The individual and cumulative effect of brominated flame retardant and polyvinylchloride (PVC) on thermal degradation of acrylonitrile-butadiene-styrene (ABS) copolymer

Acrylonitrile-butadiene-styrene (ABS) copolymers without and with a polybrominated epoxy type flame retardant were thermally degraded at 450 degrees C alone (10 g) and mixed with polyvinylchloride (PVC) (8 g/2 g). Gaseous and liquid products of degradation were analysed by various gas chromatographic methods (GC with TCD, FID, AED, MSD) in order to determine the individual and cumulative effect of bromine and chlorine on the quality and quantity of degradation compounds. It was found that nitrogen, chlorine, bromine and oxygen are present as organic compounds in liquid products, their quantity depends on the pyrolysed polymer or polymer mixture. Bromophenol and dibromophenols were the main brominated compounds that come from the flame retardant. 1-Chloroethylbenzene was the main chlorine compound observed in liquid products. It was also determined that interactions appear at high temperatures during decomposition between the flame retardant, PVC and the ABS copolymer.     

Application of an ELISA for PCB 118 to the screening of dioxin-like PCBs in retail fish

A commercially available enzyme-linked immunosorbent assay (ELISA) kit was evaluated for the determination of toxic equivalents (TEQs) of dioxin-like polychlorinated biphenyls (PCBs) in retail fish. The ELISA was highly specific for 2,3',4,4',5-pentachlorobiphenyl (PCB 118), which is generally the most abundant dioxin-like PCB isomer found in fish. The quantitative limit of the ELISA (using 3,3',4'-trichloro-4-methoxybiphenyl as a surrogate standard for PCB 118) was 10 ng ml(-1) (125 pg assay(-1)) in the standard curve, corresponding to 50 pg PCB 118 g(-1) in the tested sample. Good recoveries of PCB 118 (78.7-112.3%) were obtained for spiked purified fish extracts according to the ELISA. Good linearity was also obtained in dilution tests using purified fish extracts. No significant interference of the matrix was observed in the ELISA when this purification procedure was used. Recovery tests in which PCB 118 was added to fish samples also resulted in acceptable recoveries (60.2-82.3%) in the ELISA following purification. The ELISA results for fish samples correlated well with the TEQ concentrations of dioxin-like PCBs obtained by high-resolution gas chromatography/high-resolution mass spectrometry (r = 0.92, n = 26). These data indicate that the ELISA kit is suitable for screening retail fish for the TEQs of dioxin-like PCBs.     

Depolymerization of Waste PET with Phosphoric Acid–Modified Silica Gel Under Microwave Irradiation

Chemical recycling of waste poly(ethylene terephthalate) (PET) using phosphoric acid–modified silica gel as a solid catalyst is reported. Advantageously, microwave irradiation was used to progress the depolymerization of PET. In this study, depolymerization of PET with a small amount of water is suggested as a suitable method. The depolymerized product, terephthalic acid was obtained and assigned by ¹H NMR and FT-IR spectroscopy. Finally, over 90 % conversion to terephthalic acid was achieved when waste plastic bottles were treated with the method. This results confirm the importance of the microwave power technique as a promising recycling method for plastic bottles made from PET, resulting in monomer recovery in addition to substantial energy saving.     

Factors associated with prehospital death among traffic accident patients in Osaka City,Japan: A population-based study

Objective: Although it is important to assess the factors associated with traffic accident fatalities to decrease them as a matter of public health, such factors have not been fully identified.

Methods: Using a large-scale data set of ambulance records in Osaka City, Japan, we retrospectively analyzed all traffic accident patients transported to hospitals by emergency medical service personnel from 2013 to 2014. In this study, prehospital death was defined as that occurring at the scene or in the emergency department immediately after hospital arrival. We assessed prehospital factors associated with prehospital death due to traffic accidents by logistic regression models.

Results: This study enrolled 28,903 emergency patients involved in traffic accidents, of whom 68 died prehospital. In a multivariate model, elderly patients aged ≥75 years (adjusted odds ratio [AOR] = 4.34; 95% confidence interval [CI], 2.29–8.23), nighttime (AOR = 2.75; 95% CI, 1.65–4.70), and type of injured person compared to bicyclists such as pedestrians (AOR = 9.58; 95% CI, 5.07–17.99), motorcyclists (AOR = 2.75; 95% CI, 1.21–6.24), and car occupants (AOR = 2.98; 95% CI, 1.39–6.40) were significantly associated with prehospital death due to traffic accidents. In addition, the AOR for automobile versus nonautomobile as the collision opponent was 4.76 (95% CI, 2.30–9.88).

Conclusions: In this population, the factors associated with prehospital death due to traffic accidents were elderly people, nighttime, and pedestrian as the type of patient. The proportion of prehospital deaths due to traffic accidents was also high when the collision component was an automobile.     

