Cement for stabilisation of industrial residues containing heavy metals

A method aimed at decreasing the toxicity of heavy metals [namely, Zn(II) and Cr(III)] in real polluted residues by immobilisation has been developed. The residues were processed either with two cement-type stabilisers or lime. The cement-type stabilisers were Portland cement and Depocrete SM/2 at the self-generated pH (ca. 11) which afforded physical as well as chemical potential for the immobilisation of heavy metals. The other stabiliser, lime, reduced organic compounds, thus favouring the decrease of the chemical oxygen demand (COD) and endowing the residue with better mechanical properties for transport. After leaching the stabilised residues using the standard leaching test [Order 13/10/89, Boletín Oficial del Estado (BOE) 270 10/11/89], three ways for establishing the toxicity of the treated residues were used, namely: (1) the ecotoxicity test using Photobacterium phosphoreum (DIN 38 412); (2) determination of the concentration of heavy metals by atomic absorption spectrometry (AAS); (3) determination of the COD or oxygen required for complete chemical oxidation of a water sample. Portland cement (20%) blended with Depocrete SM/2 (3%) acted as an effective stabiliser for residues containing heavy metals as it increased the ecotoxicity index (EC50) by more than five times. Thus the heavy metal concentration in the leaching liquid was lowered to less than 0.1 mg l-1. The addition of 5% of lime afforded a residue easily transportable from the place of treatment to the landfill. The precision of the method was studied in terms of both repeatability and reproducibility. The values found with respect to EC50 and expressed as the relative standard deviation (RSD) were 1.6% and 5.1%, respectively.     

An analysis of university sustainability reports from the GRI database: an examination of influential variables

In the business context, many papers have examined whether certain variables can affect sustainability disclosure practices. However, research on universities has mainly been addressed to explore the extent of sustainability information reported with little focus on determining the factors that may affect it. This paper analyzes the influence exerted by some variables concerning the extent of information reported in the university sustainability reports included in this study. To accomplish this task, data were collected using a content analysis of the university sustainability reports extracted from the GRI sustainability disclosure database. The findings reveal that sustainability disclosure practices by universities are explained by different factors, among which are institutionalization, geographical region, external assurance and leadership. Such results are supported jointly by the underpinnings of the institutional and legitimacy theories in response to coercive and mimetic pressures and by the need to improve reputation in society.     

增强机组监控技能,确保飞行安全

良好的监控技能对确保飞行安全 ,预防飞行事故发生有十分重要的作用。但由于多方面原因 ,当前的飞行机组监控工作还存在不少问题 ,并成为多起飞行事故主要原因之一。笔者从四方面 ,对民用航空飞行中缺乏良好监控的原因予以分析和说明 :持续有效的监控工作不符合人的本性 ;现行规章制度中未把机组监控技能作为所有机组成员 ,尤其是对辅助操纵者的一项重要任务加以确定 ;现有管理制度与管理观念 ,更多关注行为结果而不是行为发生过程 ;飞行训练中未将其作为重要飞行技能加以训练。笔者强调指出 :采用标准操作程序 ,提高相应飞行阶段的监控技能 ,对不同飞行阶段的工作负荷予以计划和控制、进行工作优先排序 ,加强机组成员间配合 ,在训练中强化监控技能培养等措施 ,有助于改进和增强飞行机组的监控技能 ,确保飞行安全     

Early succession arthropod community changes on experimental passion fruit plant patches along a land-use gradient in Ecuador

Many tropical landscapes are today characterized by small forest patches embedded in an agricultural mosaic matrix. In such highly fragmented landscapes, agroforests have already been recognized as refuges for biodiversity but few studies have investigated the potential of non-forested land-use types to contribute to overall biodiversity of functionally important taxa in the tropics. This study experimentally investigated species richness, abundance, and community similarity of arthropods on Yellow Passion fruit plants, planted in standardized patches in 30 sites along a land-use intensity gradient. The gradient comprised all major land-use types of the area: forest fragments, abandoned coffee agroforests, coffee agroforests managed under shade trees, pastures, and rice fields in Coastal Ecuador. We found a total of 2123 individuals belonging to 242 species. Overall arthropod species richness increased with light intensity and leaf-surface area and decreased with land-use intensity: forest fragments and abandoned coffee agroforests harboured significantly more species than rice or pastures. Overall diversity in managed coffee agroforests was intermediate between the intensively managed and more natural habitats. However, the three most abundant taxa of arthropods (ants, spiders, and beetles) had the highest number of species in managed coffee agroforests, while ant abundance was highest in abandoned coffee agroforests and spider abundance highest in managed coffee agroforests. Analyses of community similarity revealed that open (pasture, and rice) and shaded (forest, abandoned and managed coffee agroforests) land-use types had distinct arthropod communities. In conclusion, although open agricultural land-use types tend to have fewer species in lower numbers, all land-use types contribute to overall biodiversity of the agricultural matrix because of distinct communities in shaded vs. non-shaded land-use types.     

石化企业重要环境因素识别评价方法探讨

介绍了石化企业进行环境因素识别评价的常规步骤,并总结了一些适用的识别评价方法,还对应用这些方法的注意事项进行了讨论.     

国内危险化学品管理概述

搜集整理了近年来各部委关于危险化学品管理的各种目录,提出了《危险化学品安全管理条例》(国务院令591号)实施后将要新增的目录,对不同目录的背景、主要内容和适用范围作了介绍,对国内危险化学品从业人员和企业可起到参考指导作用。     

A modelling study on 137Cs and 239,240Pu behaviour in the Alborán Sea, western Mediterranean

A model for simulating the dispersion processes of 137Cs and 239,240Pu in the Alborán Sea is described. The model consists of two hydrodynamic models: a 2D depth-averaged model and a two-layer model which provide tidal and geostrophic currents, respectively; a sediment transport model which provides suspended particle concentrations and sedimentation rates over the domain; and the radionuclide dispersion model including interactions of dissolved radionuclides with suspended particles and bed sediments. These processes are formulated using kinetic transfer coefficients. The hydrodynamic and sediment models are run and validated in advance, and their results are then used to simulate the dispersion of 137Cs and 239,240Pu, which are introduced from atmospheric fallout. Radionuclide concentrations in the water column and distributions in bed sediments have been compared with measurements in the sea. Both set of data are, in general, in agreement. The model has also been applied to calculate radionuclide fluxes through the Strait of Gibraltar. These computed fluxes have been compared with previous estimations as well.     

基于GIS的土地利用类型分形维数及稳定性研究——以滇池流域为例

应用GIS技术及分形理论,以云南省滇池流域为研究区,将土地利用类型划分为5类：耕地、林地、草地、水域及城乡工矿居民用地,并进行各土地利用类型图斑分形维数分析。结果表明：土地利用类型的分布具有分形结构,各土地利用类型分维值介于1.09～1.35之间,总分维值1.146。根据分维值对各土地利用类型稳定性排序：林地〉草地〉耕地〉水域〉城乡工矿居民用地。若不考虑水域影响,稳定性指数均介于0.2～0.5之间的土地利用类型面积占研究区土地总面积的80.18%,总体稳定性良好。说明在人为规划影响下,滇池流域土地利用总的发展比较稳定,人为因素、人工措施的实施比较合理。分维值能较好反映各土地利用类型复杂程度及稳定性。