不同基质浓度下SBR进水方式对厌氧氨氧化的影响

采用厌氧SBR反应器,分别以配水培养和以实际晚期垃圾渗滤液培养的厌氧氨氧化菌为研究对象,考察了不同基质浓度下,SBR改进式连续进水方式与一次性进水方式对厌氧氨氧化工艺运行性能的影响.结果表明,当处理人工配水时,在中低进水浓度下(NO2--N￡400mg/L),与改进式连续进水方式相比,宜采用一次性进水方式运行;在高进水浓度下(NO2--N3400mg/L)改进式连续进水方式比一次性进水方式优势明显,特别是在5h改进式连续进水方式下,平均比污泥脱氮速率增加至39.11mgN/(gVSS·h),相比一次进水方式效率提高40%.当处理进水NO2--N浓度为(300±20)mg/L的实际晚期垃圾渗滤液时, 5h改进式连续进水的SBR比污泥脱氮速率最高.由于晚期渗滤液较配水成分复杂,使得厌氧氨氧化菌面临有机物和有害物质的影响,其厌氧氨氧化的反应速率低于同等基质浓度配水条件下的厌氧氨氧化反应速率.     

Low-carbon transition of iron and steel industry in China: Carbon intensity, economic growth and policy intervention

As the biggest iron and steel producer in the world and one of the highest CO₂ emission sectors, China's iron and steel industry is undergoing a low-carbon transition accompanied by remarkable technological progress and investment adjustment, in response to the macroeconomic climate and policy intervention. Many drivers of the CO₂ emissions of the iron and steel industry have been explored, but the relationships between CO₂ abatement, investment and technological expenditure, and their connections with the economic growth and governmental policies in China, have not been conjointly and empirically examined. We proposed a concise conceptual model and an econometric model to investigate this crucial question. The results of regression, Granger causality test and impulse response analysis indicated that technological expenditure can significantly reduce CO₂ emissions, and that investment expansion showed a negative impact on CO₂ emission reduction. It was also argued with empirical evidence that a good economic situation favored CO₂ abatement in China's iron and steel industry, while achieving CO₂ emission reduction in this industrial sector did not necessarily threaten economic growth. This shed light on the dispute over balancing emission cutting and economic growth. Regarding the policy aspects, the year 2000 was found to be an important turning point for policy evolution and the development of the iron and steel industry in China. The subsequent command and control policies had a significant, positive effect on CO₂ abatement.     

实时尾气检测系统OEM的应用

机动车尾气排放实时检测系统OEM是基于车辆实际行驶路况的新型车载尾气检测系统。该系统突破了传统的定点尾气收集数据的局限性，能够方便快捷地获得不同路段、不同车型、不同时段的以秒为单位的尾气排放数据以及包括速度和加速度在内的瞬间车辆行驶数据。文中对OEM系统的基本原理和方法进行了简单的介绍，并给出了应用该系统在北京市交通网络测试尾气的一些初始结果。     

Effects of productivity on biodiversity in forest ecosystems across the United States and China

In the global campaign against biodiversity loss in forest ecosystems, land managers need to know the status of forest biodiversity, but practical guidelines for conserving biodiversity in forest management are lacking. A major obstacle is the incomplete understanding of the relationship between site primary productivity and plant diversity, due to insufficient ecosystem‐wide data, especially for taxonomically and structurally diverse forest ecosystems. We investigated the effects of site productivity (the site's inherent capacity to grow timber) on tree species richness across 19 types of forest ecosystems in North America and China through 3 ground‐sourced forest inventory data sets (U.S. Forest Inventory and Analysis, Cooperative Alaska Forest Inventory, and Chinese Forest Management Planning Inventory). All forest types conformed to a consistent and highly significant (P < 0.001) hump‐shaped unimodal relationship, of which the generalized coefficients of determination averaged 20.5% over all the forest types. That is, tree species richness first increased as productivity increased at a progressively slower rate, and, after reaching a maximum, richness started to decline. Our consistent findings suggest that forests of high productivity would sustain few species because they consist mostly of flat homogeneous areas lacking an environmental gradient along which a diversity of species with different habitats can coexist. The consistency of the productivity–biodiversity relationship among the 3 data sets we examined makes it possible to quantify the expected tree species richness that a forest stand is capable of sustaining, and a comparison between the actual species richness and the sustainable values can be useful in prioritizing conservation efforts.     

