A study was carried out on the pathway and the trend of mercury pollution of bottom sediments of the Suimon River. It was difficult to establish the actual mercury pollution level of sediment only with a data of mercury content of sediment because measured values of mercury fluctuated intensely even in an identical sampling station. Then, the triangular coordinate chart method was applied to compare the pictures of mercury pollution among different sampling stations and the years of mercury measurement. It was useful for the selection of metals in a triangular coordinate chart to check previously the probability distribution of metal concentrations in sediments. The combination of mercury, cadmium and copper was appeared to be most excellent among fifteen combination of metals in triangular coordinate charts for the investigation of mercury pollution. The plots in the Hg-Cd-Cu triangular coordinate chart successfully account for the pathway of mercury pollution of sediments. And when comparing the results of yearly analysis of mercury in sediments in the triangular coordinate chart, there was found little fluctuation of mercury pollution among the years.

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Hydrocarbons extracted from a Tokyo Pay sediment were fractionated into aliphatic hydrocarbon, alkylbenzene and polycyclic aromatic hydrocarbon fractions.
Hydrocarbons in each fraction were analyzed by a high resolution gas chromatograph and GC/MS. The total amount of n-alkanes (C₁₇-C₃₅), alkylbenzenes with C₁₀-C₁₄ alkyl carbons and PAH (one to seven rings) was 25.9, 2.9, 3.6 μg/g-dried sediment, respectively. The presence of UCM (unresolved complex mixture) and n-C₂₁-C₃₅ hydrocarbons with odd carbon predominance suggested that these hydrocarbons are of oil pollution and higher plant origin. Alkylbenzenes with C₁₀-C₁₄ alkyl carbons may have come from ABS (alkylbenzene sulfonates) pollution since their molecular distribution pattern is similar to that of ABS. The feature of PAH molecular distribution, in which alkyl homologues are minor relative to parent PAH, suggested that these PAH are mainly of combustion origin.
The availability of the present method of fractionation and determination of detailed composition of hydrocarbons to the quantitative approach to environmental pollution study is discussed.

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It has become of increasing importance to estimate spatial profile of pollutant distribution in water bodies. The simulation by means of convective diffusion model has been the most popular way so far employed for this purpose. The simulation, however, is time consuming and tiresome, nevertheless, it cannot be accurate enough. Another promising mean of evolving two dimensional profile is so called interpolation method in case measured data at discrete spots are available.
In this paper, a comparison is made of three major interpolation methods such as “moving average method”, “2 dimensional spline method with tension”, and “Kriging method”, as well as a newly proposed one named “convective diffusion method”. COD data sampled in Seto Inland Sea during four seasons of 1977-1978 were used as checking date of the comparison. With these data, 32 cases of trials were executed in order to compare the goodness of fit of these four methods.

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