Interactive effects of chromate and arsenate on their uptake and speciation in Pteris ensiformis

Abstract

Arsenate (AsV) and chromate (CrVI) inhibit each other’s uptake and translocation in As-hyperaccumulator Pteris vittata. In the present study, we extended the research to As-sensitive plant Pteris ensiformis to better understand the mechanism of their interactions. Plants were exposed to 0, 0.75 or 7.5 mg L−1 AsV and 0, 0.52, or 5.2 mg L−1 CrVI for 7 d in hydroponics. Arsenic and Cr speciation were determined in nutrient solutions and plant biomass. P. ensiformis accumulated high levels of As and Cr in the rhizomes and roots with low levels in the fronds. However, P. ensiformis was much more effective in taking up Cr than As, as much more Cr was accumulated in the roots (306–6015 vs. 87–642 mg kg−1). AsV and CrVI increased each other’s uptake in the rhizomes and roots when co-present. The AsV and CrVI taken up by P. ensiformis were reduced to arsenite (AsIII) and chromite (CrIII), possibly serving as detoxification mechanism. Uptake of As and Cr induced oxidative stress as indicated by increased lipid peroxidation and electrical conductivity. Arsenic and Cr increased each other’s uptake by P. ensiformis.