地表水中总氮的测量不确定度评定方法

文章采用碱性过硫酸钾消解紫外分光光度法测定江水中总氮的含量,其不确定度的分量主要有标准拟合引起的不确定度、由氮标准溶液配制成不同浓度的标准溶液系列时所产生的测量不确定度、平行实验数据重复性引起的测量不确定度、水样在消解等前处理过程上产生的不确定度、测量水样体积V的标准不确定度分量。经过计算,标准拟合引起的不确定度分量值最大,在实验时,应引起注意,减小对试样结果产生的影响。     

原子吸收法测定铜检出限的测量不确定度评估

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。     

工业废水中化学需氧量检测的不确定度评定

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。     

测定水样中化学需氧量的不确定度

对化学需氧量测定的不确定度进行合理评定,应充分考虑测定过程中的不确定度来源。建立了重铬酸钾法测定水样中化学需氧量不确定度的数学模型,对组成化学需氧量的各个因子的不确定度分量进行了详尽的分析和计算,得出了本次样品CODCr的测定结果为72.2mg/L,扩展不确定度为3.8mg/L。     

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。     

重量法测定水中悬浮物和全盐量的不确定度评定

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。     

某高温试验能力验证的不确定度评定

本文主要以实验室参加的一次高温试验能力验证计划为例,对影响高温试验的不确定度来源进行了分析,对各类不确定度进行了具体评定,为其他相关实验室高温试验的不确定度评定提供参考。     

氢化物发生-原子荧光光谱法测定环境空气中汞的结果不确定度评定

对氢化物发生-原予荧光光谱法测定环境空气中汞含量不确定度进行了评定.由测定过程的数学模型分析了产生不确定度因素.通过不确定度评定得出不确定度主要来源于样品的制备过程.其中消解过程带来的不确定度最大.     

离子色谱法测定大气降水中铵离子的不确定度评定

对离子色谱法测定大气降水中铵离子浓度进行了不确定度评价。通过对标准溶液、标准工作曲线拟合、进样体积和测定过程重复性等影响测定结果的不确定度分量进行分析,计算出测定结果的扩展不确定度,并找出影响该不确定度的主要因素。     

滴定法测定高锰酸盐指数的不确定度评定

本文对滴定法测定高锰酸盐指数的不确定度进行分析,找出影响不确定度的因素,对不确定度进行评估,如实反映测量的置信度和准确性.     

COMPUTING THE RISKS ASSOCIATED WITH WASTELOAD) ALLOCATION MODELING1

ABSTRACT: The risks associated with a traditional wasteload allocation (WLA) analysis were quantified with data from a recent study of the Upper Trinity River (Texas). Risk is define here as the probability of failing to meet an established in-stream water quality standard. The QUAL-TX dissolved oxygen (DO) water quality model was modified to a Monte Carlo framework. Flow augmentation coding was also modified to allow an exact match to be computed between the predicted and an established DO concentration standard, thereby providing an avenue for linking input parameter uncertainty to the assignment of a wasteload permit (allowable mass loading rate). Monte Carlo simulation techniques were employed to propagate input parameter uncertainties, typically encountered during WLA analysis, to the computed effluent five-day carbonaceous biochemical oxygen demand requirements for a single major wastewater treatment plant (WWTP). The risk of failing to meet an established in-stream DO criterion may be as high as 96 percent. The uncertainty associated with estimation of the future total Kjeldahl nitrogen concentration for a single tributary was found to have the greatest impact on the determination of allowable WWTP loadings.     

Modification of uncertainty analysis in adapted material flow analysis: Case study of nitrogen flows in the Day-Nhue River Basin,Vietnam

Nitrogen flows impacted by human activities in the Day-Nhue River Basin in northern Vietnam have been modeled using adapted material flow analysis (MFA). This study introduces a modified uncertainty analysis procedure and its importance in MFA. We generated a probability distribution using a Monte Carlo simulation, calculated the nitrogen budget for each process and then evaluated the plausibility under three different criterion sets. The third criterion, with one standard deviation of the budget value as the confidence interval and 68% as the confidence level, could be applied to effectively identify hidden uncertainties in the MFA system. Sensitivity analysis was conducted for revising parameters, followed by the reassessment of the model structure by revising equations or flow regime, if necessary. The number of processes that passed the plausibility test increased from five to nine after reassessment of model uncertainty with a greater model quality. The application of the uncertainty analysis approach to this case study revealed that the reassessment of equations in the aquaculture process largely changed the results for nitrogen flows to environments. The significant differences were identified as increased nitrogen load to the atmosphere and to soil/groundwater (17% and 41%, respectively), and a 58% decrease in nitrogen load to surface water. Thus, modified uncertainty analysis was considered to be an important screening system for ensuring quality of MFA modeling.     

