Disturbance caused by various fluctuating single noises and combined community noises

Three experiments were conducted to investigate factors influencing the (rated) disturbance caused by various noises to subjects when they were reading: (a) comparison of disturbances from various noises at 70 dB(A) L_eq; (b) comparison of exposure-response relationships between road traffic, aircraft, and train noises; and (c) the effect of road traffic background noise on the total disturbance caused by combined noise (aircraft or train noise combined with road traffic noise). From the three experiments, the following conclusions were drawn: (1) High-level components such as peak level contributed to the disturbance, since the noise was more disturbing with the increase of peak level. (2) Although the general pattern of the exposure-response relationships for aircraft and train noises was similar, the disturbance due to road traffic noise increased with L_eq level more rapidly than for aircraft and train noise. Considering that the peak level of aircraft or train noise was always higher than that of road traffic noise at equal L_eq levels, the contribution of the high-level components to the disturbance appeared to be level-dependent. (3) The background noise level did not affect the total disturbance. Because the high-level components of combined noises were almost the same, this finding was consistent with conclusions drawn in (1) and (2).     

Dechlorination/hydrogenation and destruction reactions of PCDDs in OCDD-added fly ash heated under vacuum

Octachlorodibenzo-p-dioxin (OCDD)-added, pretreated fly ash was heated under vacuum at sample temperatures ranging from T(s)=450 to 650 K. The fly ash and liquid nitrogen-cooled trap samples were analyzed for DD/DF through OCDD/DF. The total amounts of DD through OCDD decrease with increasing T(s), which indicates that dechlorination/hydrogenation (DCH) reactions are not the only reaction channels. Reduction of toxic equivalent (TEQ) for PCDDs by more than 99% was achieved in the fly ash by the vacuum heat treatment at T(s)=650 K for 4 h. The total amount of PCDDs and DD detected in the liquid nitrogen-cooled trap relative to that of added OCDD was about 17%, i.e., PCDDs and DD which were adsorbed to the fly ash surfaces can evaporate into the gaseous phase. The difference between the evaporation behavior of PCDDs in the present and the previous studies is discussed in the light of their states of existence.     

Methods of statistical analysis of quantitative data obtained by toxicological bioassays using rodents in Japan: historical transition of the decision tree

Massive amounts of quantitative data are being obtained by toxicity tests with time. These data sometimes include the data with a different distribution pattern or with different numbers of animals in each group. The tree-type algorithm has long been used commonly to promptly analyze the difference between the control group and dosage groups. In Japan, the decision tree has been used since 1982 with several modifications of the initial procedure. Recently, the method has been revised to have a high power. The changes have been made in two directions; one is a sophisticated method and the other is a simplified method. In this paper, the historical transition of the decision tree is described and the future of the decision tree forecasted.     

Production and characterization of KOH-activated carbon derived from polychlorinated biphenyl residue generated by the sodium dispersion process

Polychlorinated biphenyl (PCB) residues from the sodium dispersion (SD) process were employed as the raw materials for the production of activated carbon using KOH activation. The pore properties, such as the specific surface area and pore size distribution, were characterized using the Barrett–Joyner–Halenda method and the Horvath–Kawazoe method based on the N₂ adsorption isotherm at 77 K. The activated carbon produced showed similar adsorption capacities and specific surface areas to the commercially available product. The effects of the activation conditions on the porosity of the activated carbon produced were studied. The most significant factor affecting the specific surface proved to be the activation temperature. The activated carbon produced from PCB residues from the high-temperature (423–443 K) SD process had a binary pore size distribution well developed in the 4 nm region and in the micropore region. The pore structure of the carbon produced from PCB residues from the low-temperature (333–393 K) SD process had a wide range of micropores and mesopores.     

Laboratory Measurement of Dry Deposition of Ozone onto Northern Chinese Soil Samples

We used laboratory experiments to investigate surface resistance (R _c) to dry deposition of ozone (O₃) on different types of soil samples collected from the arid deserts and the Loess Plateau of northern China. Furthermore, we measured the factors that affected R _c, which depends on the physical and chemical interaction between trace constituents and the deposition surface, and evaluated deposition velocity (V _d). There was little influence of geometric surface area, soil weight, or O₃ concentration on V _d of O₃. The effect of relative humidity (RH) (i.e. moisture content of the soil) on O₃ uptake was in agreement with results reported in the literature: a distinct RH dependence of V _d and little uptake under water-saturated conditions were observed. R _c values for all the soil samples examined were in the range 0.21–3.3 s mm⁻¹ and were exponentially related to the surface area of the particles and the organic carbon content of each soil sample at RH of both <10 and 60%.     

