PROBABILISTIC METHODS IN STREAM QUALITY MANAGEMENT1

ABSTRACT. Recent advances in water quality modelling have pointed out the need for stochastic models to simulate the probabilistic nature of water quality. However, often all that is needed is an estimate of the uncertainty in predicting water quality variables. First order analysis is a simple method of providing an estimate in the uncertainty in a deterministic model due to uncertain parameters. The method is applied to the simplified Streeter-Phelps equations for DO and BOD; a more complete Monte Carlo simulation is used to check the accuracy of the results. The first order analysis is found to give accurate estimates of means and variances of DO and BOD up to travel times exceeding the critical time. Uncertainty in travel time and the BOD decay constant are found to be most important for small travel times; uncertainty in the reaeration coefficient dominates near the critical time. Uncertainty in temperature was found to be a negligible source of uncertainty in DO for all travel times.     

Uncertainty Analysis In Dissolved Oxygen Modeling in Streams

Uncertainty analysis in surface water quality modeling is an important issue. This paper presents a method based on the first-order reliability method (FORM) to assess the exceedance probability of a target dissolved oxygen concentration in a stream, using a Streeter–Phelps prototype model. Basic uncertainty in the input parameters is considered by representing them as random variables with prescribed probability distributions. Results obtained from FORM analysis compared well with those of the Monte Carlo simulation method. The analysis also presents the stochastic sensitivity of the probabilistic outcome in the form of uncertainty importance factors, and shows how they change with changing simulation time. Furthermore, a parametric sensitivity analysis was conducted to show the effect of selection of different probability distribution functions for the three most important parameters on the design point, exceedance probability, and importance factors. Note: This version was published online in June 2005 with the cover date of August 2004.     

浅谈环境监测数据的审核

阐述了环境监测数据审核程序与内容,对监测数据的审核方法进行了综述。     

Ecological Impact Assessment in Data-Poor Systems: A Case Study on Metapopulation Persistence

Legislation on the protection of biodiversity (e.g., European Union Habitat and Bird Directives) increasingly requires ecological impact assessment of human activities. However, knowledge and understanding of relevant ecological processes and species responses to different types of impact are often incomplete. In this paper we demonstrate with a case study how impact assessment can be carried out for situations where data are scarce but some expert knowledge is available. The case study involves two amphibian species, the great crested newt (Triturus cristatus) and the natterjack toad (Bufo calamita) in the nature reserve the Meinweg in the Netherlands, for which plans are being developed to reopen an old railway track called the Iron Rhine. We assess the effects of this railway track and its proposed alternatives (scenarios) on the metapopulation extinction time and the occupancy times of the patches for both species using a discrete-time stochastic metapopulation model. We quantify the model parameters using expert knowledge and extrapolated data. Because of our uncertainty about these parameter values, we perform a Monte Carlo uncertainty analysis. This yields an estimate of the probability distribution of the model predictions and insight into the contribution of each distinguished source of uncertainty to this probability distribution. We show that with a simple metapopulation model and an extensive uncertainty analysis it is possible to detect the least harmful scenario. The ranking of the different scenarios is consistent. Thus, uncertainty analysis can enhance the role of ecological impact assessment in decision making by making explicit to what extent incomplete knowledge affects predictions.     

THE CASE FOR DIRECT MEASUREMENT OF ENVIRONMENTAL RESPONSE TO HAZARDOUS MATERIALS1

ABSTRACT: Direct measurement of response thresholds of complex biological systems to toxic chemicals is now possible using microcosms and other simulation techniques. Extrapolation to no-observable response using application factors and data from single species toxicity tests is less precise than direct measurements.     

默克公司COD测试剂的替代品开发

德国默克（MERCK）公司制造的COD测定仪在我国环保行业、科研院所的水质监测工作中应用广泛，但配套测试剂价格昂贵，限制了该仪器的使用。设计了高量程（100～1500mg／L）和低量程（25～100mg／L）下COD测试剂替代品的开发方案。通过实验，确定了两个量程下COD测试剂替代品中K2Cr2O2，H2SO4-Ag2SO4，HgSO4的浓度和加入量以及测试方法。实验结果表明，在高量程和低量程范围内，使用COD测试剂替代品的测试结果与MERCK公司配套测试剂的测试结果比较相符，反应时间也可缩短至0．5h。     

油气田环境监测站能力验证工作

随着我国加入WTO,许多油气田实验室已先后通过了中国实验室国家认可委员会(CNAL)的验证。在该项活动中,能力检验是一项十分重要的内容。河南石油勘探局环境监测站参加了《CNAL2003年度能力验证计划》中溶液酸度检测项目活动,借鉴了国内外能力验证工作的经验,取得了较好的效果。文章论述了油气田环境监测站能力验证的基本概念,并对能力验证的定义、分类、组织和设计、运作及能力评价等问题进行了讨论,给出了与之相关的应用实例。     

环境影响报告书、表审批程序的探讨

为了搞好环境影响报告书、表的审批,针对环境影响报告书、表审批存在的一些具体问题,认真论证探讨了对环境影响报告书、表审批程序、标准和内容,提出了改进建议.     

定氢仪在环境试验中的应用

本文叙述了定氢仪的测氢原理、结构、特点及定氢仪在环境试验中的用途。     

改性环氧树脂灌封提高铝电解电容器的三防性能

针对铝电解电容器出现的三防问题，通过对环氧树脂进行改性，提高环氧树脂的防护能力，并以此对铝电解电容器进行灌封，经过三防试验检验，结果表明采用改性环氧树脂灌封能效提高铝电解电容器的三防性能。