Monitoring of iodinated X-ray contrast media in surface water

A monitoring programme was carried out in order to determine iodinated X-ray contrast media (ICM) in the River Danube and to investigate the raw water quality for drinking water production at Langenau waterworks. The study revealed that the maximum concentrations of ICM (over 500 ng l(-1) for diatrizoic acid and iopamidol) were found in 2h-composite samples taken from the downstream of the Ulm/Neu-Ulm metropolitan area. By means of a concentration profile over one month the highest ICM concentrations were observed on weekdays. The extended data evaluation with principal component analysis shows that the upstream and downstream samples had different pattern of variations in ICM concentration and also demonstrates a clear change in ICM composition by the discharge of municipal wastewater. In addition to load profiles of ICM, time-dependent plots of principal component 1 exhibited peaks, indicating a short-term discharge of ICM between the two sampling sites. In conclusion, a point source for ICM contamination between the sampling sites in Ulm upstream and Leipheim downstream seems to be the reasonable explanation for peak ICM concentrations. Due to the observed high variations of ICM concentrations in river, the evaluation of natural waters by means of a single analysis is not representative.     

PCDDs, PCDFs, and coplanar PCBs in wild terrestrial mammals from Japan: congener specific accumulation and hepatic sequestration

The present study determined the contamination levels and congener-specific accumulation features of dioxins and related compounds (DRCs) in wild terrestrial mammals such as large Japanese field mice (LJFM), lesser Japanese moles (LJMs), and raccoon dogs (RDs) collected from Kanto region in Japan during 2001. The toxic equivalent quantity (TEQ) levels in the carcasses or adipose tissues were in the order of RDs > or = LJMs > LJFM. Comparison of DRC congener profiles in the three species and principal component analysis (PCA) demonstrated a higher contribution of OCDD, T4CB77, and P5CB118 in LJMs. Analysis of liver-adipose distribution of DRC congeners in RDs showed that livers contained significantly higher TEQs than adipose tissues, indicating that liver is a depository organ and critical for determining the toxicokinetics of DRCs. As for most T4, P5, H6CDD/DFs and for P5CB126, H6CB169 and mono-ortho PCB congeners, their liver/adipose concentration ratios in RDs revealed a tendency to increase with hepatic TEQ levels, suggesting TEQ-dependent hepatic sequestration.     

Nitrogen balance and groundwater nitrate contamination: comparison among three intensive cropping systems on the North China Plain

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha(-1) on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha(-1), with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha(-1) in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha(-1) at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs.     

Joint analysis of process and operator performance in chemical process operational safety

Independent studies of case histories by the Health and Safety Commission in the UK and by a Honeywell led industrial consortium world-wide showed that human errors represent the major cause of failure in process plant operation. In contrast to this discovery the majority of previous studies on computer aided systems for fault detection and diagnosis has focused on the process side. This paper presents a methodology, which can involve human factors into the development of systems for automatic identification and diagnosis of abnormal operations and develops methods and techniques that can be used to simultaneously capture, characterise and assess the performance of operators as well as of the process. A joint process–operator simulation platform is developed which is used as a test-bed for carrying out the study. The process part is a simulator, which simulates in high fidelity the dynamic behaviour of the process that is subject to the influence of various disturbances and operators’ interventions. The operator module is developed as a real-time expert system, which emulates operator’s behaviour in interpretation of received signals, and planning and execution of decisions. The interaction between the two modules is managed through an interaction module, which handles the real-time exchange of data using Dynamic Data Exchange. The interaction module also contains the toolkits for analysing the dynamic behaviour of the joint process–operator system. The method and system are illustrated using a simulated case study.     

