Photodegradation of gaseous acetaldehyde and methylene blue in aqueous solution with titanium dioxide-loaded activated carbon fiber polymer materials and aquatic plant ecotoxicity tests

TiO₂-supported activated carbon felts (TiO₂–ACFTs) were prepared by dip coating of felts composed of activated carbon fibers (ACFs) with either polyester fibers (PS-A20) and/or a polyethylene pulp (PE-W15) in a TiO₂ aqueous suspension followed by calcination at 250 °C for 1 h. The as-prepared TiO₂–ACFTs with 29–35 wt.% TiO₂ were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and N₂ adsorption. The TiO₂–ACFT(PS-A20) samples with 0 and 29 wt.% TiO₂ were microporous with specific surface areas (S _BET) of 996 and 738 m²/g, respectively, whereas the TiO₂–ACFT(PE-W15) samples with 0 and 35 wt.% TiO₂ were mesoporous with S _BET of 826 and 586 m²/g, respectively. Adsorption and photocatalytic activity of the as-prepared samples were evaluated by measuring adsorption in the dark and photodegradation of gaseous acetaldehyde (AcH) and methylene blue (MB) in aqueous solution under UV light. The TiO₂ loading caused a considerable decrease in the S _BET and MB adsorption capacity along with an increase in MB photodegradation and AcH mineralization. Lemna minor was chosen as a representative aquatic plant for ecotoxicity tests measuring detoxification of water obtained from the MB photodegradation reaction with the TiO₂–ACFT samples under UV light.     

A GAME-THEORETIC APPROACH TO ACID RAIN ABATEMENT: CONFLICT ANALYSIS OF ENVIRONMENTAL LOAD ALLOCATION1

ABSTRACT: The detrimental impacts of acid rain have become widely publicized, but effective and equitable methods to mitigate the acid rain problem remain to be found. This paper focuses on conflicts involved in allocation of the total emission loads to be reduced to respective pollution sources of acid rain, and proposes a game-theory approach to the resolution of the conflict. With an example abstracted from a hypothetical case study in the United States of America and Canada, a systematic analysis is performed and policy implications of the results examined to assess the applicability of the proposed model.     

Respiratory tract retention of inhaled air pollutants: Report 1 : Mercury absorption by inhaling through the nose and expiring through the mouth at various concentrations

To study atmospheric mercury absorption in human respiratory passage-ways, mercury in expired air was measured in three different states of breathing: steady breathing, deep breathing and breath held after inspiration.In this study, air containing mercury was inhaled through the nose and expired through the mouth. The concentration of mercury in the exhaled air was determined by the technique of gold-amalgam trapping, heat vaporization, and flameless atomic absorption measurement.The subjects were 13 male adults, aged 25–62 years, and 38 cases were observed. Four different concentrations of mercury, 1–3, 4–6, 10–11, and 20–30 μg/m³ were used, and absorption for each was determined. When the concentration was 1–3 μg/m₃, the absorption was 74–92%, the average being 82.5%. At concentrations of 4–6, 10–11, and 20–30 μg/m₃, the absorption was 76.6–100%, 75.5–99.2%, and 79.9–95.9% respectively, and the average was 88.8%, 85.2%, and 87.7% respectively.A slightly higher rate of mercury absorption was observed in deep breathing than in steady breathing, and when expiration was suppressed for some time after inspiration, the rate increased remarkably to 97.4–99.7%. Prolonged retention of inhaled air containing mercury in the respiratory tract is believed to have caused the increased absorption.     

Metal distribution in incineration residues of municipal solid waste (MSW) in Japan

This study aimed to identify distribution of metals and the influential factors on metal concentrations in incineration residues. Bottom ash and fly ash were sampled from 19 stoker and seven fluidized bed incinerators, which were selected to have a variety of furnace capacity, furnace temperature, and input waste. In the results, shredded bulky waste in input waste increased the concentration of some metals, such as Cd and Pb, and the effect was confirmed by analysis of shredded bulky waste. During MSW incineration, lithophilic metals such as Fe, Cu, Cr, and Al remained mainly in the bottom ash while Cd volatilized from the furnace and condensed to the fly ash. About two thirds of Pb and Zn was found in the bottom ash despite their high volatility. Finally, based on the results obtained in this study, the amount of metal in incineration residues of MSW was calculated and the loss of metal was estimated in terms of mass and money. A considerable amount of metal was found to be lost as waste material by landfilling of incineration residues.     

