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在实验室分析基础上,对连续流动分析法测定水中总氮过程的不确定度进行评定。本文建立了数学模型,对不确定度来源进行了分析,并计算了不确定度分量、合成不确定度及扩展不确定度,最后给出了总氮测量结果的标准表示方法。 相似文献
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目的 对原子荧光光谱法测定水中砷含量的不确定度来源及其对测量不确定度的影响进行分析。方法 利用相对标准不确定度进行测量不确定度的评定。过程采用直观的因果图,建立有效的数学模型,利用相对标准不确定度分量进行测量不确定度评定,并在砷含量为1.7μg/L的水样测定中,获得其相对标准不确定度为3.4%,有效自由度为25。结论 原子荧光光谱法对水中砷浓度测量不确定度影响因素中,工作曲线拟合产生的不确定度较大。 相似文献
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原子吸收法测定铜检出限的测量不确定度评估 总被引:1,自引:0,他引:1
对原子吸收法测定铜检出限的测量不确定度进行分析探讨,建立了不确定度的评估方法。影响铜检出限测量不确定度的主要因素包括标准溶液不确定度;拟合曲线不确定度;检测仪器不确定度;吸光值量化误差不确定度等,提供了上述各因素的计算方法及过程。 相似文献
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文章通过对工业废水中化学需氧量检测过程中不确定度来源进行详细的分析和鉴别,确定出影响因素的不确定度分量,从而计算出合成标准不确定度和扩展不确定度。不确定度的评定有利于分析人员在分析过程中对可能产生误差的环节加以特别的关注。 相似文献
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依据不确定度评定准则,采用一种新的方法,即忽略量取样品体积的不确定分量,只考虑样品前后两次恒重的不确定分量,对重量法测定水中悬浮物和全盐量的不确定度来源进行了识别、分析和量化,确定了不确定度分量,据此计算出合成标准不确定度。重量法测定水中悬浮物和全盐量的不确定度评定的方法适用于实验室内部不确定度的评定。 相似文献
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为满足新实验室认证准则,准确报告测量结果的不确定度,本文对土壤中^90Sr测量的不确定度进行评估。通过分析测量结果不确定度来源,逐一对其不确定度分量进行量化,从而获得测量结果的合成相对不确定度和相对扩展不确定度。对于环境本底水平土壤样品合成相对不确定度和相对扩展不确定度分别为22%和44%(k=2)。结果表明,对测量结果不确定度的贡献大的因素依次是β放射性测量、仪器探测效率、样品钇化学回收率、样品质量、样品锶化学回收率,其相对不确定度分别是22%、4.4%、1.1%、0.83%、0.69%。 相似文献
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文章根据GB/T 4348.3—2002《工业用氢氧化钠铁含量的测定1,10—菲啰琳分光光度法》,以测试工业用氢氧化钠中铁含量为例,依据JJF1059—1999《测量不确定度评定与表示》与CNAS—GL06:2006《化学分析中不确定度的评估指南》对测量过程中不确定来源进行分析,采用A类、B类评定方法对各种因素引起的不确定度分量、合成不确定度、扩展不确定度进行评定,并给出评定结果。对理化分析领域测量不确定度具有借鉴意义。 相似文献
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给水水质分析中CODMn测定值是评价水质的重要指标之一,现行CODMn测定方法其检测范围为0.5—4.5mg/L,而纯净水、矿泉水、饮用净水等的CODMn低于0.5mg/L,本文提出的KMnO4褪色法可测0.02mg/LCODMn。 相似文献
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Remediating RDX-contaminated ground water with permanganate: laboratory investigations for the Pantex perched aquifer 总被引:1,自引:0,他引:1
Ground water beneath the U.S. Department of Energy Pantex Plant is contaminated with the high explosive RDX (hexahydro-1,3,5-trinitro-1,3,5 triazine). The USDOE Innovative Treatment and Remediation Demonstration (ITRD) program identified in situ oxidation by permanganate as a technology fit for further investigation. We evaluated the efficacy of KMnO(4) to transform and mineralize RDX by determining degradation kinetics and carbon mass balances using (14)C-RDX. Aqueous RDX solutions (2-5 mg L(-1)) and RDX-contaminated slurries (50% solids, w/v) were treated with KMnO(4) at 1000, 2000, 4000, and 20000 mg L(-1). Treating an aqueous RDX solution of 2.8 mg L(-1) with 20000 mg KMnO(4) L(-1) decreased RDX to 0.1 mg L(-1) within 11 d while cumulative mineralization proceeded for 14 d until 87% of the labeled carbon was trapped as (14)CO(2). Similar cumulative mineralization was obtained when Pantex aquifer material was included in the solution matrix. Other experiments using 4000 mg KMnO(4) L(-1) showed that initial RDX concentrations (1.3-10.4 mg L(-1)) or initial pH (4-11) had little effect on reaction rates. Attempts to identify RDX degradates and reaction products showed that N(2)O was a product of permanganate oxidation and constituted 20 to 30% of the N balance. Time-course measurements of a (14)C-RDX solution treated with KMnO(4) revealed few (14)C-labeled degradates but through liquid chromatography-mass spectrometry (LC-MS) analysis, we present evidence that 4-nitro-2,4-diaza-butanol is formed. Aquifer microcosm studies confirmed that the transformation products not mineralized by KMnO(4) were much more biodegradable than parent RDX. These results indicate permanganate can effectively transform and mineralize RDX in the presence of aquifer material and support its use as an in situ chemical oxidation treatment for the Pantex perched aquifer. 相似文献
