Fluoride removal performance of a novel Fe-Al-Ce trimetal oxide adsorbent

A trimetal oxide was developed as a fluoride adsorbent by coprecipitation of Fe(II), Al(III) and Ce(IV) salt solutions with a molar ratio of 1:4:1 under alkaline condition. The material retained amorphous structure and maintained relatively stable fluoride adsorption performance at calcination temperatures lower than 600 degrees C. The optimum pH range for fluoride adsorption was 6.0-6.5 and the adsorbent also showed high defluoridation ability around pH 5.5-7.0, which is preferable for actual application. A high fluoride adsorption capacity of 178 mg g(-1) was acquired under an equilibrium fluoride concentration of 84.5 mg l(-1), adsorbent dose of 150 mg l(-1) and pH 7.0. The adsorption isotherm could be better described by the two-site Langmuir model than the one-site model, suggesting the existence of two types of active sites on the adsorbent surface. Coexistence of high concentrations of phosphate or arsenate only led to partial inhibition of fluoride adsorption, which further suggests the existence of heterogeneous adsorption sites. Sulfate and chloride did not affect fluoride adsorption, and nitrate influenced it only when the concentration of NO(3)(-)-N exceeded 50 mg l(-1). A high desorption efficiency of 97% was achieved by treating fluoride loaded Fe-Al-Ce oxide with NaOH solution at pH 12.2. A column experiment using the adsorbent fabricated into 1mm pellets was performed at an initial fluoride concentration of 5.5 mg l(-1), space velocity of 5h(-1) and pH of 5.8, and 2240 bed volumes were treated with the effluent fluoride under 1.0 mg l(-1).     

应急避难场所建设进度优化模型研究

以规划效率评价为基础,定义了应急避难场所的公益收益,体现在服务性、可达性和安全性3个方面。以全部应急避难场所在整个建设规划期的总公益收益最大化为目标,建立了无偏好和有偏好两类建设进度优化模型,对应急避难场所在规划期内各年的投资额度、建设对象和建设数量进行优化。案例研究结果表明,无偏好模型能最大限度地获得公益收益,但不能很好地表达公众的真实需求;有偏好模型,不可避免会造成一定公益收益损失,但能更多地考虑实际存在的各方面影响因素,更接近真实的决策。实际应用中对模型的选择应根据具体情况确定。     

低碳城市和创新型城市双试点效果评估——基于绿色经济转型视角

全面系统评估环境规制政策协同效应对绿色经济效率的影响,对于推动生态文明建设具有重要的意义。文章基于2006—2020年281个地级市的样本数据,运用多期双重差分模型评估双试点政策对绿色经济效率的影响。研究发现：(1)相比于非试点城市,双试点政策的实施使试点城市的绿色经济效率提升约8.29%,此结论在经过平行趋势等稳健性检验后依旧成立;(2)双试点政策比单试点政策更能显著提高绿色经济效率,政策间存在协同效应;(3)双试点政策通过创新型和改进型绿色技术创新、降低能源消费强度促进绿色经济效率,同时会增加能源消费规模进而抑制绿色经济效率;(4)双试点政策对周围100～900 km以内区域的绿色经济效率产生显著的正向空间溢出效应。本文丰富了环境政策协同对绿色经济效率的影响研究,为政策的有效实施、推动减污降碳协同增效提供科学支持。     

Consumer understanding of product lifetimes

Throwing products away before they fail or are broken is at the heart of consumer behaviour in developed economies such as the UK. Products are often discarded for reasons of fashion, or to keep up with technological advances, rather than because they have reached the end of their functional life. Such behaviours contribute to resource depletion, greenhouse gas emissions, and physical waste which needs to be managed. Extending the length of time that products are kept in use (whether by their original or subsequent owners) can contribute to greater resource efficiency, with significant potential to reduce greenhouse gas emissions. This research was undertaken to support the development of evidence-based policy in the UK on the role of longer product lifetimes in achieving sustainable consumption and waste prevention. Twelve qualitative discussion groups, involving 115 consumers, were carried out to explore consumer influences on product lifetimes including: which factors influence purchase decisions; the care of products in use; and disposal decisions. A new typology was developed to describe how products meet consumers’ various needs for ‘workhorses’, ‘investment’ and ‘up-to-date’ products; and how lifetime is an outcome of the ‘nature’ of a product (functional life) and its ‘nurture’ (lifetime in use) by consumers. The results demonstrate that consumers have come to expect constant and rapid up-dating of products. In particular, having the latest versions of products is strongly associated with personal identity and feelings of success in life. There is little evidence of concern about the environmental consequences of a ‘throwaway society’. The low cost of new products, which enables rapid updating for reasons of fashion, is a key barrier to encouraging consumers to keep products in use for longer. Some opportunities were identified however for certain ‘workhorse’ and ‘investment’ products that are valued more for their functionality than fashion.     

