Interspecific Variability in Growth Characteristics and Phytoremediation of Cu by Free-Floating Azolla Macrophytes

Muhammad Shahbaz Akhtar (), Sohaib Aslam, Allah Ditta (), Bedur Faleh A. Albalawi, Yoko Oki and Yoshitaka Nakashima
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Muhammad Shahbaz Akhtar: Department of Environmental Sciences, Forman Christian College University, Lahore 54600, Pakistan
Sohaib Aslam: Department of Environmental Sciences, Forman Christian College University, Lahore 54600, Pakistan
Allah Ditta: Department of Environmental Sciences, Shaheed Benazir Bhutto University, Sheringal, Dir (U) 18000, Pakistan
Bedur Faleh A. Albalawi: Department of Biology, University of Tabuk, Tabuk 47512, Saudi Arabia
Yoko Oki: Department of Environmental Management Engineering, Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan
Yoshitaka Nakashima: Department of Environmental Management Engineering, Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan

Sustainability, 2022, vol. 15, issue 1, 1-14

Abstract: The phytoremediation potential of aquatic plants, particularly for Cu, is scarcely reported in the pertinent literature. In this regard, differential growth behavior and phytoaccumulation ability of three free-floating Azolla species ( A. japonica , A. pinnata , and A. hybrid ) were evaluated in a climatically controlled (a temperature of 25/20 °C, light/dark 16/8 h, a light intensity of 60 µmol m −2 s −1 , and a relative humidity of 65%) microcosm study. Azolla plants were exposed to solutions having three Cu concentrations (0, 3, and 6 mg L −1 ) under two incubation periods (4 and 8 days). Different Cu treatments significantly reduced Azolla biomass during both incubation periods and A. pinnata was the most sensitive species. Azolla plants grown in aqueous solutions showed substantial variations in Cu removal capacity. Higher bioconcentration values displayed by Azolla plants indicated that these plants can be deployed as potential plants for Cu removal from Cu contaminated water. Nevertheless, the plants exposed to higher Cu concentrations displayed color changes and root detachment due to Cu phytotoxic effects which may also ultimately lead to plant death. Significant correlations between Cu removed from the aqueous solutions and Cu contents of plant biomass indicated that Cu phytoremediation by Azolla plants was due to the phytoaccumulation mechanism because the removed Cu from aqueous solutions was accumulated in plant biomass. Introduced Azolla species, i.e., A. hybrid , displayed comparable Cu removal efficiency with naturally grown Azolla species, i.e., A. japonica and A. pinnata . Tested Azolla species proved to be suitable candidates to remediate Cu contaminated water and can be deployed for phytoremediation.

Keywords: Azolla biomass; bioconcentration factor; Cu removal efficiency; Cu toxicity; translocation factor (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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