不同尾水输送方案对尾水水质的影响研究

通过管道实验和明渠实验模拟尾水输送过程,研究不同输送方案对尾水中COD、BOD5、SS、TN、氨氮、TP、DO、雌酮(E1)、辛基酚(OP)、壬基酚(4-n-NP)等指标的去除规律,为徐州市截污导流工程尾水输送方案的选取提供理论依据.结果表明:(1)除DO、TP和SS外,管道输送方案对其他指标的控制能力均优于明渠;管道输送过程中,除SS和TN外,污染物的浓度变化主要发生在0～48 h.(2)在选择管道输送方案的基础上,可以考虑在实际输送时提高流速,缩短尾水在管道中的停留时间.     

MTBE in California's Drinking Water: A Comparison of Groundwater Versus Surface Water Sources

During the last decade, the fuel oxygenate methyl tertiary butyl ether (MTBE) has received widespread attention as a potential threat to water quality, primarily due to leaking underground gasoline storage tanks and watercraft with two-stroke engines. In this article, we examine the annual detection frequency, number of new source detections, and concentration of MTBE detected in California's public drinking water groundwater and surface water sources from 1995 to 2002. This work builds on our previous evaluations of California's water quality monitoring database. However, it is unique in that it includes separate evaluations for groundwater and surface water sources that are of greatest concern to regulators, and which are likely being used for current public consumption. Our evaluations also include full-year data for 2002 (which have not been published previously) and an analysis of how the sampling and reported detections of MTBE vary by geographic location. We find that MTBE was generally detected (at any level) in approximately 0.5-0.9% and 0.2-0.4% of all groundwater sources assuming a one-detection and two-detection criterion, respectively. The overall detection frequency for MTBE in surface water sources is significantly higher than for groundwater sources, although these surface water detections appear to have substantially declined since 1996 (e.g., 7-9% for all surface water sources during 1996 to 1999 and 4% for all surface water sources during 2000 to 2002, assuming a one-detection criterion). The detection frequency of MTBE concentrations at or above the state drinking water standards in all drinking water sources (both groundwater and surface water sources) and the subset of drinking water sources that are likely to currently be delivered to consumers is markedly lower (and often zero). Despite the significant increase in water sampling over time, the number of new drinking water sources found to contain MTBE in California has not increased at the same rate and appears to have remained relatively stable or to have decreased since 1998. The data also show that nearly all of the 58 counties in California have routinely sampled at least some of their groundwater and surface water sources for MTBE over the last 8 years. Geographical evaluations show that MTBE has been detected (at least once) in groundwater sources in 34 counties and in surface water sources in 18 counties but has only been detected routinely (i.e., for 3 or more years) in 16 and 7 counties, respectively. Detected concentrations of MTBE are also generally below state drinking water standards, particularly for surface water sources. In short: (1) MTBE is rarely found in California groundwater or surface water sources that are of greatest concern to regulators or the public, and (2) drinking water detections of MTBE are expected to decline in the future due to the pending phase-out of MTBE and recent regulatory programs aimed at controlling gasoline releases from underground storage tanks and two-stroke-engine watercraft.     

Salem Revisited: Updating the MTBE Controversy

I am wronged. It is a shameful thing that you should mind these folks that are out of their wits.* *Statement of Martha Carrier (excerpt), hanged as a witch on 19 August, 1692 in Salem, Massachusetts. In all, 20 innocent persons were executed in 1692 as a result of the hysteria attending the Salem witch trials. After the executions, the court was prohibited from "reliance on spectral and intangible evidence". No prosecutions were successful thereafter. See generally, The Salem Witch Trials 1692: A Chronology of Events , at www.salemweb.com/memorial This article provides background information regarding the emerging controversies involving methyl tert -butyl ether (MTBE) and litigation involving leaking underground storage tanks (USTs) in general. It examines (1) the administrative, legislative and litigation history of MTBE in the context of the Clear Air Act and state environmental statues; (2) the importance of applicable RCRA (Resource Conservation and Recovery Act) deadlines regarding UST compliance in these cases; (3) the question of MTBE toxicity for personal injury claims; and (4) the scope of damages available in cases filed by plaintiffs who are not physically impacted by contamination. The authors conclude that the MTBE controversy does not appear to be a legitimate public health or environmental crisis, but rather is yet another speculative product of the American legal industry.     

Characterisation of prompt and delayed atmospheric radioactivity releases from underground nuclear tests at Nevada as a function of release time

A database with information on about 500 cases of atmospheric radioactivity releases from underground nuclear tests is analysed. The data are statistically evaluated and systematically aggregated in order to characterise prompt uncontrolled as well as delayed operational releases of radioactivity into the atmosphere. The focus is put on the latter. The reported data compare well with theoretically derived xenon activities for reasonable nuclear test scenarios. Conclusions are drawn on the main features of releases that can be expected from underground nuclear tests as a function of release time. These findings are relevant for developing and validating methods to be applied in global monitoring of atmospheric radioactivity with respect to indications of an underground nuclear explosion.     

