The role of organic matter in surfactant-aided trace metal solubilisation in soil

The ability of surfactants to solubilize organic and inorganic pollutants from soils has been extensively discussed in the literature. However there is a lack of assessment on the effects of surfactants at environmentally relevant concentrations or after long-term applications. Moreover, surfactant-aided solubilisation of trace metals in soils is conventionally related to their micellar and chelant properties, although solubilisation of soil organic matter by surfactants appears as a major mechanism. Four soils were daily irrigated at field capacity for one month with aqueous solutions of two commercial anionic surfactants. Subsets of the soils were amended with organic materials prior to surfactant application. After one month, soil solution was extracted for each treatment and analyzed for total metal and organic carbon content. Speciation analysis was performed with WHAM VI. The surfactants assayed increased trace metal solubility in non-amended soils, primarily through solubilisation of soil organic matter, while application of surfactants on amended soils decreased metal solubilisation, most likely by preventing solubilisation of indigenous soil organic matter.status: publishe