Growth cycle and related vertical distribution of the thecosomatous pteropod Spiratella (“Limacina”) helicina in the central Arctic Ocean

The growth cycle and related vertical distribution of the thecosomatous pteropod Spiratella (“Limacina”) helicina (Phipps) were studied. S. helicina has a life cycle of approximately 1.5 to 2 years in the central Arctic Ocean (Canada Basin). It spawns mainly during the spring to summer period, and on a small scale during the winter. The young double their sizes during the winter months of October to May, slow down in growth until late summer, and attain maximum size in early winter. The oldest disappear by late March. Gonadal tissue was first seen in young pteropods of 0.7 mm diameter, the predominant size from February to April. S. helicina 0.8 mm in diameter, the size predominant from May through July, are mature and hermaphroditic. Growth during the winter months suggests that particulate organic matter is available during this period to these obligate ciliary feeders. Vertical distribution is size and season-dependent. The youngest specimens collected (0.2 to 0.4 mm) were found concentrated in the first 50 m. The larger sizes dispersed during the summer months, and tended to concentrate in the top 150 m during the rest of the year. They aggregated in the top 50 m from late winter through early spring, and fall through early winter; then concentrated in the 100 to 50 m level until the end of winter. Numerous environmental factors seem to be involved in determining the vertical distribution of the species in the central Arctic Ocean.     

Genetic relationships of pilchards (genus: Sardinops) with anti-tropical distributions

The pilchards (genus Sardinops), one of the major components of the world's harvest of fishes, is distributed sporadically in the temperate zone on a global scale. Mitochondrial DNA variation in 95 pilchards from nine worldwide localities in five current systems was examined using ten restriction enzymes. Although several opinions have been proposed on the global population structure of the genus Sardinops, our results clearly rejected the hypothesis of gene flow among geographically distant populations on a global scale. Results indicate that the Japanese pilchards and the Australian and South African pilchards were derived from the eastern Pacific populations, following the speciation of Sardinops in the Pacific, after the formation of the Isthmus of Panama. An intermixing of the northeastern and southeastern Pacific populations during the Pleistocene glacial maxima is suggested from their genetic affinities.     

A study on the Spatial Distribution of Nitrogen and Phosphorus Balance, and Regional Nitrogen Flow Through Crop Production

The spatial distribution patterns of the nitrogen and phosphorus input/intake amounts in crop production within two small basins are examined, based upon a cropping unit distribution map that is obtained from remote sensing data analysis. Firstly, we examine the availability and suitability of approaches to the spatial distribution analysis of cultivation patterns classified from material flow characteristics of crop production using seasonal remote-sensing data. Secondly, material flow units in crop production are grouped according to the cultivation patterns obtained from the remote-sensing data analysis. Consequently, the spatial patterns of the amounts of both nitrogen and phosphorus inputs/intakes through crop production on farmland are examined and their spatial distribution maps are prepared according to the material flow units. In addition, we developed a nitrogen flow and runoff model and the model is simulated based on the examination of the results of spatial distribution patterns of the material flow units. The annual nitrogen runoff from small catchments, where various crops are cultivated, varies from 2.7 kg ha^–1 year^–1 to 108 kg ha^–1 year^–1 and the annual balanced losses of nitrogen in small catchments varied from –30 kg ha^–1 year^–1 to 101 kg ha^–1 year^–1. Also, the monthly changes in soil nitrogen of each material flow unit is estimated at –55 kg ha^–1 as a maximum decrease and 114 kg ha^–1 as a maximum increase. These results indicate that the spatial distribution patterns of nutrient input and intake through agricultural activities should be considered when analyzing the material flows and nutritient movement in soil–water systems in rural areas for watershed environmental control and regional agricultural management.     

Effects of heavy metals on sea urchin embryo development. 1. Tracing the cause by the effects

The toxicity of the polluted waters originating from a disused lead mine was evaluated using both sea urchin bioassays and heavy metal analysis. Samples from three polluted waters (a seawater and two freshwaters) were collected from the mine area and one seawater sample was taken from a non-contaminated reference site. The test waters contained higher concentrations of heavy metals such as manganese, lead, cadmium, zinc, chromium, nickel, iron, and copper than did ambient seawater. The three test waters had inhibitory effects, in a dose-dependent manner, on the first cleavage of sea urchin embryos and on pluteus formation during the development. Some malformations, such as a radialized pluteus, exo-gastrula, and spaceship Apollo-like embryos were induced by the test waters without dilution. Zinc alone also induced the same anomaly. Zinc in the test seawater was ascertained as one of the metals that caused the anomalies, but not all of the toxicity was caused by zinc. It was speculated that interactive effects, involving zinc and possibly manganese and nickel, were occurring.