Current research by QAEHS investigates poorly understood mechanisms by which apparently immobile contaminants can migrate through soil to groundwater. Such transport can be facilitated by surfactants and colloids, which find widespread application in industrial, urban and agricultural products.
Surfactants can fundamentally change the behaviour of chemicals, allowing the least mobile to rapidly reach groundwater. Field evidence indicates that surfactant facilitated transport may occur across a variety of land-use areas, posing unknown risks for human and environmental exposure.
The transport potential of chemicals in soil is typically assessed based on physico-chemical properties. Some of the most toxic and environmentally persistent contaminant groups are super-hydrophobic and organic compounds (SHOCs). These compounds have extremely low water solubility and high affinity for soil organic matter, and therefore are generally considered immobile, and rarely monitored below the soil surface.
Surfactants can fundamentally change this behaviour and solubilise apparently immobile contaminants. This phenomenon is the basis of various technologies, including surfactant enhanced remediation of contaminated sites to intentionally solubilise and/or mobilise hydrophobic chemicals for groundwater treatment.
Surfactant facilitated transport (SFT) of contaminants may, however, also occur unintentionally across a variety of land-uses where surfactants are used at high levels and/or frequencies. Association of SHOCs with such facilitators increases their apparent aqueous solubility and thus their subsurface mobility in soil water.
Research by our team at QAEHS aims to improve qualitative and quantitative understanding on surfactant facilitated transport processes of apparently immobile contaminants. We apply an integrated experimental and modelling approach to understand, quantify and predict the extent of this phenomenon relevant to conditions under which surfactants are commonly released.
This information can be applied to assess groundwater and offsite contamination risks in areas where surfactants are commonly used. It will benefit current and future activities targeting the protection of Australia’s groundwater resources and freshwater ecosystems, the management of sites where surfactants are released and associated evaluation and prevention of contamination.
