Biotransformation process of tetrachloroethylene (PCE) to trichloroethylene (TCE) and successively to cis-1,2-dichloroethylene (cis-DCE) in static microcosms under anaerobic condition can be expressed by a consecutive first-order rate expression. This model implies the rules concerning stoichiometric relations and kinetics derived from the theory, and the rules enable us to evaluate the behavior of these three compounds. In this study, the data of groundwater contaminated with PCE at a study area in Yokohama city were analyzed using this kinetic model. The analytical method presented in this paper was of use for evaluating various remedial schemes and for estimating the position of pollutant source and the degree of degradation.

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Nitrate was distilled in the presence of a certain reductant by the usual cyanide distillation method, that is, the distillation with phosphoric acid and EDTA, and detection of cyanide in the distillate. Among the various reductants tested, iron, reduced iron, zinc, and aluminum powder were found to reduce nitrate to some compounds which then reacted with EDTA to form cyanide. This cyanide formation reaction could not be inhibited by the addition of ammonium amidosulfate, which is known to decompose nitrite. The nitrite and cyanide formations occured during the distillation without reductants and it was suggested that EDTA reduced nitrate. The addition of ammonium amidosulfate, however, suppressed the cyanide formation induced from the reaction of nitrate with EDTA. Based on these observations, the reduction product of nitrate by metal powder seems not to be nitrite. In addition, nitrate appears to take part in the formation of cyanide in the non-cyanide zinc plating wastes.

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The distributions of nutrients and heavy metal concentrations in sediment samples taken from Lake Kojima were surveyed, and the results of these studies were as follows :
1) Samples taken from the sediment which had accumulated around the lumberyard, contained rich organic compounds, nitrogen, sulphide, titanium and chromium with low density and small particle size.
2) Phosphorus, cadmium, lead, iron and manganese were found to have accumulated at the mouths of the two rivers.
3) The sediment samples from the center area had higher densities and larger particle size, and contained a small quantity of organic compounds, nutrient salts and heavy metals.
4) The sedimentary quantity and speed were also estimated ; quantity and speed were 4.4×10⁶ m³ and 16 mm·y^-1, respectively.
5) Results were calculated using the principal component analysis of 20 items which showed that the 1st component contributed 70.0% of the original data, pointing out the general pollution index in sediments. The 2nd component contributed 10.8% of the original data pointing out the difference of sedimentaion.

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