In vitro effects of surfactants in common use as detergents and related compounds were investigated on the erythrocyte membrane and respiratory activity of rat liver mitochondria.
The hemolytic activity of main surfactants tested was in the following order with the EC₅₀ values less than 10mg·l^-1 ; Neopelex F-25 (LAS), Spark (α-SF), Flake marseille (soap), LipolanPB-800 (AOS), standard soap (JIS K 3303) and SDS. There was weak hemolytic activity from the effect of Emulgen 108 (POEAE) and Emal 20C (AES). On the other hand, the mitochondrial respiration inhibiting activity (IC₅₀) was strong in Flake marseille (5.5mg·l^-1) and standard soap (6.8mg·l^-1) and follwed by Emulgen 108 (26.0mg·l^-1), Emal 20C (32.5mg·l^-1), SDS (38mg·l^-1), Neopelex F-25 (41.0mg·l^-1), Spark (46.0mg·l^-1) and Lipolan PB (>50.0mg·l^-1). The regression equation between the EC₅₀ (Y) and IC₅₀ (X) values was Y=-0.1198X+2.345, the coeficient of correlation r=-0.0855, indicating little correlation between them. Present data certified the hemolysis inducing and respiration inhibiting effects of surfactants on erythrocytes and mitochondria. These suggest that this system is applicable as a convenient technique to assess the toxicity of environmental contaminants.

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The pH and major ions in the precipitations collected on a weekly basis from November 1991 to October 1992 were determined in Sakata of Yamagata-ken on the northeastern coast of the Sea of Japan. Their concentrations in 49 samples were separated into two groups and shown with the rainfall-weighted average : (A) group was contributed by sea-salt transported by seasonal wind from November to March and (B) group was from other months free from sea-salt. The following are the results obtained :
(1) The pH values of both (A) and (B) groups were 4.6 and 4.5, respectively, and the concentrations of nss-SO₄^2-, NO₃^-, nss-Ca²⁺, nss-Mg²⁺ and K⁺ were found to be almost equal for both groups.
(2) The best variable ions with H⁺ were found by the regression program to be : (H⁺+nss-Ca²⁺+NH₄⁺)=0.93 (nss-SO₄^2-+NO₃^-)+3.6, r=0.94. The equivalent ratio of NO₃^- to SO₄^2- was 0.52 in both (A) and (B) groups.
(3) The ratios of SO₄^2- to alkalinity (CaCO₃) in the mountain streams and the well waters (Fig. 1) were between 0.19 and 0.33. These ratios were lower than those of the average qualities of river waters from Japan and world.

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The benthic communities in the Oh-kawa river with non-point pollution source were investigated in April and June, 1992, in order to evaluate aquatic environmental conditions. The water quality of the Oh-kawa river was characterized by the low BOD concentration and high concentrations of nutrients such as nitrate nitrogen and phosphorus.
The total recognized species of benthic animals were 56 and 71 in April and June respectively. The dominant species was Hydropsyche ulmeri in the upper reaches of the Oh-kawa river and Antocha sp. in the lower reaches.
The diversity index on the basis of dry weight was more significant than that on the basis of individual number in examining the structural change of the benthic animal community. The similarity index could be used to judge not only the change of environmental conditions at each sampling station but the stability of the benthic animal community. The pollution index was nearly correlated with water quality parameters such as BOD and so on, but would become the index for the decision of the water quality rank.
Percentages of number and standing crops for Antocha sp. were expressed by the function of NO₃-N or PO₄-P concentration respectively.

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Bacteria were isolated from the laboratory-scale activated sludge reactors operated using synthetic wastewater containing phenol as toxic organics, m-aminobenzoic acid (m-ABA) as a refractory organics and inorganic nutrients. These isolated bacteria which can utilize phenol and m-ABA as sole carbon source were used in order to clarify the effects of powdered activated carbon (PAC) on removal of the toxic and refractory organics. Biodegradation activity of phenol and m-ABA in the bacteria system with the addition of PAC was compared with that of the bacteria system with the addition of raw material of PAC (NAC) having no ability to adsorb, and the suspended bacteria system. The PAC accelerated biodegradability of phenol and m-ABA by the isolated bacteria much more than the NAC and suspended system. Number of bacteria in the systems with PAC and NAC by viable counts using phenol-selective medium and m-ABA-selective medium and number of bacteria on the surface of PAC and NAC by direct counts using SEM were almost same, irrespective of the difference in support media. Therefore, the addition of PAC would increase biodegradation activity of the toxic and refractory organics by the isolated bacteria. It was also found that biodegradation of m-ABA by isolated bacteria increase remarkably in the presence of phenol.

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This paper describes the structure and characteristics of granules which were unexpectedly formed in anaerobic-oxic activated sludge process. The activated sludge granules had prominent characteristics of sedimentation and agglomeration : sedimentation velocity was 13-15cm·min^-1 ; sludge volume for 30 minutes was 6% ; sludge volume index was 27ml·g^-1. The surface structure of the granules was densely agglomerated by various bacteia, mainly rod type bacteria. Some parts of its surface were covered by extracellular polymer, and other parts showed the complex structure with multi-layers. By the quantitical analysis of chemical compositions of the granules, the contents of Fe, Zn and Ca in the granules were found to be more than those of activated sludge. The microflora of granules was characterized using quinone profile. In the granules, Rhodoquinone-8 (RQ-8) of 1.8mol% was detected, while little RQ-8 was found in activated sludge. This result suggested that bacteria containing RQ-8 would participate in formation of the granules.

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