基于可拓学的充填管道输送可靠度分析

为评价矿山充填系统管道输送安全等级,建立充填管道输送安全可拓学评价模型。结合相关学者的研究成果和矿山实践数据,确定输送安全等级标准及评价指标量值。运用融合权重法求出评价指标的融合权重系数。运用可拓学理论,建立充填管道输送安全评价的融合赋权法-可拓学模型,并依据非对称贴近度原则评判安全等级。运用该方法对金川龙首矿充填管道进行输送安全评价,得到其综合关联度为(-0.147,-0.185,-0.245,-0.398),贴近度为(0.286,0.347,0.225,0.134),安全等级为Ⅱ级,管道输送安全性较差。建议矿山及时对管道进行维修保养,以保证矿山安全生产。     

库尔勒－鄯善输油管道工程环境风险分析与管理

管道环境风险分析与管理是预防管道泄漏事故发生的一个重要途径。利用遥感图像目视解译与实地勘察相结合的方法,对库尔勒－鄯善原油输送管道工程沿线进行环境风险因素识别;利用类比、模拟方法进行环境风险的统计分析及管线原油泄漏事故对环境的影响预测;进行环境风险的定性分析和用事故树分析方法的半定量评价;得出分段管道环境风险的相对排序;提出针对该管线环境风险管理的措施和对策。     

海水管路冲刷腐蚀数值模拟研究现状

分析了海水管路冲刷腐蚀主要影响因素,总结了国内外学者在海水管路冲刷腐蚀数值模拟方面的研究成果,并在此基础上对海水管路冲刷腐蚀数值模拟研究方向作出了展望。随着计算流体力学的发展,有效地结合试验数据与数值模拟对海水管路冲刷腐蚀现象进行研究,可以更好地预测海水管路冲刷腐蚀发生的部位及腐蚀速度。     

滑坡灾害中埋地管道稳定性分析

滑坡灾害导致的管道局部失稳是油气管道面临的严重威胁之一。为了探讨滑坡灾害中工程管道位移、应力随参数的变化规律,研究管道结构稳定性,采用有限元方法,以管道外径、径厚比、滑坡宽度为研究变量,计算并分析了在滑坡灾害中管道位移、应力和稳定性。研究结果表明:增大管道外径可以有效抑制滑坡灾害中管道位移,同时随着管道外径的增加,管道最大位移呈现二次曲线降低,并且径厚比越小管道位移增量越小;滑坡灾害中管道的最大应力发生在滑坡中心和两端位置;以外径为0.965 m管道为例,屈曲特征值分析结果显示,随着管道径厚比的增大,屈曲特征值呈二次曲线减小;随着管道外径的增加,屈曲特征值呈线性增大,并且屈曲位置发生在滑坡段中间位置,管道所能承受的极限滑坡宽度约为70 m。     

X80天然气管道在役焊接应力分析与调控

为了探究X80天然气管道在役焊接的应力分布和变化规律,在考虑天然气介质的作用下,采用有限元方法模拟了X80天然气管道在役焊接应力场分布规律,分析了天然气工况参数和环境温度对X80天然气管道在役焊接应力的影响,并根据应力变化规律提出了降低X80天然气管道在役焊接应力的措施。研究结果表明:X80天然气管道轴向焊接应力和环向应力主要呈对称分布形式,且管道外壁的应力大于管道内壁上的应力;随着天然气压力和流速逐渐增大,轴向应力先增加后降低,而环向应力逐渐增大;当环境温度增大后,管道轴向和环向应力均呈下降趋势;降低天然气压力和流速、采用焊前预热能够有效降低焊接应力。研究结果可为我国X80天然气管道在役焊接安全提供参考。     

海底管道在位状态调查实践

根据调查设备搭载器的不同,将海底管道在位状态调查方法归为船载、自治水下机器人搭载(AUV 搭载)和无人遥控潜水器搭载(ROV搭载)三类;在浅水段采用船载调查,在深水段采用AUV搭载调查,在此基础上进行重点关注区域筛选,开展ROV调查,最后进行整体评价和分析对比,这种^“(船载/AUV)+ROV^”组合模式很好地实现了多种调查方法的优势互补。实际上,采用AUV搭载进行海底管道在位状态调查在国内业界尚属首次。调查所取得的管道位置、埋深、周边障碍物的分布以及管道人工处理情况等成果,为后期开展管道维护工作提供了重要的基础数据。此次成功实践可为以后从浅水到深水的管道在位状态调查提供经验和借鉴。