Comportamento de espécies herbáceas em misturas de solo com diferentes graus de contaminação com metais pesados

Abstract

O objetivo deste trabalho foi avaliar, em casa de vegetação, o comportamento de espécies herbáceas em relação ao excesso de Cd e Zn no solo. O gradiente de contaminação foi estabelecido a partir de mistura de solo contaminado com solo sem contaminação em diferentes proporções. As sementes foram semeadas em tubetes contendo 250 mL de solo, e após 90 dias as plantas foram colhidas e avaliadas. A maioria das espécies apresentou redução no crescimento com aumento da contaminação do solo e elevadas concentrações de Cd e Zn na matéria seca da parte aérea (MSPA), na mistura com 15% de solo contaminado. A espécie Pffafia sp. mostrou-se tolerante à contaminação, crescendo em misturas de solo contendo até 90 mg kg-1 de Cd e 1.450 mg kg-1 de zinco. Além disso, apresentou concentração superior a 100 mg kg-1 de Cd na MSPA, sendo considerada hiperacumuladora desse metal. Sida glaziovii, Bidens pilosa, Rhynchelytrum repens, Cenchrus echinatus e Nicandra physaloides, por sua vez, foram severamente afetadas pela contaminação, ao contrário de Trifolium repens, Euchlaena mexicana, Cynodon dactylon, Avena strigosa, Cenchrus ciliares e Cyperus sp. que apresentaram crescimento satisfatório. As espécies avaliadas mostram-se promissoras para estudos adicionais sobre a reabilitação de áreas contaminadas com metais pesados.

Cd-tolerance markers of Pfaffia glomerata (Spreng.) Pedersen plants: anatomical and physiological features

“…In conclusion, our results demonstrated that Pfaffia glomerata has great potential for use in Cd-phytoextraction programs, being a Cdhyperaccumulator species, as previous proposed by Carneiro et al (2002). The high Cd-tolerance of this species is closely related to anatomical and physiological features, including endodermal thickness, stomatal size and number, root SOD and GPX activities, and leaf GPX and CAT activities can serve as Cd-tolerance markers for this species.…”

“…The shoot metal concentrations seen in Pfaffia glomerata classified the species as a Cd-hyperaccumulator, as previously reported by Carneiro et al (2002). Although the BCF is more important than shoot concentrations per se when evaluating the phytoremediation potential of a given species (Zhao et al, 2003).…”

“…The solutions were continuously aerated and renewed weekly. Cd concentrations used in this work were chosen based on Carneiro et al (2002). The pH of the medium was checked and adjusted on a daily basis to 5.5±0.1.…”

“…Although native vegetation types growing on naturally mineralized or metal-contaminated sites have been described in Brazil, relatively few potential phytoremediator species were also identified (Ginocchio and Baker, 2004). Carneiro et al (2002) reported high growth rates and apparent tolerance of the species of genus Pfaffia to soils contaminated with Cd and Zn (90 and 1,450 mg kg -1 respectively), and Skrebsky et al (2008), Calgaroto et al (2010), and Gupta et al (2011) demonstrated reasonable degrees of Cd, Hg, and Pb tolerances in Pfaffia glomerata (Spreng.) Pedersen.…”

“…Therefore, the present study evaluated Cd-tolerance at both physiological and anatomical levels in Pfaffia glomerata seedlings grown under increasing Cd concentrations in nutrient solution, and Cd-tolerance markers were established. We also investigated Cd uptake and distribution in this plant, and its classification as a Cd-hyperaccumulator species (Carneiro et al, 2002) was revised.…”