Hexavalent chromium reduction, uptake and oxidative biomarkers in Halimione portulacoides

Abstract

The in situ reduction of Cr (VI) to its less toxic form Cr (III) may be a useful detoxification mechanism for phytoremediation. Using a hydroponics mesocosmos approach, we evaluated the ability of Halimione portulacoides to reduce and uptake Cr (VI) and its anti-oxidative feedback and biomarkers. It was found that this specie can, not only reduce large amounts of Cr (VI) in the external medium, but also withdrawn and accumulate this element in its roots and aboveground organs. Both these mechanisms were found to be dose dependent. Jointly with this phytoremediative potential the oxidative feedback was also assessed. Chromium uptake had its major implications on the chlorophyll content and flavonoid content, with potential consequences in the photosynthetic and photo-protective mechanisms. Although the high Cr root accumulation in H. portulacoides, there were no inactivation of the enzymatic defenses, allowing a continuous defense against reactive oxygen species. In fact, GPX and specially SOD revealed to be an excellent dose-related biomarker of Cr induced stress. All these aspects make this specie suitable for Cr (VI) phytoremediation processes, either by phytoextraction or by reduction of Cr (VI) to Cr (III) and also for monitoring programs using SOD and GPX as biomarkers of Cr environmental contamination.