Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4425385 | Environmental Pollution | 2011 | 8 Pages |
Long-term applications of small concentrations of surfactants in soil via wastewater irrigation or pesticide application may enhance trace metal solubility. Mechanisms by which anionic surfactants (Aerosol 22, SDS and Biopower) affect trace metal solubility were assessed using batch, incubation and column experiments. In batch experiments on seven soils, the concentrations of Cu, Cd, Ni and Zn in the dissolved fraction of soils increased up to 100-fold at the high application rates, but increased less than 1.5-fold below the critical micelle concentration. Dissolved metal concentrations were less than 20% affected by surfactants in long-term incubations (70 days) up to the largest dose of 200 mg C kg−1 soil. Leaching soil columns with A22 (100–1000 mg C L−1) under unsaturated conditions increased trace metal concentrations in the leachates 2–4 fold over the control. Correlation analysis and speciation modelling showed that the increased solubility of metals upon surfactant application was more related to the solubilisation of soil organic matter from soil than to complexation of the metals with the surfactant. Organic matter from soil was solubilised in response to a decrease of solution Ca2+ as a result of Ca–surfactant precipitation. At environmentally relevant concentrations, surfactant application is unlikely to have a significant effect on trace metal mobility.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights►Anionic surfactants increase metal mobility by solubilising soil organic matter. ► Metal complexation with surfactants is relevant only at elevated surfactant doses. ► Surfactants have little effect on metal mobility at environmentally relevant doses.