熔融制样X射线荧光光谱法测定碳化钨及其废料中的钨

碳化钨被广泛应用于硬质合金生产材料,其钨的含量关系碳化钨的性能及货物结算,生产过程中因配比错误、打磨等原因还会产生大量的含钨废料,从废料中回收钨能弥补钨资源的不足,因此测定碳化钨及其废料中的钨具有重要意义。目前碳化钨中钨含量的测定通常参照国家标准采用辛可宁重量法,准确度较高,但只适用于检测三氧化钨含量大于50%的样品,且过程繁琐,工作量大。本文根据碳化钨在高温下易氧化的特点,借鉴国际标准ASTM B890-07,提出将碳化钨转化为三氧化钨,采用熔融制样-X射线荧光光谱(XRF)测定钨含量的方法。即碳化钨先在马弗炉中灼烧至钨完全转化为三氧化钨,再加入五氧化二钽作内标,四硼酸钠-四硼酸锂为混合熔剂,在1150℃下熔融制成试样片,用XRF法测定钨的含量。结果表明,最佳的灼烧温度为800℃,在此温度下碳化钨完全转化成三氧化钨,有效地解决了碳化钨熔融制样的难点;方法精密度(RSD)为0.2%,实际样品的测定值与国家标准方法(辛可宁重量法)一致,可测量三氧化钨含量的范围为30%~100%,且分析时间大大缩短,可满足大量实际样品检测的需要。     

高放废物处置库芨芨槽预选场址深部地下水同位素研究

深地质处置是目前国际上普遍接受的高放废物安全处置方案.对于这种方案而言,安全处置高放废物的前提是选择适宜的场址,而场址的适宜性在很大程度上取决于其水文地质条件.高放废物处置库场址需要低渗透岩体作为处置库围岩,对于低渗透岩体而言,经典和传统的水文地质研究方法受到了很大的限制,而同位素技术与其他水文地质方法结合时,却能发挥出良好的作用.本文以目前我国高放废物处置库预选场址之一的芨芨槽场址为例,重点讨论了同位素方法在花岗岩体场址水文地质研究中的应用.根据钻孔不同深度的地下水环境同位素(δD、δ18O、3H和14C)组成特征,结合场址水文地质条件,识别了区内地下水的来源,揭示了控制地下水运移交替速率的主要因素.结果表明,该区深部地下水14C年龄高达8000 a左右,说明其交替、运移十分缓慢,但同时也含有少量的氚,说明地下水以侧向补给的“老水”为主,接受当地大气降水入渗补给的“新水”所占比例很小.此外,通过地下水14C年龄与取样段岩芯采取率的对比,认识到对于区内的花岗岩体而言,决定地下水交替、运移速率的主要因素是裂隙的发育程度,而不是深度.     

考虑降解效应的城市固体废弃物非线性本构模型

基于城市固体废弃物(MSW)的降解及土力学特征,在应力降解模型、等向压缩特性和邓肯-张模型的理论基础上,建立了一个能够描述MSW应力和降解耦合作用的全量非线性本构模型。给出了不同应力状态下单元体体积和轴向变形随时间变化的数学表达,同时给出了所有参数的确定方法。采用该模型对不同龄期和不同围压条件下填埋场现场试样的三轴CD应力-应变曲线以及室内长期一维降解压缩试验进行了模拟。结果表明,模型概念合理、参数明确,能够较全面地描述不同降解龄期垃圾的本构关系,可用于分析填埋场的长期变形。     

To be ethical or to be good? The impact of ‘Good Provider’ and moral norms on food waste decisions in two countries

One-third of all food produced in the world is lost or wasted, which has negative consequences for societies and the environment. Thus, curbing food waste is critical to securing human well-being and protecting the environment. This study examines the drivers of household food waste decisions by investigating the activation and deactivation of moral norms and introducing the concept of the ‘good provider’ in an augmented norm-activation model (NAM). A survey of 643 consumers in Australia and Singapore explores the ‘good provider’ norm as a driver of food waste behaviours in both cultures. For Australians, ‘good provider’ norms suppress intentions to avoid food waste, most likely to provide for the immediate family, which can be a motive that overrides moral concern about food waste in an individualistic culture. For Singaporeans, ‘good provider’ norms do not suppress food waste intentions, possibly due to the value placed on thrift by a long-term-oriented culture. The paper significantly extends the previous research on norms, culture and sustainable consumption and provides policy and practical implications for curbing food waste in different cultural contexts.     

中国工业废气排放的空间特征及其影响因素研究

基于2000~2012年中国31个省（市、自治区）面板数据,运用探索性空间数据分析方法对中国工业废气排放的空间分布特征进行研究,结果显示中国各省域（不含港澳台）工业废气排放存在显著的空间自相关和空间集聚效应;总体呈现东部、西部地区集聚的空间分布特征,其中东部多为高-高集聚区、西部则多为低-低集聚区,并且高值集聚现象的显著性逐渐增强,显著区域呈持续扩张趋势。在此基础上,以STIRPAT模型为基础构建空间计量模型,分析经济发展、人口规模、产业结构、技术水平和国家政策等因素对工业废气排放量的影响。研究结果表明,中国各省域工业废气排放存在空间依赖作用和正的空间溢出效应;经济发展、产业结构与工业废气排放之间呈现显著的正相关关系;技术进步和国家政策对工业废气排放具有抑制作用,而人口增长对工业废气排放的影响并不显著。     

