CONICET | Buscador de Institutos y Recursos Humanos

In the nature, the Cr exists in two stable oxidation states: trivalent, Cr(III) and hexavalent, Cr(VI). Both forms are present in aquatic systems differing in their chemical properties, mobility and toxicity. Chromium toxicity upon depends of its concentration and bioavailability, being this last dependent of both the solution pH and redox potential. Because its extreme toxicity, chromium must be remove from polluted aquatic systems to avoid deleterious environmental effects. Chromium removal by aquatic macrophytes has become in inexpensive and easily applicable method for water decontamination. In this work we analyzed the effect of Cr(VI) and pH on three physiological stress parameters: content of soluble (SP) and insoluble (IP) phenolics, accumulation of malondialdehyde (MDA) and plasma membrane damage (electrolyte leakage, EL) in S. minima and S. rotundifolia, exposed to 5 and 20 mg l-1 of K2Cr2O7 at pH 4.0, 6.0 and 7.6. Results show that studied parameters were differentially affected by both Cr(VI) and pH in both salvinia species. Plant responses also depend on analyzed organs (fronds or lacinias). SP accumulation profiles were different and pH-dependent in both species. IP decreased with increasing pH, but increased in presence of Cr(VI). EL and MDA, also showed differential results according to metal concentration and pH value, being lacinias the most sensitive organ for both species. However, visual damage was only observed in S. minima fronds. Additive or synergic effects between metal and pH value seem to be occur in both salvinia species. Evaluated parameters enhance the knowledge on the performance of salvinia species to adverse environmental conditions which can constrain the sustainability of phytoremediation processes under a changing pH scenario.