Toxic cyanobacteria and microcystin dynamics in a tropical reservoir: assessing the influence of environmental variables

Environmental Science and Pollution Research - Toxic cyanobacterial blooms (TCBs) have become a growing concern worldwide. The present study investigated the dynamic of toxic cyanobacteria and...     

Effect of transition metal doping under reducing calcination atmosphere on photocatalytic property of TiO2 immobilized on SiO2 beads

TiO₂ immobilized on SiO₂ (TiO₂/SiO₂) have been prepared by sol-gel method and various ions of transition metals (Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) were doped on the photocatalyst using wet impregnation method under reducing calcination atmosphere. The photocatalytic activity of metal doped TiO₂/SiO₂ towards phenol degradation under black light irradiation were investigated and compared with undoped TiO₂/SiO₂. The results showed that the photoresponse of Cu²⁺ and Zn²⁺ doped TiO₂/SiO₂ were larger than undoped TiO₂/SiO₂, indicating that the photogenerated carriers were separated more efficiently in Cu²⁺ and Zn²⁺ doped TiO₂/SiO₂. The reactivity was in the order of Cu²⁺ > Zn²⁺ > Ni²⁺ > Cr³⁺ > Co²⁺. The different photoreactivity was ascribed to combine effect of the different ionic radii and photocorrison tendency of the dopants. The sample was also characterized by surface analytical methods such as X-ray diffraction, scanning electron micrograph/electron dispersive X-ray analyzer and UV-Vis absorption spectrum.     

Liquefaction process for a hydrothermally treated waste mixture containing plastics

Most landfilled plastic waste is a mixture or is in the form of composites with incombustible wastes such as glass, metals, and ceramics. After hydrothermal treatment, including a steam-explosion process, the separation of mixed waste (MW) into organic and inorganic substances becomes easy. However, the effect of hydrothermal pretreatment on the subsequent liquefaction of organic substances from MW is not obvious. In this study, the effects on the liquefaction of polystyrene and high-density polyethylene are discussed. Moreover, optimum conditions for the liquefaction of organic substances from hydrothermally treated MW are identified. By means of this hydrothermal pretreatment, including the steam-explosion process, polystyrene and high-density polyethylene can be significantly converted to oil by liquefaction at 300°–400°C. In comparison with liquefaction of hydrothermally pretreated mixed waste (HMW) at 300°–400°C with a batch type reactor, the yield of oil increases significantly on liquefaction using a semi-batch type reactor. It is considered that the radical chain and termination reactions among the radicals from HMW were inhibited in the semi-batch type reactor. On liquefaction of HMW in a semi-batch reactor, the conversion of HMW to oil was enhanced on increasing the liquefaction temperature to 350°C and the holding time to 60 min. Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6     

Historical and geographical aspects of the increasing perfluorooctanoate and perfluorooctane sulfonate contamination in human serum in Japan

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have recently received attention due to their widespread contamination in the environment, as well as in wildlife and humans. We measured the PFOS and PFOA concentrations in historically recorded human serum samples at an age range between 20 and 59 years collected in Kyoto, 20 persons per each time point (n=100), and also the PFOS and PFOA concentrations in human serum samples at an age range between 20 and 59 years from 10 locations throughout Japan (n=200). The historical samples collected from 1983 to 1999 demonstrated that the PFOA concentrations in males and females from Kyoto have increased 4.4-fold and 4.3-fold at a rate of increase of 0.49 ng/ml/year and 0.42 ng/ml/year, respectively. In contrast, serum concentrations of PFOS reached a plateau in the late 1980s. There are also regional differences in both the PFOS and PFOA serum concentrations. The concentrations in serum [geometric mean (geometric standard deviation)] (ng/ml) in 2003-2004 ranged from 7.6(1.6) in the town of Matsuoka in Fukui prefecture to 27.8(1.6) in Kyoto city, and ranged from 2.3(1.5) in Matsuoka to 14.5(1.3) in Osaka city for PFOS and PFOA, respectively.     

Biodegradation of heptachlor and heptachlor epoxide-contaminated soils by white-rot fungal inocula

The ability of certain white-rot fungi (WRF) inocula to transform heptachlor and heptachlor epoxide and its application in artificially contaminated soil were investigated. Fungal inoculum of Pleurotus ostreatus eliminated approximately 89 % of heptachlor after 28 days of incubation, and chlordene was detected as the primary metabolite. The fungal inoculum of Pleurotus ostreatus had the highest ability to degrade heptachlor epoxide; approximately 32 % were degraded after 28 days of incubation, and heptachlor diol was detected as the metabolite product. Because Pleurotus ostreatus transformed heptachlor into a less toxic metabolite and could also effectively degrade heptachlor epoxide, it was then selected to be applied to artificially contaminated soil. The spent mushroom waste (SMW) of Pleurotus ostreatus degraded heptachlor and heptachlor epoxide by approximately 91 and 26 %, respectively, over 28 days. This finding indicated that Pleurotus ostreatus SMW could be used to bioremediate heptachlor- and heptachlor epoxide-contaminated environments.     

