Phytoremediation potential of sweet flag (Acorus calamus L.), an emergent macrophyte, to remove inorganic arsenic from water

Abstract

In this study, the emergent macrophyte sweet flag (Acorus calamus L.) was used to remove different concentrations (200, 500, and 1,000 µg L‒1) of arsenate [As(V)] and arsenite [As(III)] from water. The removal efficiencies of As(V) and As(III) reached more than 95%. As(III) could be removed by A. calamus L. more efficiently than As(V). In both As(V)- and As(III)-exposed A. calamus L., the arsenic contents were much higher in the root than in the stem and leaf. The translocation factors of As(V) and As(III) were no more than 0.152. Both As(V) and As(III) were found in the whole plant, whereas dimethylarsinic acid (DMA, 0.06‒0.13 mg kg‒1) was only present in the aboveground part (leaf). As(V) was the main species in the As(V)-exposed plants (45.86%‒70.21%). As(III) was the main species in the stem and leaf of As(III)-exposed plants (55.76%‒85.52%), while As(V) was still dominant in the root. A. calamus L. could keep its green leaves during the 31 days of inorganic arsenic (iAs) exposure. However, As(V) had a little inhibitory effect on height growth, and As(III) could slightly inhibit the weight gain. The concentrations of malondialdehyde (MDA) and hydrogen peroxide (H2O2), as well as the activity of catalase (CAT) were significantly higher in the root than those in the stem and leaf. The oxidative stress response of A. calamus L. to As(III) was more than that to As(V). Our findings indicated that A. calamus L. was regarded as a promising material for the removal of iAs.