The growth and reproduction of Plectus sp. and Rhabditis sp., the most frequent detected nematodes from tap water, were investigated at different conditions. Only females of Plectus sp. were found, but most of Rhabditis sp. were. self-fertilizing hermaphrodite while males were rare. It was found that Plectus sp. and Rhabditis sp. did not reproduced well or survived when temperature was below 5°C and/or above 35°C, respectively. It is shown that pH range for reproduction of Rhabditis sp. was wider than Plectus sp. The specific growth rate of Rhabditis sp. was still high even at pH4 or pH9, whereas that of Plectus sp. was very low or not observed at these conditions. Inoculated concentrations of bacteria (E. coli C600) as food highly influenced to the egg-laying of both nematodes. However, the mortality of Rhabditis sp. was far larger than Plectus sp. at the same bacterial concentrations. At 20°C, pH6 and inoculated bacterial concentrations of 10⁸ cells·ml^-1, the specific growth rates of Plectus sp. and Rhabditis sp. were 1.0 and 0.6d^-1, respectively.

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The organisms in the rock bed contact-purification channel were investigated in the experimental plant (30m long × 1m wide × 1.3m deep × 6 channels) operated at the innermost part of Tokyo Bay to understand the biological aspects in the channels for improvement of the eutrophic coastal water. The dominant species of phytoplankton in the influent were diatoms such as Skeletonema costatum, Navicula and Nitzschia often observed in the coastal water. As for microanimals in the biofilms on the rocks, Carchesium, Vorticella and Zoothamnium became the dominant species sequentially. S. costatum and Navicula were present in all seasons as the dominant species of microplants in the biofilms. Other than the above microorganisms, 17 species of large size sessile and benthic animals were observed in the biofilms, in the rock beds and on the channel walls after 9 months of operation. Those sessile or benthic animals gradually decrease the porosity of the rock bed with its individual growth and their growth in numbers and finally may cause clogging of the channel, while they contribute to water purification and sediment reduction. The result of the observation indicates that the fauna (sessile and benthic animals) observed in the rock bed channel are similar to those of nearby water areas, especially those of the quaywall of No.13 Marine Terminal and the artificial beach of Kasai Seaside Park located in the innermost part of the Tokyo Bay in this study.

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The membrane separation properties for pesticides included in the standard and the guideline for potable water were examined with 4 kinds of nanofiltration membranes: nominal NaCl rejection ranging from 92% to 15%. Pesticides were analyzed at sub ppb level by HPLC direct injection method with a ODS column. The highest desalting membrane rejected all pesticides at more than 92% and at more than 99.9% for 8 pesticides. Isoxathion, CNP, EPN, and bebsulide were rejected at more than 98% by the lowest desalting membrane, although the rejection for the other pesticides decreased with decrease in salt rejection of the membranes.
From the relationship between rejection and molecular width for the highest desalting membrane, the molecular sieving effect was indicated as an important factor for solute separation. In addition, it was pointed out that the pesticides highly rejected by all membranes are strongly hydrophobic and include a phenyl group.

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The mutagenicities of river water from in the upper of Nagara river which was non-pollution river from judgment by pollution indicator with chemical-analysis were investigated by using XAD-2 resin column concentration method and Ames assay as toxic micropollution indicator with bio-assay. And these mutagenicity were compared with those in the lower areas of Nagara river.
In the upper areas of Nagara river, the mutagenicity was detected a little, which was primarily the direct- and indirect-frameshift types. But their intensities of mutagenicity were low, and did not relate to the developments in the uppers. Therefore, these mutagenic materials might be in nature. However, the mutagenic materials which derived from the polar and indirect-base-pair change mutagens were detected only in winter.
In the lower areas of Nagara river, the mutagenicity showed to be derived from the non-polar, direct- and indirect-frameshift mutagens. These intensities of mutagenicity elevated with the increase of COD and TOC.

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Water quality of Laguna de Bay, the largest lake in the Philippines, was survyed as a small joint survey of Japanese and Philippine NGO groups. The lake water had relatively high concentration of SS caused by resuspending silt and fine clay from the bottom sediment due to shallow water depth and strong wind. Chl a concentration was low in spite of high concentrations of nitrogen and phosphorus. Trihalomethane formation potential test showed high formation of bromine compounds due to intrusion of sea water into the lake. Relatively high concentration of SS, COD, nitrogen and phosphorus was observed at the mouth of the most polluted tributary.

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