Rare earth elements (lanthanides) assessment in rocky shore organisms and surface sediment along Peninsular Malaysia coastal waters

Abstract

This study emphases on the assessment of REEs in rocky shore ecosystem along Peninsular Malaysia coastal waters, describing their partitioning between surface sediment and selected body parts of Saccostrea cucullata, Thais clavigera and Nerita chameleon, and deliberating on interspecies, inter-tissue and interspatial variability. Samples was digested using Teflon Bomb technique and concentrations of 14 naturally occurring REEs were measured using ICP-MS technique, along with selected trace metals for additional data. The REEs fractionation patterns normalized to chondrite or shale were remarkably similar, indicating a common source of the REEs for the whole region, however, mean concentration suggested that east Peninsular Malaysia provides higher REEs compared to west peninsula area. Consistent REEs abundance patterns were found in all samples, with enrichment of LREEs over HREEs, which implies that REEs are transported as a coherent group through aquatic ecosystems. There are dissimilarities in the REEs abundance for each site, but they demonstrate similarities in their REEs distribution patterns, which propose that they are of parallel origins. The contaminant metals As, Mn, Cu, and Cd were significantly correlated with REEs (p<0.05 and p<0.01), consequently suggests that these metals are probably non-anthropogenic in origin as the REEs are geogenic in origin. Quantification of anomalies calculated using values normalized to chondrite, PAAS and NASC data presented ratios higher than unity for Ce and ratios lower than unity for Eu in all sites. Filter feeder S. cucullata is considered to be highly potential as a bioindicator for REEs, undoubtedly due to its feeding behaviour that is much related to particulates as REEs sources. Consistent chondrite-normalized pattern strongly suggests that the REEs accumulated by S. cucullata, T. clavigera and N. chameleon are derived mostly from indigenous rocks. Results showed that the values are considerably below the safety limit, with the exception of Ce and Nd in the soft tissue of S. cucullata. With regards to sediment, comparative analysis resolved that the concentration of surface sediment in this study is very low compared to limit sets.