A musty odor compound, geosmin, causes problems of water treatment at water purification plant (WPP). To remove the odor, a large amount of powdered activated carbon is needed every year. The compound is produced by some kinds of filamentous cyanobacteria, genus Anabaena (Dolicospermum), inhabit in the water source. Usually, by monitoring cell numbers of the Anabaena with microscopy and geosmin concentration with solid phase micro extraction gas chromatography mass spectrometry (SPME-GC/MS) analysis, we determine how much amount of powdered activated carbon is needed to dose. In 2013, from the result of the experiment with microscopy, geosmin-producing Anabaena increased in two peaks for 3 months. During the second peak period, the geosmin concentration per one Anabaena cell was low level, about 4% of that of the 1st peak. It seemed that there was a possibility the cause of the difference of the geosmin concentration between the two peaks relates to a geosmin synthesis gene in cyanobacteria. To study a PCR detection method on raw water at WPP, we constructed two primers, 16SANB primer and GE1 primer, and had experiment of PCR amplifications with those primers. 16SANB primer is based on 16S rRNA gene in Anabaena and as the PCR reference gene. GE1 primer is based on geosmin synthesis operon gene and as the PCR target gene. From the results of the experiments, we could confirm that this detection method can be used practically.

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Under the Food Sanitation Act of Japan, some residual pesticides in food are regulated as total level including their metabolites. However, in the area of drinking water quality regulation, some of these metabolites are not included in the list of target substances set by Ministry of Health, Labour and Welfares. In this study, we developed and validated the methods for analysis of four pesticides (orysastrobin, prothiofos, amitraz and iprodione) and their corresponding metabolites in water samples. Using the established methods, a survey was conducted at 21 water treatment plants in Osaka and the concentration of each substance was determined before and after water treatment process. As a result, orysastrobin and (5Z)-orysastrobin, a metabolite of orysastrobin, were detected in tap water at several plants. Our result suggests that orysastrobin in drinking water should be regulated along with its metabolite.

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