Efficient low-temperature soot combustion by bimetallic Ag–Cu/SBA-15 catalysts

In this study, the effects of copper(Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag–Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5 Ag_1-Cu_(0.1)/SBA-15 catalyst, on which the soot combustion starts at T_(ig)= 225°C with a T_(50)= 285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C(Aneggi et al., 2009). Physicochemical characterizations of the catalysts indicated that addition of Cu into Ag could form smaller bimetallic Ag–Cu nanolloy particles, downsizing the mean particle size from 3.7 nm in monometallic catalyst to 2.6 nm in bimetallic Ag–Cu catalyst. Further experiments revealed that Ag and Cu species elicited synergistic effects, subsequently increasing the content of surface active oxygen species. As a result, the structure modifications of Ag by the addition of Cu strongly intensified the catalytic performance.     

常州市可持续发展限制因子辨识及发展对策

本文对我国最早的国家级社会发展综合实验区常州市可持续发展的限制因子进行了辨识，并针对限制因子提出了常州市可持续发展的对策     

A global change of specialization and generalization in pollination networks from the plant perspective

A view of pollination systems is that they tend to generalization. Here we show that patterns exist in pollination systems that suggest otherwise. We examine how specialization may be affected by latitude, species richness and plant life-forms in 33 plant-pollinator interaction networks. Connectance increases with latitude (P = 0.040), but specialization at the community level significantly declines with increasing latitude, with the strongest evidence in the Northern Hemisphere (P = 0.001). The relationship between specialization level and connectance is negative (P < 0.001). While plants are more specialized in tropical areas and are more generalized at higher latitudes, specialization level also increases with plant richness (P < 0.001), total species richness (P = 0.041) and network size (P = 0.009). Specialization level of life forms of 1129 species differ substantially (P < 0.001), with herbs showing the highest specialization (74%), and tree species the lowest (62%).     

城市绿色规划分析与评述

全球城市化的无序扩展给城市生态系统平衡带来了极大的挑战,在这种背景下倡导绿色规划随之成为国际潮流,因为其可以促进城市生态平衡、提供市民休憩场所和产业支持等。本文首先就城市园林、城市森林公园、都市农业等3个方面介绍了国外城市的绿色规划发展概况,着重分析了绿色规划的作用与特点,并在此基础上,本文指出了国内城市绿色规划特点和不足之处。     

关于荒漠化地区可持续发展的几点思考——以北方沙漠化地区为例

荒漠化的发生、发展和逆转过程蕴涵着丰富的生态学、社会学和经济学原理。本文首先提出了荒漠化地区人地关系研究的技术路线,即现状诊断－－演变历程－－矛盾与冲突分析－－协调性分析－－调控与管理;继之以北方沙漠化地区为例,对路线涉及的具体内容加以简要分析;在此基础上,对如何协调人地关系提出建议。     

Coastal wetland loss and environmental change due to rapid urban expansion in Lianyungang,Jiangsu, China

To address the growing need for developable land, many coastal cities are draining and filling wetlands, transforming them into urban built-up areas, and thereby substantially altering the structure and function of coastal ecosystems. We demonstrate an integrative approach for investigating the dynamics and impacts of coastal development in China’s Jiangsu Province, where urban expansion has resulted in extensive wetland losses and sea reclamation (the process of creating new land from ocean or coastal waters). Remotely sensed data reveal that landscape change in the study area has been accompanied by an increase in total impervious surface area and an increase in mean surface “heat island effect.” These indicators of change can be detected with remote sensing data and used to support a strategic environmental assessment (SEA) for urban coastal planning. Changes detected in Lianyungang during 2000–2006 suggest that reclaimed areas are environmentally sensitive and should be a focus of concern in future development planning, which has historically targeted coastal salt pond wetlands for conversion to land for the development. Given the current and projected rate of coastal development in China and elsewhere in the developing world, our findings and assessment approach have implications for coastal management decisions in the developing coastal zones of China and other regions of the world that are experiencing rapid urban growth.     

Land cover transitions and effects of transhumance on available forage biomass of rangelands in Benin

This study examined the effects of transhumance pressure on total abavoe-ground biomass and forage availability on rangelands in Benin. We also investigated the implications of land cover transitions on rangelands over a 31-year period. Our work was carried out in three regions of Benin representing distinct phytogeographic regimes: Ketou, Tchaourou, and Sinende. Ground-truthing and biomass sampling of the herbaceous and phanaerophyte strata were carried out between the 2016 peak vegetation period and the onset of the 2017 rainy season. Herbaceous biomass was determined by destructive sampling, and biomass of shrub and trees was estimated using non-destructive sampling and allometric equations. Historical and present-day Landsat data allowed an analysis of land cover change for the 1986–2002 and 2002–2017 periods. Land cover analyses yielded evidence of significant expansion of agricultural areas, especially in the latter period. The data also revealed progressive landscape fragmentation and transformations to a land cover of reduced total phytomass. There were no long-term effects of transhumance on trees, but likely on herbaceous biomass. Land cover changes in the study regions seem primarily the result of population pressure, infrastructural changes, persisting norms, and traditions regarding environmental management and the increasing popularity of livestock keeping as an insurance strategy. Rangeland transformations had negative impacts on transhumant herds’ mobility and forage availability. As rangeland stability and consent between agricultural and pastoral land users are at a tipping point, informed policies, and land use planning that foster compromises among all stakeholders are needed.

     

制备条件对锰氧化物SCR脱硝性能的影响

分别考察不同沉淀剂、溶液pH、煅烧温度和煅烧时间对制备MnOx催化剂及其低温SCR脱除NO性能的影响,并借助XRD和BET等表征手段分析各催化剂的物相和孔隙特性。结果表明,不同沉淀剂制备的MnOx催化剂的低温活性依次为:MnOx(Na2CO3) > MnOx((NH4)2CO3) > MnOx(NaOH) > MnOx(NH4OH)。表征结果表明,MnOx(Na2CO3)和MnOx((NH4)2CO3)催化剂之所以表现出突出的低温SCR活性,归因于混合氧化态的无定型结构和较大的比表面积。优选Na2CO3沉淀剂制备MnOx催化剂,最佳的煅烧温度和时间分别为350℃和6 h,而溶液pH对制备的MnOx催化剂的催化还原NO活性影响不明显。     

A dual-permeability hydro-biodegradation model for leachate recirculation and settlement in bioreactor landfills

Environmental Science and Pollution Research - A dual-permeability hydro-biodegradation model is developed to describe the leachate flow in municipal solid waste (MSW) and predict the long-term...     

基于响应面法的新型餐厨垃圾菌剂制备

设计三因素三水平实验并采用响应面优化法对反应适宜的实验参数进行了优化。选择温度、供氧条件和反应时间作为菌剂制备的可控因素,选择温度、菌剂投加量和木屑投加量(水分调节)作为菌剂处理厨余垃圾的可控因素,研究菌剂制备与处理垃圾的优化工艺参数。研究结果表明,菌剂的最优制备条件为:温度35℃、间歇震荡、培养108 h,按重量百分比为碎花生壳:刨花:鱼骨粉:麸皮:菌体=2:1:1:1:1比例制得的固体菌剂具有较高的活性。菌剂处理厨余垃圾的响应面优化法分析结果表明,当温度为45℃,菌剂投加量为6%,木屑投加量为30%时,厨余垃圾的减量率最大,2 d降解率可达40%。