碱性高锰酸钾法测量海水化学耗氧量(COD)不确定度的研究

以葡萄糖 谷氨酸为海水COD的标准物质。用人工海水和标准物质配制成系列标准溶液。根据对系列标准溶液的测量结果,获得了碱性高锰酸钾法海水COD测量不确定度的分布规律。     

燃烧氧化-非分散红外吸收总有机碳分析仪测定海水DOC 的不确定度分析

采用实验测定和误差分析的方法, 对燃烧氧化-非分散红外吸收总有机碳分析仪vario TOC cube测定海水DOC 含量的不确定度进行了分析, 对导致测定结果不确定度的各分量进行了量化估算。结果表明, 其测定结果的不确定度主要来源于四个方面, 即样品重复性测量、标准曲线拟合、标准溶液配制(包括称量、定容、移液产生的不确定度, 标准物质纯度和相对原子质量产生的不确定度)及测量仪器本身, 相对标准不确定度分量分别为0.016、0.018、0.0086、0.0079。标准曲线拟合与样品重复性测量是影响海水DOC 测定不确定度的主要因素, 但标准溶液配制和测量仪器所引起的不确定度亦不可忽略。对实际海水DOC 浓度为1.20 mg/L 的样品分析,合成以上四种不确定度分量得到DOC 测定结果的标准不确定度为0.21 mg/L。按照正态分布,取扩展因子k=2, 则扩展不确定度为0.07 mg/L, 此海水样品中DOC 含量的测定结果应为(1.20±0.07) mg/L(k= 2)。     

GGA试剂的COD_(Mn)测定研究

介绍了盐度对碱性高锰酸钾法CODMn测定值影响的研究。以BOD的标准物质——GGA试剂(葡萄糖+谷氨酸)作为海水COD的标准物质,目的是探寻BOD与COD的关系。用人工海水和标准物质配制成系列标准溶液。系列标准溶液实验结果表明:海水COD测定值与BOD是线性关系。实验结果还表明盐度对碱性高锰酸钾法CODMn测定值有很大影响,并且此影响与盐度不是线性关系,盐度影响的是测量灵敏度而不是本底。此外,还进行了碱性高锰酸钾法测定值零点的研究。结果表明,任何不含有机物的样品都可以作为CODMn零点。文中提出了绝对COD的概念,指出绝对COD小于0.2 mg/L的样品都可以认为是不含有机物的样品,都可以作为CODMn零点。     

电位测定法测海水氧化还原电位的不确定度评定

采用电位测定法对实际海水的氧化还原电位进行测定,分析了影响测量不确定度的主要来源,对曲线拟合、测定过程的标准溶液的使用、仪器使用和测量重复性等影响不确定度的分量进行分析,按JJF1059—1999《测量不确定度评定与表示》的规定进行合成,最终给出扩展不确定度。结果表明,实际海水电位值的合成标准不确定度为14.18 mV,扩展不确定度为28.4 mV(近似95%置信概率)。这样结果的表达更加客观和真实,更具有参考意义。     

氯化钾标准溶液制备技术研究

参照78国际实用盐标基本定义及其背景材料,利用国内现有的技术条件,成功地配制出了特定电导率的KCl标准溶液.采用国际标准海水重新定值法对标准溶液的电导率准确度进行了验证.实验结果表明,新的盐度测量值与原标称值之差最大为-0.0008,最小为0.0000,均在国际标准海水盐度标称值总不确定度士0.001范围之内,复现技术达到国际同等水平,该项研究为建立我国海水实用盐度全程量值传递奠定了基础.     

中国系列标准海水制备与质量评价

中国系列标准海水是国家二级标准物质 [GBW (E) 130 0 11],在盐度或电导率传感器的现场检定 ,实验室盐度计的检定和校准中应用广泛。主要介绍中国系列标准海水的制备和不确定度分析。     

海水COD流动注射测量技术研究

利用流动注射分析技术(FIA)快速、连续测定海水化学耗氧量(COD)。高锰酸钾作为氧化剂,NaOH溶液和硫酸溶液作为载流分别进入流路,“葡萄糖 谷氨酸”作为标准物质。采用人工海水与标准物质配制系列COD浓度的测量水样以及海水加标测量,得到的分析结果具有很好的重现性和分辨率。     

