高浓度污染地块基坑清理效果评估采样布点方案研究

Soil sampling of foundation pits during verification of high-concentration polluted soil remediation

为研究钢铁工业高浓度污染地块异位修复过程中基坑清理效果评估方法、布点设计适用性,该研究通过设计布点方案,对清理后的9个基坑88个采样点PAHs检测结果进行分析。结果表明,清理后各基坑ΣPAHs最大值在7.80~378.25 mg/kg之间,目标污染物BaP超标率为34.1%,污染成因主要为场地填埋有煤渣、焦油渣等固体废物,以煤的燃烧源为主。土壤中BaP质量浓度变差系数为251.1%,样本数据不服从所检验的分布形态,统计分析法对于连续超标且异质性特征明显的高污染地块应用受限。超标点位扩挖次数与BaP质量浓度的Pearson相关系数为0.95,呈明显线性相关。基坑点位超标原因可分为点位数据异常或清挖不到位两种情形,对于扩挖方案的选择,可把目标污染物BaP质量浓度12.60 mg/kg或超标率41.7%作为划分标准。

In order to study the applicability about the assessment method and monitoring of digging of contaminated soils which were severely polluted in iron and steel industrial sites,88 soil samples of PAHs from foundation pits were collected.The maximum values ofΣPAHs after digging ranged from 7.80 to 378.25 mg/kg in 9 foundation pits.The rate of over standard of Bap was 34.1%,which caused by coal cinder,tar residue and other solid wastes mainly created from coal combustion.The coefficient of variation of BaP content in soil was 251.1%,the sample data did not follow the distribution pattern tested,statistical analysis methods were restricted if the site was seriously and continuously polluted and the pollution characteristic was obviously heterogeneous in soil.Pearson correlation coefficient between the frequency of expanding excavation and BaP content over standard was 0.95,the two factors had obviously linear correlation.The causes that values exceeded the allowed standard in soil could be divided into two cases which were data exception and digging insufficient.It can take 12.60 mg/kg(BaP content)or 41.7%(exceed ratio)as the standard to choose the implementations of the expanding excavation.