Top-down法评定水溶性油田化学剂中金属元素的测量不确定度

采用Top-down技术评定微波消解-电感耦合等离子体质谱法测定水溶性油田化学剂样品中砷、铅、镉、铬含量的测量不确定度。对实验数据偏倚和精密度受控情况进行验证后,以实验内稳定样品的重复测定结果计算实验室内期间相对标准偏差（SP,rel）和实验室内重复性相对标准偏差（Sr,rel）,以能力验证结果计算检 测过程偏倚及实验室间精密度相对标准偏差（Sbias,rel）,据此评定测量不确定度,从而反映测定方法和实验室的 精密度控制情况。微波消解 电感耦合等离子体质谱法测定水溶性油田化学剂样品中砷、铅、镉、铬含量的扩展 不确定度分别为17.7％,26.1％,18.7％,19.8％。Top-down精密度法评定测量不确定度操作简便,可反映实验室分析人员操作、仪器重复性和环境条件等因素对不确定度的干扰,避免了繁复的分量计算和模型建立过 程,但Top-down法不能识别分析测试过程中对测量不确定度有较大影响的关键分量。Sbias,rel对扩展不确定度的贡献最大,实验室可通过能力验证结果数据评估检测过程精密度控制情况。     

TOA-MIBK萃取火焰原子吸收法同时测定土壤及蔬菜中铅镉

用氢氟酸、硝酸、高氯酸消化土壤样品,干灰化法消解蔬菜样品,用相对TOA-MIBK系统萃取,火焰原子吸收光谱法在同一条件下测定土壤、蔬菜中的铅、镉。在选定条件下,测得土壤铅、镉的相对标准偏差分别为2．3％～4．4％和3．0％～4.3％,蔬菜铅、镉的相对标准偏差分别为2．9％～4．5％和2．6％～4．5％;土壤铅、镉的回收率分别为96％～104％和95％～101％,蔬菜铅、镉的回收率分别为93％～102％92％104％。由测定结果得出离公路越近,蔬菜、土壤铅、镉含量越高。     

固相萃取-高效液相色谱法测定土壤中苯并(a)芘不确定度分析

为了建立适用于自动固相萃取结合高效液相色谱法测定土壤中苯并(a)芘含量的不确定度分析方法。采用如下方法:样品用正己烷-丙酮索式提取后,加入适量吸附剂和去离子水,经过固相萃取小柱净化、浓缩定容,再用Agilent Eclipse XDB-C18色谱柱(4.6×150mm×5μm)对苯并(a)芘含量进行分析,流动相以乙腈-水(体积比为80∶20)进行等度洗脱,采用紫外检测器检测,外标法定量。依据JJF 1135—2005《化学分析测量不确定度评定》中相关规定,考查称量、定容体积、标准曲线、仪器测量重复性和回收率等引入不确定度的主要因素,并对不确定度的各分量进行计算和合成。结果表明:当土壤样品中苯并(a)芘含量为6ng/kg时,在95%的置信区间下,其扩展不确定度为0.50ng/kg(k为2)。评定结果表明,标准曲线拟合和标准溶液配置产生的不确定度对合成不确定度的影响较大,而样品称量所引入的不确定度较小,可忽略不计。得出:该评定方法客观准确,适用于固相萃取结合高效液相色谱法测定土壤中苯并(a)芘含量的不确定度分析,对检测结果准确度的提高具有参考意义。     

环境气溶胶中90Sr分析测量的不确定度评定

⁹⁰Sr是高毒性的纯β放射性核素,其物理半衰期和生物半衰期长,环境气溶胶中的⁹⁰Sr通过吸入途径进入人体,对人类的危害主要为长时间积集在人体骨骼中并很难排出。在多堆型核设施运行场址中环境气溶胶的测定是辐射环境监测的重要内容,也是评价核设施运行对环境影响的重要指标。为了科学评价环境气溶胶中测量结果的准确性和可靠性,进行了气溶胶中⁹⁰Sr分析测量不确定度评定的方法研究,通过计算模型识别不确定度的来源,并对各分量进行量化分析,计算合成标准不确定度;结合典型样品分析实例,对环境气溶胶中⁹⁰Sr分析测量的不确定度进行了评定,气溶胶中的分析测量采用的是色层萃取的方法,利用草酸钇沉淀制成样品源,测量样品中β计数率。不确定度评定结果表明:环境气溶胶中⁹⁰Sr分析测量不确定度的来源主要有样品净计数率,探测效率,化学回收率,样品取样体积,测量期间半衰期修正;典型实例分析结果显示环境气溶胶中的相对标准不确定度可控制在15%内。文章中不确定度评定方法为气溶胶⁹⁰Sr分析测量结果的不确定度评定提供参考。     

