Effect Of Reagent (Dye) Addition In Wet Chemical Method Of Sulfur Dioxide Determination In Ambient Air

For measurement of sulfur dioxide (SO₂) in ambient air, the United States Environment Protection Agency (US EPA) had recommended the PRA dye-based colorimetric method as a reference technique. The method has been developed and applied in many countries for a longtime; however information regarding the sensitivity of the method with respect to sampling and analysis conditions is not available. Collaborative studies conducted in some of the South East Asian countries indicated substantial variations (of the order of 50%) in the measured concentrations against the true values. It was observed that dye used for color development plays an important role and even a slight variation in the way the dye solution is prepared can cause substantial variation in the measured SO₂ concentration. Because a major objective of air quality measurements is to relate air pollution concentration to the effects of air pollution, it is important that the method used should yield accurate levels of the pollutant, so that appropriate management plans can be devised and implemented effectively. In the present investigation, therefore, the role of dye used in SO₂ monitoring method has been highlighted. Different makes of dyes prepared in different modes were used to study the variation in the measured SO₂ concentration levels. Specifications of all the dyes were also tested. Need for use of certified reference material (CRM) for SO₂ has also been emphasized.     

用EDTA代替CDTA测定SO2的探索

通过实验验证了盐酸副玫瑰苯胺分光光度法测定大气中SO2的标准方法中,用EDTA代替CDTA去掩蔽金属离子的干扰是可行的,即方便,又经济。     

2016年秋季新乡市空气质量模式预报效果评估

基于新乡市空气质量数值预报平台,采用相关系数（r）、标准化平均偏差（NMB）等统计指标,系统评估2016年秋季新乡市嵌套网格空气质量预报模式（NAQPMS）和通用多尺度空气质量模式（CMAQ）的预报效果,对比分析2套模式不同预报时效和不同水平分辨率的空气质量等级预报准确率。结果显示：2套模式均较好地表征了各主要污染物的浓度变化特征,2套模式的等级预报准确率高于60%,其中CMAQ对中度及重度的预报等级准确率达到70%。对比模式24、48、72 h 3种预报时效效果,24 h预报时效的统计数据最优,说明24 h预报时效模拟结果可作为业务预报重要的支撑。     

环境监测数据的数值修约规则探讨

数值修约问题看似简单,实则行之不易。由于目前并没有一种统一的数值修约方式可以处理实际工作中遇到的各种类型的数据,这就导致环境监测报告及科研论文中普遍存在着分析数据数值修约不规范的问题。分析阐明了数值修约的内涵:一是修,是保留几位的问题;二是约,是如何舍入的问题。在此基础上,提出了数值修约的两条原则:准确性和保守性。最后,总结了环境监测常用数据的数值修约规则。     

Deposition in boreal forests in relation to type, size, number and placement of collectors

Open precipitation and throughfall was collected at a Norway spruce stand in Finland using funnel-type collectors and at a black spruce stand in Canada using trough-type collectors. The presence or absence of a rim on the funnel, funnel diameter (9, 14 and 20 cm) and length of sampling period (1, 2 and 4 weeks) on monthly values were evaluated at the Norway spruce stand, and the number of collectors required for defined levels of accuracy and precision of throughfall loads to be reached and the influence of the spatial arrangement of collectors on solute concentrations was studied at both stands. The presence of a rim had no significant effect on open precipitation and throughfall amounts, but did on throughfall DOC, Ca²⁺, Mg²⁺, K⁺, Na⁺ and Cl⁻ ion loads. Deposition loads increased with decreasing funnel diameter; for open precipitation, this was due to increased catch efficiency while for throughfall the increase was attributed to canopy interaction and leaching of litter trapped in the collectors. Calculated monthly H⁺ loads decreased and those for all other constituents increased with collection period length. Using 15 collectors at the Norway spruce stand would allow throughfall loads to be determined to within 20% of the true mean weekly value with a confidence level of 95% for most solute, but not for NH₄ ⁺–N, NO₃ ⁻–N, Mg²⁺ and SO₄ ²⁻-S. Using 15 trough collectors, the same confidence level at the more heterogeneous black spruce stand would only be achieved for H⁺, Cl⁻, DOC and SO₄ ²⁻-S loads. In both stands, using either random or systematic placements of throughfall collectors gave similar results.     

