Dry and wet deposition of water-insoluble dust and water-soluble chemical species during spring 2007 in Tsukuba,Japan

Dry and wet depositions were sampled daily in Tsukuba, Japan, in spring 2007. Temporal variations in the dry and wet deposition fluxes of dust and water-soluble chemical species were controlled largely by air mass origin, the water vapor mixing ratio, and Asian dust events. The contribution of local sources to dry deposition of dust was large when the wind speed was high. Dry deposition fluxes of water-soluble chemical species were larger in humid air masses than in dry air masses. Wet deposition fluxes of dust and water-soluble chemical species indicated that air masses that passed over dust source regions and industrial regions became mixed with the maritime air masses over the coastal site of the Asian continent and western part of the Japanese islands. The total deposition of dust was 4220 mg m^?2 month^?1, and that of water-soluble chemical species ranged from 10 to 636 mg m^?2 month^?1. Wet deposition fluxes of the total deposition flux of dust accounted for 72% and those of water-soluble chemical species was for 72–96%. In particular, the largest wet deposition occurred during a single Asian dust event on 3 April. This event accounted for 23% (950 mg m^?2 month^?1) of the monthly dust deposition flux and for 2–28% (0.43–51 mg m^?2 month^?1) of the monthly deposition flux of water-soluble chemical species. This result implies that the wet deposition flux associated with even one sporadic Asian dust event can have extensive impacts on both terrestrial and oceanic ecosystems in East Asia.     

Moving towards urban sustainability in Kenya: a framework for integration of environmental,economic, social and governance dimensions

Global urban development is increasingly becoming an aspect of focus as nations fight sustainability challenges. A review of the current literature on urban sustainability suggests that research on development of cities, in both developed and developing countries, is growing fast, with an emphasis on sustainable development. However, very little of this research contains an integrated framework to systematically identify and examine the various dimensions of urban sustainability and to measure and evaluate them appropriately. Cities are more than the sum of their sectors, and are complex and interdependent systems on whose dynamics the quality of life of millions of human beings and a good part of the economy depend. Environmental, economic, social and governance problems can create formidable barriers to urban sustainability. Governance remains a critically important dimension of urban sustainability, especially when discussing urbanization in developing countries, given rapid population movements and imbalances in socio-economic development. Understanding how cities function is fundamental to resolving these imbalances. The aim of this paper is to provide a review and analysis of the concept of urban sustainability and to propose the development of a holistic framework through integration of environmental, economic, social, and governance dimensions of sustainability. Such a review would make it possible to understand the complex dynamics of the four dimensions and to assess the progress and challenges in moving towards urban sustainability, taking the case of Nairobi, Kenya, as an example. The paper argues that, for urban sustainability in developing countries, more emphasis should be placed on the governance dimension, because this is where the biggest challenge exists, with increasing needs for immediate management of rapid urbanization.     

Study of the effect of political measures on the citizen participation rate in recycling and on the environmental load reduction

Obtaining the cooperation of citizens to participate in separate waste collection is essential to create a recycling-oriented society. In this research, the degree of change in the citizen participation rate, which occurs when the contents of political measures such as the raising of awareness, provision of information, and the conditions of collection services were changed, was estimated together with the effect on the reduction in environmental load. A questionnaire survey was conducted, targeted at residents of Itabashi Ward, while logistic regression analyses were also conducted to create predictive models for recycling behavior, and sensitivity analyses of the models were carried out to estimate the increase in citizen participation rate achievable through the implementation of various political measures. It was found that the effect of "thorough perception of information" was the largest, followed by "minimization of evaluation of trouble" and "thorough perception of efficacy of measures." The effect of the improvement in the citizen participation rate on the reduction in environmental load was also evaluated quantitatively by life cycle inventory analyses. It was indicated that "maximization of perception of information" had the greatest effect. However, the reduction effect with "paper packs" and "PET bottles" was relatively small compared with that of "bottles/cans."     