Experimental assessment on the moving capabilities of mobility-impaired disabled

To take into account reasonably the safety requirements of the disabled on emergency evacuation in the design, usage, management and emergency response of public places, the authors of this paper organized on-site experiments for 100 disabled individuals (40 people with no supporting tools, 20 people using a single crutch and 40 people two crutches) and 17 healthy people at a subway station in Beijing. The experiments were designed to measure the unimpeded free walking speed of the participants during horizontal and stair ascending/descending movement, and to assess the possible impact of passage width on movement speed. Based on the results of the tests, the authors systematically analyzed the speed variation patterns with disability grade, gender and passage width. The validity of the value of an important parameter for evacuation safety design in the prescribed fire codes in mainland China, the width of a single stream of people, is assessed. Finally the results of the experiments are compared with that from other researches to identify the similarities and differences between them.     

基于FDS的车厢火灾烟气流动的数值模拟分析

使用FDS火灾模拟软件对列车车厢进行火灾模拟,得到车厢内温度与烟气浓度随时间变化的规律,计算出临界温度与临界可视距离出现的时间,发现在车厢火灾中,总是烟气浓度先达到临界点。车厢火灾的疏散防控措施中,控制烟气浓度应是重点工作。     

基于多Agent的危险化学品安全生产信息采集系统设计

安全生产监管是政府的重要职责,直接关系到国家财产和人民生命安全.安全生产监管中,以危险化学品的监管为重中之重.提高安全生产监管的信息化程度是降低监管强度、提高监管效率行之有效的方法.构建了由管理Agent、采集Agent、故障诊断Agent、通信Agent组成的分布式信息采集多Agent系统,将安监局监管中心对危险化学品生产过程监管的信息采集任务下移到企业端,利用多Agent系统实现危险源生产状态参数的采集、监控及分析;设计了该信息采集系统各类Agent的结构和功能.利用多Agent系统实现分散于各企业的危险源生产状态参数的信息采集、监控及分析,预测和诊断生产过程中的异常状况.通过Agent之间的合作、并行求解使危险化学品安全生产信息采集的问题得到较好地解决.     

HDTMA改性蒙脱土的稳定性

利用十六烷基三甲基溴化铵(HDTMA)改性天然蒙脱土,观察其在不同环境条件下的稳定性.试验结果表明:随着阳离子交换量(CEC)的增加改性蒙脱土在蒸馏水中的稳定性逐渐降低,1.0CEC改性蒙脱土中HDTMA发生解吸.改性蒙脱土在水体中的稳定性随着振荡强度的加强而降低.从室温到70℃对改性蒙脱土的稳定性几乎无影响.超声波处理使改性蒙脱土的稳定性有所降低.NaCl能提高水体中改性蒙脱土的稳定性,而CaCl₂却使其稳定性有所下降.同酸性条件相比,在碱性条件下改性蒙脱土的稳定性更好.因此,废水的温度、pH和无机盐对低改性蒙脱土稳定性的影响都比较小,这为改性蒙脱土处理废水和它的再生提供了可能.同时在较低振荡强度下,改性蒙脱土也许还能成为废水生物处理的载体.     

基于高通量分析方法的长江干流重庆段抗生素种类特征及来源初探

采用高通量分析方法对长江干流重庆段11个流域断面、2个市政污水处理厂进水和6个养殖场废水的潜在抗生素进行筛查,并结合抗生素使用调查探讨其来源。结果表明,(1)共检出83种抗生素,其中流域内检出36种,污水处理厂和养殖场废水中检出70种;磺胺间甲氧嘧啶检出率最高,在流域水体和废水的检出率分别为91%和55%,喹诺酮类是检出抗生素的主要类型;(2)长江干流重庆段下游检出抗生素数量高于上游检出抗生素;(3)有20种抗生素可能由上游携带和重庆市内排放2种方式进入流域,7种抗生素可能由上游携带入境,9种抗生素可能由重庆市内排放引入长江。     

Propagation characteristics of subaerial landslide-generated impulse waves

Environmental Fluid Mechanics - Subaerial landslide-generated impulse waves were investigated in a rectangular prismatic channel based on the Froude similarity criterion. Landslides were modeled...