Evaluation of different algal species sensitivity to mercury and metolachlor by PAM-fluorometry.

In this study, the pulse-amplitude-modulation (PAM)-fluorometric method was used to evaluate the difference in the sensitivity to mercury (Hg) and metolachlor of six algal species: Ankistrodesmus falcatus, Selenastrum capricornutum, Chlorella vulgaris, Nannoplankton (PLS), Microcystis aeruginosa and Pediastrum biwae. We found that the fluorescence parameters (phiM, the maximal photosystem II (PSII) quantum yield, phi'M, the operational PSII quantum yield at steady state of electron transport, Q(P), the photochemical quenching value, and Q(N), the non-photochemical quenching value) were appropriate indicators for inhibitory effects of mercury but only phi'M and Q(N) were useful for metolachlor. The examined algal species showed very different levels of sensitivity to the effect of Hg and of metolachlor. The most sensitive species to Hg and metolachlor were respectively M. aeruginosa and A. falcatus, while the least sensitive were C. vulgaris and P. biwae. We interpreted these differences by the action mode of pollutants and by the different metabolism properties and morphological characteristics between algal species. These results related to fluorescence parameters may offer useful tool to be used in bioassay for different pollutants. Heterogeneous algal sensitivity to the same pollutant suggests the need to use a battery of species to evaluate the effects of mixtures of pollutants in aquatic systems.     

Occurrence of Viruses and Protozoa in Drinking Water Sources of Japan and Their Relationship to Indicator Microorganisms

A nationwide survey of viruses, protozoa, and indicator microorganisms in drinking water sources of Japan was conducted. Among 64 surface water samples collected from 16 drinking water treatment plants, 51 (80?%) samples were positive for at least one of the 11 pathogen types tested, including noroviruses of genogroups I (positive rate, 13?%) and II (2?%), human sapoviruses (5?%), human adenoviruses of serotypes 40 and 41 (39?%), Cryptosporidium oocysts (41?%), and Giardia cysts (36?%). Total coliforms, Escherichia coli, and F-specific coliphages were detected in 63 (98?%), 33 (52?%), and 17 (27?%) samples, respectively, and E. coli was judged to be the most suitable indicator of pathogen contamination of drinking water sources. Genogroup-specific real-time PCR for F-specific coliphages revealed the presence of F-specific RNA coliphages of animal genogroup I and human genogroups II and III in 13 (41?%), 12 (39?%), and 1 (3?%), respectively, of 31 plaques isolated.     

Behavior of flames propagating through lycopodium dust clouds in a vertical duct

The structure of flame propagating through lycopodium dust clouds has been investigated experimentally. Upward propagating laminar flames in a vertical duct of 1800 mm height and 150×150 mm square cross-section are observed, and the leading flame front is also visualized using by a high-speed video camera. Although the dust concentration decreases slightly along the height of duct, the leading flame edge propagates upwards at a constant velocity. The maximum upward propagating velocity is 0.50 m/s at a dust concentration of 170 g/m³. Behind the upward propagating flame, some downward propagating flames are also observed. Despite the employment of nearly equal sized particles and its good dispersability and flowability, the reaction zone in lycopodium particles cloud shows the double flame structure in which isolated individual burning particles (0.5–1.0 mm in diameter) and the ball-shaped flames (2–4 mm in diameter; the combustion time of 4–6 ms) surrounding several particles are included. The ball-shaped flame appears as a faint flame in which several luminous spots are distributed, and then it turns into a luminous flame before disappearance. In order to distinguish these ball-shaped flames from others with some exceptions for merged flames, they are defined as independent flames in this study. The flame thickness in a lycopodium dust flame is observed to be 20 mm, about several orders of magnitude higher than that of a premixed gaseous flame. From the microscopic visualization, it was found that the flame front propagating through lycopodium particles is discontinuous and not smooth.     

