Cadmium accumulation by Phragmites australis and Iris pseudacorus from stormwater in floating treatment wetlands microcosms: Insights into plant tolerance and utility for phytoremediation

Abstract

Environmentally sustainable remediation is needed to protect freshwater resources which are deteriorating due to severe industrial, mining, and agricultural activities. Treatment by floating wetlands could be a sustainable solution to remediate water bodies. The study aimed to examine the effects of Cd on Phragmites australis and Iris pseudacorus growth (height, biomass, root length and chlorophyll contents), anatomy, Cd accumulation in their biomass and their ability to remove Cd, N and P. Seedlings of both plants were grown in a greenhouse for 50 days in artificially prepared stormwater amended with Cd, N, and P. The treatments were: control (Cd _0), Cd_1, Cd_2, and Cd_4 mg L−1. N and P contents were 4 mg L−1 and 1.8 mg L−1, respectively. In the case of P. australis, the maximum plant height, root length, and total dry biomass production was increased in medium dose (Cd_2) treatment while the chlorophyll index (CCI) increased in high dose (Cd_4) treatment as compared to all treatments. For I. pseudacorus, the maximum plant height and total dry biomass production, root length and CCI values were improved in low dose (Cd_1) and high dose (Cd_4) treatments, respectively among all treatments. Results showed that P. australis accumulated 10.94–1821.59 μg · (0.05 m2)−1 in roots and 2.45–334.65 μg · (0.05 m2)−1 in shoots under Cd_0, Cd_1 and Cd_4 treatments. I. pseudacorus accumulated the highest Cd in roots up to 5.84–4900 μg · (0.05 m2)−1 and 3.40–609 μg · (0.05 m2)−1 in shoots under Cd_0, Cd_1 and Cd_4 treatments. The translocation factor was observed as <1 and the bioconcentration factor >1 for both species, which indicates their phytostabilization potential. Results demonstrate that P. australis and I. pseudacorus are suitable for use in floating wetlands to remediate contaminated sites.