原子荧光法测定污泥中总砷含量的不确定度评定

对采用原子荧光法测定污泥中总砷过程中引入的不确定度进行分析,找出了影响测定结果的因素,并对各不确定度分量及合量进行了评定。测量不确定度主要来源于试样称量、标准溶液配制、工作曲线拟合、污泥含水率、各种玻璃量器的使用及测量重复性。其中样品预处理、样品消解液中总砷的质量浓度及污泥含水率所产生的不确定度较大。这对进一步优化试验方法,提高检测结果的准确性有重要意义。     

火焰原子吸收法测定总铜不确定度的评定

依据线性最小二乘法的数学特性,提出采用火焰原子吸收法测定地表水中总铜的不确定度的简化评定方法,通过识别和分析不确定度源,对不确定度进行量化,计算合成标准不确定度。此方法适用于地下水、地表水和废水中的总铜含量直接法测定中不确定度的快速评定。     

SENSITIVITY ANALYSIS,CALIBRATION, AND VALIDATIONS FOR A MULTISITE AND MULTIVARIABLE SWAT MODEL1

The ability of a watershed model to mimic specified watershed processes is assessed through the calibration and validation process. The Soil and Water Assessment Tool (SWAT) watershed model was implemented in the Beaver Reservoir Watershed of Northwest Arkansas. The objectives were to: (1) provide detailed information on calibrating and applying a multisite and multivariable SWAT model; (2) conduct sensitivity analysis; and (3) perform calibration and validation at three different sites for flow, sediment, total phosphorus (TP), and nitrate‐nitrogen (NO₃‐N) plus nitrite‐nitrogen (NO₂‐N). Relative sensitivity analysis was conducted to identify parameters that most influenced predicted flow, sediment, and nutrient model outputs. A multi objective function was defined that consisted of optimizing three statistics: percent relative error (RE), Nash‐Sutcliffe Coefficient (R_NS²), and coefficient of determination (R²). This function was used to successfully calibrate and validate a SWAT model of Beaver Reservoir Watershed at multi‐sites while considering multivariables. Calibration and validation of the model is a key factor in reducing uncertainty and increasing user confidence in its predictive abilities, which makes the application of the model effective. Information on calibration and validation of multisite, multivariable SWAT models has been provided to assist watershed modelers in developing their models to achieve watershed management goals.     

原子荧光法测定污泥中总汞的不确定度评定

对王水消解-原子荧光法测定污泥中总汞的不确定度进行评定,从测定过程和计算方法的角度,对样品称量、曲线拟合、样品消解、稀释、仪器测量重复性及污泥含水率等影响不确定度的分量进行分析。结果表明：影响原子荧光法测定污泥中总汞的不确定度的主要因素是工作曲线的非线性和样品消解过程造成的损失,其次是样品消解液的稀释和仪器重复测定,而样品称量与污泥含水率的影响较小,可忽略不计。     

微波消解-紫外法测定水中总氮与国标方法的比较研究

将微波消解-紫外法测定总氮从方法检出限、校准曲线、精密度和准确度、实际样品测定4个方面与国标紫外法作了比较研究,进行了消解时间比对实验,说明了微波消解-紫外法测定总氮的注意事项。结果表明,微波消解-紫外法检出限为0.115 mg/L,高于国标紫外法;校准曲线具有较好线性相关系数,斜率与国标紫外法一致;方法精密性和准确性较好,实际样品测定结果与紫外法保持一致,在总氮监测中具有可行性。微波消解-紫外法节省了总氮监测的整个用时。     

土壤全氮量测定的方法改进研究

对经典的土壤全氮量测定方法进行改进,采用修正的凯氏法消煮-凯氏定氮仪蒸馏-纳氏试剂分光光度法比色测定土壤全氮量,测定含氮量为0.2~0.8g/kg土壤样品时,RSD为3.72%~8.67%,加标回收率为85.7%~98.7%,方法检出限为0.0125g/kg,具有较好的准确度和精密度。     

紫外法测定水质中总氮的影响因素研究

结合紫外法测定水质中总氮空白校正吸光度值易偏高、测定结果准确度低的问题,分别从检测试剂含氮量、选择实验用水、清洗玻璃器皿、改进实验操作、改进消解环境等多个方面分析了各影响因素对总氮测定的影响,相应提出了采用测定含氮量的方法筛选试剂、新制备的去离子水作为总氮实验用水、每次总氮实验使用新刷好的器皿、增加颠倒混匀步骤提高测定结果的准确度和精密度、高压蒸汽灭菌器应定时清洗换水等对策与建议。