short-membership countries in all regions. There were also incremental increases in the number of ratifications for OSH-related conventions according to the national income status. Common regional characteristics that could not be explained by the factors studied also existed. Future efforts to increase ratification at an international level will need to consider the factors influencing ratification practice among the member states.     

Carbon Molecular Sieving Membranes Derived from Lignin-Based Materials

Carbon molecular sieving membranes were prepared by pyrolysis of lignocresol derived from lignin by the phase-separation method. Lignocresol membranes formed by a dip process on a porous -alumina tubing were carbonized at 400–800°C under nitrogen atmosphere. The thickness of the membrane formed on the outer surface of the substrate was about 400 nm judging from SEM observation. Gas-evolving behavior of lignocresol was measured using thermogravimetry-mass spectrometry (TG-MS). The gaseous products evolved from lignocresol included a number of fragments with higher molecular weights; whereas those from phenolic resin are mainly due to phenol and methylphenol. These evolved pyrolysis fragments effectively contribute to micropore formation of carbonized lignocresol membranes. Gas permeation rates through the membrane decreased in the order of increasing kinetic molecular diameter of the penetrant gas, and the membrane behaved like a molecular sieve. The permeation properties were dependent on heating conditions, and a pyrolysis temperature of 600°C gave the best membrane performance. Gas selectivities of the membrane prepared at 600°C were 50, 8, 290, and 87 for CO₂/N₂, O₂/N₂, H₂/CH₄, and CO₂/CH₄ at 35°C, respectively.