Ecotoxicity assessment of hydrophobised soils

Hydrophobised soils are a new geomaterial to be used in hydraulic barriers. Insufficient knowledge of their potential harm and environmental risks is a primary hindrance in their application as a fill material. To address this environmental concern, leachate tests and seed germination tests were conducted on two soils (Fujian sand and completely decomposed granite) induced by two hydrophobising compounds (tung oil and dimethyldichlorosilane). Biological indicators – that is, soil respiration, enzyme assays and biosensor assays – were conducted on the hydrophobising agent, tung oil. The total concentrations of heavy metals measured by leachate tests remained below guideline values, indicating that leaching hazard will be negligible during their service life. Biological assays revealed minimal impact on soil microorganisms by tung oil. The results demonstrate negligible environmental impact of hydrophobised soils as fill materials.