It has been found that vanadium serves as a suitable indicator to evaluate urban air quality. Since vanadium in suspended particulate matters mainly comes from use of fossil fuel, it effectively indicates the influence of human activities on environmental quality of urban atmosphere. The concentration of this element in air samples ranges 10-9-10-8g/m3. Both of graphite furnace atomic absorption spectrophotometry and inductively coupled plasma emission spectrometry lack the required sensitivity and selectivity for those measurements. In this study, ion-pair reversed-phase partition high performance liquid chromatography has been successfully applied to the trace vanadium at ng/m3 level in air. No interference from the complex matrix of airborn-particulates was observed . Determination of vanadium in the suspended particulate matters in Sendai City by the use of the proposed technique has been performed to prove the validity of this element as a sensitive indicator for urban environment.

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The quality of environment in urban area has been markedly deteriorated because of traffic noise by motorcars. To control traffic noise and improve the quality of the environment, we have to examine to what extent traffic noise lowers the utility of residents. In this research, we examined how much the utility of residents along road (Kannjou 7 gousen) has been affected by the traffic noise. It is well known that the disutility of noise discounts the land prices. Using cross-section data, we estimated a regression model which described the relationship between the noise of motorcars and the land prices. And we could calculate the external cost of noise by motorcars.

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Pot experiment was conducted to elucidate the effects of soil type (Brow Lowland Soil and Gray Lowland Soil), type of fertilization, and growth stage of rice plant on the methane emission fluxes from paddy field. The methane emission fluxes from non-planted plots kept very low level and they were 1/3 to 1/500 of respective planted plots. Among the planted plots, the emission fluxes were far larger in the rice straw applied plot than in other plots up to the heading stage. The methane emission fluxes in the chemical fertilizer plot increased steadily along the growth stage and it maintained high level during its ripening stage. From the total methane emission calculated separately before and after the heading stage, it was known that the main stage when the manurial treatment and soil type reflect on the methane emission is in the early growth stage (before the heading stage), and that methane emission is similar each other and large in the late stage (after the heading stage), irrespective of manurial treatment and soil type. Thus, it is considered that the methane emission in the late stage is controlled by the rice plant itself. maybe by means of root exudates and slough-off. Midsummer drainage decreased the methane emission in the late stage effectively in spite of short drainage period.

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Individual particle analysis combined with cluster analysis of airborne particulates collected beside a roadway was performed to make a source apportionment . We collected 12 samples using a low volume air sampler (L samples) and 6 samples using an Andersen air sampler (A samples), during December 11-12, 1989 ; at a site situated at 3 m from a highway in Tokyo, Japan. All L samples and one A sample (A1-A8 fractions) collected from 3 p. m. to p. m., were analyzed by an electron probe micro analyzer (EPMA). Al to A8 fractions were collected on the 1st stage to 8th stage and the fraction BF was collected on the backfilter of the Andersen sampler, respectively. Their aerodynamic sizes were >11 pm, 7-11 pm, 4.7-7 pm, 3.3-4 .7 pm, 2.1-3.3 pm, 1. 1-2.1 p m, 0.65-1.1 p m, 0.43-0.65 p m, and <0.43 p m, respectively. Cluster analysis was performed on the compositional data of 100 particles in each of Al-A8 fractions and L samples. The results of source apportionment from A sample showed that the fractions of particle size >2.1 pm had more (1) tire dusts and (2) soil minerals ; and the fractions of particle size <2.1 pm had more (3) motor exhaust soot ; particles mainly containing (4) iron, (5) calcium, (6) silicon or (7) sea salt were also detected . The contributions of the seven sources described above were 22 .6, 8.4, 46.3, 7.4, 2.8, 1.6, and 3.4 by weight percent. From the results of the L samples, the one-hour interval variations of the mass concentrations of the 7 sources described above were obtained . The contribution of soot showed clear correlation with the percentage of diesel vehicles in the traffic. From these examples we can conclude that source apportionment of airborne particulates by this method is effective and practically useful. The monitoring of airborne particulates from any source can be performed even its contribution is very small in the total mass.

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Seasonal fluctuations of bacterial numbers were surveyed at four points in the Minoh River and the ma River between 1989-1990 for 18 months. The ratio of the colony forming unit to the total direct count (CFU/TDC) was the minimum at oligotrophic points, while it tended to high values at eutrophic points. It was corre-sponded with the saprobity of environment. It was suggested that the CFU/TDC ratio is useful as the parameter of the environmental evaluation.

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