Identification of the dimethylbenzyl mercapturic acid in urine of rats treated with 1,2,3-trimethylbenzene.

The structure was investigated of the mercapturic acid excreted in urine of rats after the i.p. administration of 1,2,3-trimethylbenzene. Of the two regioisomeric mercapturic acids, i.e. N-acetyl-S-(2,3-dimethylbenzyl)-L-cysteine and N-acetyl-S-(2,6-dimethyl-benzyl)-L-cysteine, only the former was isolated by preparative HPLC and identified, by comparison with an authentic specimen. The excretion rate of the mercapturate was estimated to be approximately 5% of dose, not a substantial metabolic route.     

The Effect of Local Biomass Projects on Energy Balance and GHG Emission: A Life Cycle Approach

Emerging attention has been given to the use of biomass in local areas for its contribution to reducing fossil fuel dependence and mitigating global warming. The objective of the present study is to develop a method that quantitatively assesses the effects of local biomass projects on fossil fuel consumption and greenhouse gas (GHG) emission. A practical method based on a life cycle approach is proposed and applied to a case of bioethanol project in Miyako Islands of Japan. The project is aiming to produce bioethanol from molasses within the islands, and to replace the entire gasoline consumed in the islands to E3 fuel (i.e., a mixture of 3% ethanol and 97% gasoline by volume). The assessment using the developed method revealed that, first, the complete shift from gasoline to E3 fuel allows for decreases in fossil fuel consumption and GHG emission. Second, the performance of the project is improved by the integration of the ethanol plant and the sugar factory. Moreover, the assessment found that, in small-scale bioethanol projects, the contribution of capital goods to life cycle fuel consumption and GHG emission is not negligible.     

Age-related settlement success by cyprids of the barnacleBalanus amphitrite,with special reference to consumption of cyprid storage protein

Newly molted (0-d-old) cyprids of the barnacleBalanus amphitrite Darwin were prevented from settling for 0 to 14 d at four different temperatures (25, 20, 15 and 5°C treatments). The effect on settlement success of prolonging the cyprid lifetime was evaluated using a nitrilocellulose membrane assay. In addition, protein extract prepared from these cyprids was analyzed using gel electrophoresis to characterize the effect of age on protein content and composition. Settlement success was significantly affected for larvae aged at 25 (P < 0.001), 20 (P < 0.001) and 15°C (P < 0.05), while differences in settlement success between age groups was negligible at 5°C (P = 0.09). Settlement success of cyprids increased with time for up to 3 d (P < 0.001, Phase 1), following which settlement success significantly declined (P < 0.001, Phase 11). Temperature had no significant effect on settlement in Phase I (P = 0.17), but did enhance the decline in settlement success with age during Phase II (P < 0.001). Gel electrophoresis revealed a significant decline in the quantity of the cyprid storage protein CMP (Cyprid Major Protein) with increasing age at 25, 20 and 15°C, but CMP levels remained constant at 5°C. These results suggest that, upon molting to the cyprid stage, larvae may still require a settlement-competence attainment period. This may be achieved by CMP utilization during Phase I, depletion of which during Phase II may be responsible for reduction in settlement success with cyprid age such that remaining CMP stores can no longer support the production of adult structures following settlement.     

Identification of the dimethylbenzyl mercapturic acid in urine of rats administered with 1,2,4-trimethylbenzene

A study was undertaken of the mercapturic acid metabolism of 1,2,4-trimethylbenzene in the rat. Of three regioisomeric dimethylbenzyl mercapturic acids, i.e. 2,4-, 2,5- and 3,4-dimethylbenzyl isomers, the third isomer was not found in the urinary mercapturic acid isolated by preparative HPLC, from the comparison of NMR spectrum of the isolate with those of authentic specimens. The urinary mercapturate was then assigned to 2,4- and/or 2,5-dimethylbenzyl isomers. The excretion rate of the mercapturic acid was 14-20% of dose as 2,4-dimethylbenzyl isomer.     

Formation of mutagens by photolysis of amino acids in neutral aqueous solution containing nitrite or nitrate ion

Nine amino acids, i.e., alanine, threonine, cysteine, glutamic acid, arginine, proline, tryptophan, phenylalanine and tyrosine, were irradiated with UV light in water containing nitrite or nitrate ion under neutral conditions. The mutagenicities of the ether extracts and the residual water layers of the reaction mixtures were assayed with and without S-9 mix using $\text{Salmonella typhimurium}$ TA98 and TA100. Three aromatic amino acids, tryptophan, phenylalanine and tyrosine, were found to give direct-acting and frameshift mutagens by irradiation in aqueous nitrite solution. Among them, the ether extract of tryptophan exhibited the strongest mutagenicity toward TA98. In the case of irradiation in aqueous nitrate solution, only the ether extract of tryptophan exhibited weak mutagenicity toward TA98 without S-9 mix. The effects of nitrite concentration, irradiation time and pH on mutagen formation from tryptophan and some characteristics of the produced mutagens were examined.