Phytoremediation for Removal of Inorganic Arsenic in Water by an Emergent Macrophyte: A Case Study on Sweet Flag (Acorus calamus L.)

Arsenic in drinking water threatens public health worldwide. Phytoremediation has brought new vitality to solve this problem. The aim of this work was to study the role of emergent macrophyte sweet flag (Acorus calamus L.) in phytoremediation of arsenate [As(V)] and arsenite [As(III)] from polluted water. For that, the methods of analytic chemistry and physiology were used. The results showed that As(III) could be removed by A. calamus more efficiently than As(V). The removal efficiencies of As(V) and As(III) both reached more than 95%. In As(V)- and As(III)-exposed A. calamus, the arsenic contents were much higher in root than in 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. As(V) was the main species in the As(V)-exposed plants (45.86-70.21%). As(III) was the main species in stem and leaf of As(III)-exposed plants (55.76-85.52%), while As(V) was still dominant in root. A. calamus could keep its green leaves during the 31 days of inorganic arsenic (iAs) exposure. However, iAs had a little inhibitory effect on biomass accumulation, and high-concentration iAs was beneficial to promote root growth. The concentrations of malondialdehyde (MDA) and hydrogen peroxide (H2O2), as well as the activity of catalase (CAT) were significantly higher in root than those in stem and leaf. The oxidative stress response of A. calamus to As(III) was more than that to As(V). The findings of this study indicated that A. calamus was regarded as a promising material for the phytoremediation of arsenic from water.