Heavy metal contents and rare earth element patterns in dried edible seaweed from Japan market

Abstract

The analysis of rare earth elements in food products has been neglected even though rare earth elements are valued as fingerprints of samples in the earth sciences. In this study, we analyzed heavy metal elements and rare earth elements in seaweed food products commercially available in Japan (80 samples of cultivated seaweed from various regions of Japan and 20 samples of imported seaweed from Korea). The distinction between Japanese and Korean products was made for cadmium and thorium, which can be distinguished next to threshold values of 0.5 ppm and 3.3 ppm, respectively, but not between regions of origin within Japan. Among the analytical values of rare earth elements, anomalous values of europium were found to reflect the geology of the junior locality and are helpful for the classification of the locality of origin for Ariake Sea and Seto Inland Sea, Japan's two major seaweed production areas and also made-in-Korea. This study suggests that the analysis of rare earth elements in foods is beneficial for provenance traceability.