Abstract
Contamination of soils with organic pollutants is an increasing global problem, so novel soil remediation techniques are urgently needed. One such technique is electrokinetic remediation, in which an electric field is applied over the soil to extract contaminants. Previous evaluations of the technique have been limited to a few specific compounds. In this study, we integrated the latest advances in high-resolution mass spectrometry (HRMS) to identify molecular fingerprints, and used the results to improve the mechanistic understanding necessary for successful remediation. A laboratory-scale 0.38 mA cm−2 electrodialytic treatment was applied for 21 days to a contaminated soil from a firefighter training facility in Sweden. Non-target analysis allowed generic evaluation of changes in the soil organic fraction by tentatively determining the elemental composition of compounds present. The results showed that smaller oxygen-rich molecules were significantly transported to the anode by electromigration, while larger hydrogen-saturated molecules were transported to the cathode by electroosmotic flow. Wide suspect screening with >3000 per- and polyfluoroalkyl substances (PFASs) tentatively identified seven new PFASs in the test soil, including perfluoroheptanesulfonic acid (PFHpS), and PFASs with butoxy, ethoxy, ethanol, and ethylcyclohexanesulfonate functional groups.
Highlights
Due to unsolicited leaching of pollutants from diffuse and point sources in soil to surface water and groundwater, contaminated soils pose a risk to aquatic environments and can affect the quality of drinking water sources [1,2]
All remedia tion options have some disadvantages, such as high costs, limited applicability, a need for expert knowledge and, differing remediation efficiency for different groups of contaminants. The latter is especially challenging as regards emerging contaminants, because it is difficult to assess the success of a specific soil remediation method owing to the high variability in physicochemical properties, and thereby behavior, of different classes of chemicals (e.g., per- and polyfluoroalkyl substances (PFASs), pesticides, pharmaceuticals, antibiotics, industrial chemicals) [4]
No significant change in the number of natural organic matter (NOM) formulae identified was observed with distance from the anode (Fig. 2), which indicates that comparisons along the distance from the anode are valid
Summary
Due to unsolicited leaching of pollutants from diffuse and point sources in soil to surface water and groundwater, contaminated soils pose a risk to aquatic environments and can affect the quality of drinking water sources [1,2]. All remedia tion options have some disadvantages, such as high costs, limited applicability, a need for expert knowledge and, differing remediation efficiency for different groups of contaminants. The latter is especially challenging as regards emerging contaminants, because it is difficult to assess the success of a specific soil remediation method owing to the high variability in physicochemical properties, and thereby behavior, of different classes of chemicals (e.g., per- and polyfluoroalkyl substances (PFASs), pesticides, pharmaceuticals, antibiotics, industrial chemicals) [4]. New methodologies based on suspect and non-target screening [7,8] can generate knowledge that assists in selection of remediation method/s for emerging soil pollutants.
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