This study presents the latest results of the groundwater monitoring of a research project, which tested an innovative pump and treat method in combination with an in-situ remediation. This technique was assessed on an abandoned site in Austria, where two hot spots of hexavalent chromium (Cr(VI)) were located. For the in-situ remediation, a strong reducing agent (sodium dithionite) was injected into the underground to reduce Cr(VI) to Cr(III) by using different injection strategies. Throughout this treatment, part of the Cr(VI) is mobilized and not instantly reduced. To prevent a further spreading of the mobilized Cr(VI), the pump and treat method, which uses zero-valent iron to clean the groundwater, was installed downgradient of the hot spots. Based on the groundwater sample analyses, it was possible to distinguish different remediation phases, characterized by excess chromate and excess sulfite. During the excess sulfite conditions, Cr(VI) was successfully removed from the system, but after terminating the sodium dithionite injection, the Cr(VI) rebounded.

中文翻译：

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原位六价铬污染的场地修复对地下水的影响。

这项研究提供了一个研究项目的地下水监测的最新结果，该项目测试了一种创新的泵和处理方法以及现场修复技术。该技术在奥地利的一个废弃地点进行了评估，该地点位于两个六价铬热点（Cr（VI））。对于原位修复，通过使用不同的注入策略，将强还原剂（连二亚硫酸钠）注入地下，以将Cr（VI）还原为Cr（III）。在整个处理过程中，部分Cr（VI）会动员且不会立即还原。为了防止动员的Cr（VI）进一步扩散，安装了使用零价铁清洁地下水的泵送和处理方法，以降低热点的位置。根据地下水样品分析，可以区分不同的修复阶段，特征在于过量的铬酸盐和过量的亚硫酸盐。在过量的亚硫酸盐条件下，成功地从系统中除去了Cr（VI），但是在终止连二亚硫酸钠注射后，Cr（VI）反弹了。