氨氮测量不确定度的评定

采用纳氏试剂光度法测定水质氨氮的测量不确定度评定,应该考虑工作曲线、测量重复性、标准溶液、仪器读数分辨率等对测量的影响.     

Three-Dimensional Modeling of an Urban Park and Trees by Combined Airborne and Portable On-Ground Scanning LIDAR Remote Sensing

In this study, we confirmed the utility of airborne and portable on-ground scanning light detection and ranging (LIDARs) for three-dimensional visualization of an urban park and quantification of biophysical variables of trees in the park. The digital canopy height model (DCHM) and digital terrain model generated from airborne scanning LIDAR data provided precise images of the ground surface and individual tree canopies. The heights of 166 coniferous and broadleaf trees of 11 species in the park were estimated from the DCHM images with slight underestimation (mean error = −0.14 m, RMSE = 0.30 m). Portable on-ground scanning LIDAR provided images of individual trees with detailed features. Tree height and trunk diameter were estimated to be within 0.31 m and 1 cm, respectively, from the on-ground LIDAR images. We combined airborne and on-ground LIDAR images to overcome blind regions and created a complete three-dimensional model of three standing trees. The model allowed not only visual assessment from all viewpoints but also quantitative estimation of canopy volume, trunk volume, and canopy cross-sectional area.     

采用能力验证数据评估环境监测结果测量不确定度

测量不确定度评估是实验室检测能力的体现,能力验证是实验室质量控制的有效方法,对环境监测领域实验室采用能力验证数据进行测量结果不确定度评估方法进行了研究。依据Nordtest准则,根据实验室内再现性标准差和测量偏倚,评估了重铬酸钾法测定水中质量浓度为100 mg/L的化学需氧量测量结果的相对不确定度为6.00%。该评估方法避免了ISO GUM评定方法自下而上不确定度评估过程的繁琐,还充分考虑了实验室内外误差的来源,能够促进环境监测结果不确定度评定的一致性。     

环境湿度对PM2.5手工测量(重量法)的影响

为了解天平室环境湿度对PM_(2.5)手工称重的影响,利用滤膜自动称重系统,在45%、50%、55%3个环境相对湿度条件下对同一组滤膜进行称重。结果显示:45%、55%湿度条件下测量的大部分滤膜质量与50%基准湿度条件下滤膜质量绝对差值均超过0.04 mg,且随着滤膜质量即PM_(2.5)浓度的增加,绝对差值显著上升,难以满足手工称重规范中的要求。PM_(2.5)手工测量浓度在150μg/m~3以下时,3种湿度条件下测量结果的标准偏差保持在2μg/m~3范围之内,而PM_(2.5)手工测量浓度在150μg/m~3以上时,标准偏差超出2μg/m~3范围,且随着浓度升高,标准偏差显著增大,这会给PM_(2.5)的手工测量准确度带来较大影响,说明手工称量环境湿度±5%的允许变化范围并不适合PM_(2.5)平均浓度较高的国家和地区。     

环境污染物快速检测技术的国内外研究进展

介绍了环境污染物的分类与危害,基于目前国内外不同类型污染物快速检测技术的研究进展,综述了包括离子传感器、气体传感器和生物传感器等在内的化学传感器选择性强、成本低廉、可检测痕量污染物的优势,以及便携式检测设备节省时间、避免样品采集、应用领域广泛的特点,并提出了污染物快速检测技术的未来发展方向。     

Estimate of the uncertainty in measurement for the determination of mercury in seafood by TDA AAS

An approach for the estimate of the uncertainty in measurement considering the individual sources related to the different steps of the method under evaluation as well as the uncertainties estimated from the validation data for the determination of mercury in seafood by using thermal decomposition/amalgamation atomic absorption spectrometry (TDA AAS) is proposed. The considered method has been fully optimized and validated in an official laboratory of the Ministry of Agriculture, Livestock and Food Supply of Brazil, in order to comply with national and international food regulations and quality assurance. The referred method has been accredited under the ISO/IEC 17025 norm since 2010. The approach of the present work in order to reach the aim of estimating of the uncertainty in measurement was based on six sources of uncertainty for mercury determination in seafood by TDA AAS, following the validation process, which were: Linear least square regression, Repeatability, Intermediate precision, Correction factor of the analytical curve, Sample mass, and Standard reference solution. Those that most influenced the uncertainty in measurement were sample weight, repeatability, intermediate precision and calibration curve. The obtained result for the estimate of uncertainty in measurement in the present work reached a value of 13.39%, which complies with the European Regulation EC 836/2011. This figure represents a very realistic estimate of the routine conditions, since it fairly encompasses the dispersion obtained from the value attributed to the sample and the value measured by the laboratory analysts. From this outcome, it is possible to infer that the validation data (based on calibration curve, recovery and precision), together with the variation on sample mass, can offer a proper estimate of uncertainty in measurement.     

