Photo-electrochemical degradation of some chlorinated organic compounds on n-TiO2 electrode

The electrolysis of some chlorinated organic compounds such as chloroacetic acids, chloromethanes and chloroethenes were carried out on a photo-irradiated n-TiO(2) electrode applied a constant potential, 1.0 V vs. Ag/AgCl, and the alternated pulse potentials of +1.0 V and various negative potentials, -1.0, -1.2 and -1.4V vs. Ag/AgCl in 0.1 mol dm(-3) Na(2)SO(4) solutions saturated with oxygen or with nitrogen. These compounds were degraded on the n-TiO(2) electrode by the photo-electrolysis and mineralized to carbon dioxide, carbon monoxide and chloride ion. When the alternated pulse potentials were applied, the mineralization yields were increased for these compounds, especially for trichloroacetic acid and carbon tetrachloride, both of which were comparatively stable to the degradation in the constant potential electrolysis. The presence of oxygen in the solution was effective for the mineralization of these compounds, while little effective for that of trichloroacetic acid and of carbon tetrachloride.     

Seasonal and spatial variation of atmospheric 210Pb and 7Be deposition: features of the Japan Sea side of Japan

Monthly depositional fluxes of (210)Pb and (7)Be at Tatsunokuchi, Japan which faces the Japan Sea were studied over a 12-year period from 1991 to 2002. The data were compared with the spatial variability of these fluxes at Taejon in Korea and at 11 other sites in Japan from Ishigaki of the southern islands of Okinawa to Wakkanai of the northern end of Hokkaido over a 2-year period from 2000 to 2001. The monthly depositions of both (210)Pb and (7)Be at Tatsunokuchi revealed very similar seasonal variations with a single peak; both depositions were high in winter and low in summer. This phenomenon was found to be not transient but stationary. The deposition of these nuclides was much greater on the Japan Sea side of Japan than on the Pacific Ocean side. The cause for high deposition of (210)Pb and (7)Be in winter might be explained by a combination of a series of the following processes: blowing out of air masses with a high (210)Pb concentration near the surface layer over the continent by strong winter monsoons, additional flow of cold air masses with high (7)Be concentration at high latitude, well-mixing with generation of ascending current and convection clouds over the Japan Sea, and heavy snowfalls accompanying them.     

Oxidation of antimony(Ⅲ) in soil by manganese(Ⅳ) oxide using X-ray absorption fine structure

The oxidation of antimony(III) in soils was studied using X-ray absorption fine structure(XAFS)spectra.An andosol soil sample and artificial soil samples(SiO_2 blended with iron(III) hydroxide and manganese(IV) oxide) were used herein.After adding antimony(III) oxide to all soil samples,the oxidation process was observed by recording the XAFS spectra of Sb K-edge,Fe Kedge,and Mn K-edge.The results indicated that manganese(IV) oxide played an important role in the oxidation of Sb(III);however iron(III) hydroxide was not directly related to the reaction.During a 2-hr continuous Sb K-edge X-ray absorption near edge structure(XANES) measurement with an interval of 1 min of one of the artificial soil samples(SiO_2+ MnO_2+ Sb_2O_3),a pseudo-first-order reaction was determined with an average estimated rate of 0.52 ± 0.04 hr-1.Compared to the lower oxidation rate of andosol,it is suggested that because of the low concentration of Mn(IV) in natural soils,the oxidation process of Sb(III) might be relatively slow and require more time to convert Sb(III) to Sb(V).     

Evaluation of mercury contamination using plant leaves and humus as indicators

Plant leaves and humus were collected from three areas with and without mercury emission sources. Mercury in these samples were determined by cold flameless atomic absorption spectrometry. A part of mercury emitted from the source into the atmosphere is absorbed by plant leaves, and move to humus through fallen leaves. Consequentry, plant leaves are able to be used as an indicator for the evaluation of mercury in air at present. Humus is usefull for the evaluation of mercury contamination through the air from the past to present.     

90Sr, 137Cs and (239,240)Pu concentration surface water time series in the Pacific and Indian Oceans--WOMARS results

Under an IAEA's Co-ordinated Research Project "Worldwide Marine Radioactivity Studies (WOMARS)" 90Sr, 137Cs and (239,240)Pu concentration surface water time series in the Pacific and Indian Oceans have been investigated. The Pacific and Indian Oceans were divided into 17 latitudinal boxes according to ocean circulation, global fallout patterns and the location of nuclear weapons test sites. The present levels and time trends in radionuclide concentrations in surface water for each box were studied and the corresponding effective half-lives were estimated. For the year 2000, the estimated average 90Sr, 137Cs and (239,240)Pu concentrations in surface waters of the Pacific and Indian Oceans varied from 0.1 to 1.5 mBq/L, 0.1 to 2.8 mBq/L, and 0.1 to 5.2 microBq/L, respectively. The mean effective half-lives for 90Sr and 137Cs in surface water were 12+/-1 years for the North, 20+/-1 years for the South and 21+/-2 years for the Equatorial Pacific. For (239,240)Pu the corresponding mean effective half-lives were 7+/-1 years for the North, 12+/-4 years for the South and 10+/-2 years for the Equatorial Pacific. For the Indian Ocean the mean effective half-lives of 137Cs and (239,240)Pu were 21+/-2 years and 9+/-1 years, respectively. There is evidence that fallout removal rates before 1970 were faster than those observed during recent decades. The estimated surface water concentrations of 90Sr, 137Cs and (239,240)Pu in latitudinal belts of the Pacific and Indian Oceans for the year 2000 may be used as the average levels so that any new contribution from nuclear facilities, nuclear weapons test sites, radioactive waste dumping sites and from possible nuclear accidents can be identified.     

