Concentration and specific activity of fallout 137Cs in extracted and particle-size fractions of cultivated soils

Fallout (137)Cs and stable Cs in soils were separated with two extractants (1M CH(3)COONH(4) solution and 0.8M CH(3)COONH(4) in 5% HNO(3) solution after H(2)O(2) oxidization). The residue remaining after removal of the oxidizable organic-bound fraction was separated into the particle-size fractions including clay, silt, fine sand and coarse sand with a sieving and sedimentation method. Then, the concentrations of (137)Cs and stable Cs in the extracted fractions and the particle-size fractions were determined. The (137)Cs contents in the exchangeable and organic-bound fractions in the soil were approximately 10 and 20%, respectively. The (137)Cs content in the strongly bound fraction was about 70%, and the concentration of (137)Cs in the clay was the richest among the particle-size fractions. The specific activity of (137)Cs (concentration ratio of fallout (137)Cs/stable Cs) decreased in the order exchangeable, organic-bound and strongly bound fractions. The data suggest that equilibrium between (137)Cs and stable Cs was not reached among those fractions, even though most of the (137)Cs that had been deposited on the soil was derived from fallout weapons tests that occurred several decades ago. The concentration of (137)Cs among the particle-size fractions in each soil was different, whereas the specific activity of (137)Cs in the particle-size fractions had a relatively similar value.     

Performance of water cut-off and remediation promotion techniques at coastal waste landfill sites

This paper proposes the construction of steel pipe sheet pile (SPSP) cutoff walls for promoting remediation of water-soluble toxic substances and containment of water-soluble toxic substances at landfill sites in order to maintain and ensure the environmental safety of waste landfill sites over time. It investigates environmental safety at coastal waste landfill sites by applying water cut-off and remediation promotion techniques to the joint sections of SPSP water cut-off walls that provide shore protection for waste landfills. Results from the research herein show that the construction of SPSP water cut-off walls with features such as the containment of water-soluble toxic substances and remediation promotion is possible by applying water cut-off and remediation techniques to H–H joints, which are structural joint components of SPSP walls. In addition, they show that the performance of remediation in H–H joints can be controlled by adjusting the water cut-off efficiency of the H–H joint flange.     

Control of Mercury Emissions from a Municipal Solid Waste Incinerator in Japan

Abstract

The control of Hg emissions from a municipal solid waste incinerator (MSWI) is very important, because more than 78% of municipal solid waste (MSW) is incinerated. The Hg content of coal used in utility boilers is relatively low in Japan. In this study, recent trends in the Hg content of MSW in Japan and activated carbon (AC) injection as a control technology of Hg emission from an MSWI are discussed. The effect of AC injection on Hg removal from flue gas in an MSWI was investigated by pilot-scale experiments using a bag filter (BF). The injection of AC increases the Hg reduction ratio by 20–30% compared with cases without AC injection. The Hg reduction ratio increases as the flue gas temperature decreases. The Hg reduction ratio is closely related to the inlet Hg concentration and was expressed with a Langmuir-type adsorption isotherm.     

Novel enzymatic activity of cell free extract from thermophilic Geobacillus sp. UZO 3 catalyzes reductive cleavage of diaryl ether bonds of 2,7-dichlorodibenzo-p-dioxin

We characterized the ability of the cell free extract from polychlorinated dibenzo-p-dioxins degrading bacterium Geobacillus sp. UZO 3 to reduce even highly chlorinated dibenzo-p-dioxins such as octachlorodibenzo-p-dioxins in incineration fly ash. The degradation of 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) as a model dioxin catalyzed by the cell free extract from this strain implicates that the ether bonds of 2,7-DCDD molecule undergo reductive cleavage, since 4′,5-dichloro-2-hydroxydiphenyl ether and 4-chlorophenol were detected as intermediate products of 2,7-DCDD degradation.     

