The objective of this study was to evaluate river water chemical environments in order to compile basic information on spatial and seasonal variations of water chemical environments to determine the corresponding loads from the catchments. The research field was in the basin of the Ongagawa river, which has one of the worst water qualities of Kyushu Island, Japan. We monitored electric conductivity (EC), pH, dissolved oxygen (DO) and major elemental concentrations of the surface river water at 1 to 2 km intervals from the origins to the river mouth at every month from 2002 to 2003. The increasing rate of EC of the river water per unit distance along with the water flow indicates high peaks at several points adjacent to the confluence of tributaries. Constantly high EC (> 300μS/cm) may be due to the high loadings and the consequent accumulation of nutrients and organic material. From the correlation analysis between cation concentrations and EC, we have obtained two different regressions. The difference between the two regression lines may reflect the contribution of organic ions with lower mobility than major ions in water. This regression analysis would give the qualitative information on organic anions such as pollutants. The data obtained in this study could be used as basic data for developing a simple and precise monitoring method for organic pollutants without determining the concentration of the pollutants.

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The objective of this study is to identify the characteristics of SS and nitrate removal using hybrid sludge bed filter and combined with electrode system for advanced treatment of secondary clarifier effluents. The following results were obtained. The hybrid filter could remove SS and nitrate simultaneously. Larger particles than about 5μm in diameter were removed completely at filtration rate 15 m·d^-1 and sludge bed thickness 20cm. The head loss of the filter was less than 0.34 m of water at the highest value. The denitrification rate by the bio-electrochemical process was estimated to be around 0.036 mg-N·mg-SS^-1·d^-1 at the applied electric current density, 0.76 mA cm^-2 and the endogenous denitrification rate in the subsided sludge bed was 0.0052 mgN·mg-SS^-1·d^-1. The nitrate removal rate was enriched by the bio-electrochemical reaction. The hybrid filter may be substituted for conventional granular bed and biofilters from not only the SS removal point of view but also nitrate removal point of view.

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In this study, the law for recycling specified kinds of home appliances was compared with the EU Directive (WEEE Directive & RoHS Directive). There are common features between the law and EU Directive. For example, one is that the laws had recovery system built by using the selling system, the other one is the laws stated the manufacture being imposed duty in the recycling. However, there were differences between the two in the composition, purpose, object products, role assignment, the burden of recycling expense, collection standard etc.. So, the factors of such differences were discussed. It was thought that the cause existed in the difference in the legal proposal system, recognition of the manufacturer, the civic participation grade, the correspondence of the environmental problems.

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Di(2-ethylhexyl)phthalate (DEHP) is predominantly used as a plasticizes in flexible polyvinyl chloride (PVC). DEHP is emitted to the environment during the production of PVC products, during their use and after disposal. Hazard and risk of DEHP have been assessed in varying degrees by both domestically and abroad, however, human health risk to general population has not been sufficiently evaluated in Japan. In this study, the distributions of age-specific and gender-specific daily intakes of DEHP via indoor/outdoor air, diet, baby formula and baby food were estimated. Furthermore, the human health risks of DEHP were evaluated based on testicular and reproductive toxicity data. The results of the daily intake estimations indicate that the 1-year-old child showed the largest amount of DEHP daily intake among all the age-specific groups and its major pathway was estimated to be the food intake. The estimated risk levels of DEHP to the testicular and reproductive endpoints were judged to be of no particular concern for all the age groups in Japan.

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This special issue presents a review of environmental modeling studies which aims to contributing to better decision making through improved understanding about the interaction between human activities and nature. This paper presents an overview of this issue comprising six papers on the following topics: Modeling related to the climatic change; Modeling of land use/cover change; Systematic description of material flows among anthroposhere and ecosphere; Modeling for risk assessment of chemicals; Approach to the integrated assessment of urban environment; and Indicators to evaluate environmental loads of human activities.

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In order to solve global environmental problems such as climate change and global warming, the computer model has played an important role because an experimental approach cannot be taken to clarify mechanism of global phenomena scientifically. Many types of models have been developed in this research fields. They are climate models and carbon circulation models for predicting future change in climate, and greenhouse gas emission and energy models for predicting future change in socio-economic condition. In addition to the model development in respective research field, integrated assessment models (IAM) have also been developed to analyze complicated phenomena due to climate change in a comprehensive manner. In this paper, the current state of the arts in model development and application is introduced with some examples, and future research needs are also discussed in brief.

