Recent advances in catalytic decomposition of ozone

Ozone (O₃), as a harmful air pollutant, has been of wide concern. Safe, efficient, and economical O₃ removal methods urgently need to be developed. Catalytic decomposition is the most promising method for O₃ removal, especially at room temperature or even subzero temperatures. Great efforts have been made to develop high-efficiency catalysts for O₃ decomposition that can operate at low temperatures, high space velocity and high humidity. First, this review describes the general reaction mechanism of O₃ decomposition on noble metal and transition metal oxide catalysts. Then, progress on the O₃ decomposition performance of various catalysts in the past 30 years is summarized in detail. The main focus is the O₃ decomposition performance of manganese oxides, which are divided into supported manganese oxides and non-supported manganese oxides. Methods to improve the activity, stability, and humidity resistance of manganese oxide catalysts for O₃ decomposition are also summarized. The deactivation mechanisms of manganese oxides under dry and humid conditions are discussed. The O₃ decomposition performance of monolithic catalysts is also summarized from the perspective of industrial applications. Finally, the future development directions and prospects of O₃ catalytic decomposition technology are put forward.     

Modeling Postfire Response and Recovery using the Hydrologic Engineering Center Hydrologic Modeling System (HEC‐HMS)1

Abstract: This paper investigates application of the Army Corps of Engineers’ Hydrologic Engineering Center Hydrologic Modeling System (HEC‐HMS) to a burned watershed in San Bernardino County, California. We evaluate the HEC‐HMS’ ability to simulate discharge in prefire and postfire conditions in a semi arid watershed and the necessary parameterizations for modeling hydrologic response during the immediate, and subsequent recovery, period after a wildfire. The model is applied to City Creek watershed, which was 90% burned during the Old Fire of October 2003. An optimal spatial resolution for the HEC‐HMS model was chosen based on an initial sensitivity analysis of subbasin configurations and related model performance. Five prefire storms were calibrated for the selected model resolution, defining a set of parameters that reasonably simulate prefire conditions. Six postfire storms, two from each of the following rainy (winter) seasons were then selected to simulate postfire response and evaluate relative changes in parameter values and model behavior. There were clear trends in the postfire parameters [initial abstractions (I_a), curve number (CN), and lag time] that reveal significant (and expected) changes in watershed behavior. CN returns to prefire (baseline) values by the end of Year 2, while I_a approaches baseline by the end of the third rainy season. However, lag time remains significantly lower than prefire values throughout the three‐year study period. Our results indicate that recovery of soil conditions and related runoff response is not entirely evidenced by the end of the study period (three rainy seasons postfire). Understanding the evolution of the land surface and related hydrologic properties during the highly dynamic postfire period, and accounting for these changes in model parameterizations, will allow for more accurate and reliable discharge simulations in both the immediate, and subsequent, rainy seasons following fire.     

Distribution of some trace metals and their fluxes in the Genesee River,NY

Total and particulate metal concentrations, measured during intensive synoptic studies of the Genesee River, NY, correlated with suspended-sediment concentration and river discharge. Dissolved metal concentrations, on the other hand, showed little systematic variation over the length of the river. Metal and sediment fluxes for two elevated-discharged periods peaked at a midbasin sampling site. For most metals at most sampling sties particulate materials comprised over one-half of the total material. Comparison of particulate material metal concentrations, normalized to the measured suspended-sediment concentrations had with basinwide average values shows that sites having low suspended-sediment concentrations had high particulate material metal contents relative to the basin averages, while sites with high suspended-sediment concentration had low metal contents. These results are consistent with a metal transport mechanism in the Genesee River involving (1) a nearly constant dissolved component, (2) a fine acid-soluble component, and (3) a coarse component that is effectively a neutral diluent in the sediment. Chemical factors, such as sediment organic content, also appear to affect metal transport in the Genesee River.     

Mapping Outlets of Iowa Flood Center and National Water Center River Networks for Hydrologic Model Comparison

River networks based on Digital Elevation Model (DEM) data differ depending on the DEM resolution, accuracy, and algorithms used for network extraction. As spatial scale increases, the differences diminish. This study explores methods that identify the scale where networks obtained by different methods agree within some margin of error. The problem is relevant for comparing hydrologic models built around the two networks. An example is the need to compare streamflow prediction from the Hillslope Link Model (HLM) operated by the Iowa Flood Center (IFC) and the National Water Model (NWM) operated by the National Water Center of the National Oceanic and Atmospheric Administration. The HLM uses landscape decomposition into hillslopes and channel links while the NWM uses the NHDPlus dataset as its basic spatial support. While the HLM resolves the scale of the NHDPlus, the outlets of the latter do not necessarily correspond to the nodes of the HLM model. The authors evaluated two methods to map the outlets of NHDPlus to outlets on the IFC network. The methods compare the upstream areas of the channels and their spatial location. Both methods displayed similar performance and identified matches for about 80% of the outlets with a tolerance of 10% in errors in the upstream area. As the aggregation scale increases, the number of matches also increases. At the scale of 100 km², 90% of the outlets have matches with tolerance of 5%. The authors recommend this scale for comparing the HLM and NWM streamflow predictions.     

