Two laboratory-scale biological filter treatment systems packed with ceramics media and plastic media and control system withuot biological filter process were operated to treat polluted pond water. Three algal culture tanks with sufficient nutrient and light for growth were used as polluted ponds. A portion of water from the algal culture tank was withdrawn and treated through the biological filter process. The effluent was recirculated into the algal culture tank. Treatment performance of biological filter system was compared based on water quality of three algal culture tanks. The range of circulation ratio (feeding rate to biological filter process divided by the volume of the algal culture tank) was varied from 1.5 d^-1 to 0.1 d^-1. Growth of algae was depressed and sedimentation rates of suspended solids increased in the tank with biological filter process even if the circulation ratio was low (i.e., 0.1 d^-1). There was no difference between water quality and algal composition in the two tanks with two different packing media. The biological filter process could increase the transparency of polluted pond water and the diversity of algal species compared to the control tank.

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Trace element contaminations were monitored in a stream by using of the larvae of an aquatic insect, caddisfly Stenopsyche marmorata as a bio-monitor of trace element contamination every other year from April 1979 to April 1989. The caddisfly was distributed widely in rivers and streams in Japan. In April 1989, high concentrations of cadmium and copper in the larvae which seemed to be caused by a factory waste water were detected. Accordingly, concentrations of trace elements in water, sediments, periphytons (substances adhering onto the river bed) and the larvae were mesured.
The concentrations of cadmium and copper in the larvae were higer than those of water, sediments, or periphytons of the stream. When discharge of the waste water from a factory which was the pollution source was stopped, the concentrations of both elements in the larvae gradually decreased with time elapsed, finally reaching to the background levels after one year.
These findings indicate that the caddisfly larvae can be used as a good bio-monitor for detection of low level contaminations of trace elements in rivers, of which sensitive detection with water, sediments and periphytons is offen very difficult.

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The background value of phosphorus in the Kako river watershed was estimated by using both the percentage of different types of strata occuring in the watershed and the average concentrations of phosphorus in rocks from the strata. The background value is 227μg·g^-1. The phosphorus concentration of sandy bottom sediment in Kako river corresponded with the mean value of rocks from strata distributed around the sampling stations. The mean value of the phosphorus concentration in sandy bottom sediment (228μg·g^-1) also agrees with the background value of phosphorus.
The phosphorus concentration in sandy bottom sediment doesn't seemingly change, even though an artificial phosphorus load flows into the river. On the other hand, the phosphorus concentration of muddy bottom sediment is higher than the background value for phosphorus. This indicates that there is an accumulation of phosphorus in the bottom sediment.
Most of phosphorus in rocks and bottom sediment is I-P(inorganic phosphorus). I-P fractionation was also carried out using a modification of the method of Williams et. al. HCI-P is a major component of I-P in the rocks, and CDB-P is a major form of I-P in the bottom sediment. The results suggest that phosphorus changes its form through a weathering and sedimentation process.

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Biodegradation of volatile chlorinated hydrocarbons by phenol-utilizing bacterium (strain P7) from river sediment was studied and the following results were obtained.
1) The strain cultured in a phenol containing medium degraded trichloroethylene (TCE) and cis-1,2,-dichloroethylene (DCE).
2) Apparent K_s and V_max values obtained from Lineweaver-Burk plot were 12μM and 1.1 nmol·min^-1 per mg protein for TCE ; 3.3μM and 4.9 nmol·min^-1 per mg protein for DCE.
3) The degradation rate of tetrachloroethylene (PCE) was estimated to be less than 0.01 nmol·min^-1 per mg protein as the degradation of PCE was not observed. TCE and DCE degradations were inhibited by the addition of PCE.

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