营养盐自动分析仪测量海水氨氮盐度效应分析及解决方案探讨

以营养盐自动分析仪为研究对象,研究海水氨氮测量过程中海水盐度效应的特点,并在此基础上研究降低盐度效应的方法。采用营养盐自动分析仪测量不同盐度标准溶液,标准曲线线性度都能达到0.999 0以上,说明海水盐度对分析仪标准曲线线性度基本没有影响;随海水盐度增加,标准曲线斜率呈增加趋势。通过对比15条不同盐度标准曲线测量准确性,确定在海水盐度已知情况下选取与被测海水盐度最为相近的人工海水定标能够最大程度降低盐度效应;在海水盐度未知或海水盐度变化较大情况下,以盐度15的人工海水定标,能够最大程度降低盐度效应对氨氮测量结果的影响。     

平衡法海水BOD快速测量仪的测量不确定度评定

介绍了一种新型的生化需氧量(BOD)快速测量仪,其采用生物反应器法的工作原理.根据其对系列标准溶液的实测结果,采用A类的评定方法,做出了该仪器测量不确定度评定.该仪器测量不确定度分段表示更能反映实际情况,即在2～8 mg/L范围,用相对不确定度表示;在2 mg几以下时,用绝对不确定度表示.该仪器在2～8 mg/L范围的相对扩展不确定度U95rel=17.3%,与标准五日法相当.     

海水基质活性磷酸盐标准物质研制

本研究以西太平洋表层海水为基质,制备了浓度为0.5～4.0μmol/L的海水活性磷酸盐系列标准物质。通过对所研制的4批次样品进行均匀性、稳定性评估,确定样品性能良好。对基于磷钼蓝分光光度法的气泡间隔连续流动分析系统的反应和操作条件进行优化,优化后的方法检出限低至0.03μmol/L。不同浓度样品的相对标准偏差为0.37%～2.45%(n=9);通过与国际已有有证标准物质比对,本研究方法测量误差小于0.05μmol/L。经6家具有中国计量认证资质且具备海水磷酸盐检测能力的实验室联合定值,确定了该系列标准物质的标准值,并对定值结果的不确定度进行了分析评价,相对扩展不确定度为2%～10%。     

海水中钾的测定——交流示波极谱滴定在海水分析中的应用(Ⅰ)

研究用交流示波极谱测定海水中钾的方法。海水试样用NaOH调节pH约12,加入过量四苯硼化钠标准溶液,用微孔滤膜(或滤纸)过滤沉淀。收集游液,用TI(Ⅰ)标准溶液滴定过量的四苯基硼离子。方法回收率为99.5％。测定结果与四苯硼化钾重量法结果一致。海水中共存离子不干扰测定,并可用于海水及多种盐溶液中钾的测定。本法因其简便、快速、准确而易于推广。     

碱性高锰酸钾法海水化学耗氧量(COD)在线测量仪的研制

一种新型的海水COD在线测量仪已经研制出来,其采用了碱性高锰酸钾法和流动注射分析技术,仪器的测量结果与标准方法有很好的一致性,它们的相关系数超过0.98。     

Inconsistency in the conductivity of standard potassium chloride solutions made from different high-quality reagents

The salinity of seawater has been defined in terms of the ratio of its electrical conductivity to that of a standard potassium chloride solution. The potassium chloride solution is obtained by dissolution of high-purity potassium chloride in ultrapure water. However, even high-purity potassium chloride is not 100% pure, and suppliers do not certify it, as the standard for electrical conductivity. We prepared defined solutions using several kinds of high-purity potassium chloride and examined the difference between the measured electrical conductivity ratio and the value calculated from the experimental equation given in the UNESCO background papers. The differences between the electrical conductivity ratios of the solutions made from the various potassium chloride reagents were equivalent to about 0.0012 in salinity. The solution may not actually become a standard for salinity measurements even if it is prepared exactly according to the present definition. The lot dependency of the electrical conductivity ratio of the potassium chloride solutions may result in a systematic error in the measurement of salinity.     

The concentration of the KCl solution whose conductivity is that of standard seawater (35 ‰) at 15°C

The concentration of the potassium chloride solution (KCI) which has the same conductivity as15degC at P79 standard seawater corrected to35.0000permilhas been evaluated. The variation of the conductivity ratio of KCI solutions to standard seawater (35permil) has been measured between 14.8 and15.2degC for KCI solutions whose concentration varies from 32 to 33 g.kg^-1.     

