Comparative analysis of trace and macro-element bioaccumulation in four free-floating macrophytes in area contaminated by copper smelter

Effectiveness of four free-floating macrophytes, Lemna minor, Lemna trisulca, Salvinia natans, and Azolla filiculoides, at accumulation of elements from polluted water and their usefulness in phytoremediation was determined. Concentrations of 14 elements were analyzed in plants and water from river affected by smelting industry. Under the same environmental conditions bioaccumulation ability of closely related species differed. The duckweed species contained more K, Mg, and Na than ferns; L. trisulca had higher concentrations of Co, Ni, and Zn (18.4, 13.0, 158 mg kg(-1), respectively) than L. minor. S. natans characterized with the highest As, Cr, and Fe contents (27.1, 10.4, 15,475 mgkg(-1), respectively). The overall bioaccumulation capability (metal accumulation index [MAI]) was ordered as follows: L. trisulca (2.33) > S. natans (1.91) > L. minor (1.50). All species studied were found to be accumulators of several metal(loid)s but L. trisulca distinguished by the highest bioaccumulation for Cd, Co, Cu, Mg, Na, Pb, and Zn, S. natans for As, Cr, Fe, Mn, and Ni, while L. minor for alkali cations. S. natans and both Lemna species may find application in phytoextraction, with L. trisulca as the best choice. A. filiculoides showed lower concentrations of trace metal(loid) than S. natans and L. trisulca. Novelty statement This is the first study that comprehensively compares Salvinia natans, Lemna minor, Lemna trisulca, and Azolla filiculoides growing in the field; industrially affected conditions in respect of elements contents, water-plant transfer, and bioaccumulation using statistical analyses and indexes and their suitability for phytoremediation was considered. Secondary aim of the study was to fill the gap in research on the impact of copper smelters on aquatic ecosystems. Although the manuscript describes a case study performed near copper smelter in Poland, due to the novel results and cosmopolitan distribution of the species and significant world-wide impact of industry on the environment the results may be interested to broad publicity and find substantial application.