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.

Acknowledgements

The authors acknowledge the service of the Spectrometry and Chromatography core facility at A.O. Kovalevsky Institute of Biology of the Southern Seas of the Russian Academy of Sciences (RAS) for carrying out the ICP-MS analysis. The authors are grateful to anonymous reviewers for the valuable suggestions aimed to help improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary information

The following supplementary material is accessible via the Supplementary Content tab on the article’s online page at https://doi.org/10.1080/09670262.2021.2016985

Supplementary table S1. Results of the permutational multivariate analysis of variance (PERMANOVA) with three individual factors (Species, Location, Age) affecting the REE contents in Cystoseira spp. branchlets of five age groups from two locations

Supplementary table S2. Results of the permutational analysis of multivariate dispersions (PERMDISP) with three factors (Location, Species, Age) affecting the REE contents in Cystoseira spp. branchlets of five age groups from two locations.

Supplementary table S3. Results of PERMANOVA and PERMDISP applied to the rare earth element contents in the sediments with Location as the grouping term.

Supplementary table S4. Results of pairwise PERMANOVA and PERMDISP applied to the rare earth element contents in the seaweed branchlets with Location and Species as the grouping terms.

Supplementary fig. S1. Dendrogram of group-averaged logarithm-transformed concentrations of REE in Cystoseira barbataand C. crinita.

Supplementary fig. S2. Graphical matrices of correlation among mean contents of several selected elements (the variable is age groups for both Cystoseira species at both stations) based on (a) Pearson’s coefficient r and (b) Spearman’s coefficient ρ. The significant correlations (p < 0.05) are boxed.

Supplementary fig. S3. Age-averaged contents of all REE in Cystoseira spp. branchlets from the two stations (legend) against REE contents in sediments. The power-law correlations and the corresponding R² coefficients are shown in the legend.

Supplementary fig. S4. Age-averaged contents of all REE in Cystoseira spp. branchlets from the two stations (legend) against REE concentration in seawater. The power-law correlations and the corresponding R² coefficients are shown in the legend.

Additional information

Funding

This work has received financial support within the state assignments #121030300149-0 and #121041500203-3 from A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS and partially were supported by the Russian Science Foundation (grant 18-16-00001 for A. Prazukin, the data analysis and editing manuscript). The authors are grateful to anonymous reviewers for the helpful suggestions for improving the manuscript.