化工搬迁场地地下水中氯苯三维空间分布特征

以浙江省绍兴市某化工搬迁场地为例,通过建设丛式井组(1～5、5～9和10～14 m)进行地下水中氯苯浓度的三维空间调查,在调查结果统计分析的基础上分别采用普通克里格、反距离权重、改进反距离权重和最邻近点插值法进行地下水中氯苯浓度的三维空间插值计算,对比了不同插值模型及参数的预测精度、不同计算方法获取的超标地下水方量和氯苯的浓度特征,并选择最优插值方法进行氯苯的三维空间分布研究。结果表明:地下水中氯苯浓度在不同深度空间分布差异较大,随着深度增加浓度逐渐降低,最大检出浓度为8 050μg/L,3个不同深度的平均浓度分别为484.45、230.43和23.08μg/L;地下水中氯苯浓度存在一定的正向全局空间自相关关系;改进反距离权重插值法预测精度高于其他方法,并在水平与垂直异性比系数为3和权函数为6时插值精度最高,该方法估算的污染地下水超标方量和氯苯的总体平均浓度适中,能够较好反映污染物的空间分布特征。

Three-Dimensional Spatial Distribution Characteristics of Chlorobenzene in Groundwater of A Chemical Relocation Site

A typical case with chlorobenzene contamination in a chemical factory relocation site in Shaoxing city Zhejiang Province, was selected, and some nested well groups (1~5, 5~9 and 10~14m) was set up to investigate the concentration of chlorobenzene in groundwater in three-dimensional space.On the basis of statistical analysis of the survey results, the 3D spatial interpolation calculation of chlorobenzene concentration in groundwater was performed by ordinary Kriging interpolation method (OK), inverse distance weight interpolation method (IDW), improved inverse distance weight interpolation method (IDWN) and nearest neighbor interpolation method (NN), respectively. The optimal interpolation method was selected to study the three-dimensional spatial distribution of chlorobenzene, after the comparison of the prediction accuracy of different interpolation models and parameters, and the comparison of the amount of groundwater above certain management target value and the concentration characteristics of chlorobenzene obtained by different calculation methods. The results showed that the spatial distribution of chlorobenzene content in groundwater varied greatly at different depths, and that the concentration of chlorobenzene in groundwater decreased gradually with the increase of depth. The maximum detection concentration was 8050 μg/L, and that the average concentrations were 484.45 μg/L, 230.43 μg/L and 23.08 μg/L, at three different depths. The results also showed that there existed a certain positive global spatial autocorrelation relationship in the concentration of chlorobenzene in groundwater, and the accuracy of IDWN prediction was the higher than other methods, and the interpolation accuracy was the highest when the vertical anisotropy ratio coefficient was 3 and the weight function was 6. The amount of contaminated groundwater above the third level of groundwater quality standard in china and the average concentration of chlorobenzene were suitable, estimated by this interpolation method, which can better reflected the spatial distribution characteristics of pollutants.