Quantifying the transferability of hydraulic parameters using geostatistics: The Boom Clay Case

The Boom Clay is currently investigated as potential host formation for the deep disposal of high-level and/or long-lived radioactive waste in Belgium. As such, the formation is expected to play a role of natural barrier, to slow the migration of radionuclides towards the biosphere for a sufficiently long time when the man-made barriers are no longer effective. In this context, the Boom Clay aquitard requires to be precisely characterized in terms of hydrogeological parameters, to confirm its role of geological barrier between its surrounding aquifers. Therefore, hydraulic conductivity and migration parameters have been intensively measured over the years in a few boreholes in Belgium; the latter are mainly located in the Mol-Dessel area, assuming historically a good lateral continuity of the geology. Combining these measurements with more densely acquired geophysical information allows quantifying their spatial variability and consolidating the continuity assumption. From a methodological point of view, the modeling of hydrogeological parameters requires to solve several issues. First, it is required to find a consistent geo-reference coordinate system allowing to laterally correlate thin observations derived from boreholes separated by several tens of kilometers. Then, in order to provide a reliable 3D model, it is compulsory to integrate the correlation between the scarcely sampled target parameters (core measurements) and numerous geophysical logs (gamma ray, resistivity). Geostatistics provides a suitable framework to analyze and solve these issues. Finally, a 3D model of the target parameters is proposed, together with an uncertainty envelope. This uncertainty quantification is of significant added value to assess the efficiency of the geological barrier. Besides the actual modeling of target parameters, the paper also presents sampling recommendations for forthcoming boreholes.     

Effect of Ozone and Ozone/Fenton in the Advanced Oxidation Process on Biodegradable Characteristics of Semi‐aerobic Stabilized Leachate

This study investigated the effects of O₃ and O₃/H₂O₂/Fe²⁺ in the advanced oxidation processes (AOPs) on the biodegradable and soluble characteristics of semi‐aerobic stabilized solid waste leachate. The biodegradability (BOD₅/chemical oxygen demand, COD) ratio improved from 0.034 to 0.05 and 0.1 following O₃ and O₃/H₂O₂/Fe²⁺, respectively. Fractions of biodegradable COD_(bi) (24%), non‐biodegradable COD_(ubi) (76%), soluble COD_(s) (59%), biodegradable soluble COD_(bsi) (38%), non‐biodegradable soluble COD_(ubsi) (62%), and particulate COD (PCOD) (41%) in stabilized leachate were also investigated. The fraction of COD_(bi) increased to 28 and 36% after applying O₃ and O₃/AOPs, respectively. COD_(S) increased to 59% after O₃ and to 72% after O₃/AOPs, whereas COD_(bsi) increased to 38 and 51% after O₃ and O₃/AOPs, respectively. The removal efficiency of COD_(S) was obtained at 5% after O₃ alone and improved to 51% following ozone‐based AOPs, whereas the removal efficiency of PCOD improved from 25% after O₃ to 71% after ozone‐based AOPs.     

Using Dasymetric Mapping to Identify Communities at Risk from Hazardous Waste Generation in San Antonio,Texas

The primary objective of this study is to examine if minorities, the poor, and non-homeowners have a higher potential for exposure than the general population to large-quantity hazardous waste generation in Bexar County, Texas. Results indicate that this is indeed the case: people living near the generators are more often Black non-Hispanic or Hispanic, and more likely to live below the poverty level and not own their own home. Although previous studies conducted in the United States have used states, counties, zip codes, or census tracts as the unit of spatial analysis, we use dasymetric mapping to create population maps at a resolution of 30 m. This allows for the reconfiguration of the areal aggregations chosen for the analysis while preserving its findings. It also reduces, if not eliminates, the effects of the Modifiable Area Unit Problem (MAUP) on the results.     

Estimating Climate-Change Impacts on Colorado Plateau Snowpack Using Downscaling Methods

This study develops observed climate-based downscaling transfer functions that are used with general circulation model (GCM) output to assess potential global-change impacts on Upper Colorado Plateau, USA, water resources. Daily automated snow water equivalent stations are used with 700 mb atmospheric circulation to determine empirical transfer functions. Downscaling methodologies using multiple regression and neural networks are evaluated, with the neural network results explaining approximately 70%of the daily snowfall variance. The neural network-based transfer functions are used with the GENESIS GCM to simulate snowfall characteristics in both a 1xCO₂ and a 2xCO₂ climate. While the total precipitation simulated by the 2xCO₂ analysis remains nearly the same as today, less will fall as snow; specifically, snow water equivalence shows significant reduction (except in the Green River Basin) as the snow season is reduced by 58 days on average.     

Locating a Community Recycling Center within a Residential Area: A Belgian Case Study

This article demonstrates the operation of a simple optimal location-allocation technique for solving the problem of locating one or several community recycling center(s) within a residential area. The article attempts to measure both transportation and externality costs in comparable units, and to incorporate them into the model. A sensitivity analysis of the results at the level of the nuisance provides further insight into the operation of the model and the relative importance of the quantification of pollution in applied location-allocation problems.