Measurements of short-lived cosmic-ray-produced radionuclides in rainwater

Cosmic-ray-produced (CP) nuclides with half-lives shorter than 21h were measured in rainwater by ultra-low-background gamma spectrometry at Ogoya Underground Laboratory. As levels of CP nuclides are extremely low and their half-lives are very short, quick sampling methods for a large volume of rainwater and rapid chemical separations by ion exchange method were developed. The nuclides measured were short-lived (24)Na, (28)Mg, (38)S, (38)Cl, (39)Cl, as well as nuclides with longer half-lives (7)Be and (22)Na. The number of atoms of CP nuclides in rainwater were evaluated to range from 30 to 1500L(-1) for (24)Na (n=16, mean; 520 [6.7mBqL(-1)]), 80 to 600L(-1) for (28)Mg (n=13, mean; 260 [2.4mBqL(-1)]), 400 to 1900L(-1) for (39)Cl (n=6, mean; 1200 [250mBqL(-1)]), 1x10(6) to 4x10(7)L(-1) for (7)Be (n=16, mean; 7x10(6) [1.05BqL(-1)]) and 2x10(3) to 1x10(5)L(-1) for (22)Na (n=9, mean; 2x10(4) [0.2mBqL(-1)]).     

Bacterial community succession during the enrichment of chemolithoautotrophic arsenite oxidizing bacteria at high arsenic concentrations

To generate cost-effective technologies for the removal of arsenic from water, we developed an enrichment culture of chemolithoautotrophic arsenite oxidizing bacteria (CAOs) that could effectively oxidize widely ranging concentrations of As(III) to As(V). In addition, we attempted to elucidate the enrichment process and characterize the microbial composition of the enrichment culture. A CAOs enrichment culture capable of stably oxidizing As(III) to As(V) was successfully constructed through repeated batch cultivation for more than 700 days, during which time the initial As(III) concentrations were increased in a stepwise manner from 1 to 10-12 mmol/L. As(III) oxidation activity of the enrichment culture gradually improved, and 10-12 mmol/L As(III) was almost completely oxidized within four days. Terminal restriction fragment length polymorphism analysis showed that the dominant bacteria in the enrichment culture varied drastically during the enrichment process depending on the As(III) concentration. Isolation and characterization of bacteria in the enrichment culture revealed that the presence of multiple CAOs with various As(III) oxidation abilities enabled the culture to adapt to a wide range of As(III) concentrations. The CAOs enrichment culture constructed here may be useful for pretreatment of water from which arsenic is being removed.     

Modeling the influence of biogenic volatile organic compound emissions on ozone concentration during summer season in the Kinki region of Japan

Tropospheric ozone adversely affects human health and vegetation, and biogenic volatile organic compound (BVOC) emission has potential to influence ozone concentration in summer season. In this research, the standard emissions of isoprene and monoterpene from the vegetation of the Kinki region of Japan, estimated from growth chamber experiments, were converted into hourly emissions for July 2002 using the temperature and light intensity data obtained from results of MM5 meteorological model. To investigate the effect of BVOC emissions on ozone production, two ozone simulations for one-month period of July 2002 were carried out. In one simulation, hourly BVOC emissions were included (BIO), while in the other one, BVOC emissions were not considered (NOBIO). The quantitative analyses of the ozone results clearly indicate that the use of spatio-temporally varying BVOC emission improves the prediction of ozone concentration. The hourly differences of monthly-averaged ozone concentrations between BIO and NOBIO had the maximum value of 6 ppb at 1400 JST. The explicit difference appeared in urban area, though the place where the maximum difference occurred changed with time. Overall, BVOC emissions from the forest vegetation strongly affected the ozone generation in the urban area.     

Chlordane residues in krill,fish and Weddell seal from the Antarctic

Chlordane compounds (CHLs) were quantitated in krill (Euphausia superba), benthic fish (Trematomus bernacchii) and Weddell seal (Leptonychotes weddelli) collected around the Japanese Antarctic Research Station (Syowa Station: 69°00'S, 39°35'E). The concentrations of ZCHL (cis‐, trans‐chlordane+ cis‐, fraws‐nonachlor + oxych‐lordane) in krill was much lower than that of benthic fish. The ratio of SCHL to sum of SCHL, SDDT and PCBs decreased with the trophic levels. These results indicate that CHLs appear to be easily degraded in higher organisms.     

Post furnace formation of PCDDs and PCDFs in MSWI: Observations in an incinerator installed with quench reactor

Reduction of dioxin emission by a quench reactor with lime spray was investigated in relation to post furnace formation pathways. Results showed that the quench reactor performed to supress post furnace reaction of precursor molecules to form selected congeners of PCDD and PCDF.     

River system in Japan from a landscape ecological aspect

The objective of this study was to elucidate characteristics associated with rivers by classification of major rivers in Japan into sereral types based on riparian conditions.As the results of principal compoent analysis(PCA) with use of parameters reflecting forms and artificial alterations of respective rives,four major components such as“comprehensive riparian size”,“intactness of water front”,“continuity of streams” and “silmplicity of landform in river basin”were extracted.Subsequently,cluster analysis was performed based on principal component scores,leading to succesful classification of major rivers into 6 types.These findings disclosed that(1) the extracted principal components provide effective viewpoint for classification of rivers;(2) distribution of respective classes indicates are properties;and (3) the emplyed quantitative procedures were found effective for classification of major rivers.     

Effects of low protein diet and sex difference on the amounts of metallothionein in liver and kidney of cadmium-administered rats

Cadmium (Cd) was orally administered in a dose of 100 μg daily for a total of 100 times to investigate the effects of the intake of low (5%) protein diet and sex difference on the amounts of metallothionein (MT) in the liver and kidney. The amount of MT in the liver was significantly increased by the intake of low protein diet. In females, the increase in the amount of MT was proportional to the amount of Cd accumulated. The concentration of copper-thionein in the liver was higher in females than in males and further increased after intake of low protein diet. The levels of MT, cadmium-thionein, zinc-thionein and copper-thionein in the kidney were not influenced by the intake of low protein diet nor did show a sex difference.     

Studies on transitory laxative effects of sorbitol and maltitol: III: Alterations in serum contents due to laxative effects

Maltitol or sorbitol was administered in doses of 0.8 g/kg to 20 physically healthy subjects (10 males and 10 females) and 6 diabetic patients (3 males and 3 females). Maltitol and sorbitol caused diarrhea in 75% and 95% of the subjects, respectively. Stool was watery in most of the subjects. The serum concentration of each sweetening agent was as low as approximately 0.3 mg/dl 2 hours after administration. The serum concentrations of Na, K, Cl, BUN, glucose and insulin did not change 2 hours after administration.