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It was argued the difference of LUCC (Land Use/Cover Change) study stance between geographers and other field researchers, reviewing results of related study projects like LU/GEC in Japan on an international study plan of the LUCC Progra established in 1996. While geographers attach greater importance to field investigation for collecting real data, and discussing LUCC mechanism, modeling studies are struggled on simulating imaginary field without examining real data. An advantage of modeling is to predict future. Joint researches using advantages of both geographers and modeling are necessary. The model development predicting LUCC started from field of urban planning based on regional metric model. System dynamics model appears today, however, it is the field where elucidation of mechanism is not enough . Then, in the field of LUCC, modeling of future prediction simulation that incorporated dynamics model as precise as modeling in natural sciences has not yet realized. At present, it is common to discuss the relations between LUCC and various factors, such as social, economic, natural indexes, as driving forces. Most of them assume temporal stability about explanatory function of Land Use/Cover ratio. However, there are a few studies indicating that temporal stability can not be applied. In addition, the author mentioned recent new attempts which introduced a concept of GA (Genetic Algorithm) and AGENT.

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Material Flow Analysis (MFA) is a system-analytic tool to capture the interrelationships between anthrosphere and ecosphere, in which material flows can be described according to a part of quadrants. Various approaches of MFA were categorized into two types; Type I accounts for specific elements, substances, materials or products which have relevance to specific environmental impacts. Type II accounts for material flows across a system boundary such as firms, sectors or regions. By classifying them to six more detailed types, diversified studies of MFA were characterized by their scope and applications. Possibilities of the integration among different types of MFA and the extension of MFA to incorporate impact assessment studies were examined . Interrelationships between MFA and environmental science studies were also discussed.

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The environmental issues concerning toxic chemical species have been getting much public attention. To make countermeasures against these issues, the concepts of risk assessment and risk management are getting popular, and they have been nearly established. Throughout these steps to know the human exposure against toxic chemicals, it is so important to know the environmental concentrations of them. However, it is difficult to obtain enough informations on these concentrations only by monitoring, and it is necessary to cover these lacks by model concentrations . Other kinds of importance have been pointed out. This paper describes on the status and importance of modeling techniques concerning such problems, and aims to discuss on their future status and perspectives.

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Necessity of integrated evaluation with holistic view of urban environment has been increased, but such integration still has difficulty. Trade off between quality of life and environmental loadings and that between different aspects of environmental loading need to be evaluated. Utilization of life cycle assessment (LCA), evaluation by monetary value and their combination are promising tools. Inventory analysis of LCA can compare the trade off of same environmental aspect. LCA has to solve the problem of uncertainty in impact analysis and limitation in evaluating regional environmental impact in order to compare the trade off between different environmental aspects. Using monetary evaluation of regional environmental impact in addition to LCA is effective method. Risk reduction and environmental loading can be compared using DALYs (disability adjusted life years) that is used in the impact analysis of LCA. Wastewater treatment facility reduces the risk of pathogen whereas its construction and operation cause environmental loading which increases the risk. The trade off between these two is compared using DALYs. Conjoint analysis is an effective tool to compare different environmental aspects. An example is shown in which protection of human health, protection of living environment and preservation of wild life are compared together with monetary value using conjoint analysis.

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This paper looks back the history of environmental indicators which have been developed to evaluate the environmental impact of human activities, and discuss their new roles in the age of global environmental issues. It reviews various indicators of sustainable development which aim to integrating economy and environment while focusing on embodied environmental loads and ecological footprints which are useful to assess environmental loads embodied in goods and services. Finally it discusses the use of LCA in environmental management.

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We evaluated the ammonium emission from food production based on statistical dataof fertilizer consumption, meat production etc. Total ammonium emission of Japan was 39×10³t N y^-1 from fertilizer and 185×10³ t N y^-1 from livestock, which roughlycoincide with the existing estimates by the different method . Ammonium emission was distributed to each 1 km×1 km grid cell in proportion to the farmland and grassland distribution. Using the estimated ammonium emission and existing NOx emission, spatial distribution of nitrogen deposition was calculated assuming the isotropic diffusion with exponential attenuation. Nitrogen concentration in stream water was then estimated with a simple nitrogen balance model in which internal cycle due to plant growth andlitterfall, nitrogen discharge from soil to stream were taken into consideration . Nitrate concentrations in stream water at 1270 catchments measured in the “Japan-Wide StreamMonitoring (JWSM) 2003” were roughly correlated with the estimated nitrogen deposition on the catchments and also with the estimated stream nitrogen concentration.It suggests that long-term nitrogen deposition is an important factor to determine the nitrogen concentration in stream water in the natural ecosystems.

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