用同一水样测定NO3-N和TN

文章阐述了用紫外分光光度法,以同一水样测定NO3 -N和TN,保证了其相对差值的合理性,揭示了S2O82-在220nm波长上特征吸收,这是空白吸光度高的重要原因,提出了降低空白吸光度的方法.K2S2O8和NaOH分别配制,克服了K2S2O8碱液使用时间短的缺点.     

Prediction of effluent concentration in a wastewater treatment plant using machine learning models

Of growing amount of food waste, the integrated food waste and waste water treatment was regarded as one of the efficient modeling method. However, the load of food waste to the conventional waste treatment process might lead to the high concentration of total nitrogen (T-N) impact on the effluent water quality. The objective of this study is to establish two machine learning models—artificial neural networks (ANNs) and support vector machines (SVMs), in order to predict 1-day interval T-N concentration of effluent from a wastewater treatment plant in Ulsan, Korea. Daily water quality data and meteorological data were used and the performance of both models was evaluated in terms of the coefficient of determination (R²), Nash–Sutcliff efficiency (NSE), relative efficiency criteria (d_rel). Additionally, Latin-Hypercube one-factor-at-a-time (LH-OAT) and a pattern search algorithm were applied to sensitivity analysis and model parameter optimization, respectively. Results showed that both models could be effectively applied to the 1-day interval prediction of T-N concentration of effluent. SVM model showed a higher prediction accuracy in the training stage and similar result in the validation stage. However, the sensitivity analysis demonstrated that the ANN model was a superior model for 1-day interval T-N concentration prediction in terms of the cause-and-effect relationship between T-N concentration and modeling input values to integrated food waste and waste water treatment. This study suggested the efficient and robust nonlinear time-series modeling method for an early prediction of the water quality of integrated food waste and waste water treatment process.     

原子吸收法测定水中镉的质量控制指标研究

通过全国多家实验室的大量监测数据,研究分析了镉测定的质量控制指标,并与《水质镉的测定双硫腙分光光度法》（GB/T 7471-1987）和《环境水质监测质量保证手册》（第二版）进行了比较,旨在为环境监测工作提供质量控制依据和质量控制指标。研究表明,标准样品的精密度质量控制指标范围：RSD≤5.0%和RSD’≤8.0%;准...     

2018年11—12月北京市重污染天气过程数值预报能力评估

2018年11—12月北京市发生了4次以PM_2.5为首要污染物的重污染天气过程,为了分析数值模型对4次重污染过程的预报能力,将CMAQ模式提前1~7 d对北京市PM_2.5的小时预报结果与观测结果对比,分别从离散统计和分类统计2个方面评估CMAQ模式对4次重污染天气过程的预报效果,并简要分析了偏差产生的气象方面原因。结果表明：CMAQ模式提前1~6 d对重污染天气过程的预报显示出良好的性能,为日常业务预报提供了可借鉴的参考信息,可较好地预报出PM_2.5小时浓度变化趋势和浓度水平,离散统计结果显示提前1~4 d的预报结果好于提前5~7 d,相关系数r基本大于0.8,但有一定程度的低估趋势;分类统计结果显示不同预报时效预报准确率大于70%,探测准确率高于55%,部分时段可以达到80%~90%,对人工预报起到了良好的参考作用;输入的气象场的变化及其偏差对于重污染的起始时间、持续时间及清除时间有一定的影响,对相对湿度预报偏小和风速预报偏大是造成CMAQ模式低估的一个重要原因。     

实验室无源效率刻度技术的准确性检验

为检验无源效率刻度技术的准确性,本文用9个可溯源的典型放射性样品进行测试,并用LabSOCS计算结果。结果表明,点源在低能区（〈150KeV）偏差为9.2%,中高能区5.9%以内。对于单一核素体源,偏差在5%以内,而复合核素体源偏差在12%以内,无源效率刻度技术是一种准确、可靠的刻度技术。