Diagnosis of dissolved organic matter removal by GAC treatment in biologically treated papermill effluents using advanced organic characterisation techniques

Granular activated carbon (GAC) exhaustion rates on pulp and paper effluent from South East Australia were found to be a factor of three higher (3.62 cf. 1.47 kg m⁻³) on Kraft mills compared to mills using Thermomechanical pulping supplemented by Recycled Fibre (TMP/RCF). Biological waste treatment at both mills resulted in a final effluent COD of 240 mg L⁻¹. The dissolved organic carbon (DOC) was only 1.2 times higher in the Kraft effluent (70 vs. 58 mg L⁻¹), however, GAC treatment of Kraft and TMP/RCF effluent was largely different on the DOC persisted after biological treatment. The molecular mass (636 vs. 534 g mol⁻¹) and aromaticity (5.35 vs. 4.67 L mg⁻¹ m⁻¹) of humic substances (HS) were slightly higher in the Kraft effluent. The HS aromaticity was decreased by a factor of 1.0 L mg⁻¹ m⁻¹ in both Kraft and TMP/RCF effluent. The molecular mass of the Kraft effluent increased by 50 g mol⁻¹ while the molecular mass of the TMP/RCF effluent was essentially unchanged after GAC treatment; the DOC removal efficiency of the GAC on Kraft effluent was biased towards the low molecular weight humic compounds. The rapid adsorption of this fraction, coupled with the slightly higher aromaticity of the humic components resulted in early breakthrough on the Kraft effluent. Fluorescence excitation-emission matrix analysis of the each GAC treated effluent indicated that the refractory components were higher molecular weight humics on the Kraft effluent and protein-like compounds on the TMP/RCF effluent. Although the GAC exhaustion rates are too high for an effective DOC removal option for biologically treated pulp and paper mill effluents, the study indicates that advanced organic characterisation techniques can be used to diagnose GAC performance on complex effluents with comparable bulk DOC and COD loads.     

Does Divergence of Nutrient Load Measurements Matter for Successful Mitigation of Marine Eutrophication?

Successful implementation of an international nutrient abatement agreement, such as the Baltic Sea Action Plan (BSAP), requires consistent understanding of the baseline nutrient loads, and a perception of acceptable costs and fairness in targeted reductions of these base line loads. This article presents a general framework for identifying the implications of divergence between different nutrient load quantification approaches, with regard to both cost and fairness criteria outcomes, for the international agreement to decrease nutrient loads into the Baltic Sea as presented in the BSAP. The results indicate that even relatively small divergence in the nutrient load quantification translates into relatively large differences in abatement cost for different Baltic Sea countries. A robust result, irrespective of differences in nutrient load assessments, is a conflict between abatement cost effectiveness and fairness, with relatively poor countries facing heavy abatement cost burdens for cost-effective international load abatement.     

高低温试验能力验证常见不满意原因分析

测量审核和实验室间比对是能力验证计划的有效补充形式,是实验室或者检查机构用于实验室质量控制及申请CNAS认可的重要手段。本文随机抽取2010年～2012年低温试验测量审核与高温试验实验室间比对结果为不满意的报告各8份作为样本,进行原因分析,并给出技术建议,旨在让参加实验室在以后的相关试验中能规避常见问题,提高测试能力。     

The dependence of the beta coefficient of REA system with dynamic deadband on atmospheric conditions

We simulated the REA system with dynamic deadband to study numerical value and the effect of atmospheric conditions on the empirical constant beta which relates vertical flux to concentration difference between updrafts and downdrafts. We found that the value of beta depends only weakly on the friction velocity and atmospheric stability. In agreement with previous studies, the median value obtained for a system with dynamic deadband proportional to 0.5 times the running mean of the standard deviation of vertical wind speed was beta=0.42+/-0.03. For a single half-hour measurement one has to consider the large uncertainty of +/-0.2. According to our study, the dynamic deadband enables the use of a constant value of beta in flux calculation.