Current status of waste to power generation in Japan and resulting reduction of carbon dioxide emissions

We discuss the current status of waste to power generation (WPG) in Japan and various scenarios involving indirect reduction of carbon dioxide emissions by WPG. The number of WPG facilities domestically as of 2005 was 286. Power generation capacity attained 1,515 MW and power generation 7,050 GWh/year. This amount substitutes energy otherwise acquired from natural resources such as fossil fuels in thermal power plants. If the basic unit of carbon dioxide is 0.555 kg-CO₂/kWh, then the corresponding carbon dioxide emission reduction is calculated to be 3.9 million tons, equivalent to 26.7% of the 14.6 million tons emitted by municipal solid waste incinerators (MSWI) in 2005. Using various existing technological options, the power generation efficiency could reach more than 20% in MSWI facilities with capacity of 300 tons/day, although present efficiency is only 12.0%. If about 85% of MSW were incinerated in MSWI with power generation efficiency of 20% as a feasible assumption, the total power generation and the corresponding carbon dioxide reduction would be 16,540 GWh/year and 9.18 million tons, respectively, equivalent to 62.7% of the carbon dioxide emitted by MSWI. Also, the ratio of the additional reduction of carbon dioxide emissions by WPG to the total additional reduction (20,000 ktons/year) in Japan during the first commitment period would be 26.3%, suggesting that promotion of WPG in MSWI is an effective option for prevention of global warming.     

Community-scale analysis of the farmland abandonment occurrence process in the mountain region of Ladakh,India

Farmland abandonment has been a significant issue in mountain regions. Thus, many studies have attempted to uncover its driving factors. Most existing studies take a large- or meso-scale view of mountain regions, and there are a few studies that provide community-level analysis. Therefore, it is unclear how ecological and sociopolitical factors are actually combined to influence farmland abandonment at a community level. Thus, we conducted a field survey in the mountain village of Ladakh, northern India, beginning in 2009 and tried to understand the farmland abandonment occurrence process from the viewpoint of traditional altitudinal models of land use. Using data collected during the survey, a relationship between altitude and farmland abandonment was established. However, this relationship was complex, combining traditional forms of land use system in the village. The altitudinal model of land use was very common in mountain regions; thus, discussions of current land use issues should be based on an understanding of such traditional altitudinal systems.     

Change in the concentrations of iron in different size fractions during growth of the oceanic diatom Chaetoceros sp.: importance of small colloidal iron

 Laboratory culture experiments were performed to study the changes in size-fractionated Fe concentrations during the growth of the oceanic diatom Chaetoceros sp. Fe concentration was estimated for three size fractions: large labile particles (>0.2 μm), small colloidal particles (0.2 μm to 200 kDa) and soluble species (<200 kDa). The size-fractionated Fe concentration in the nutrient-enriched filtered seawater medium without diatom cells became stable within 4 d after the spike of FeCl₃ solution. Light irradiation by white fluorescent tubes with a 14 h light:10 h dark cycle did not significantly alter concentrations of the size-fractionated Fe. For the phytoplankton culture experiment, Fe-starved diatom cells were inoculated into the nutrient-enriched media aged for 19 d after the addition of FeCl₃. With the growth of diatom cells, total acid-labile Fe concentrations decreased from 0.60 to 0.46 nM during 7 d of incubation. However, only the concentration of the small colloidal particles showed a significant decrease; the concentration of the other size fractions remained relatively constant. Although the media still contained sufficient amounts Fe as large labile particles and soluble species, diatom cells appeared to be Fe-limited once Fe as small colloidal particles had been used up. These results suggest that Fe in the small colloidal particle fraction was the most dynamic size fraction during the growth of the diatom Chaetoceros sp. In addition, to better understand Fe dynamics in the ocean, we must consider the influence of phytoplankton growth on small colloidal Fe [which is typically included in the dissolved Fe fraction (<0.2 μm)]. Received: 9 December 1999 / Accepted: 5 May 2000     

