Fail-safe solar radiation management geoengineering

To avoid dangerous changes to the climate system, the global mean temperature must not rise more than 2 °C from the 19th century level. The German Advisory Council on Global Change recommends maintaining the rate of change in temperature to within 0.2 °C per decade. This paper supposes that a geoengineering option of solar radiation management (SRM) by injecting aerosol into the Earth’s stratosphere becomes applicable in the future to meet those temperature conditions. However, a failure to continue the use of this option could cause a rapid temperature rebound, and thus we propose a principle of SRM use that the temperature conditions must be satisfied even after SRM termination at any time. We present economically optimal trajectories of the amounts of SRM use and the reduction of carbon dioxide (CO₂) emissions under our principle by using an economic model of climate change. To meet the temperature conditions described above, the SRM must reduce radiative forcing by slightly more than 1 W/m² at most, and industrial CO₂ emissions must be cut by 80 % by the end of the 21st century relative to 2005, assuming a climate sensitivity of 3 °C. Lower-level use of SRM is required for a higher climate sensitivity; otherwise, the temperature will rise faster in the case of SRM termination. Considering potential economic damages of environmental side effects due to the use of SRM, the contribution of SRM would have to be much smaller.     

Mutagenicity of anaerobic fenitrothion metabolites after aerobic biodegradation

Previous studies have revealed that the mutagenicity of fenitrothion increases during anaerobic biodegradation, suggesting that this insecticide's mutagenicity could effectively increase after it pollutes anaerobic environments such as lake sediments. To investigate possible changes to the mutagenicity of fenitrothion under aerobic conditions after it had already been increased by anaerobic biodegradation, batch incubation cultures were maintained under aerobic conditions. The mutagenicity, which had increased during anaerobic biodegradation, decreased under aerobic conditions with aerobic or facultative bacteria, but did not disappear completely in 22 days. In contrast, it did not change under aerobic conditions without bacteria or under continued anaerobic conditions. These observations suggest that the mutagenicity of anaerobically metabolized fenitrothion would not necessarily decrease after it arrives in an aerobic environment: this would depend on the presence of suitable bacteria. Therefore, fenitrothion-derived mutagenic compounds may pollute the water environment, including our drinking water sources, after accidental pollution of aerobic waters. Although amino-fenitrothion generated during anaerobic biodegradation of fenitrothion was the principal mutagen, non-trivial contributions of other, unidentified metabolites to the mutagenicity were also observed.     

Neighborhood influences on the diffusion of residential photovoltaic systems in Kyoto City,Japan

Environmental Economics and Policy Studies - This study investigates the factors influencing the diffusion of residential photovoltaic systems. Factors examined are related to social attributes,...     

An exquisitely preserved troodontid theropod with new information on the palatal structure from the Upper Cretaceous of Mongolia

Troodontidae is a clade of small-bodied theropod dinosaurs. A new troodontid, Gobivenator mongoliensis gen. et sp. nov., is described based on the most complete skeleton of a Late Cretaceous member of this clade presently known, from the Campanian Djadokhta Formation in the central Gobi Desert. G. mongoliensis is different from other troodontids in possessing a pointed anterior end of the fused parietal and a fossa on the surangular in front of the posterior surangular foramen. The skull was superbly preserved in the specimen and provides detailed information of the entire configuration of the palate in Troodontidae. Overall morphology of the palate in Gobivenator resembles those of dromaeosaurids and Archaeopteryx, showing an apparent trend of elongation of the pterygoid process of the palatine and reduction of the pterygopalatine suture toward the basal Avialae. The palatal configuration suggests that the skull of Gobivenator would have been akinetic but had already acquired prerequisites for later evolution of cranial kinesis in birds, such as the loss of the epipterygoid and reduction in contact areas among bones.     

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.     

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.     

上海金桥出口加工区引进CGS的优化评价

以燃煤锅炉集中供热的上海金桥出口加工区引进天然气热电联供系统（CGS）为例，对其成本和效率作了评价。开发了1个最优化模型，它由季节小时平均热电供需平衡的制约条件和CGS设备容量的目标函数所组成。利用该模型能够在燃料价格和CGS投资费用变化的情况下，便捷地评价最佳的设备容量。引进CGS使氧化硫和二氧化碳排放降低，本模型也能对此作定量评估。     

Changes in mutagenicity during biodegradation of fenitrothion

In order to investigate changes in the mutagenicity of fenitrothion during its biodegradation in solution, measurements were conducted at intervals in batch cultures incubated under anaerobic or aerobic conditions. Fenitrothion-degrading bacteria were obtained from a green onion field on the west side of Gifu University, Japan. Fenitrothion was almost completely decomposed by day 12 under both types of incubation condition. The indirect mutagenicity of the solution to strains YG1029 and YG1042, however, increased markedly during anaerobic biodegradation. The increase in mutagenicity was partially due to amino-fenitrothion, a metabolite formed during anaerobic biodegradation of fenitrothion.     

Catalytic liquid-phase oxidation of acetaldehyde to acetic acid over a Pt/CeO2–ZrO2–SnO2/γ-alumina catalyst

Pt/CeO₂–ZrO₂–SnO₂/γ-Al₂O₃ catalysts were prepared by co-precipitation and wet impregnation methods for catalytic oxidation of acetaldehyde to acetic acid in water. In the present catalysts, Pt and CeO₂–ZrO₂–SnO₂ were successfully dispersed on the γ-Al₂O₃ support. Dependences of platinum content and reaction time on the selective oxidation of acetaldehyde to acetic acid were investigated to optimize the reaction conditions for obtaining both high acetaldehyde conversion and highest selectivity to acetic acid. Among the catalysts, a Pt(6.4 wt.%)/Ce_0.68Zr_0.17Sn_0.15O_2.0(16 wt.%)/γ-Al₂O₃ catalyst showed the highest acetaldehyde oxidation activity. On this catalyst, acetaldehyde was completely oxidized after the reaction at 0°C for 8 hr, and the selectivity to acetic acid reached to 95% and higher after the reaction for 4 hr and longer.     

Flame acceleration and transition to detonation in an array of square obstacles

We study flame acceleration and DDT in a two-dimensional staggered array of square obstacles by solving the compressible multidimensional reactive Navier–Stokes equations. The energy release rate for a stoichiometric H₂-air mixture is modeled by a one-step Arrhenius kinetics. The space between obstacles is filled with a stoichiometric H₂-air mixture at 1 atm and 298 K. Initially, the flow is at rest, and a flame is ignited at the center of the array. Computations show effects of the obstacles as a series of events leading to DDT. During the initial flame acceleration, the speed of the flame depends on the direction of flame propagation since some directions are more obstructed than others. This affects the macroscopic shape of the expanding burned region, which forms concave boundaries in more obstructed directions. As the flame accelerates, shocks form ahead of the flame, reflect from obstacles, and interact with the flame. There are more shock–flame interactions in more obstructed directions, and this leads to a greater flame acceleration and stronger leading shocks. When the shocks become strong enough, their collisions with obstacles ignite the gas mixture, and detonations form. The simulation shows four independent DDT events within a 90-degree sector, all in more obstructed directions. Resulting detonations spread in all directions. Some parts of detonation fronts are quenched by diffractions around obstacles, but they are reignited by collisions of decoupled shocks, or overtaken by other detonations. Thus detonations continue to spread and quickly burn all the material between the obstacles.