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摘要: 地下水污染场地的监控需要依据水文地质条件、地下水流场和溶质运移特征，利用水化学的示踪作用开展空间分析,以识别地下水和溶质运移特征。该方法具有简易和经济的优点。以台湾苗栗县某化工污染场地为例，通过对地下水中多种离子浓度的空间等值线分析及对比，判断污染物的来源和分布范围。采用离子浓度的统计特征值P95、P75、P50、P25构成的等值线，作为判断离子空间分布特征的依据，并形成离子之间对比的统一标准。所有离子都采用浓度P95等值线包围的区域作为其污染源，其它三种等值线表示可能出现的污染物扩散范围。在此基础上通过对比发现10种离子的污染源集中出现在场地一个范围内，并形成一个污染带，表明它们的来源具有密切的联系。10种离子P75等值线划出的污染物分布范围同样比较集中，但几乎都分布在污染带的南部，显示离子的迁移方向和迁移距离是一致的。根据离子空间分布的相似性将其分为三组，空间分布相似性高的离子组同时出现在一个区域的机会更多。通过多种水化学成分识别地下水流场和溶质运移特征，提高了结论的可信度，为污染物监控提供参考。Abstract: Monitoring of groundwater contamination needs to consider the hydrogeological conditions, groundwater flow and characteristics of contaminates in the study site. Using spatial distributions of hydrochemical tracers to identify groundwater flow and solute transportation has advantages in easy operation and cost saving. In this study, a petrochemical contamination site was used as an example. By mapping contours of the measured ion concentrations and comparing among them, the source area and plume of the contaminations were identified. In order to make contours for the measured properties, we use four statistic values: P95, P75, P50 and P25 to classify the concentration levels of the measured properties based on their percentage rank. For example, P50 represents the medium number which is 50% of the total concentrations for a certain ion. In so doing, the ten measured ions can compare their relative concentrations with the contours. The area enclosed by contour of P95 is considered as the contamination hotspots. The other contour maps show the probable contamination plume and immigration direction. The results show that the hotpots (P95 contour) of all measured properties are located in a narrow band, and the contours of P75 are similar, indicating close relationship of those solutes. The contour mapping indicates that the contamination source is located in the southwest of the manufactory or the contamination site and move toward southwest with the groundwater flow. This method enhances the reliability of contamination hotspots detection, and can be good reference for contamination monitoring.
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Key words:
- groundwater /
- multi-contamination /
- spatial analysis /
- pollutant transport
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