Growth and reproduction ofCaprella danilevskii (Crustacea: Amphipoda) reared in the laboratory

Caprella danilevskii Czerniavski, an epifaunal amphipod crustacean, was successfully reared for two generations under laboratory conditions. Amphipods were maintained in pairs or fours in a Petri dish. Temperature and photoperiod were maintained at 20°C, and 14 h light: 10 h dark, respectively. Colonies of the diatomCylindrotheca closterium (Ehrenberg) Reumann and Lewin were provided as food source. The red algaGelidium amansii (Lamouroux) Lamouroux was used to provide an attachment substrate for the caprellids. Juveniles that emerged from the brood pouch were described as instar I. Subsequent instars were identified by molts. Juveniles molted successively at 2.5 to 6.5 d intervals. The body length of males at each instar increased exponentially, while that of females followed a sigmoid curve. A different pattern of flagellar segment addition in the antenna I of males and females was revealed. At the age of 20.8 d, females reached instar VII, and produced their first embryos. After 5.1 d, juveniles emerged from the brood pouch. On average, females produced 5.4 clutches successively at 5.0 d intervals. The number of offspring per spawning increased from 6.3 at instar VII to 22.0 at instar XII. The total number of offspring was 69.0 for a female throughout her life span.     

Seasonality of spawning by tropical anguillid eels around Sulawesi Island, Indonesia

Remarkably little is known about the life histories of the many tropical anguillid eels distributed across the Indo-Pacific region, and since the Danish expedition to study eels in the region in 1928 and 1929, research on these eels has only begun again in recent years. Sampling for anguillid leptocephali in the Indonesian Seas has been carried out recently to learn about the spawning ecology and larval distributions of tropical eels there. The leptocephali of Anguilla marmorata, Anguilla bicolor pacifica, Anguilla borneensis, Anguilla interioris, and Anguilla celebesensis were collected around Sulawesi Island both in May 2001 and October of 2002. The development of genetic identification techniques has enabled these leptocephali to be identified to species, and their distributions and sizes during different seasons indicated that there are differing life history patterns among sympatric species in the region. A. celebesensis was found to have been spawning in Tomini Bay of northeastern Sulawesi Island in March and April 2001, but apparently, no spawning had occurred in the late summer and fall of 2002. Studies on anguillid glass eels have suggested that tropical anguillids may spawn throughout much of year, but our research on leptocephali in Tomini Bay and data on the downstream migration of tropical anguillids in the major tributary to Tomini Bay indicate that A. celebesensis may have a distinct seasonal pattern of spawning possibly related to the regional monsoon cycles. This is the first evidence of seasonality of spawning in tropical anguillid eels whose life histories are only just beginning to be revealed.     

Do we need to examine the quantitative data obtained from toxicity studies for both normality and homogeneity of variance?

Most of the statistical techniques used to evaluate the data obtained from toxicity studies are based on the assumption that the data show a normal distribution and homogeneity of variance. Literature review on toxicity studies on laboratory animals reveals that in most of the cases homogeneity of variance alone is examined for the data obtained from these studies. But the data that show homogeneity of variance need not always show a normal distribution. In fact, most of the data derived from toxicity studies, including hematological and biochemical parameters show a non-normal distribution. On examining normality of data obtained from various toxicity studies using different normality tests, we observed that Shapiro-Wilk test is more appropriate than Kolmogorov-Smimov test, Lilliefors test, the normal probability paper analysis and Chi square test. But there are situations, especially in the long-term toxicity studies, where normality is not shown by one or more than one of the dosage groups. In this situation, we propose that the data maybe analyzed using Dunnett multiple comparison test after excluding the data of the groups that do not show normality However, the biological relevance of the excluded data has to be carefully scrutinized. We also observed that the tendency of the data to show a normal distribution seems to be related to the age of the animals. Present paper describes various tests commonly used to test normality and their power, and also emphasizes the need of subjecting the data obtained from toxicity studies to both normality and homogeneity tests. A flow chart suggesting the statistical techniques that maybe used for both the types of data showing a normal or non-normal distribution is also proposed.