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A spatially resolved and geo-referenced dynamic multimedia environmental fate model, G-CIEMS (Grid-Catchment Integrated Environmental Modeling System) was developed on a geographical information system (GIS). The case study for Japan based on the air grid cells of 5 x 5 km resolution and catchments with an average area of 9.3 km2, which corresponds to about 40,000 air grid cells and 38,000 river segments/catchment polygons, were performed for dioxins, benzene, 1,3-butadiene, and di-(2-ethyhexyl)phthalate. The averaged concentration of the model and monitoring output were within a factor of 2-3 for all the media. Outputs from G-CIEMS and the generic model were essentially comparable when identical parameters were employed, whereas the G-CIEMS model gave explicit information of distribution of chemicals in the environment. Exposure-weighted averaged concentrations (EWAC) in air were calculated to estimate the exposure ofthe population, based on the results of generic, G-CIEMS, and monitoring approaches. The G-CIEMS approach showed significantly better agreement with the monitoring-derived EWAC than the generic model approach. Implication for the use of a geo-referenced modeling approach in the risk assessment scheme is discussed as a generic-spatial approach, which can be used to provide more accurate exposure estimation with distribution information, using generally available data sources for a wide range of chemicals.

Organic compounds and inorganic elements were determined in leachates from 11 landfill sites in Japan. With regard to the inorganic elements, the concentration of boron was found to be fairly high. More than 100 organic compounds were detected and several important compounds such as organic phosphates, 1,4‐dioxane, phthalates, and bisphenol A were present at high concentrations. Waste plastics are a possible origin for these compounds. The ratio of characterized compounds to total organic carbon was unexpectedly low. Phenols and ethers were the main components as deduced from the carbon contents. Most of the chlorine appears to be present as non‐volatile substances.

The groundwater pollution by volatile organochlorines has been increasingly becoming a major environmental issue in many developed nations. In particular, trichloroethylene and tetrachloroethylene were widely detected in regional groundwaters of Japan. The paper describes the characteristics of groundwater pollution of Japan on the basis of the nationwide survey results, and introduces an incident in industrial site and subsequent counter-measures. In this site detailed investigations of 26 monitoring wells surrounding the pollutant source have continued to date since remedial operation in 1984, and cis-l,2-dichloroethylene was discovered to be created as intermediate product from trichloroethylene during the biodegradation process. Furthermore, the long-term continuous surveys reveal two types of organochlorine behavior in ground-water, that is, (l)cis-l,2-dichloroethylene concentration is proportional to that of trichloroethylene and (2)cis-l,2-dichloroethylene concentration is nearly constant in no relation with trichloroethylene behavior, in seasonal variation of individual well-water.