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Siderite (FeCO3) is commonly found in coal overburden and, when present, can cause interference in the determination of neutralization potential (NP). Under acidic testing conditions, FeCO3 reacts to neutralize acid, which contributes to the NP. However, continued weathering of FeCO3 (oxidation of Fe2+ and hydrolysis of Fe3+) produces a neutral to slightly acidic solution. The effects of hydrogen peroxide (H2O2), potassium permanganate (KMnO4), and O2 on the laboratory measurement of NP of siderite samples taken from overburden were examined. All oxidation treatments lowered the NP values of the siderite samples as compared with the standard USEPA method. However, oxidation with H2O2 produced variable results depending on the amount of H2O2 added. Neutralization potential values obtained after oxidation treatments were highly correlated with Mn concentration. Reaction products (i.e., 2-line ferrihydrite) of siderite samples with H2O2 and KMnO4 were not representative of natural siderite weathering. Oxidation with O2 produced the lowest NP values for siderite samples. The reaction products produced by oxidation with O2 most closely represent those intermediate products formed when siderite is exposed to atmospheric weathering conditions. Oxidation with O2 also proved to be the most reproducible method for accurately assessing NP when siderite is present in overburden samples. 相似文献
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Paul JF 《Journal of environmental management》2003,67(2):175-185
Environmental conditions in the Mid-Atlantic region of United States are presently being documented in a series of reports that use 'environmental report cards' to summarize the condition of individual natural resources (e.g. estuaries, streams, forests, and landscapes) over the entire region and within major subregions. An 'index of environmental integrity' (IEI) approach has been developed and is illustrated using the information content of these report cards to evaluate the overall condition throughout the region. The IEI approach is a four-step process: (1) select individual components for the index, (2) calculate subindex values for each of the individual components, (3) aggregate the subindex values into the overall index, and (4) interpretation of index values. The IEI approach was illustrated by applying to the Mid-Atlantic estuaries and wadable streams in the Mid-Atlantic Highlands. Because the IEI approach is new, application should not be made without considering issues such as evaluation of the selection of the indicators, weighting scheme, uncertainties, and appropriate way to interpret the values. 相似文献
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针对干旱生态敏感区水电站环境影响后评价的要求,设计备选指标集,采用频次分析法进行指标初选,采用专家咨询法进行指标精选,建立由4项二级指标、14项三级指标构成的干旱生态敏感区水电站环境影响后评价指标体系,采用层次分析法给每个指标赋予权重.将该评价指标体系用于某水电站建设的实例分析,结果表明,水电站运行以来总体上有利影响大... 相似文献
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An Ecological Integrity Index for Littoral Wetlands in Agricultural Catchments of Semiarid Mediterranean Regions 总被引:1,自引:0,他引:1
The main goal of the present study was to develop an ecological integrity index for littoral wetland management and conservation in semiarid Mediterranean areas that have been highly impacted by agriculture, including the selection of pressure and state indicators at landscape and wetlands scales that reflect the status, condition, and trends of wetlands ecosystems. We used a causality framework based on the relationship between pressure of anthropogenic activities and the ecological state of wetlands and their catchments, integrating environmental, biologic, economic, and social issues. From the application of 51 indicators in 7 littoral wetlands in the southeastern Iberian Peninsula, we selected 12 indicators (5 at catchment scale and 7 at wetland scale) to constitute the ecological integrity index proposed. The potential nitrogen export per area at catchment scale and the potential relative nitrogen export from the area surrounding the wetlands were the best pressure single predictors of state indicators with a causal relationship with environmental meaning. Wetlands in catchments with more agriculture had less ecological integrity than those in less impacted areas. A wide riparian zone in some wetlands acts as a buffer area, diminishing the effects of intensive agriculture. The index of ecological integrity developed here has a number of essential characteristics that make it a useful tool for ecosystem managers and decision-makers. The index can be used to (1) assess and control ecological integrity, (2) diagnose probable causes of ecological impairment, (3) establish criteria for protecting and restoring wetland ecosystems, and (4) integrate catchment management.
Published online 相似文献