A simple model to predict lake water qualities with the aid of easily obtained data is necessary for many lakes where detail observations have not been carried out. For the second step to build such a model, relationships among the concentrations of nutrients, COD, and chlorophyll-a (Chla) were analyzed and discussed as follows.
(1) Comparing the yearly minimum concentration of COD (COD_min) with the value of COD at Chla=0 on the regression line between COD and Chla in several lakes, it is assumed the excess of COD concentration over COD_min expresses the COD concentration derived from phytoplankton production.
(2) Oligotrophic and mesotrophic lakes have the greater values of the slope of the regression line between Chla and COD than eutrophic lakes And, the slope of the regression line between log of annual average concentration of Chla (Chla) and log of ΔCOD (, which equals the annual average concentration subtracted by COD_min, ) is much less than 1.0. These facts suggest that relationship between COD and Chla can not be regarded as linear.
(3) The annual average concentration of limited nutrient concentration (Nu) is estimated by eq. (1). The retention time influences the relationship between ΔCOD and Nu, and the relationship between Chla and Nu. Taking into account this effect, eq. (3) and eq. (6) are proposed to predict ΔCOD and Chla by the use of Nu. The ratio of the predicted to the observed value of ΔCOD is within the range of 1/1.5-1.5 in more than 90% of normal lakes.

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The reactions of 24 amino acids in aqueous solution with chlorine were studied, and the products were identified fractionally.
Chloroform, tetrachloromethane, trichloroethylene and chloropicrin were detected as volatile organic chlorides. The formation potential of chloroform was increased at pH 11. The concentration level of chloroform was much higher than those of tetrachloromethane, trichloroethylene and chloropicrin.
Aldehydes and nitriles, which had one less carbon numbers than the original amino acids, were detected in the pentane extracts. In the case of phenylalanine, benzaldehyde and o-, p-chlorobenzyl cianide were also detected.
By sililation of the water-soluble nonvolatile substances, monochlorophenylalanine, and p-hydroxy-benzyl cianide and monochloro-p-hydroxybenzyl cianide were identified in the cases of phenylalanine and tyrosine, respectively. Moreover some unknown peaks were observed on the chromatograms in the cases of several amino acids.

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