环境分析中地下水放射性及重金属微量组分未检出数据估算方法研究

A STUDY OF ESTIMATION METHOD ON UNDETECTED DATA OF RADIOACTIVE AND HEAVY METAL TRACE COMPONENTS OF GROUNDWATER IN ENVIRONMENTAL ANALYSIS

地下水中放射性及金属微量组分中在地下水中含量相对较低,或多或少地存在着未检出限的数据。在地下水环境分析过程中忽视未检出数据势必引入误差,因此合理估算未检出数据对于准确地下水环境分析尤为重要。本文在广泛调研总结国内外未检出数据估算方法体系的基础上,针对地下水数据的不同检出率采用不同估算方法,检出率>75%的数据采用简单替代法替换未检出数据。检出率在25%~75%的数据采用KM法估算整体数据的平均值和标准偏差。检出率<25%的数据直接采用95百分位数或检出限作为整体数据的统计特征值。

Concentrations of radioactive and heavy trace components in groundwater are relatively low,which results in more or less data beyond detection limit.Ignoring these undetected data would inevitably introduce errors in the process of groundwater environment analysis.In consequence,a reasonable estimation of undetected data is particularly important for an accurate analysis of groundwater environment.Based on an extensive investigation and summary on estimation methods of undetected data at home and abroad,.different estimation methods used for groundwater data sets of different detection rates are proposed in this study.The undetected data of the data set with detection rate>75%can be replaced by using simple alternative method.The average value and standard deviation of the overall data are estimated by KM method for the data with detection rate 25%~75%.Data with detection rate<25%directly use the 95 percentile or detection limit as the statistical characteristic value for overall data.