Butyltin residues in livers of humans and wild terrestrial mammals and in plastic products

Butyltin compounds (BTs) including mono-(MBT), di-(DBT) and tributyltin (TBT) were determined in livers of humans and wild terrestrial mammals, such as raccoon dogs (Nyctereutes procyonoids) and monkeys (Macaca fuscata) from Japan. In addition, 22 samples of plastic products were analyzed. BT residues were detected in all the liver samples of humans and raccoon dogs, with concentrations of <360 ng/g wet wt, whereas concentrations in the liver of monkeys were either less than the detection limit or were only in trace levels. Elevated concentrations of BTs, particularly DBT (<140,000 ng/g) and MBT (<130,000 ng/g), were found in some plastic products, such as baking parchments made from siliconized paper and gloves made up from polyurethane. The results of a cooking test using the above baking parchment indicated the transfer of BTs to foodstuffs. These observations suggest expansion of BT contamination among terrestrial mammals. BT pollution from industrial appliances, such as plastic stabilizers and catalysts other than those of marine origin as antifouling agents, are suggested as alternative sources of exposure.     

100-year simulation of mercury emissions from landfilled stabilized mercury waste

Journal of Material Cycles and Waste Management - Owing to Minamata Convention on mercury, the final disposal of mercury in environmentally safe manners will be required. Mercury disposal in...     

Estimation of critical ratio of bentonite addition to tuff sand

A design method was proposed to determine the critical ratio of bentonite addition, based on a macro void ratio that considers the swelling property of bentonite. The critical ratio of bentonite addition was defined as the ratio corresponding to a macro void ratio of zero. However, when lightweight soil such as tuff sand is mixed with bentonite, the estimated critical ratio of bentonite addition is too high. Several tests on the water absorbing property of tuff sand and its permeability were conducted to confirm the concept of a revised macro void ratio. The revised macro void ratio, which takes into account the swelling of bentonite and the particle pores of lightweight soil, is much smaller than the former macro void ratio for a given ratio of bentonite addition. The estimated critical ratio of bentonite addition to tuff sand that gives a revised macro void ratio of zero is around 18% and is in good agreement with the ratio of bentonite addition beyond which the value of hydraulic conductivity does not decrease markedly.     

Aromatization of waste polyolefin pyrolysate over H-ZSM-5 zeolite-supported gallium oxide catalysts

H-ZSM-5 zeolite-supported gallium oxides were studied as aromatization catalysts for polyolefin pyrolysate. The catalysts were prepared by a conventional physical mixing method with a gallium content of 1.0 and 4.5 wt% and were reduced in flowing hydrogen at 585°C. To test their activity, a polyolefin sample was pyrolyzed and passed over a heated catalyst layer; the product was analyzed by gas chromatography/mass spectrometry. A continuous-flow fixed-bed reactor was used for aromatization of a model gas of polyolefin pyrolysate. For chlorine-free sources at 450°C, the catalyst with only 1.0 wt% gallium exhibited activity comparable to a gallium silicate catalyst. For chlorine-contaminated sources, the catalyst with 4.5 wt% gallium sustained catalytic activity for long periods. From the activity test results, it was found that zeolite-supported gallium catalysts prepared by the physical mixing method are suitable for converting polyolefin into aromatic hydrocarbons.     

Effect of complexation with humic substances on diffusion of metal ions in water

Most studies on diffusion of metal ions in various water-rock systems have dealt with free ions (hydrated ions). However, it is often the case that metal ions are dissolved as complexed species such as with humic substances (HS) in natural waters. Hence, we need to study the diffusion behavior of these complexes in order to understand fully the diffusion phenomenon in natural. In this study, the diffusion coefficients of free metal ions (M(z+)) and their complexes with HS (M-HS) were compared to understand the effect of complexation with HS on the diffusion of metal ions such as Co(2+), Cd(2+), and rare earth elements (REE(3+)). Although the diffusion coefficients of free metal ions depend on ionic potential, such dependence was not observed in the presence of HS. Comparing the diffusion coefficients of metal complexes with ethylenediaminetetraacetate (EDTA), fulvic acid, and humic acid showed that the molecular weight (MW), or the size of the ligand, is of primary importance for the diffusion of M-HS. As a consequence, the diffusion coefficients of all REE(3+) were similar in the presence of HS, while they were different in the absence of HS due to the different size of each REE(3+). The similarity among the diffusion coefficients of REE-HS was caused by the much larger size of HS compared with each ion. However, the distribution coefficients of M-HS were not similar among REE(3+), Cd(2+), and Co(2+). REE(3+) and Cd(2+) which have higher affinities for larger MW fraction in HS diffused slower than Co(2+) which favors smaller MW fraction. The results show that the affinity for different MW fractions among HS controls the diffusion of M-HS, which must be important to predict precisely the diffusion behavior of metal ions bound to HS in natural systems.     

Mechanical treatment of automobile shredder residue for its application as a fuel

Enforcement of the Automobile Recycling Law in Japan requires utilization of automobile shredder residue (ASR). However, the high contents of copper (∼5%) and chlorine (∼1%) in ASR stand in the way of practical application. We studied methods for the removal of copper and chlorine from ASR so that it could be utilized as a fuel. By compression of the ASR for solidification with an extruder, the polyvinylchloride (PVC) that covered electrical cables was softened and stripped from the copper wire. The solidified ASR was comminuted with cutter mills and classified by dry density separation. The copper content of the obtained light products was 0.2%–0.5%. Furthermore, we studied the possibility of dechlorination of the ASR by mechanochemical (MC) activation. The light product of the ASR was milled with CaO or CaCO₃. The chlorine content decreased to about one-tenth of the original value after MC activation over 8 h. Therefore, the combined processing of softening–stripping and comminution liberated the PVC-covered cables and decreased the copper content of the ASR. In addition, dechlorination of the ASR was also possible by MC activation with the addition of calcium compounds.     

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.     

Coastal hazards and community-coping methods in Bangladesh

Addressing one of the most vulnerable coastal communities in Bangladesh, this paper explores people’s perception and vulnerabilities to coastal hazards. At the same time, it investigates the methods that communities apply to cope with different coastal hazards. Findings revealed that people perceived an increase in both the intensity of hazards and their vulnerabilities. In spite of having a number of socio-economic and locational factors enhancing their vulnerabilities, the community is creating their own ways to cope with these hazards. For different aspects of life like shelter, employment, water supply, and health, communities apply different coping methods that vary with the types of hazard. Efforts have also been made by governments and NGOs to manage coastal hazards. By highlighting both community-coping methods and efforts of development organizations, this paper attempts to devise an integrated approach for managing the coastal hazards that occur in Bangladesh.     

Urban climate in the Tokyo metropolitan area in Japan

Long-term climate changes related with urbanization in Tokyo, Japan, and recent temperature and heavy rainfall distribution in the Tokyo metropolitan area are reviewed. A relatively high temperature increase in annual mean temperature at the rate of 3.0°C/century was detected in Tokyo for the period 1901–2015. Some observational evidence showed the existence of both thermal and mechanical effects of urbanization on recent heavy rainfall occurrences, and modeling studies also support precipitation enhancement. Urban influences were recognized in other climatological elements, such as number of fog days, relative humidity, and wind circulation.