Factors contributing to seasonal variations in wet deposition fluxes of trace elements at sites along Japan Sea coast

In this study, we measured the wet deposition fluxes of ten trace elements (As, Cd, Cr, Cu, Mn, Ni, Pb, Sb, V and Zn) from December 2002 to March 2006 at three sites along the Japan Sea coast, which have been strongly affected by the long-range transport of air pollutants from the Asian continent. Also, factors, contributing to their seasonal variations were investigated. At the northern and central sites, the monthly wet deposition fluxes of all or most trace elements greatly increased during the cold season (typically, November–April), along with their monthly average (volume-weighted) concentrations in the precipitation. The cold/warm season ratios for the average concentrations of trace elements in precipitation were within the range of 2.7–5.1 at the northern site and 1.8–5.9 at the central site, which were similar to the average scavenging ratios (= concentration in precipitation/concentration in air) at each site. However, there were small differences (0.47–1.2 at the northern site and 0.73–1.7 at the central site) in the ratios of average concentrations in air between the two seasons. These suggest that the increase in the wet deposition fluxes of trace elements during the cold season is due to increases in their scavenging ratios. On the other hand, the result for the southern site was different from those at the other sites. The number of days when the daily maximum wind speed exceeded 10 m s^?1 at the meteorological observatories near the study sites increased markedly during the cold season at the northern and central sites, showing that strong winds usually blow during the cold season at those sites, but not at the southern site. Higher wind speed transports larger amounts of constituents into the cloud system, which can result in their increased concentrations in precipitation. Thus, high scavenging ratios of trace elements during the cold season may be caused by the increase in their amounts of discharge into the cloud system owing to high wind speed, suggesting that wind speed is an important factor in the seasonal variations in the wet deposition fluxes.     

A choice experiment of the residential preference of waste management services - the example of Kagoshima city, Japan

Municipal governments have attempted to reduce waste disposal and increase recycling rates in Japan. However, it is difficult to get full cooperation from residents. Using experiments in which residents are given an opportunity to choose the components of the waste management system (choice experiments), we measure the cost of each characteristic of the waste collection services. The estimation result reveals that there are trade-offs between the risk, payments, and handling costs. The marginal loss in utility revenues from an increase in the types of waste being separated is almost 200 yen (US$ 1.74) and a 1% increase in the recycling rate raises the cost of service by 53 yen (US$ 0.46). In addition, the results show the need for communications about risks between municipal authorities and residents.     

Identifying a breeding habitat of a critically endangered fish, <Emphasis Type="Italic">Acheilognathus typus</Emphasis>, in a natural river in Japan

Freshwater biodiversity has been severely threatened in recent years, and to conserve endangered species, their distribution and breeding habitats need to be clarified. However, identifying breeding sites in a large area is generally difficult. Here, by combining the emerging environmental DNA (eDNA) analysis with subsequent traditional collection surveys, we successfully identified a breeding habitat for the critically endangered freshwater fish Acheilognathus typus in the mainstream of Omono River in Akita Prefecture, Japan, which is one of the original habitats of this species. Based on DNA cytochrome B sequences of A. typus and closely related species, we developed species-specific primers and a probe that were used in real-time PCR for detecting A. typus eDNA. After verifying the specificity and applicability of the primers and probe on water samples from known artificial habitats, eDNA analysis was applied to water samples collected at 99 sites along Omono River. Two of the samples were positive for A. typus eDNA, and thus, small fixed nets and bottle traps were set out to capture adult fish and verify egg deposition in bivalves (the preferred breeding substrate for A. typus) in the corresponding regions. Mature female and male individuals and bivalves containing laid eggs were collected at one of the eDNA-positive sites. This was the first record of adult A. typus in Omono River in 11 years. This study highlights the value of eDNA analysis to guide conventional monitoring surveys and shows that combining both methods can provide important information on breeding sites that is essential for species’ conservation.     

The effects of current water management practices on methane emissions in Japanese rice cultivation

Cultivated wetland rice fields are a source of methane (CH₄) emissions. To estimate CH₄ emissions and develop policies to reduce such emissions, information on water management at the farm level is crucial. It is known that farmers implement midseason drainage (MD) to increase rice yields and save water. However, little is known about whether MD is carried out in soils where CH₄ emissions are high and how part-time status will influence management. The objective of this study is to identify factors that determine MD implementation using a binomial logistic regression model based on a farm-level survey in Japan and to indicate possible changes in estimates of CH₄ emissions, accounting for current water management practices. The implementation rates were significantly higher where the soil types were classified as having the potential for high CH₄ emissions. Under current water management practices, the duration of MD and the percentage of continuous flooding were 5 to 7 days longer and approximately 7 % higher, respectively, than the values used by the Greenhouse Gas Inventory Office of Japan, which in turn are used to report greenhouse gas emissions to the United Nations Framework Convention on Climate Change. By accounting for current water conditions with the Tier 2 method, this study indicates that national estimates of CH₄ emissions from rice straw application areas could be lowered by 12.7 %. These results may contribute to the development of a mitigation policy that will help to further reduce CH₄ emissions.     

Influence of americium-241 on the microbial population and biodegradation of organic waste

The present study investigated the influence of ²⁴¹Am on microbial growth and the degradation of organic waste. Leachate samples collected in a lysimeter were periodically analyzed for bacterial growth, under both aerobic and anaerobic conditions. ²⁴¹Am inhibited bacterial growth, and the degradation of organic matter was delayed in comparison with the control. Minimal inhibitory concentration assays and survival curves revealed that it inhibits the growth of Pseudomonas putida F1. The assay also revealed that ²⁴¹Am is more toxic than ²³⁸U, Zn²⁺ and Cd²⁺. This study further led to the finding of four new radionuclide-tolerant bacterial strains: Flavobacterium spp., Pseudomonas gladioli, Chryseobacterium indologenes and Ochrobactrum anthropi. The survival curves of P. gladioli, C. indologenes revealed that these bacteria are resistant to metal as consortia.