新型城市环卫和用水基础设施

"生态环卫"技术提供了共同解决两个关键水难题的办法:如何使世界缺乏用水和卫生设备的人数比例下降一半;如何解决湖泊、水库和内海的富营养化.氮和磷超标,主要来源于城市污水和农业肥料的流失.尿液和粪便(特别是尿液)含有氮和磷.一个新的人类废物管理办法,有可能使这些物质在农业领域循环.     

Assessment of potential impacts of municipal solid waste treatment alternatives by using life cycle approach: a case study in Vietnam

In Vietnam, most of municipal solid waste (MSW) is disposed of at open dumping and landfill sites, and the methane gas from waste is the un-ignorable source of greenhouse gas (GHG) emission. It is indispensable to explore the possibility for GHG mitigation in MSW management. The objective of this study was to estimate alternative waste treatment practices towards the GHG emission mitigation, energy consumption and generation, reduction of landfill volume, and various benefits for proposing the appropriate selection by scenario analyses for representative Vietnam’s cities. Impacts were calculated by utilizing life cycle assessment (LCA) method. A literature review survey on the current applicability of LCA database for assessing impacts from waste sector in developing countries, especially for Vietnam, was carried out. This study assessed the contribution of alternative solid waste treatment practices. The result showed that, except investment and operation costs, incineration with energy recovery seems the suitable alternative for treating waste from representative cities of Vietnam according to reduction of GHG emission and waste burden to landfill sites and energy recovery and generation. Besides, MSW composition was identified as an important factor directly influencing to impacts as well as other products and benefits of waste treatment alternatives. Reliable data on waste composition are indispensable for assessing to choose, improve, or plan the waste treatment practices towards sustainable development.     

Contribution of metabolites to mutagenicity during anaerobic biodegradation of fenitrothion

The contribution of fenitrothion and its microbial metabolites to the mutagenicity of a fenitrothion-containing solution was investigated during anaerobic biodegradation. Although a mixed culture of bacteria obtained from a paddy field degraded fenitrothion and reduced its concentration from 4.6 to 0.1 mg/l in 6 days, the indirect mutagenicity of the solution in Salmonella strain YG1029 increased. This increase was found to be partially due to amino-fenitrothion generated during the biodegradation. In addition, other unidentified metabolites contributed to the mutagenicity. In contrast, the indirect mutagenicity in strain YG1042, which was initially large because of fenitrothion, then decreased, and increased again. This increase in mutagenicity was also due to amino-fenitrothion and other unidentified metabolites. The mutagenicity in strains YG1029 and YG1042 decreased after day 6. The greatest contribution of amino-fenitrothion to the mutagenicity was calculated to be 73% and 61% in YG1029 and YG1042 on day 3 of incubation, respectively. That of unidentified metabolites was calculated at 49% and 61% on day 20, respectively. Therefore, because not all the toxic metabolites of a compound can be identified, it is important to evaluate the toxicity of a whole solution in a bioassay such as the Ames assay rather than deducing the toxicity of the solution from the combined toxicities of known metabolites.     

Biosynthesis and release of methylarsenic compounds during the growth of freshwater algae

Arsenic transformations by freshwater algae have been studied under laboratory conditions. By the use of a new analytical method, we identified methylarsenic(III) species in the growth medium of green-alga Closterium aciculare incubated under axenic conditions. The arsenate concentration in the experimental medium began to decrease just after inoculation, and the levels of arsenite and methylarsenicals increased with the growth of C. aciculare. Initially, most of the arsenate was converted into arsenite, which peaked in concentration during the exponential phase. Methylarsenicals accumulated rapidly in the stationary phase. DMAA(V) production was enhanced when the ratio of phosphate to arsenate decreased in the culture medium. The levels of DMAA(V) increased continuously toward the end of the experiment. On the other hand, methylarsenic(III) species remained relatively steady during the stationary phase. Methylarsenic(III) species accounted for 0-35% of methylarsenicals. These results suggest that arsenite and methylarsenicals (containing methylarsenic(III) species) are supplied by phytoplankton, and serve as evidence of the origin of methylarsenic(III) species in natural waters.     

