Promoting more effective countermeasures that is really able to eliminante the offensive odor injury, actually, caused by complex of odoriferous gases, almost of them are very low concentration, is a pressing need today. Most of the controling methods or techniques apllied up to now generally have doubts about the substantial efficiency, because they have no regards for such aspecial characteristics of odor.
Paying attention to solving some of those characteristics of odor, we made experiments on absorption of hydrogen sulfide (H₂S) in hydrated sodium (NaOH) solution flowing on the wirenetting of 9 mesh. And, as the result of the work, we got the following conclusios;
i) When the concentration of H₂S is under than 2.0 ppm, the absorption rate of H₂S gas in NaOH solution is in proportion to the interface concentration of H₂S and independent of NaOH concentration.
ii) When SO₂ and H₂S gas simultaneously react with NaOH of liquid phase instantly, the function of absorption rate of H₂S “NA” is shown as follow:
_??_
where the coefficient ‘a’ is constant that is given by the function of such as the diffusivity of th absorbed component, and we got a=0.0029 from this work.

View full abstract

The statistical treatment was pursued for determination of average emission rates of polynuclear aromatic hydrocarbons (PAH) from a single automobile. Intermittent sampling (20 samples at random intervals) from the same car gave a broad distribution for PAHemission rate, while continual sampling (20 successive samples during a continuous run ofthe car) gave a narrow distribution. The average of PAH emission rates from the intermittent sampling will reflect the average emission rate characteristic of an individual automobile. A linear relation between the standard deviation and the mean of PAH emission rates was obtained for each sampling method, and the quasi-constancy of the standard deviation of the logarithm of PAH emission rate was observed regardless of the difference of cars, operating conditions, mileages and species of PAH. The sampling errors for the average determined from n intermittent samples were estimated as follows. n=5:±17%, n=12% and n=20:±8%. The broad distribution of PAH emission rate by the intermittent sampling seems to result from the fluctuations of the consumption rate of engine oil.

View full abstract

The composition and pnotochemical reactivity of exhaust hydrocarbons from four kinds of vehicles equipped with various emission control systems are investigated by using five kinds of fuels varying in aromatic content and four kinds of test procedures.
An oxidation catalyst-equipped vehicle shows a small olefin and aromatic contentunder a warmed-up condition. As a result it is estimated that the specific reactivity of its exhaust hydrocarbons is significantly small under the warmed-up condition. The specific reactivities of two vehicles with other typesof the advanced emission control systems, however, are almost the same as that of a conventional engine-modified vehicle. On the contrary it is estimated that the overall reactivities of three advanced vehicles are almost close to one another.
We define the modified non-methane HC mass emission such as eq.(6). By assuminga curvilinear regression relation between the modified non-methane HC mass emission and the overall reactivity, eq.(9) is derived. This equation is possible to estimate the photochemical exhaust reactivity only by measuring the HC mass emission and the exhaust methane content. On the basis of eq.(9), it is estimated that the photochemical reactivity of the exhaust hydrocarbons significantly changes with the methane content, even if the vehicles show the same HC mass emissions.

View full abstract

A method was developed to monitor the thermal stability in the planetary boundary layer, based on infrared radiation measurements. By the theoritical consideration, a non-dimensional index
F(ν, θ)=I(ν, θ)-B(ν, T₀)/B(ν, T₀)
was introduced to describe the thermal stability, where I (ν, θ) is the radiation for the frequency ν and the elevation angle θ, B (ν, T₀) is the Planck function for the absolute temperature T₀ at ground surface.
Numerical simulations were performed to examine the capability of the index by setting various model temperature profiles. As the results, it was shown that the index is available for describing temperature gradients from ground surface to a certain altitude if applicable frequency and elevation angle were chosen. Observational values also agreed well with theoritical ones. It appears that this method is useful for the routine observation of the thermal stability and its temporal variation in the planetary boundary layer.

View full abstract

The diurnal variation of air pollutant concentrations in Sapporo was analyzed inconnection with the sources of pollution and meteorological factors. As a result, the bi-modal variation of air pollutant concentrations was qualitatively explained by the interaction between the man's impact and the mixing that is, the furnace, traffic, thermal stability and wind speed

View full abstract