水样品中挥发酚的测量不确定度的评定方法

根据环境监测的要求,中国石油集团安全环保技术研究院实验室在出具数据时要对测量结果进行测量不确定度评定。用实例建立了分光光度法测定水样品中挥发酚的合成标准不确定度的数学模式,它由质量的标准测量不确定度和体积的标准测量不确定度组成;并对这两部分标准不确定度的分量作了详尽的分析和计算。得出测量扩展不确定度结果。     

水中砷的原子荧光光谱测定结果的不确定度评定

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。     

土壤中总汞测定的不确定度评定

对原子荧光光度法测定土壤中总汞含量的不确定度进行了评定。按GB／T22105．1—2008,对土壤样品进行检测,建立数学模型,系统分析和量化不确定度各分量,求得其扩展不确定度。分析结果表明,影响土壤中总汞测定的不确定度主要来源于试样的重复测定,而样品稀释和样品称重产生的不确定度很小。其中,在试样的重复测定所产生的不确定度因素中,又以最小二乘法拟合标准曲线所产生的不确定度最大,样品多次重复测试过程中随机误差次之,而仪器校准和标准物质所产生的不确定度较以上小很多。     

火焰原子吸收法测定土壤镍结果的不确定度评定

根据《土壤和沉积物铜、锌、铅、镍、铬的测定火焰原子吸收分光光度法HJ 491-2019》测定某土壤样品镍的含量,分析测试过程中不确定度的来源,并对样品测定结果进行不确定度的评定。测得样品中镍的含量为38.7 mg/kg,扩展不确定度为4.30mg/kg(k=2)。采用新标准首次建立了火焰原子吸收法测定土壤镍含量的不确定度评定方法,得到标准曲线的配制和拟合过程、测量重复性是土壤镍含量不确定度的主要影响因素;为采取措施降低不确定度提供参考,为定量评价测量的质量提供帮助,为影响规范限度的符合性提供依据。     

土壤中铅的测量不确定度评定

本文分析探讨了就石墨炉原子吸收分光光度法测量土壤铅的不确定度的方法,得出其测量扩展不确定度,结果令人满意。     

放射性比对土壤样品制备的不确定度评定分析

基于放射性比对土壤样品的制备过程,全面的分析了不确定度的来源。5种核素参考值的相对标准不确定度为1.569%~2.708%(k=1),并将评定结果应用于参比实验室测量结果的评价过程。评定方法适用于同类固体放射性比对样品的制备过程。     

环境监测中仪器分析方法不确定度的评估(Ⅱ)——原子吸收光谱分析中的测量不确定度

通过对环境样品分析中常用的原子吸收光谱法测量不确定度分量的分析,探讨了原子吸收光谱法测量不确定度的评估方法,针对不同环境基体样品、不同测定组分以及不同前处理方法的扩展不确定度进行了评定。原子吸收光谱分析中的测量不确定度主要来源于样品称量、消化液定容、仪器漂移及由吸收值通过标准曲线拟合求浓度部分,其中最主要的分量是由吸收值通过标准曲线拟合求样品溶液浓度时引起的测量不确定度。     

分光光度计测量铁含量不确定度评定

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。     

环境监测中仪器分析方法不确定度的评估(Ⅲ)——色谱分析中的测量不确定度

通过对环境样品分析中常用的色谱分析法测量不确定度分量来源及影响的讨论,探讨了色谱分析法测量不确定度的评估方法,获得了针对不同环境基体样品、不同测定组分以及不同前处理方法中的扩展不确定度。色谱分析中的测量不确定度主要来源于流速稳定性、柱箱温度稳定性、基线噪声、程序升温重复性、定量重复性、标准物质进样量及由峰面积通过标准曲线拟合求浓度等部分。     

Stochastical analysis of surfactant-enhanced remediation of denser-than-water nonaqueous phase liquid (DNAPL)-contaminated soils

Stochastical analysis was performed to assess the effect of soil spatial variability and heterogeneity on the recovery of denser-than-water nonaqueous phase liquids (DNAPL) during the process of surfactant-enhanced remediation. UTCHEM, a three-dimensional, multicomponent, multiphase, compositional model, was used to simulate water flow and chemical transport processes in heterogeneous soils. Soil spatial variability and heterogeneity were accounted for by considering the soil permeability as a spatial random variable and a geostatistical method was used to generate random distributions of the permeability. The randomly generated permeability fields were incorporated into UTCHEM to simulate DNAPL transport in heterogeneous media and stochastical analysis was conducted based on the simulated results. From the analysis, an exponential relationship between average DNAPL recovery and soil heterogeneity (defined as the standard deviation of log of permeability) was established with a coefficient of determination (r2) of 0.991, which indicated that DNAPL recovery decreased exponentially with increasing soil heterogeneity. Temporal and spatial distributions of relative saturations in the water phase, DNAPL, and microemulsion in heterogeneous soils were compared with those in homogeneous soils and related to soil heterogeneity. Cleanup time and uncertainty to determine DNAPL distributions in heterogeneous soils were also quantified. The study would provide useful information to design strategies for the characterization and remediation of nonaqueous phase liquid-contaminated soils with spatial variability and heterogeneity.     

