By the recycle of heat used once in urban area, it is possible to reduce the emission of environmental load like carbon dioxide from urban activities. But for the realization of this recycle system like a district heating system with its heat source from sewage, not only the reduction of energy consumption or carbon dioxide emission but also its initial and running cost should be estimated and discussed. In this study, energy consumption, carbon dioxide emission and cost for the demand of space heating and hot water supply through the initial and running stage of the district heating system with its heat source from sewage was compared with an alternative plan, i.e. nonconstruction of district heating system. The fine geographic information data like precise mesh data of land use type or number of stories and the areal energy consumption were input in Geographic Information Systems (GIS). Main target of Life Cycle Assessment (LCA) had been products or materials. In this study, its target is "area" and the location of urban infrastructure is evaluated in the spatial field. In this meaning, this study is one of the attempts of new methodology for LCA itself. The application of LCA on the district heating system and the area on GIS is available and a large amount of demand for space heating and hot water supply gives an advantage for the introduction of a district heating system also in terms of LCA.

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An environmental risk assessment is typically conducted to determine the environmental safety of new and existing substances. Within this assessment process, fate and effects assessments are performed for each environmental compartment that receives a substance of concern. The fate assessment involves estimating environmental concentrations to which organisms will be exposed. This prediction is based on an understanding of the emission pathways as well as what ultimately happens to a substance when it is released into the environment. In this paper, a mathematical model was developed to estimate the concentration of consumer product ingredients in a river as a result of multiple discharges. This model was tested with linear alkylbenzenesulf onate (LAS), a major ingredient in many laundry and cleaning products, using information on the emission routes of consumer product ingredients for the Tamagawa River basin in Japan.

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To estimate the sulfate-removing ability of a freshwater pond, sulfate-reducing activities were measured in sediments of the pond by a convenient method based on the HPLC analysis of sulfate. In this method, samples suspended with an assay solution were anaerobically incubated, and rates of sulfate reduction (μmol of sulfate reduced/hr) were determined by monitoring sulfate concentrations in assay mixtures. During anaerobic incubation of assay solution inoculated with pure cultures of sulfatereducing bacteria, sulfate reduction proceeded at constant rates until the sulfateconcentration decreased to about 70, μM. The rate of sulfate reduction was propor tional to the inoculum size of sulfate-reducing bacteria. The threshold value of sulfate concentration and the activation energy for sulfate reduction were about 20 μM and 20 kcal, respectively. The sulfate-reducing activity and the density of sulfate-reducing bacteria were determined in sediment layers sampled from the pond. In all layers of the sediment down to 35 cm depth, sulfate-reducing activities (umol/h/cm³ of sediment sample) were detected in the range of 4.5-32.1 at 30°c, and sulfate-reducing bacteria were enumerated at the densities of 10⁴ CFU/cm³ level. In this pond, the sulfateremoving ability was estimated to exceed 46 mmol/m²/day in summer.

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