Rare earth elements in brown algae of the genus Cystoseira (Phaeophyceae) (Black Sea)

Abstract Rare earth metals are widely used in various technologies, and their environmental impact needs to be assessed. Brown algae are recognized bioindicators of xenobiotic pollution in coastal marine areas, so we studied the rare earth element contents in short-lived branchlets of the two most abundant species of Cystoseira (C. barbata and C. crinita) on Black Sea coasts. The abundance of rare earth elements including scandium (Sc), yttrium (Y), lanthanum (La) and 14 lanthanides in the algae, seawater and sediments were determined using inductively coupled plasma mass spectrometry. The average contents of the prevalent elements in the algae decreased in the following order: Sc ≥ La > Europium (Eu) > Y > Neodymium (Nd) > Cerium (Ce). The factors affecting rare earth element content were age > locality > species of the alga. Most of the rare earth metals reached their maximum levels in branchlets > 5 month old, presumably associated with biosorption processes, whereas others (Eu, Terbium (Tb), Lutetium (Lu)) were most concentrated in 2–5 month old branchlets. In contrast to existing reports on the possible use of brown seaweeds for monitoring rare earth elements in coastal waters, the suitability of Cystoseira spp. branchlets, which have a 7 month life cycle, for short-term rare earth contamination monitoring was not confirmed in this study. Highlights Cystoseira spp. branchlets accumulate many rare earth elements with age. The dominant elements in Cystoseira spp. are Sc ≥ La> Eu > Y > Nd > Ce. The most significant factors affecting rare earth element content are age > locality > species.