Fate of mutagenicity produced during anaerobic biodegradation of the herbicide chlornitrofen (CNP)

The mutagenicity of chlornitrofen (CNP)-containing solutions has been reported to increase during anaerobic biodegradation. In the present study, the fate of this increased mutagenicity under subsequent aerobic and anaerobic incubation conditions was investigated using two Salmonella tester strains, YG 1024 (a frameshift-detecting strain) and YG 1029 (a base-pair-substitution-detecting strain). Mutagenicity for both YG 1024 and YG 1029 strains increased during nine-day anaerobic biodegradation. During subsequent anaerobic incubation, the increased mutagenicity decreased gradually for YG 1029 but did not change significantly for YG 1024. By contrast, the increased mutagenicity decreased rapidly after the conversion to aerobic incubation for both YG 1024 and YG 1029 strains. The rapid decrease in mutagenicity during aerobic incubation was due to decreases, not only in an identified mutagenic metabolite (CNP-amino) but also in unidentified mutagenic metabolites.     

Intramolecular distribution of stable nitrogen and oxygen isotopes of nitrous oxide emitted during coal combustion

The intramolecular distribution of stable isotopes in nitrous oxide that is emitted during coal combustion was analyzed using an isotopic ratio mass spectrometer equipped with a modified ion collector system (IRMS). The coal was combusted in a test furnace fitted with a single burner and the flue gases were collected at the furnace exit following removal of SO(x), NO(x), and H2O in order to avoid the formation of artifact nitrous oxide. The nitrous oxide in the flue gases proved to be enriched in 15N relative to the fuel coal. In air-staged combustion experiments, the staged air ratio was controlled over a range of 0 (unstaged combustion), 20%, and 30%. As the staged air ratio increased, the delta15N and delta18O of the nitrous oxide in the flue gases became depleted. The central nitrogen of the nitrous oxide molecule, N(alpha), was enriched in 15N relative to that occupying the end position of the molecule, N(beta), but this preference, expressed as delta15N(alpha)-delta15N(beta), decreased with the increase in the staged air ratio. Thermal decomposition and hydrogen reduction experiments carried out using a tube reactor allowed qualitative estimates of the kinetic isotope effects that occurred during the decomposition of the nitrous oxide and quantitative estimates of the extent to which the nitrous oxide had decomposed. The site preference of nitrous oxide increased with the extent of the decomposition reactions. Assuming that no site preference exists in nitrous oxide before decomposition, the behavior of nitrous oxide in the test combustion furnace was analyzed using the Rayleigh equation based on a single distillation model. As a result, the extent of decomposition of nitrous oxide was estimated as 0.24-0.26 during the decomposition reaction governed by the thermal decomposition and as 0.35-0.38 during the decomposition reaction governed by the hydrogen reduction in staged combustion. The intramolecular distribution of nitrous oxide can be a valuable parameter to estimate the extent of decomposition reaction and to understand the reaction pathway of nitrous oxide at the high temperature.     

A minority group's response to a severe climatic event: a case study of rural Indo-Fijians after Tropical Cyclone Winston in 2016

This paper investigates the impacts of Tropical Cyclone Winston (2016) on rural Indo-Fijians and their response to the devastation. Studies have previously examined how rural communities in Pacific Island countries respond to severe climatic events, arguing that traditional knowledge of the climate, together with indigenous techniques, contribute substantially to recovery from a disaster. Strong communal bonds have also been identified as an influencing factor. Disaster risk reduction frameworks often assume the availability of such knowledge and capital. Yet, little research has been done on how minority groups with limited access to such knowledge and capital cope with disaster-related damage. The current study shows that rural Indo-Fijians responded to the consequences of Tropical Cyclone Winston differently to indigenous Fijians, owing to relatively limited access to traditional awareness of the climate, communal labour sharing, and intra- and/or inter-community networks. The findings point to the necessity to implement a more inclusive disaster risk reduction framework.