共查询到18条相似文献,搜索用时 125 毫秒
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以大量实地监测数据为依据,建立了同一时间周期内、环境空气中二氧化物及氮氧化物平均浓度与最大浓度及平均取样时间相关的经验数学模式。应用该模式估算二氧化硫及氮氧化物的年平均浓度,其准确度分别为6.64%及6.90%;用该模式所得估算值与间断监测法所得监测结果相比,其可靠性分别提高83.18%及71.04%。从而使积累长达十多年的间断监测数据能合理延用。 相似文献
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对氮氧化物分析仪在不同测量量程范围内采集室外环境空气分析的结果进行了讨论和统计检验,得出分析仪在不同测量量程范围采集室外环境空气分析的结果基本一致,它们之间具有高度的一致性、相关性及可比性。 相似文献
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刘菊英 《环境监测管理与技术》1992,4(3):33-35
在环境监测分析工作中,大多数是相对测量,未知量是通过标准的已知量进行比较而求得,而这种比较又往往是通过一个中间指示量(如仪器响应值)来实现的,为此,先要用已知的标准确定未知量(如浓度)与指示量(如吸光度)之间的关系,人们曾把这种关系绘制在直角座标纸上,把成直线的部分作为校准曲线或标准曲线,以此来查得未知量.目前人们常在校准曲线的直线范围内,根据最小二乘法原理求出直线回归方程 y=bx+a,以此计算测定结果.为检查标准曲线的线性应计算相关系数r.一般当r大于0.9990时,该直线方程才能使用.但如何才能正确求出直线回归方程,使它最能说明随着浓度变化时吸光度也随之变化的依存关系,仍存在一些问题,例如:在计算回归方程时,如何处理试剂空白值和n 相似文献
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吴汉冲 《环境监测管理与技术》2005,17(3):44-47
阐述了在大气自动监测多点线性校准中,气体流量对仪器示值误差的影响,分析了标准气流量影响仪器浓度示值的原因,以及控制低浓度校准气仪器示值误差的方法。通过比较相对固定标准气流量和崮定校准气流量两种校准方法,得出校准气(或零空气)流量大小对校准气浓度的准确性影响不显著,而标准气流量大小对校准气浓度的准确性影响显著,故在大气自动监测多点线性校准中,宜采用相对固定标准气流量的办法,以降低仪器示值的误差。 相似文献
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介绍了原子吸收光度法中的光谱干扰和非光谱干扰,指出标准加入法和分析校准曲线法是消除和减少某些干扰最简单、快速的校准方法。在标准加入法中,当分析曲线呈线性时,表明分析结果可信,当分析曲线不呈线性,表明方法灵敏度随质量浓度变化而变化,分析结果的准确性有问题。以改变基体的质量浓度和在同一质量浓度的基体溶液中加入不同量的标准两个实验可以验证标准加入法在原子吸收光度法中的适用性。 相似文献
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陈怀玉 《环境监测管理与技术》2000,12(3):38-38
对环境监测样品的分析大部分采用校准曲线定量法,校准曲线拟合方程的质量对监测结果的可靠性影响很大。把测量信号值(y)对标准物质含量(x),用最小二乘法拟合校准曲线方程有两种方法,一种是直接拟合,一种是扣除空白信号值后再拟合,两种方法截距(a)的含义不同,这里论述的截距是指后者。1 截距误差产生的原因分析方法的依据是测量信号值与样品待测物质含量成某种确定的直线关系,空白信号估计值应是空白实际测定值。理论上校准曲线的截距应是0。非零截距是由截距误差产生的,其中包括随机误差、系统误差和过失误差。11 截距的随机误差以分光… 相似文献
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李中愚 《环境监测管理与技术》1992,4(1):47-51
本文以大量实地监测数据为依据,建立了二氧化硫及氮氧化物平均浓度经验数学模式.用该模式估算二氧化硫及氮氧化物的年平均浓度,提高了原间断监测结果的准确度和代表性.二氧化硫及氮氧化物年平均浓度模式估算值的准确度分别为6.64%及6.90%;其代表性分别提高83.18%及71.04%.从而使累积长达十多年的原间断监测数据能合理延用. 相似文献
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In this paper we introduce a new method of analysing the relationship between nitrogen dioxide (NO2) and oxides of nitrogen (NOx) concentrations using data from the UK National Air Quality Archive. The study includes analyses of measurements from two different types of site in London, a kerbside site: Cromwell Rd, and three background sites: Bridge Place, London Bloomsbury and West London, over several years (1991–7). The data in some years showed that hourly NO2 concentrations exceeded the UK Standard of 150 ppb. Data were binned, averaged, and polynomials fitted at each site. Analysis of the resulting polynomials was used to estimate reductions in NOx emission required to achieve the National Air Quality Strategy Objective. Examination of the empirical ratio NO2:NOx (the 'yield') gives an indication of the sensitivity of the NO2 to NOx controls and the amount of NO2 that would arise from modelled values of total oxides of nitrogen. The response of NO2 to emission changes is very non-linear, implying 30–45% controls on NOx may be required. 相似文献
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Benjamin J. Mullins Roger D. Braddock Igor E. Agranovski 《Environmental Modeling and Assessment》2002,7(1):1-7
The current paper investigates the possibility of establishing an empirically based model for predicting the emission rate
of nitrogen oxides (NO
x
) from oil refinery furnaces, in order to continually track emissions with respect to environmental licence limits. Model
input data were collected by direct stack monitoring using an electrochemical cell NO
x
analyser, as well as a range of telemetry sensors to obtain refinery process parameters. Principal Component Analysis (PCA),
in conjunction with Partial Least Squares (PLS) regression was then used to build a series of models able to predict NO
x
emissions from the furnaces. The models produced were proven to be robust, with a relatively high accuracy, and are able
to predict NO
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levels over the range of operating conditions which were sampled. It was found that due to structural/operational variations
