Accumulation patterns and species-specific characteristics of yttrium and rare earth elements (YREEs) in biological matrices from Maluan Bay, China: Implications for biomonitoring

The critical usage of rare earth elements (REEs) in a variety of industrial applications has increased their release to the environment as emerging contaminants, while little is known about the fate and transport of REEs in coastal aquatic biota. In the present study, seven common species were collected and the concentrations of 15 naturally occurring REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) were determined. Significant differences in total REEs concentrations were found among species even in the same taxa or phylum, suggesting that REEs bioaccumulation patterns appeared to be species- and element-dependent even in the same taxa or phylum, but with limited potential for bio-magnification based on the nitrogen isotope signatures (delta N-15). Except for occasional anomalies for redox-sensitive elements of Ce and Eu, the abundance patterns of REEs normalized to chondrite revealed similar REE distribution trends, indicating a common source of REEs in all samples. Additionally, the abundances of light REEs (from La to Eu) were much higher than those of heavy REEs (from Gd to Lu and Y), demonstrating the fractionation between the light and heavy REEs. Furthermore, REEs concentrations in molluscs were notably higher than other species, implying their potential as bio-indicators of REEs due to the habitat and specific feeding behavior. Overall, this is not only the first study to focus on distribution levels, accumulation characteristics, geochemical and fractionation patterns of REEs in coastal species from identical area, but quantifying and tracing REE behavior will contribute to better evaluating the possible environmental impacts of REEs enrichment for future biomonitoring research.