Effect of air supply on the performance of an active direct methanol fuel cell (DMFC) fed with neat methanol

Unlike the situation in the direct methanol fuel cell (DMFC) fed with dilute liquid methanol solution, the required water in anode for a DMFC fed with neat methanol is entirely transported from cathode. In this study, the water concentration in anode catalyst layer of such a DMFC operating with fully active mode is theoretically analyzed, followed by the experimental investigations on the effects of air flow rate and operating temperature on cell performance. The results revealed that the air flow rate has a strong impact on cell performance, especially at larger current density. Overmuch air causes rapid decline of cell performance, which results from the dehydration of membrane and lack of water in the anode reaction sites. Raising temperature induces faster reaction kinetics, while undesired stronger water dissipation from the DMFC. In practice, the stable cell resistance can be used as a criterion to help the DMFC to achieve a high and sustainable performance by finely combining the air flow rate and operating temperature.     

Active moss biomonitoring of trace elements with Sphagnum girgensohnii moss bags in relation to atmospheric bulk deposition in Belgrade, Serbia

Active biomonitoring with wet and dry moss bags was used to examine trace element atmospheric deposition in the urban area of Belgrade. The element accumulation capability of Sphagnum girgensohnii Russow was tested in relation to atmospheric bulk deposition. Moss bags were mounted for five 3-month periods (July 2005-October 2006) at three representative urban sites. For the same period monthly bulk atmospheric deposition samples were collected. The concentrations of Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, and Pb were determined by instrumental neutron activation analyses and atomic absorption spectrometry. Significant accumulation of most elements occurred in the exposed moss bags compared with the initial moss content. High correlations between the elements in moss and bulk deposits were found for V, Cu, As, and Ni. The enrichment factors of the elements for both types of monitor followed the same pattern at the corresponding sites.     

Novel sampling methods for atmospheric semi-volatile organic compounds (SOCs) in a high altitude alpine environment

High- and low-volume active air samplers as well as bulk deposition samplers were developed to sample atmospheric SOCs under the adverse conditions of a mountain environment. Active sampling employed separate filters for different European source regions. Filters were switched depending on daily trajectory forecasts, whose accuracy was evaluated post hoc. The sampling continued on three alpine summits over five periods of four months. The prevailing trajectories varied stronger between sampling periods than between stations. The sampling equipment (active and bulk deposition) proved dependable for operation in a mountain environment, with idle times being mainly due to non-routine manipulations and connectivity.     

填埋气竖直井收集与渗滤液导排复合系统构造与施工技术

阐述了填埋气竖直井及渗滤液导排复合系统的构造及优势功能,分解了系统主要构造结构,主导排槽、支导排槽、竖直井、冷凝井等施工过程中的技术要点及参数控制,工程实践检验了系统的采气与导排效果,产生了较优的环境效益。     

开发区回顾性环境影响评价工作要点探讨——以江苏某开发区为例

回顾性环境影响评价是环境影响评价制度的重要组成部分。目前,我国开展回顾性环境影响评价的研究尚处于起步阶段。本文以江苏某开发区为例,重点探讨了开发区回顾性环境影响评价的内涵、作用、意义、程序和内容,旨在为今后开展开发区回顾性环境影响评价提供借鉴。     

在评价微污染水体中均值污染指数评价方法和活性污染指数评价方法的比较

针对均值污染指数评价方法在微污染水体环境质量评价上存在的缺陷,提出新的改进方法即活性污染指数法进行评价.根据吉林省白城市月亮湖水库2001～2005年监测结果,同时利用这两种方法进行评价,结果显示活性污染指数法评价白城市水库水质更客观和真实有效.     

欧洲大气颗粒物标准及监测体系

以欧洲环境空气质量及清洁空气指令为基础,从标准限值、监测点位布设、监测方法等多个方面,对欧洲大气颗粒物标准及监测体系进行了综合阐述。由极限值、目标值、暴露浓度限值、评价上限和下限等构成的标准限值体系协同作用,将欧洲大气颗粒物浓度控制在一定范围内;大气颗粒物监测点位布设方法遵循基本布设原则和最少点位数及AEI计算要求的详细规定;在颗粒物监测方法上,参比方法和等效方法并存,近年多种方法的应用情况也有所变化。通过对欧洲大气颗粒物标准及监测体系的综述,以期为中国大气颗粒物监测管理提供先进思路和技术参考。     

江苏省机动车环保检验机构现场评审要点解析

现场评审是机动车环保检验机构委托流程中的关键技术环节,按评审性质的不同梳理机动车环保检验机构现场评审的重点内容,解析各项内容的检查要点,为指导全省机动车环保检验机构的评审工作并统一评审尺度起到一定作用。     

物元分析法在水质监测优化布点中的应用

物元分析法是处理不相容问题的一种有效方法。以竺山湾2010年7月水质监测数据为例,利用物元分析法分析太湖竺山湾水质监测点位分布情况,并将分析结果与系统聚类法的分析结果相比较,发现物元分析法的分析结果是准确、可信的。综合使用物元分析法和系统聚类法,最终确定水质监测点位可由14个优化至11个。     

气相色谱法测定有机磷农药残留的常见问题探讨

针对气相色谱法测定有机磷农药残留过程中常见的基线噪声大、活性位点吸附、热分解和基质效应等4个问题,从气相色谱仪的结构和有机磷农药的性质出发,探讨了解决办法。提出从气路故障、检测器、外部干扰等3个方面排查,降低基线噪声;正确使用玻璃衬管和色谱柱,消除活性位点;合理设置进样口和检测器温度,防止发生热分解现象;采用基质净化、基质匹配校准及加入分析保护剂的方法,避免基质效应。