a separate model is usually required for each furnace. The models can be integrated with the refinery operating system to
predict NO
x
emission rates on a continuous basis. Two models representing structurally different furnaces are considered in this paper.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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2022年春季,受新一轮新冠疫情影响,长三角各城市采取了一系列管控措施,使得大气污染物排放水平降低。对2022年春季(3—5月)南京及长三角地区的六项污染物尤其是臭氧(O3)的变化特征进行了分析,从气象因素和O3前体物方面,同时利用基于观测的模型(OBM)对南京O3污染变化原因进行了研究,并分析了南京挥发性有机物(VOCs)的关键活性组分和来源。结果表明:2022年春季,南京PM2.5、PM10、NO2和CO均值浓度均同比下降,但O3日最大8 h滑动平均质量浓度(O3-8 h)同比上升19.8%,O3-8 h超标时间同比增加9 d;长三角区域O3-8 h同比上升17.9%,O3-8 h超标天数为2021年同期的2.5倍。南京O3浓度上升的原因:一方面是由于不利的气象条件,另一方面是由于南京O3生成处于VOCs控制区,但氮氧化物(NOx)降幅大于VOCs降幅,同时结合O3前体物削减方案的分析结果发现,VOCs和NOx不当的削减比例会导致O3浓度不降反升。南京O3生成的关键VOC活性物种依次为乙醛、丙烯、间/对二甲苯、丙烯醛和乙烯;正定矩阵因子分解(PMF)解析结果显示,机动车尾气是南京城区VOCs的主要来源,其次为液化石油气/天然气使用和石油化工。 相似文献
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Josef Brechler 《Environmental monitoring and assessment》2000,65(1-2):269-275
Results of relatively simple gaussian dispersion model are presented. This model, developed in the beginning of this decade, is suitable mainly for determination of spatial distributions of annual mean concentrations of such kinds of air-pollution as sulphur dioxide (SO2), mixture of nitrogen oxides (NOx) or suspended particulate matter (SPM) from all types of emission sources located within the city - point sources, line sources and area sources. Model has been used in years 1994, 1996 and 1998 to assess the air-pollution distributions of the above mentioned kinds in the Prague area and the development of the air quality state. It contributed to the decision making process when possible impact of some changes in traffic system or in system of domestic heating, for example, has been investigated. In this contribution, behaviour of sulphur dioxide (SO2) and mixture of nitrogen oxides (NOx) ground concentration distributions are analyzed with respect to changing emission situation in Prague in recent years. Results show that SO2 ground concentration level decreases mainly due to changes in local heating methods and type of fuel used. Different trend can be seen in NOx ground concentrations thanks to rapid increase in the traffic density. 相似文献
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中国城市臭氧的形成机理及污染影响因素研究进展 总被引:1,自引:0,他引:1
中国城市臭氧(O_3)污染问题日趋严重。O_3主要来源于汽车尾气及工业排放氮氧化合物(NO_x)和挥发性有机物(VOCs)光化学反应生成,少部分来自于平流层的向下传输。文章介绍了城市O3形成机理研究情况,概述了中国城市臭氧污染浓度特征及气象因子、气候变化、前体物等影响因素研究进展情况,并对未来研究方向进行了展望。 相似文献
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Chaulya SK 《Environmental monitoring and assessment》2005,105(1-3):369-389
This investigation presents the assessment of ambient air quality carried out at an open pit coal mining area in Orissa state of India. The 24-h average concentrations of suspended particulate matter (SPM), respirable particulate matter (RPM, particles of less than 10 m aerodynamic diameter), sulphur dioxide (SO2) and oxides of nitrogen (NOx) were determined at regular interval throughout one year at 13 monitoring stations in residential area and four stations in mining/industrial area. During the study period, the 24-h and annual average SPM and RPM concentrations exceeded the respective standards set in the Indian ambient air quality standard (NAAQS) protocol in most of the residential and industrial areas. However, the 24-h and annual average concentrations of SO2 and NOx were well within the prescribed limit of the NAAQS in both residential and industrial areas. A management strategy is formulated for effective control of particulate matter at source and other mitigative measures are recommended including implementation of green belts around the sensitive areas. 相似文献
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利用2015年臭氧(O_3)自动监测数据和源排放清单,分析了中原城市群O_3浓度的空间、时间分布情况,探讨了中原城市群中城市间O_3的相关性,以及O_3浓度、NOx、VOCs、CO及汽车保有量间的相关性。指出中原城市群是全国更是河南O_3污染的严重地区,O_3浓度年内月度变化呈倒"V"型分布,具有明显的北部城市特征;中原城市群9个城市间除开封外其他8个城市间都呈高度正相关性,相关系数均为0.892~0.991;9个城市机动车保有量及NOx、VOCs和CO等前体物的年排放量与其年均O_3浓度之间存在正相关性。分析认为,NOx、VOCs和CO等前体物的排放是中原城市群O_3浓度偏高的主要影响因素,同时O_3浓度也与日照时间、降雨量、植物源VOCs排放量及相邻城市间污染物的空间输送等因素有着密切的关系。 相似文献