Towards a national reference center for environmental information in The Netherlands: A review

For improvement of the accessibility and use of environmental information a prototype national reference center (CIMI) was constructed in the Netherlands in 1986. Target groups were identified on the basis of an analysis of the demand side. They were questioned about their needs in the field of environmental information. On the basis of these experiences an automated integrated system has been built that is composed of subsystems for reference to expertise in organizations (specialisms), literature, research, and databases of site-specific data. This system is also equipped with a thesaurus. The system has been tested and examined in several ways. The outcome of these independent tests and investigations confirm the usefulness of this center for information transfer. The reference center can be helpful in providing overviews on and structuring of environmental information in the Netherlands. The results of the activities have been presented in several ways and were described extensively in a number of reports.     

Environmental anomalies at the World Trade Center: evidence for energetic materials

Investigators monitoring air quality at the World Trade Center, after the September 11th attacks, found extremely high levels of volatile organic chemicals as well as unusual species that had never been seen before in structure fires. Data collected by the U.S. Environmental Protection Agency indicate striking spikes in levels of benzene, styrene, and several other products of combustion. These spikes occurred on specific dates in October and November 2001, and February 2002. Additionally, data collected by researchers at the University of California Davis showed similar spikes in the levels of sulfur and silicon compounds, and certain metals, in aerosols. To better explain these data, as well as the unusual detection of 1,3-diphenylpropane, the presence of energetic nanocomposites in the pile at Ground Zero is hypothesized.     

APEC期间北京空气质量改善对比分析

为了评估APEC期间强化减排措施对北京空气质量的改善效果,利用2014年11月1~15日中国环境监测总站发布的奥体中心监测点空气质量监测数据,分析其空气质量演变特征,并与2013年同期监测数据进行对比研究.结果表明:1PM_(2.5)是当前北京最重要的污染物,APEC期间空气质量以优良为主,期间有3次明显的污染过程,与2013年同期相比较有所好转,显示出强化减排措施对北京空气质量的改善有显著的效果;2与世界卫生组织(WHO)的标准值相比,APEC期间PM_(2.5)有5d在WHO标准值(25μg·m~(-3))以下,而SO_2均小于标准值;3APEC期间,在空气质量为优时PM_(2.5)/PM_(10)小于0.5,且随污染浓度的增加比值逐渐增大,在严重污染情况下PM_(2.5)/PM10达到0.9以上;4与2013年同期相比,强化减排措施对PM_(2.5)的减少有一定的贡献,但与SO_2和CO的减少量相比,颗粒物的减少量又相对较少,NO_2减少量相对最小,实施强化减排措施对污染物减排的排序为SO_2COPMNO_2,说明北京空气污染中的PM_(2.5)的来源、影响和减排的复杂性,有待进一步深入研究.     

Elements of resilience after the World Trade Center disaster: reconstituting New York City's Emergency Operations Centre

In this paper we examine the reconstitution of the Emergency Operations Centre (EOC) after its destruction in the World Trade Center attack, using that event to highlight several features of resilience. The paper summarises basic EOC functions, and then presents conceptions of resilience as understood from several disciplinary perspectives, noting that work in these fields has sought to understand how a natural or social system that experiences disturbance sustains its functional processes. We observe that, although the physical EOC facility was destroyed, the organisation that had been established to manage crises in New York City continued, enabling a response that drew on the resources of New York City and neighbouring communities, states and the federal government. Availability of resources--which substituted for redundancy of personnel, equipment and space--pre-existing relationships that eased communication challenges as the emergency developed and the continuation of organisational patterns of response integration and role assignments were among the factors that contributed to resilience following the attack.     

基于DIAHP的旅游环境容量分析及相关对策研究

基于普通层次分析法的基本原理,融入"权变"思想,针对旅游环境容量的动态性,提出了1种动态改进层次分析法(DIAHP),分析旅游环境容量随时间变化的动态波动特征.最后,通过对南戴河国际娱乐中心的实证研究,验证了其可行性和有效性.