Assessing local-scale inclusive wealth: a case study of Sado Island,Japan

Present trends of urbanization are accompanied by increasing demographic and economic shrinkage of rural regions. In countries such as Japan, these rural regions trail behind metropolitan counterparts according to GDP, the conventional measure used to guide governmental policies. Yet, past research suggests that these regions may be undervalued. Further, the Inclusive Wealth Index (IWI), largely only used at the national level, may be able to capture aspects previously missed. As such, our study attempts to highlight the wealth of rural regions by comparing the inclusive wealth of Sado Island and Japan between 1990 and 2014. Minor methodological modifications were made according to data availability at the local level and to improve the accuracy of human capital estimations. Results captured the ongoing shrinkage of Sado and demonstrate the distinct potential of the IWI as a stock measure. Sado’s per capita wealth was about 10% lower than the national averages, but its natural capital was about threefold national averages. Supplementary estimations of the natural capital of fisheries and cultivated forests suggest that inclusion of additional factors in the evaluation would further increase the relative valuation of rural regions. We discuss implications of our estimations for wellbeing, and conclude with a critical appraisal of the IWI calculation towards policy implementation of the index.     

Removing arsenic from groundwater in Cambodia using high performance iron adsorbent

In Cambodia, groundwater has been contaminated with arsenic, and purification of the water is an urgent issue. From 2010 to 2012, an international collaborative project between Japan and Cambodia for developing arsenic-removing technology from well water was conducted and supported by the foundation of New Energy and Industrial Technology Development Organization, Japan. Quality of well water was surveyed in Kandal, Prey Veng, and Kampong Cham Provinces, and a monitoring trial of the arsenic removal equipment using our patented amorphous iron (hydr)oxide adsorbent was performed. Of the 37 wells surveyed, arsenic concentration of 24 exceeded the Cambodian guideline value (50 μg L^?1), and those of 27 exceeded the WHO guideline for drinking water (10 μg L^?1). Levels of arsenic were extremely high in some wells (>1,000–6,000 μg L^?1), suggesting that arsenic pollution of groundwater is serious in these areas. Based on the survey results, 16 arsenic removal equipments were installed in six schools, three temples, two health centers, four private houses, and one commune office. Over 10 months of monitoring, the average arsenic concentrations of the treated water were between 0 and 10 μg L^?1 at four locations, 10–50 μg L^?1 at eight locations, and >50 μg L^?1 at four locations. The arsenic removal rate ranged in 83.1–99.7 %, with an average of 93.8 %, indicating that the arsenic removal equipment greatly lower the risk of arsenic exposure to the residents. Results of the field trial showed that As concentration of the treated water could be reduced to <10 µg L^?1 by managing the As removal equipment properly, suggesting that the amorphous iron (hydr)oxide adsorbent has high adsorbing capacity for As not only in the laboratory environment but also in the field condition. This is one of the succeeding As removal techniques that could reduce As concentration of water below the WHO guideline value for As in situ.     

Measures to prevent emissions of PCDDS/DFs and co-planar PCBs from crematories in Japan

In this study, PCDDs/DFs and co-planar PCBs concentrations in flue gases from 17 crematories and in fly ashes and bottom ashes (mainly bone) from several crematories were measured to grasp the present state of PCDDs/DFs emissions from crematories. The effects of several factors were discussed to prevent PCDDs/DFs emissions from crematories. Total concentration (normalized by 12% O2) of PCDDs/DFs was ranged from 4.9 to 1200 ng/m3 N, and toxic equivalent concentration was ranged from 0.064 to 24 ng TEQ/m3 N. As the results obtained in this research, the following measures to reduce PCDDs/DFs emission are recommended for existing crematories: (1) keeping the temperature at 800 degrees C in main/secondary chambers during a whole cremation, and (2) lowering the temperature in the dust collector. For newly installed crematories, following measures to prevent PCDDs/DFs emission including the measures for existing ones are recommended: (1) connecting one secondary chamber to one main chamber, (2) installing the high efficiency dust collector and reducing dust concentration to less than 0.01 g/m3 N, and (3) installing the sampling point for monitoring of PCDDs/DFs.