Uncertainty Assessment for Management of Soil Contaminants with Sparse Data

In order for soil resources to be sustainably managed, it is necessary to have reliable, valid data on the spatial distribution of their environmental impact. However, in practice, one often has to cope with spatial interpolation achieved from few data that show a skewed distribution and uncertain information about soil contamination. We present a case study with 76 soil samples taken from a site of 15 square km in order to assess the usability of information gleaned from sparse data. The soil was contaminated with cadmium predominantly as a result of airborne emissions from a metal smelter. The spatial interpolation applies lognormal anisotropic kriging and conditional simulation for log-transformed data. The uncertainty of cadmium concentration acquired through data sampling, sample preparation, analytical measurement, and interpolation is factor 2 within 68.3 % confidence. Uncertainty predominantly results from the spatial interpolation necessitated by low sampling density and spatial heterogeneity. The interpolation data are shown in maps presenting likelihoods of exceeding threshold values as a result of a lognormal probability distribution. Although the results are not deterministic, this procedure yields a quantified and transparent estimation of the contamination, which can be used to delineate areas for soil improvement, remediation, or restricted area use, based on the decision-makers probability safety requirement.     

工业总排放水中Cr~(6+)含量测量不确定度的评定

采用分光光度法对工业总排放水中Cr6+进行不确定度评定,充分考虑测量重复性、标准溶液的配制、标准曲线的制备等因素对测量的影响,测得Cr6+的合成标准不确定度为0.023mg/L。     

Quantification of uncertainty of experimental measurement in leaching test on cement-based materials

When mineral wastes are reused in construction materials, a current practice is to evaluate their environmental impact using standard leaching test. However, due to the uncertainty of the measurement, it is usually quite difficult to estimate the pollutant potential compared to other materials or threshold limits. The aim of this paper is to give a quantitative evaluation of the uncertainty of leachate concentrations of cement-based materials, as a function of the number of test performed. The relative standard deviations and relative confidence intervals are determined using experimental data in order to give a global evaluation of the uncertainty of leachate concentrations (determination of total relative standard deviation). Various combinations were realized in order to point out the origin of large dispersion of the results (determination of relative standard deviation linked to analytical measured and to leaching procedure), generalisation was suggested and the results were compared to literature. An actual example was given about the introduction of residue (meat and bone meal bottom ash--MBM-BA) in mortar, leaching tests were carried out on various samples with and without residue MBM-BA. In conclusion large dispersion were observed and mainly due to heterogeneity of materials. So heightened attention needed to analyse leaching result on cement-based materials and further more other tests (e.g. ecotoxicology) should be performed to evaluate the environmental effect of these materials.     

自然通风热老化试验箱换气量不确定度评定

自然通风热老化试验箱(以下简称老化试验箱)主要用于电线电缆的热老化性能测试试验。而需要对箱体性能进行评估的多为老化试验箱的生产厂、电线电缆生产厂的产品检验实验室和开展相关项目的检测机构等公司和部门。温度参数和换气量参数是老化试验箱计量的主要项目,其测量结果的准确程度将直接影响对箱体性能的评估,分析并计算出了换气量测量结果扩展不确定度,对换气量参数的测量结果的可信赖程度具有参考意义。     

Utilization of biosolids during the phytoremediation of hydrocarbon-contaminated soil

Addition of anaerobically digested sewage sludge (biosolids) to soil may improve conditions for phytoremediation of petroleum hydrocarbons (PHCs) through improved soil chemical, biological, and physical properties. A 32-wk greenhouse study investigated three rates of biosolids addition (0, 13.34, and 26.68 g oven-dry biosolids kg(-1) oven-dry soil) and the presence or absence of smooth brome (Bromus inermis Leyss. cv. Carlton) plants on the removal of diesel (3.5 g kg(-1) oven-dry soil) in an industrial, sandy loam soil. Diesel PHCs were divided into two fractions based on equivalent normal straight-chain boiling point ranges (F2: nC10-nC16; F3: nC16-nC34). The addition of biosolids did not increase the extent of PHC degradation but did result in significantly greater first-order decay constants compared to unamended controls. Overall, the presence of plants did not increase the rate or extent of PHC degradation, relative to that observed in unamended, non-vegetated soils. Vegetation was, however, an important factor within the biosolids-amended soils as was observed by a greater extent of PHC degradation. Some of this decrease was attributed to plant-induced removal of biosolids components that were contributing to the F3 fraction. Overall, the low-amendment rate (13.34 g oven-dry biosolids kg(-1) oven-dry soil) was considered to be the most effective treatment because it produced the greatest overall PHC degradation rate (0.226 wk(-1) for total PHCs) and resulted in the greatest recovery of biosolids-derived N by smooth brome (26.6%).