High-resolution simulation of volcanic sulfur dioxide dispersion over the Miyake Island

After severe eruptions of the volcano at Miyake Island in August 2000, a large amount of volcanic gas was released into the atmosphere. To simulate flows and dispersion of sulfur dioxide (SO₂) over Miyake Island, a set of numerical models was developed. The multi-nesting method was adopted to reflect a realistic meteorological field and to sufficiently resolve the flow over the island with a diameter of 8 km. The outermost model was the Regional Spectral Model (RSM) of the Japan Meteorological Agency (JMA) with a horizontal grid size of 10 km. Finer atmospheric structure was simulated with the nonhydrostatic model jointly developed by the Meteorological Research Institute and the Numerical Prediction Division of JMA (MRI/NPD-NHM) with grid intervals of 2 km, 400 m and 100 m. Realistic topography of the island was represented in the innermost model. The Lagrangian particle method was applied to the dispersion model, which is driven by the meteorological field of the 100 m grid MRI/NPD-NHM. The random walk procedure was used to represent the turbulent diffusion. The model was verified in four cases. Simulated SO₂ concentrations agreed well with observed concentrations at a monitoring station including temporal variation. Under a large synoptic change, however, accurate prediction became difficult. Further numerical experiments have been done to investigate characteristics of the flow and the distribution of SO₂. Steady inflows, classified according to the surface wind speed and direction, were assumed. Simulated SO₂ distribution on the ground apparently depends on the surface wind. Under relatively weak inflow, there is a large diurnal change in SO₂ distribution, affected by the thermally induced flow. SO₂ gas is widely spread downstream in the nighttime but hardly reaches the coastal area in the daytime. On the other hand, SO₂ gas steadily reached the downstream coast with little diurnal variation under the stronger inflow. Ground temperature, as well as the static stability of the inflow, also influences downstream wind, turbulent diffusivity and SO₂ distribution.     

Generation amount prediction and material flow analysis of electronic waste: a case study in Beijing, China.

The draft legislation on e-waste prepared by the Chinese national government assigns management responsibility to local governments. It is an urgent task for the municipal government to plan an effective system as soon as possible to divert the e-waste flow from the existing informal e-waste recycling processes. This paper presents a case study implemented in Beijing, the capital city of China, with the purpose of predicting the amount of obsolete equipment for five main kinds of electronic appliances from urban households and to analyse the flow after the end of their useful phase. The amount to be handled was 885,354 units in 2005 and is predicted to double by 2010. Due to consumption growth and the expansion of urbanization it is estimated that the amount will increase to approximate 2,820,000 units by 2020: 70% of the obsolete appliances will be awaiting collection for possible recycling, 7% will be stored at the owner's home for 1 year on average and 4% will be discarded directly and enter the municipal solid waste collecting system. The remaining items will be reused for about 3 years on average after the change of ownership. The results of this study will assist the waste management authorities of Beijing to plan the collecting system and facilities needed for management of e-waste generated in the near future.     

Polyethylene conversion by partial oxidation in supercritical water

This paper gives the results of partial oxidation experiments of polyethylene (PE) in supercritical water (SCW). The experiments were carried out at a reaction temperature of 693K and a reaction time of 30 min using 6 cm³ of a batch-type reactor. The loaded sample weight was 0.3 g and there was 2.52 g water (0.42 g/cm³). The ratio of oxygen atoms to carbon atoms was 0.3. The results show a significant CO formation in O₂–SCW, and the 1-alkene/n-alkane ratio in partial oxidation was higher than that in SCW pyrolysis. These results suggest the possibility of the hydrogenation of hydrocarbon through partial oxidation followed by a water–gas shift reaction. Received: July 19, 2000 / Accepted: September 28, 2000     

Development and verification of new evaluation indicators for chemical management in corporations to meet WSSD goals