Optimization of Chemical Oxygen Demand Determination in Seawater Samples Using the Alkaline Potassium Permanganate Method

Chemical oxygen demand (COD) is a practical parameter that is used to estimate the amount of organic pollutants in aqueous systems. It is generally used as a guideline to control the quality of waste treatment effluent globally and is a management tool to evaluate the total pollution load in the highly developed coastal regions of Korea. It is a preferred method because of the speed and simplicity of the analysis and because there are fewer instrumentation requirements. The Ministry of Oceans and Fisheries (MOF) of the Republic of Korea developed a standard procedure for the measurement of COD. It has been revised several times, and the most recent revision was made in 2013 (MOF 2013–230). In this study, we modified the standard COD measurement procedure (MOF 2013–230), especially the sample digestion apparatus, to enhance analytical efficiency for a large sample number (batch), which is called a Korea Institute of Ocean Science and Technology (KIOST) modified MOF 2013–230. We examined uncertainty related to each experimental step and optimized laboratory conditions to reduce such uncertainties. The detection limit and estimated expanded uncertainty related to the KIOST modified MOF 2013–230 was 0.18 and 0.11 mg O₂/L at a 95% confidence level (k = 2), respectively. This study also provides several tips to maintain consistent COD measurements in seawater using the alkaline potassium permanganate method.     

The fluorine complexation degree in seawater

Ionometric measurements of the complexation degree of fluorides in seawater of 5–35‰ salinity at 25°C were carried out using two procedures for the standardization of the measuring electrochemical circuits. It was shown that, if we determine the degree of the fluorine complexation in seawater using the measured values of the total coefficients of the activity, the fraction of free ions is much dependent on the value used of the activity coefficient of the free ions calculated by means of one of the versions of either the second or third approximation of the Debye-Huckel electrostatic theory of strong electrolyte solutions. With the more correct measurement of the fluorine complexation degree in seawater on the basis of the comparison of the EMF values in pure KCl-KF solutions and in mixtures of these solutions and seawater at equal ionic power and fluoride concentrations, a close correlation was revealed for the free ion fraction in three series of experiments at fluorine contents of 0.2, 0.3, and 0.4 mM (the concentration of the fluorine in seawater of 35‰ salinity amounts to 0.421 ± 0.014 mM.)     

秋季和春季黄渤海黄色物质空间分布特征

利用2013年秋季和2014年春季两个季节黄渤海现场数据对黄色物质的水平分布及垂向分布的变化进行研究,并初步分析了其主要控制因素。垂向黄色物质表现为底部高上层低的特征。其中,秋季混合作用加强导致上层40m黄色物质混合较为均匀;春季北黄海温盐跃层已经形成,黄色物质分布开始出现明显的分层现象,上下层浓度差约为2?g/L。春季南黄海盐度跃层尚未形成,水深小于50m的水层黄色物质垂向分布均匀,近岸和远岸海域浓度分界线明显。水平方向上,黄色物质在秋季和春季分布趋势一致,由渤海、北黄海至南黄海浓度依次降低,且呈现出由近岸向中央海区递减的趋势,但整体上春季浓度较秋季明显偏低。海表盐度与黄色物质浓度两者整体上呈现负相关关系,可以将黄色物质浓度分布作为研究黄海暖流走向、划分水团性质的重要指标。     

秋季长江口北支表层海水pCO2变化特征

根据2009年9月首次获得的长江口北支海水pCO2实测数据,结合温度、盐度等参数,对长江口北支海水pCO2时空分布、变化特征及其影响因素进行了研究.研究结果表明,长江口北支海水pCO2总体呈现出淡水端高,咸水端低的特点;在同等盐度条件下,长江口北支海水pCO2明显高于长江口南支;长江口北支南段海水pCO2与盐度之间有着...     

DIRECT DETERMINATION OP TRACE CADMIUM IN SEAWATER BY DERIVATIVE-VOLTAMMETRY

An analytical method is proposed for the direct determination of Cd in seawater by differential pulse anodic stripping voltammetry and the derivative technique with a hanging mercury drop electrode. The process of determination is quick, simple and convenient. The concentration of Cd in seawater is only determined by adjusting the acidity of seawater to pH 2 and by taking three minutes' plating time. Sensitivity of the method is about 1×10-10M, and accuracy of that satisfactory. Relative standard deviation is about 12% when the concentration of Cd in seawater is approximately 0.04 ppb. A good agreement was obtained by a standard curve and a standard addition technique respectively from determining Cd in the same seawater. Actual measurement time per sample is about 10 min.