Phytoextraction Potential of Arsenic by Castor Bean In Nutrient Solution.

Phytoextraction is a remediation technique that consists in using plants to remove contaminants from soils and water. Castor bean is a plant well adapted to high metal content environments and has been recently recognized as an attractive potential crop for biodiesel production. This study evaluated arsenic (As) accumulation in Castor bean (Ricinus communis cv. Guarany) grown in nutrient solution in order to assess the plant’s potential for metal phytoextraction. Castor bean plants were grown under greenhouse conditions in pots containing Hoagland and Arnon’s nutrient solution amended with increasing doses of As (0, 10, 50, 100, 250, 500 and 5000 µg L^-1) in a completely randomized design, with four replications. Shoot and roots dry matter production as well as arsenic and nutrient tissue concentrations were measured at the end of the experiment. Increasing concentrations of arsenic in nutrient solution decreased plant’s root and shoot dry matter production, but did cause severe symptoms of phytotoxicity in castor bean. Arsenic concentrations were greater in roots than in shoot tissue. Addition of increasing doses of As to hydroponics solution did not interfere with plant nutrients accumulation. Castor bean did not present characteristics of a phytoextracting plant, but could be used in phytoestabilization of As-contaminated areas.