During the World Summit on Sustainable Development (WSSD), it was agreed that adequate chemical management based on risk assessment should be achieved by 2020. To achieve the WSSD goals, it is important to evaluate and enhance the voluntary activities of corporations because they are the main agents dealing with chemical management. To this end, we developed new evaluation indicators that were combined with the SCP Axes (Science Axis - evaluation of the scientific basis; Capacity Axis - evaluation of the abilities of personnel and organizations; and the Performance Axis - evaluation of results of activities and information disclosure to the community, etc.) and 4 elements (hazard assessment, exposure assessment, risk assessment, and risk management). We administered surveys to Japanese corporations from 2006 to 2008 to verify the developed indicators. The survey results showed that the activities concerning chemical management were very different across corporations for each industry category and that the hazard assessment improved, reflecting a vigorous social movement that included legal obligations. Therefore, the new evaluation indicators possessed high resolution and precisely grasped the changes in corporate activities. We found that these indicators provided an effective way to understand corporate activities designed to meet the goals of the WSSD.     

Effects of dioxins and polychlorinated biphenyls (PCBs) on thyroid function in infants born in Japan – the second report from research on environmental health

Dioxins (PCDD + PCDF) and polychlorinated biphenyl (PCB) are potentially hazardous compounds and have structural similarity to thyroid hormones. Our research group on “Dioxins and PCB in Human Milk” was organized in 1997 and has been active for the past three years. We collected breast milk from 80 mothers living in Tokyo, Saitama, Ishikawa and Osaka Prefecture in Japan at 5, 30, 150, 300 postpartum days and measured PCDDs, PCDFs and PCBs during 1998–1999. We added another 20 prefectures and cities during 1999–2000. Breast milk was obtained from 415 mothers at 30 postpartum days (breast-feeding group). Blood was taken from infants who were breast-fed at the age of 1 year for evaluation of thyroid and immune functions. Blood was also taken from 53 infants who were bottle-fed (bottle-feeding group) as a control. Serum T4, T3, FT4 and TSH levels in the breast-feeding (n=337) and bottle-feeding (n=53) groups were within normal ranges and were not significantly different between the two groups. Although there were a large geographic differences of dioxins and co-PCB content in breast milk, there were no differences in serum T4, T3, FT4, TSH levels and no significant correlation between the mean serum levels of TSH and TEQ in breast milk. There was a significant correlation between serum TSH at 1 year of age and that from blood on dried filter paper TSH at 5 days of age. We concluded that dioxin intake from breast milk in Japanese infants did not impair thyroid function. However, long-term effects remain to be evaluated.     

Possible change in Asian dust source suggested by atmospheric anthropogenic radionuclides during the 2000s

Decades-long monitoring of anthropogenic radionuclides in the atmospheric deposition in Tsukuba, Japan suggests not only the substantial impacts of the Asian dust (Kosa) on the deposition but also the possible change of the Kosa source region, especially during springs of the 2000s. In order to know more about such change, 4 single wet deposition events occurred in the spring of 2007 were scrutinized. The largest anthropogenic radionuclides wet deposition was supplied by the April 2–4 event. It brought several tens % of the monthly depositions (April 2007) of the dust (residue) mass (4.5 g m^?2) and anthropogenic radionulides (⁹⁰Sr: 16, ¹³⁷Cs: 97 and Pu: 3 mBq m^?2). None of the events observed fulfilled both criteria of the specific activities and ⁹⁰Sr/¹³⁷Cs activity ratio to the Tsukuba soil; they did not exhibit local soil dust signature. The Kosa events in fact have extensive impacts on the atmospheric environment over Japan in spring season. Considering the elevated specific activities as well as greater ¹³⁷Cs/⁹⁰Sr activity ratio in the deposited dust, it is hypothesized that the dust source areas in Asian continent would be shifting from the arid zone to the desert-steppe zone suffering from desertification during the 2000s. This type of the Kosa may be called as the ‘new-regime Kosa’. Chemical observation in the far downwind region of the Kosa dust could allow us to know possible shift in the source regions.