Influence of surfactants on the Cu phytoremediation potential of a salt marsh plant

To assess the possible effect that surfactants commonly found in the aquatic environment may have on the remediation potential of the salt marsh plant Halimione portulacoides, a non-ionic (Triton X-100) and an anionic (sodium dodecyl sulfate, SDS) surfactants were used. Experiments were carried out in the laboratory, either in hydroponics (sediment elutriate) or in sediment soaked in elutriate, using sediment and water from an estuarine salt marsh (Cávado River, NW Portugal). Groups of H. portulacoides (grown in a greenhouse) were exposed for 6 d to media with 0.16 mM added Cu(II) in the absence and in the presence of each one of the two selected surfactants, at concentrations lower than the respective micellar critical concentration. Cu was determined in solutions, sediments and in different plant tissues before and after experiments. Plant photosynthetic efficiency did not indicate deletory effects of the exposure to the added pollutants. The non-ionic surfactant Triton X-100 and, to a lesser extent, the anionic surfactant SDS too, favored Cu accumulation in the plant roots but not Cu translocation, indicating that surfactants may favor Cu adsorption to the roots (phytostabilization). On the other hand, both surfactants favored Cu solubility from the sediment. Therefore, the presence of surfactants, which are frequently found in estuarine areas, as a result of urban and industrial effluent discharges, may condition metal distribution in those environments.