Algae (Selenastrumn capricornutum and Micocystis aeruginosa) were cultivated in the condition of coexistence with various amounts of macrophyte to evaluate the inhibitory effect of macrophyte on algal growth. The effect of water extract and methanol extract from macrophyte on algal growth also was investigated. Egeria densa, Cabomba caroliniana and Myriophyllum spicatum were used as macrophyte.
As the macrophyte increased in the algae-macrophyte mixed culture system, algal growth was reduced. It was also shown that the water extract and methanol extract inhibited algal growth and that the inhibitory effect of macrophyte were species-specific to algae. EC₅₀ of macrophyte, water extract and methanol extract for algal growth showed that Myriophyllum spicatum had the most inhibitory effect on the growth of both S. capricornutum and M. aeruginosa among the these macrophytes.

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The equations of reaction rate were proposed in the ozonolysis of veratrole and guaiacol which were chosen as the lignin model compounds. The reaction rate constants and reaction orders were estimated. The reaction was first order with respect to organic compound concentration and dissolved ozone concentration, respectively. The calculated values by the model equations were in satisfactory agreement with the experimental data in the ozonolysis of lignin model compounds which were adjusted at the same amounts of lignin aromatic moieties in the pulp wastewater. The main course of the rection of lignin model compounds was predicted from the reaction rate constants of several organic compounds in the degradation processes of lignin model compounds. The values of reaction rate constants in the structural types of organic compounds could be arranged according to their ease of ozonation in the following order : the values of phenolic structers > the values of muconic acid type intermetiates > the values of non-phenolic structers and they were in agreement with the results of Eriksson et al. who reported about the ozonolysis of lignin model compounds.

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As an analytical method for determining aromatic constituents of humic substances, as possibly the main precursors of organic chlorine compounds, the premethylation-KMnO₄ oxidation method was investigated. The humic substances were reagent grade humic acid, humic acid in the moat, humic acid and fulvic acid in a leaf mold, and fulvic acid in a treated sewage. All were extracted and refined prior to analysis.
When the humic substances were oxidized directly with KMnO₄, small amounts of aromatic compounds possessing methoxyl groups were obtained from methylated samples of oxidation products. Decomposition of aromatic rings possessing hydroxyl groups may be the reason for this. However, when hydroxyl and carboxyl groups of the humic substances were methylated before KMnO₄ oxidation, large amounts of aromatic compounds possessing methoxyl groups were obtained, and it was thus possible to clarify the characteristics of the humic substances.
It is evident from the present results that the premethylation-KMnO₄ oxidation method is useful for accurately determing the aromatic constituents of humic substances otherwise not possible by the direct KMnO₄ oxidation method.

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Application of a motion analysis system to the acute toxicity test of Daphnia was investigated.
Mobility of neonate Daphnia placed in the dilution water on a 24 wells micro culture dish was observed with a CCD camera. Observed data were analyzed using the motion analysis system “MAS”.
It turned out that neonate Daphnia magna swims constantly at the velocity about 5 mm·s^-1.
It was suggested that toxicity quantification becomes possible because the loss of mobility caused by an additive corresponds to the toxicity of the additive.
The motion analysis method has an advantage as regards the short period for the test because the toxicity can be judged according to the change of mobility before death.
Furthermore, it is expected that troublesome works, the counting of the number of moving Daphnia, involved in the determination of EC₅₀ can be omitted.

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