Rare earth elements in the red, brown, green algae and the seagrass from Kazachya Bay (Crimea, Black Sea)

Abstract

The present study is focused on the first ever quantification of rare earth elements (REE) in four mass plants of the Black Sea coast of Crimea: the brown alga Gongolaria barbata, the green alga Ulva rigida, the red alga Ceramium ciliatum, and the seagrass Zostera noltei using inductively coupled plasma mass spectrometry. The REE contents in the macrophytes were found to be one to two orders of magnitude lower than in the sediments. In the plants, three groups of REE with similar levels have been identified. The first group included the most abundant elements Sc, Y, La and Ce; the second group consisted of Pr and Nd with the intermediate contents; and the third group contained the elements with the lowest contents: Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. The contribution of light REE (Sc, Y, La, Ce, Pr, Nd) to the total REE content in the plants was 91–96%. The highest REE levels were found in the red alga and seagrass rhizomes. Higher translocation factors of Sc, Pr, La, Ce and Tb between seagrass rhizomes and leaves were noted. In terms of the REE content decrease, the marine plants are arranged in the following order: seagrass rhizomes > red alga > brown alga > seagrass leaves > green alga. Brown algae attached to the rocky seabed are widespread in the upper sublittoral, have a long lifespan, and accumulate relatively high amounts of REE. Therefore, they can be used as effective bioindicators of REE pollution in the marine environment.