城市电力供应系统公共安全风险评估体系及应用

城市电力供应系统与城市公共安全关系紧密，文章分析了导致城市电力供应系统故障或事故的主要风险因素、事故类型及其风险程度，建立了城市电力供应系统公共安全风险评估体系。利用建立的风险评估体系，对某市电力供应系统的安全性进行了风险评估，同时验证了该体系在城市电力供应系统风险评估中的良好适用性。     

Soil C and N models that integrate microbial diversity

Industrial agriculture is yearly responsible for the loss of 55–100 Pg of historical soil carbon and 9.9 Tg of reactive nitrogen worldwide. Therefore, management practices should be adapted to preserve ecological processes and reduce inputs and environmental impacts. In particular, the management of soil organic matter (SOM) is a key factor influencing C and N cycles. Soil microorganisms play a central role in SOM dynamics. For instance, microbial diversity may explain up to 77 % of carbon mineralisation activities. However, soil microbial diversity is actually rarely taken into account in models of C and N dynamics. Here, we review the influence of microbial diversity on C and N dynamics, and the integration of microbial diversity in soil C and N models. We found that a gain of microbial richness and evenness enhances soil C and N dynamics on the average, though the improvement of C and N dynamics depends on the composition of microbial community. We reviewed 50 models integrating soil microbial diversity. More than 90 % of models integrate microbial diversity with discrete compartments representing conceptual functional groups (64 %) or identified taxonomic groups interacting in a food web (28 %). Half of the models have not been tested against an empirical dataset while the other half mainly consider fixed parameters. This is due to the difficulty to link taxonomic and functional diversity.     

Catalytic activities and mechanism of formaldehyde oxidation over gold supported on MnO<Subscript>2</Subscript> microsphere catalysts at room temperature

MnO₂ microspheres with various surface structures were prepared using the hydrothermal method, and Au/MnO₂ catalysts were synthesized using the sol-gel method. We obtained three MnO₂ microspheres and Au/MnO₂ samples: coherent solid spheres covered with wire-like nanostructures, solid spheres with nanosheets, and hierarchical hollow microspheres with nanoplatelets and nanorods. We investigated the properties and catalytic activities of formaldehyde oxidation at room temperature. Crystalline structures of MnO₂ are the main factor affecting the catalytic activities of these samples, and γ-MnO₂ shows high catalytic performance. The excellent redox properties are responsible for the catalytic ability of γ-MnO₂. The gold-supported interaction can change the redox properties of catalysts and accelerate surface oxygen species transition, which can account for the catalytic activity enhancement of Au/MnO₂. We also studied intermediate species. The dioxymethylene (DOM) and formate species formed on the catalyst surface were considered intermediates, and were ultimately transformed into hydrocarbonate and carbonate and then decomposed into CO₂. A proposed mechanism of formaldehyde oxidation over Au/MnO₂ catalysts was also obtained.     

Trends in the development of Estonian coastal land cover and landscapes caused by natural changes and human impact

The structure of coastal land cover in Estonia is intricate and exhibits considerable differences from site to site. The diverse geomorphology of the seashores is one of the key factors affecting the speed and magnitude of land cover changes. Likewise, the history of human inhabitance on the coast has also shaped the character of land cover. The Estonian coastal zone has experienced abrupt and radical changes in land ownership and its related land use during the last century. The main objectives of this paper are: 1) to give an overview of land use and the trends of development of land cover pattern along different parts of the Estonian coast; and 2) to analyze the relationships of natural and human processes and their cumulative impact on the evolution of coastal land cover pattern in Estonia. This study is based on results obtained during fieldwork in the study areas and on the analysis of large-scale (1:10,000) historical maps. In agriculturally dominant coastal areas, the traditional open landscape of fields and grassland at the beginning of the 20th century had been replaced by woodland and grasslands with shrubs by the start of the 21st century. Expansion of reed beds in areas of former seashore grasslands is another striking phenomenon. The structure of land cover on forested coasts has been fairly stable during the last 100 years. Areas of urban sprawl are characterised by dramatic changes in land cover structure. Rapidly increasing population and expanding settlements imposes on the ecological balance of the fragile dune forests in the coastal zone.     

CFD Investigation of Particle Deposition in a Horizontal Looped Turbulent Pipe Flow

This paper presents comprehensive 3D numerical investigations on depositions of particles flowing through a horizontal pipe loop consisting of four bends. The multiphase mixture model available in FLUENT 6.2 was used in this study. In this numerical simulation, five different particle sizes have been used as secondary phases to calculate real multiphase effect in which inter-particle interaction has been considered. The deposition of particles along the periphery of the pipe wall was investigated as a function of particle size and fluid velocity. The simulations showed that near the upstream of the bends, maximum particle concentration occurred at the bottom of the pipe. However, downstream the bends, the maximum particle concentration occurred at an angle of 60° from the bottom. The larger particles clearly showed deposition near the bottom wall except downstream. As expected, the smaller particles showed less tendency of deposition and lesser at higher velocity. This numerical investigation showed qualitative agreement with the experiments conducted by Commonwealth Scientific and Industrial Research Organisation, Melbourne team for similar conditions.     

Alternative amendment for soluble phosphorus removal from poultry litter

Background, aim, and scope  

Alum (aluminum sulfate) is the currently preferred chemical amendment for phosphorus (P) treatment in poultry litter (PL). Aluminum-based drinking-water treatment residuals (Al-WTRs) are the waste by-product of the drinking-water treatment process and have been effectively used to remove P from aqueous solutions, but their effectiveness in PL water extracts has not been studied in detail. Elevated cost associated with alum could be minimized by using the equally effective WTRs to remove soluble P from PL, and they can be obtained at a minimal cost from drinking-water treatment plants.