Changes in metal fractionation in the rhizosphere of the Ni hyperaccumulator Alyssum serpyllifolium subsp. lusitanicum

摘要

This study determined root-induced changes in soil physicochemical properties and metal (Co, Cr, Ni) availability in three populations of the Ni hyperaccumulator, Alyssum serpyllifolium, and the non hyperaccumulator Dactylis glomerata, growing in two geographical regions of the NW Iberian Peninsula. Soil pH and CEC were significantly increased at the rhizosphere, and this was most pronounced in Portuguese populations of the hyperaccumulator. Significant changes in metal distribution were found at the rhizosphere of the hyperaccumulator but not in that of Dactylis: residual Ni decreased while reducible (Ni) and oxidisable (Co/Ni) fractions increased. Results reinforce the possible replenishment of Ni by hyperaccumulators through their root activities.