Negligible effect of potentially toxic elements and rare earth elements on mercury removal from contaminated waters by green, brown and red living marine macroalgae

Mercury (Hg) removal by six different living marine macroalgae, namely, Ulva intestinalis, Ulva lactuca, Fucus spiralis, Fucus vesiculosus, Gracilaria sp., and Osmundea pinnatifida was investigated in mono and multi-contamination scenarios. All macroalgae were tested under the same experimental conditions, evaluating the competition effects with all elements at the same initial molar concentration of 1 mu mol dm(-3). The presence of the main potentially toxic elements (Cd, Cr, Cu, Ni, and Pb) and rare earth elements (La, Ce, Pr, Nd, Eu, Gd, Tb, and Y) has not affected the removal of Hg. Characterizations of the macroalgae by FTIR before and after the biosorption/bioaccumulation assays suggest that Hg wasmainly linked to sulfur-functional groups, while the removal of other elementswas relatedwith other functional groups. Themechanisms involved point to biosorption of Hg on themacroalgae surface followed by possible incorporation of thismetal into themacroalgae bymetabolically active processes. Globally, the green macroalgae (Ulva intestinalis, Ulva lactuca) showed the best performances for Hg, potential toxic elements and rare earth elements removal from synthetic seawater spiked with 1 mu mol dm(-3) of each element, at room temperature and pH 8.5. (C) 2020 Elsevier B.V. All rights reserved.