ECONOMIC EVALUATION OF ON-FARM WATER MANAGEMENT PROJECTS1

ABSTRACT: During the last three decades, developing countries have invested enormous amounts of resources (running into billions of dollars) in the development of large surface irrigation systems. Investment funds were largely spent on the development of the main systems such as dams, canals and distributaries. Very little attention and resources have been spent on the development of below-the-outlet subsystems, in spite of very low levels of water use efficiency due to lack of proper land leveling, high water losses in field channels, and skewed distribution of available water among farmers served by individual water courses. This state of affairs has resulted in a lack of confidence on the part of most farmers in the reliability of surface irrigation systems to deliver water on time and in adequate quantities which, in turn, has resulted in farmers using below optimum levels of all other complementary inputs except labor. Realizing the importance of improving water use efficiency, both the domestic governments and donor agencies are increasingly paying serious attention to these problems. On-Farm Water Management (OFWM) as a strategy to improve water use efficiency and consequently agricultural production in many developing countries has been currently receiving very wide and vigorous consideration among economists, water management experts, policymakers, and donor agencies. A judicious use of the newly allocated funds of OFWM projects obviously needs proper evaluation procedures so that money could be allocated for the most deserving purposes and projects. In particular, recently, private profitability calculations due to public investments in OFWM activities have received attention from economists and decision makers in developing countries’governments and in donor agencies are very much interested in knowing the impacts of their investments in OFWM activities on farmers’income and welfare. However, the evaluation procedures commonly used in empirical studies, using a production function approach, seem to be at variance and sometimes inconsistent with proper comparative-static procedures. Thus, the primary objective of this paper is to develop consistent procedures for evaluating the impacts created by OFWM investments on farmers’income and resource use. In this context, the paper examines the critical relationship between the market price of the agricultural output and production function parameters which are affected by the OFWM investments.     

四湖地区猕猴桃高效栽培模式与关键技术

针对地处四湖腹地的湖北省监利县果树资源利用率低及涝洼湿地的地理环境和生态条件 ,提出加快果树资源品种结构的调整 ,监北地势稍高 ,排灌方便的地方大力发展以猕猴桃为主的产业 ,同时利用架面下的行间土地套种蔬菜、瓜类作物、草莓、食用菌以及耐荫湿的中草药植物等立体生态农业的栽培模式 ,达到经济效益和生态效益的同步增长 ,与其相配套的栽培关键技术是采用地下通气排灌暗沟设施 ,重施有机质肥加磷肥 ;高畦壮苗定植 ;巧施追肥 ;适时排灌 ;树盘覆草保墒 ;人工辅助授粉和疏花疏果     

Environmental and economic impacts of water scarcity and market reform on the Mooki catchment

Over-allocation of irrigation water has led to widespread environmental degradation in the Murray-Darling Basin (MDB) in Australia, prompting discussions of the water efficiency performance of irrigated industries. There is increasing pressure for irrigators to adopt water efficient practices in line with ecologically sustainable principles, especially with current drought conditions. However, there is great uncertainty surrounding the available practices to improve irrigation efficiency from both ecological and economic standpoints. This paper examines the economic and environmental impact of several possible water efficient practices and government policies, using an interdisciplinary approach combining biophysical modelling and economic modelling. This is done for the case-study of the Mooki catchment in the MDB, located in northern New South Wales, Australia.     

汽车乘务舱半物理环境模拟的甲醛光净化效果分析

汽车乘务舱半物理环境模拟系统,以测试室作为汽车乘务舱的模拟环境,采用平衡子系统作为甲醛污染物生成装置,用于研究在不同条件下甲醛污染物的光净化效果。实验结果表明:良好的通风条件可以改善甲醛的降解效果;甲醛初始浓度升高后虽然其降解效果有所下降,但是降解效果仍然可以达到80%以上;用改变电压来改变光强,9V和12V不同光强条件下,12V的效果好于9V;光照面积的增加可以明显地改善光催化降解的效果;玻璃和皮革作为载体时,皮革载体的降解效果要远好于玻璃载体。实验研究证明,光净化材料完全可以应用于汽车内环境中,且对甲醛空气污染物具有良好的净化效果。     

关于排污权的一级市场和二级市场问题

在分析建立和完善排污权市场机制必要性的基础上,提出了排污权一级市场和二级市场的概念,阐述了参与主体不同、实施手段不同、风险大小不同和作用效果不同是一级市场与二级市场的主要区别;指出排污权一级市场需要解决的核心是公平问题,二级市场需要解决的核心是效率问题,并提出了保证排污权一级市场的公平性和提高二级市场效率的若干重要措施.这对于当前我国实施排污权有偿取得与排污交易,建立排污权市场机制具有重要借鉴意义.     

运用模拟方法解决步行街人车混流区问题

在分析城市步行街及其周边存在人车混行、人员密度高、通行效率低、潜在的危险大的基础上,笔者用计算机模拟方法研究了沈阳市中街步行街的一个人车混行的交叉路口,实际勘察了十字路口道路格局、车流、人流状况,测量、估计通过路口的人数、流量,根据获得的数据,对不设置交通信号灯、设置信号灯、建设过街天桥或地下通道等几种情况进行模拟,得到各种情况下的通行效率,并对不同的过街方案的优缺点进行比较。最终选择过街方案需要综合考虑影响安全和效率的多种因素,包括地域、人流量、路口宽度、周边交通等因素,用较小的经济投入取得最大的通行效率。文中的模拟采用EXODUS软件。