The behavior of multi-elements in water samples from the Fuji and Sagami rivers has been geochemically investigated. Water samples were filtered through 0.45μm hydrophilized PTFE membrane filters and acidified to pH<2 with ultra pure nitric acid. Major and minor and trace elements were determined by inductively coupled plasma atomic emission spectrometry and mass spectrometry, respectively. Vanadium(V), which exists with sensitive characteristics in igneous rocks showed sensitively and validly the differences in its concentrations between the Fuji River whose geology is mainly andesitic and granitic, and the Sagami River which is mainly basaltic. This result suggested that V can be used as a sensitive indicator to trace the migration of river water and to elucidate the rock types surrounding the sampling locations. Moreover, all elements (Na, Mg, Al, K, Ca, Cr, Mn, Co, Cu, Zn, Ga, Sr, Mo, Cd, Cs, Ba, W, Pb) except V, which do not give sensitive characteristics in igneous rocks also showed obscure characteristics in river waters. The geochemical source classification of multi-element in river waters which reflects the geology was successfully achieved using differences in the distribution areas in relation to the V concentration. These results suggested that the behavior of not only V but also other elements was influenced by the geological nature of the sampling locations.

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In order to elucidate the structural characteristics of the halocline in shallow Brackish Lake Obuchi, located virtually in the center of the Shimokita Peninsula in Aomori Prefecture, continuous observations were made of the salinity, current velocity, wind, meteorological tide and water level from April 1998 to December 2000. The results showed that in the center of the lake at a water depth of 4.5 m, the mean salinity was 15, 17 and 25 psu at a depth of 0, 2 and 4 m, respectively. Almost throughout the observation period a halocline formation could be seen at the lake center. The depth of the maximum density gradient tended to be deeper from summer to spring. From calculation of the Richardson number (Ri), an indicator of halocline structural stability, the halocline was clearly very stable at the center because Ri indicated approximately>10 (maximum 4.0×10⁵, minimum 1.0×10^-1). By analyzing the relationships of the halocline disappearance to the wind direction and speed, the salinity tended to become uniform at a depth from 0 m to 3 m with a wind speed of 6-8 m s^-1 in an east-west direction. However, when winds higher than 10 m s^-1 continued to blow for over 3 h, the water churned and mixed so that the halocline obviously disappeared. Nevertheless, the halocline rapidly reappeared after the wind subsided.

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Rare earth element (REE) contents in Obuki spring waters from the Tamagawa geothermal system, Akita Prefecture, Japan, have been determined by ICP-MS to investigate their long-term variations over a thirty-year period. The contents of REE in hot spring waters were at ppb levels, showing zigzag patterns that obeyed Oddo-Harkins law. The REE pattern in those waters resembled that of andesite rock, which was collected near Obuki spring. The REE contents in hot spring waters during 30 years have been synchronous with those of sulfate ion. The light rare earth element (LREE) contents tend to increase with raising sulfate ion concentrations. This indicate that most of the REE in Obuki spring waters has been derived from water-rock interaction in acid under certain conditions, especially the predominance of sulfate ion and leaching rates of LREE from the rock that exceed those of the heavy rare earth elements. The behavior of REE in acid under such conditions was also confirmed by dissolution experiments conducted on andesite rock in sulfuric acid, hydrochloric acid, and a combination of both.

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Bacterial communities in the epilithon and epipelon of the riverbed were studied at Nishiaokidaira in the Akigawa River in Tokyo, Japan. The biomass of the epipelon calculated by dry weight and ignition loss was larger than that in the epilithon. Chlorophyll contents and algal activity as shown by Chlorophyll a/Chlorophyll a+Pheophytin a (C/C+P), however, were higher in the epilithon bacterial community than in the epipelon. The physiological properties of the isolated bacterial strains showed that there were many fermentative facultative anaerobic bacteria in the epipelon community. On the other hand, many yellowish colonies were observed in the epilithon bacterial community and identified as Flavobacterium spp. and Cytophaga spp. Thus, it was clarified that the bacterial communities were different between the epilithon and epipelon. It was concluded that, based on the estimation of its self-pulifying ability, we must consider the overall structure of the riverbed.

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