Tree-ring strontium-90 and cesium-137 as potential indicators of radioactive pollution

To examine whether tree rings can be used to detect or assess local historical 90Sr or 137Cs fallout, such as that resulting from the Hiroshima atomic bomb, radial distribution of 90Sr and 137Cs in trees was examined. We studied a gymnosperm [Japanese cedar, Cryptomeria japonica (L. f.) D. Don] and an angiosperm (Japanese persimmon, Diospyros kaki Thunb.) tree species from the vicinity of the atomic bomb hypocenter, and from other locations in Japan. A significant amount of 137Cs was detected in tree rings formed before 1945, indicating lateral migration of Cs. In contrast, the specific activity of 90Sr in the Hiroshima Japanese cedar showed the highest level in 1945, due to relatively immobile characteristics of Sr compared with Cs. Strontium-90 and Sr analyses in tree rings helped identify and distinguish between residual 90Sr activity from the Hiroshima atomic bomb and the atmospheric nuclear testing. This indicates the possibility of detecting or assessing previous local 90Sr pollution through with treering analysis.     

Recovery of zinc and lead from fly ash from ash-melting and gasification-melting processes of MSW--comparison and applicability of chemical leaching methods

Fly ash generated from MSW ash-melting and gasification-melting plants, known as Melting Furnace Fly Ash (MFA), contains considerable amounts of heavy metals such as Pb and Zn. These metals can be recovered using a smelting furnace after "pre-treatment" for removal of unnecessary elements such as Cl, Sn and Si. Chemical methods have been studied for pretreatment in the past. However, they have been discussed only with regard to treatment cost and the concentration of Pb and Zn recovered, but neither applicability to various types of MFA nor the environmental impact have been considered. In this study, acid, alkaline and ammonia/chloride leaching methods were compared from the standpoints of: (1) applicability to MFA, (2) concentration of Pb and Zn recovered, (3) treatment cost, and (4) environmental impact. Twenty-three samples of MFAs were collected and classified into 4 types based on element contents. A Pb and Zn recovery experiment was conducted for the representative MFA of those types. The results showed: (1) MFA from gasification-melting plants cannot be treated by chemical methods; (2) the other MFA can be treated to an acceptable quality by existing smelting furnaces; (3) only MFA from electric resistance ash-melting plants can be treated easily by the water washing method; and (4) alkaline and ammonia/chloride leaching methods were more effective than acid leaching.     

Metabolism of potassium bromate in rats II. In vitro studies

To learn more about the biodegradation of potassium bromate, the decomposition of bromate in various tissues of rats was studied. Bromate was degraded very slowly in human saliva and plasma of rat. However, nearly all tissue homogenates and red blood cells could degrade bromate by a mechanism which exhibited some stability to heat. Furthermore, it was suggested that the bromate degradation active component in the supernatant fraction of a liver homogenate was in part glutathione.     

Reproduction-related interactions and loads induce continuous turn alternation leading to linearity in a terrestrial isopod

The Science of Nature - Red propolis is a substance produced by bees by mixing resins from plants with wax, oils, and other secretions to protect the hive against natural enemies. Dalbergia...     

Distribution of coccolithophores in marginal seas along the western Pacific Ocean and in the Red Sea

The distribution of coccolithophores was studied in the neritic environment along the western margin of the Pacific Ocean: the Inland Sea of Seto, Yellow Sea, East China Sea, South China Sea, Java Sea, Timor Sea, Arafura Sea and Gulf of Carpentaria. The coccolithophore community in the Red Sea was also studied for comparison with the Pacific marginal seas. With minor exceptions, the coccolithophore communities were very similar throughout the neritic areas investigated, but differed completely from the pelagic community in three aspects. Firstly, almost all neritic coccolithophores, regardless of species, suffered various degrees and forms of malformation with relation to the morphology of their coccoliths, while such malformation was rare in the pelagic population. Nitrogen deficiency may cause such malformation. Secondly, the diversity of species in these marginal seas was much lower than in the pelagic environment, although no species was found to be exclusively neritic. Emiliania huxleyi, usually ubiquitous in oceanic areas and in various neritic environments of higher latitudes, was scarce, while Gephyrocapsa oceanica dominated the flora throughout the studied areas. Finally, the horizontal and vertical distributions of the neritic populations were sporadic compared to those of the rather uniform pelagic environments.